U.S. patent application number 16/795041 was filed with the patent office on 2020-08-27 for use of lifr or fgfr3 as a cell surface marker for isolating human cardiac ventricular progenitor cells.
The applicant listed for this patent is Procella Therapeutics AB. Invention is credited to Kenneth R. CHIEN, Xiaojun Lance LIAN.
Application Number | 20200268803 16/795041 |
Document ID | / |
Family ID | 1000004816233 |
Filed Date | 2020-08-27 |
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United States Patent
Application |
20200268803 |
Kind Code |
A1 |
CHIEN; Kenneth R. ; et
al. |
August 27, 2020 |
USE OF LIFR OR FGFR3 AS A CELL SURFACE MARKER FOR ISOLATING HUMAN
CARDIAC VENTRICULAR PROGENITOR CELLS
Abstract
The present invention provides LIFR and FGFR3 as cell surface
markers for isolating human cardiomyogenic ventricular progenitor
cells, in particular progenitor cells that preferentially
differentiate into cardiac ventricular muscle cells. Thus, the
invention provides human ventricular progenitor (HVP) cells. The
invention provides in vitro methods of the separation of Islet 1+
LIFR+ ventricular progenitor cells and/or Islet 1+/FGFR3+
ventricular progenitor cells and/or Islet 1+/LIFR+/FGFR3+
ventricular progenitor cells, and the large scale expansion and
propagation thereof. Large clonal populations of isolated LIFR+
and/or FGFR3+ ventricular progenitor cells are also provided.
Methods of in vivo use of LIFR+ and/or FGFR3+ ventricular
progenitor cells for cardiac repair or to improve cardiac function
are also provided. Methods of using the LIFR+ and/or FGFR3+
ventricular progenitor cells for cardiac toxicity screening of test
compounds are also provided.
Inventors: |
CHIEN; Kenneth R.;
(Cambridge, MA) ; LIAN; Xiaojun Lance; (State
College, PA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Procella Therapeutics AB |
Tullinge |
|
SE |
|
|
Family ID: |
1000004816233 |
Appl. No.: |
16/795041 |
Filed: |
February 19, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14984783 |
Dec 30, 2015 |
10596200 |
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16795041 |
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14832324 |
Aug 21, 2015 |
10597637 |
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14984783 |
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62194016 |
Jul 17, 2015 |
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62040892 |
Aug 22, 2014 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C12N 5/0657 20130101;
A61K 35/34 20130101; C12N 2506/45 20130101; C12N 2501/119 20130101;
C12N 2506/02 20130101; C12N 2501/415 20130101; G01N 33/5014
20130101; C12N 2513/00 20130101; C12N 2501/42 20130101; C12N
2501/235 20130101 |
International
Class: |
A61K 35/34 20060101
A61K035/34; G01N 33/50 20060101 G01N033/50; C12N 5/077 20060101
C12N005/077 |
Claims
1.-38. (canceled)
39. A method for isolating human cardiac ventricular progenitor
cells, the method comprising: 1) providing a culture of human
embryonic stem (ES) cells or induced pluripotent stem cells
(iPSCs); 2) at day 0, activating Wnt/.beta.-catenin signaling in
said culture from step 1; 3) at day 3-5, inhibiting
Wnt/.beta.-catenin signaling in said culture from step 2 to
generate human cardiac progenitor cells (CPCs); 4) on day 5, day 6
or day 7, contacting said human CPCs from step 3 with one or more
agents reactive with a cardiac progenitor marker selected from the
group consisting of PDGFRA, TNFSF9 and FZD4; 5) separating cardiac
progenitor marker positive cells from negative cells; and 6)
isolating the cardiac progenitor marker positive cells to thereby
isolate the human cardiac ventricular progenitor cells.
40. The method of claim 39, wherein at step 4) the human CPCs are
contacted with an antibody that binds the cardiac progenitor
marker.
41. The method of claim 39, wherein at step 4) the human CPCs are
contacted with a soluble ligand that binds the cardiac progenitor
marker.
42. The method of claim 39, wherein the cardiac progenitor marker
is PDGFRA.
43. The method of claim 42, wherein the human CPCs are contacted
with an anti-PDGFRA antibody.
44. The method of claim 39, wherein the cardiac progenitor marker
is TNFSF9.
45. The method of claim 44, wherein the human CPCs are contacted
with an anti-TNFSF9 antibody.
46. The method of claim 39, wherein the cardiac progenitor marker
is FZD4.
47. The method of claim 46, wherein the human CPCs are contacted
with an anti-FZD4 antibody.
48. The method of claim 39, wherein the cardiac progenitor marker+
cells are separated from negative cells by fluorescence activated
cell sorting or magnetic activated cell sorting.
49. The method of claim 39, wherein at step 1), a culture of human
ES cells is provided.
50. The method of claim 39, wherein at step 1), a culture of human
iPSCs is provided.
51. The method of claim 39, wherein Wnt/.beta.-catenin signaling is
activated in the CPCs by culture with a Gsk3 inhibitor.
52. The method of claim 39, wherein Wnt/.beta.-catenin signaling is
inhibited in the CPCs by culture with a Porcn inhibitor.
53. The method of claim 39, wherein step 4) is conducted on day
5.
54. The method of claim 39, wherein step 4) is conducted on day
6.
55. The method of claim 39, wherein step 4) is conducted on day
7.
56. The method of claim 39, wherein the human cardiac ventricular
progenitor cells are further differentiated such that they are
Myosin Light Chain 2v (MLC2v) positive.
57. The method of claim 39, which further comprises administering
the human cardiac ventricular progenitor cells directly into the
heart of a subject.
58. The method of claim 39, wherein the human cardiac ventricular
progenitor cells are administered directly into a ventricular
region of the heart of the subject.
59. The method of claim 39, which further comprises contacting the
human cardiac ventricular progenitor cells with a test compound and
measuring toxicity of the test compound for the cells, wherein
toxicity of the test compound for the cells indicates cardiac
toxicity of the test compound.
Description
RELATED APPLICATIONS
[0001] This application is a continuation of U.S. Ser. No.
14/984,783, filed on Dec. 30, 2015, which is a continuation in part
of U.S. Ser. No. 14/832,324, filed on Aug. 21, 2015, which claims
the benefit of the priority date of U.S. Provisional Application
No. 62/040,892, filed on Aug. 22, 2014, and U.S. Provisional
Application No. 62/194,016, filed on Jul. 17, 2015. The content of
these applications is hereby incorporated by reference in its
entirety.
BACKGROUND OF THE INVENTION
[0002] Heart failure, predominantly caused by myocardial
infarction, is the leading cause of death in both adults and
children worldwide and is increasing exponentially worldwide (Bui,
A. L. et al. (2011) Nat. Rev. Cardiol. 8:30-41). The disease is
primarily driven by the loss of ventricular muscle that occurs
during myocardial injury (Lin, Z. and Pu, W. T. (2014) Sci. Transl.
Med. 6:239rv1) and is compounded by the negligible ability of the
adult heart to mount a regenerative response (Bergmann, O. et al.
(2009) Science 324:98-102; Senyo, S. E. et al. (2013) Nature
493:433-436). Although heart transplantation can be curative, the
markedly limited availability of human heart organ donors has led
to a widespread unmet clinical need for a renewable source of pure,
mature and functional human ventricular muscle tissue (Segers, V.
F. M. and Lee, R. J. (2008) Nature 451:937-942; Spater, D. et al.
(2014) Development 141:4418-4431).
[0003] Human pluripotent stem cells (hPSCs) offer the potential to
generate large numbers of functional cardiomyocytes for potential
clinical restoration of function in damaged or diseased hearts.
Transplantation of stem cells into the heart to improve cardiac
function and/or to enrich and regenerate damaged myocardium has
been proposed (see e.g., U.S. Patent Publication 20040180043).
Combination therapy, in which adult stem cells are administered in
combination with treatment with growth factor proteins has also
been proposed (see e.g., U.S. Patent Publication 20050214260).
[0004] While cell transplantation into the heart offers a promising
approach for improving cardiac function and regenerating heart
tissue, the question of what type(s) of cells to transplant has
been the subject of much investigation. Types of cells investigated
for use in regenerating cardiac tissue include bone marrow cells
(see e.g., Orlic, D. et al. (2001) Nature 410:701-705; Stamm, C. et
al. (2003) Lancet 361:45-46; Perin, E. C. et al. (2003) Circulation
107:2294-2302), adult stem cells (see e.g., Jackson, K. A. et al.
(2001) J. Clin. Invest. 107:1395-1402), bone marrow-derived
mesenchymal stem cells (see e.g., Barbash, I. M. et al. (2003)
Circulation 108:863; Pettinger, M. F. and Martin, B. J. (2003)
Circ. Res. 95:9-20), bone marrow stromal cells (Bittira, B. et al.
(2003) Eur. J. Cardiothorac. Surg. 24:393-398), a combination of
mesenchymal stem cells and fetal cardiomyocytes (see e.g., Min, J.
Y. et al. (2002) Ann. Thorac. Surg. 74:1568-1575) and a combination
of bone marrow-derived mononuclear cells and bone marrow-derived
mesenchymal stem cells (see e.g., U.S. Patent Publication
20080038229). Dedifferentiation of adult mammalian cardiomyocytes
in vitro to generate cardiac stem cells for transplantation has
also been proposed (see e.g., U.S. Patent Publication
20100093089).
[0005] A significant advancement in the approach of cell
transplantation to improve cardiac function and regenerate heart
tissue was the identification and isolation of a family of
multipotent cardiac progenitor cells that are capable of giving
rise to cardiac myocytes, cardiac smooth muscle and cardiac
endothelial cells (Cai, C. L. et al. (2003) Dev. Cell. 5:877-889;
Moretti, A. et al. (2006) Cell 127:1151-1165; Bu, L. et al. (2009)
Nature 460:113-117; U.S. Patent Publication 20060246446). These
cardiac progenitor cells are characterized by the expression of the
LIM homeodomain transcription factor Islet 1 (Isl1) and thus are
referred to as Isl1+ cardiac progenitor cells. (Ibid). In contrast,
Isl1 is not expressed in differentiated cardiac cells. Additional
markers of the Isl1+ cardiac progenitor cells that arise later in
differentiation than Isl1 have been described and include Nkx2.5
and flk1 (see e.g., U.S. Patent Publication 20100166714).
[0006] The renewal and differentiation of Isl1+ cardiac progenitor
cells has been shown to be regulated by a Wnt/beta-catenin
signaling pathway (see e.g., Qyang, Y. et al. (2007) Cell Stem
Cell. 1:165-179; Kwon, C. et al. (2007) Proc. Natl. Acad. Sci. USA
104:10894-10899). This has led to the development of methods to
induce a pluripotent stem cell to enter the Isl1+ lineage and for
expansion of the Isl1+ population through modulation of Wnt
signaling (see e.g., Lian, X. et al. (2012) Proc. Natl. Acad. Sci.
USA 109:E1848-57; Lian, X. et al. (2013) Nat. Protoc. 8:162-175;
U.S. Patent Publication 20110033430; U.S. Patent Publication
20130189785).
[0007] While human pluripotent stem cells hold great promise, a
significant challenge has been the ability to move from simply
differentiation of diverse cardiac cells to forming a larger scale
pure 3D ventricular muscle tissue in vivo, which ultimately
requires vascularization, assembly and alignment of an
extracellular matrix, and maturation. Toward that end, a diverse
population of cardiac cells (atrial, ventricular, pacemaker) has
been coupled with artificial and decellurized matrices (Masumoto,
H. et al. (2014) Sci. Rep. 4:5716; Ott, H. C. et al. (2008) Nat.
Med. 14:213-221; Schaaf, S. et al. (2011) PLoS One 6:e26397),
vascular cells and conduits (Tulloch, N. L. et al. (2011) Circ.
Res. 109:47-59) and cocktails of microRNAs (Gama-Garvalho, M. et
al. (2014) Cells 3:996-1026) have been studies, but the goal
remains elusive.
[0008] While the identification of Isl1 as a marker of cardiac
progenitor cells was a significant advance, since Isl1 is an
intracellular protein it is not a suitable marker for use in
isolating large quantities of viable cells. Rather, a cell surface
marker(s) is still needed. Furthermore, Isl1 as a marker identifies
a population that can differentiate into multiple cell types within
the cardiac lineage, and thus there is still a need for markers
that identify cardiac progenitor cells that are biased toward a
particular cell type within the cardiac lineage, in particular for
progenitor cells that differentiate into ventricular cells.
Accordingly, there is still a great need in the art for additional
markers of cardiac progenitor cells, in particular cell-surface
markers of cardiac progenitor cells, that predominantly give rise
to cardiomyocytes and that would allow for rapid isolation and
large scale expansion of cardiomyogenic progenitor cells.
Furthermore, there is still a great need in the art for methods and
compositions for isolating cardiac ventricular progenitors, which
differentiate into ventricular muscle cells in vivo, thereby
allowing for transplantation of ventricular progenitors or
ventricular muscle cells in vivo to enhance cardiac function.
SUMMARY OF THE INVENTION
[0009] This invention describes the use of Leukemia Inhibitory
Factor Receptor (LIFR) or Fibroblast Growth Factor Receptor 3
(FGFR3) as a cell surface marker for isolating human cardiac
progenitor cells. Furthermore, these human cardiac progenitor cells
are biased toward the ventricular lineage such that they
differentiate predominantly into ventricular muscle cells both in
vitro and in vivo. That is, these cardiac progenitor cells can be
cultured under conditions in vitro such that they are biased toward
the ventricular lineage and thus are human ventricular progenitor
(HVP) cells. Moreover, when introduced into the ventricular region
of the heart in a subject, these progenitor cells differentiate
almost exclusively into ventricular muscle cells that function
according to their ventricular programming. In particular, the
human ventricular progenitor cells provided herein utilize a cell
autonomous pathway by which these cells can build a pure 3-D
vascularized, functional and mature ventricular cell wall in vivo
on the surface of normal murine kidney or heart, thereby allowing
for organ-on-organ in vivo tissue engineering.
[0010] Using Islet 1 (ISL1) as a marker, a scalable two-step
culture protocol for generating HVPs has been developed and cell
surface markers (LIFR/FGFR3) have been identified that allow the
generation and purification of billions of pure HVPs from human
pluripotent stem cells (hPSCs). These HVPs can also be identified
in the 4 week human fetal heart ventricular chambers.
[0011] Transplantation of the ventricular progenitor cells provided
herein produces a pure, functional and mature human ventricular
muscle organ of large size (e.g., twice the size of the murine
heart) that can generate force, respond to catecholamines, lose
automaticity, contain T tubules and display hypertrophic growth of
adult rod-shaped cells by 5 months post-transplantation. Thus,
human ventriculogenesis can be achieved via a cell autonomous
pathway driven by the purified ISL1/LIFR/FGFR3 human ventricular
progenitors provided herein. These HPVs provided herein allow for
new in vivo models of human cardiac disease in murine-human
chimeras and for the development of organ-on-organ regenerative
therapeutic strategies for cardiac disease.
[0012] This identification of a key cell surface marker of cardiac
ventricular progenitor cells allows for easy and rapid isolation of
the cells. Furthermore, determination of culture conditions for
expansion and ventricular lineage bias of the cells allows for the
preparation of large cultures (a billion or more cells) of a clonal
population of cardiac ventricular progenitor cells. These cells can
be used, for example, to improve function in a damaged heart in a
subject, particularly damage in the ventricular region. The
progenitor cells can be transplanted in vivo for differentiation
into ventricular cells in situ or, alternatively, a heart muscle
patch, comprising ventricular muscle cells, can be prepared in
vitro from the progenitors for subsequent transplantation in vivo.
The cells also can be used, for example, in in vitro toxicity
screening assays to evaluate the cardiac toxicity of test
compounds, as well as for biochemical studies to identify relevant
pathways used in cardiac maturation and differentiation.
[0013] Thus, the invention provides for the first time human
cardiac ventricular progenitor cells in purified form. The human
cardiac ventricular progenitors are capable of differentiation into
ventricular muscle cells in vitro and in vivo. These progenitor
cells can be expanded to large numbers of cells in vitro and when
transplanted into the ventricular region of the heart in vivo they
differentiate essentially exclusively into ventricular muscle
cells. Still further, the cells have the capacity to migrate in
vivo to different sites and, when transplanted in vivo the cells
does what they are programmed to do as a ventricular cell (as
opposed to a cardiac myocyte which simply contracts). Thus, the
ventricular progenitor cells can be grafted to native tissue to
enhance ventricular function and have the ability to call in
vasculature into the new ventricular tissue.
[0014] Using the RNA-seq technique combined with a robust cardiac
differentiation protocol, transcriptional expression at a
genome-scale level at different time points of hPSC differentiation
was performed. These experiments led to the identification of
Leukemia Inhibitory Factor Receptor (LIFR) and Fibroblast Growth
Factor Receptor 3 (FGFR3) as cell surface markers for Isl1+
cardiomyogenic progenitor cells derived from hPSCs. Co-expression
of Isl1 and LIFR, or Isl1 and FGFR3, on cardiomyogenic progenitor
cells in vitro was demonstrated. Still further, after
transplantation of purified human cardiomyogenic progenitor cells
into normal or injured hearts in mice, enriched human
cardiomyogenic progenitor cells gave rise to cTnT+ cardiomyocytes
demonstrating the cardiomyogenic nature of the progenitor cells. In
these in vivo transplantation studies, larger grafts were observed
in the injured hearts transplanted with the cardiomyogenic
progenitor cells, as compared to normal hearts, demonstrating the
capacity of the cardiomyogenic progenitor cells for cardiomyocyte
regeneration.
[0015] Still further, the RNA-seq experiments identified additional
potential surface markers, including the following markers for
mesoderm cells expressing brachyury: FZD10, CD48, CDID, CD8B,
IL15RA, TNFRSF1B, TNFSF13, ICOSLG, SEMA7A, SLC3A2, SDC1 and HLA-A;
and the following markers for cardiac mesoderm mesp1 positive
cells: CXCR4, ANPEP, ITGA5, TNFRSF9, FZD2, CDID, CD177, ACVRL1,
ICAM1, LICAM, NGFR, ABCG2, FZD7, TNFRSF13C and TNFRSF1B; and the
following markers for cardiac progenitor cells: PDGFRA, Jagged 1
(JAG1), TNFSF9 and Frizzled 4 (FZD4). Any of these additional
cardiac progenitor markers can be used in the methods of the
invention to isolate progenitors at different stages of
differentiation. In particular, the cardiac progenitor markers
PDGFRA, JAG1, TNFSF9 or FZD4 can be used in a similar manner to
LIFR and FGFR3, as described herein, for isolation of
cardiomyogenic progenitors.
[0016] Accordingly, in one aspect, the invention pertains to a
method for isolating human cardiac ventricular progenitor cells,
the method comprising:
[0017] contacting a culture of cells containing human cardiac
progenitor cells with one or more agents reactive with LIFR and/or
FGFR3; and
[0018] separating LIFR and/or FGFR3 reactive positive cells from
non-reactive cells to thereby isolate human cardiac ventricular
progenitor cells.
[0019] In one embodiment, the human cardiac progenitor cells are
contacted both with an agent reactive with LIFR and with an agent
reactive with FGFR3 to thereby separate LIFR and FGFR3 reactive
positive cells from non-reactive cells.
[0020] Preferably, the human cardiac progenitor cells are Islet 1+
human cardiac progenitor cells. In another embodiment, the culture
of cells is also contacted with an agent reactive with Islet 1; and
LIFR reactive/Islet 1 reactive positive cells, or FGFR3
reactive/Islet 1 reactive cells, are separated from non-reactive
cells to thereby isolate cardiac ventricular progenitor cells. The
culture of cells can be simultaneously contacted with the agent
reactive with LIFR and/or FGFR3 and the agent reactive with Islet
1. Alternatively, the culture of cells can be contacted with the
agent reactive with Islet 1 before contacting with the agent
reactive with LIFR and/or FGFR3. Alternatively, the culture of
cells can be contacted with the agent reactive with LIFR and/or
FGFR3 before contacting with the agent reactive with Islet 1. In
another embodiment, the human cardiac ventricular progenitor cells
are further cultured and differentiated such that they express the
ventricular marker MLC2v.
[0021] In another aspect, the invention pertains to a method for
isolating human cardiac ventricular progenitor cells, the method
comprising:
[0022] culturing human pluripotent stem cells under conditions that
generate cardiac progenitor cells to obtain a cultured cell
population;
[0023] contacting the cultured cell population with one or more
agents reactive with LIFR and/or FGFR3; and
[0024] separating LIFR and/or FGFR3 reactive positive cells from
non-reactive cells to thereby isolate human cardiac ventricular
progenitor cells.
In one embodiment, the human cardiac progenitor cells are contacted
both with an agent reactive with LIFR and with an agent reactive
with FGFR3 to thereby separate LIFR and FGFR3 reactive positive
cells from non-reactive cells.
[0025] In one embodiment, the culture of cells is also contacted
with an agent reactive with Islet 1; and LIFR reactive/Islet 1
reactive positive cells, or FGFR3 reactive/Islet 1 reactive
positive cells, are separated from non-reactive cells to thereby
isolate human cardiac ventricular progenitor cells. The culture of
cells can be simultaneously contacted with the agent(s) reactive
with LIFR and/or FGFR3 and the agent reactive with Islet 1.
Alternatively, the culture of cells can be contacted with the agent
reactive with Islet 1 before contacting with the agent(s) reactive
with LIFR and/or FGFR3. Alternatively, the culture of cells can be
contacted with the agent(s) reactive with LIFR and/or FGFR3 before
contacting with the agent reactive with Islet 1. In another
embodiment, the human cardiac ventricular progenitor cells are
further cultured and differentiated such that they express the
ventricular marker MLC2v.
[0026] In the methods for isolating human cardiac ventricular
progenitor cells, various types of agents that bind to LIFR or
FGFR3 can be used as the agent(s) reactive with LIFR or FGFR3. For
example, in one embodiment, the agent reactive with LIFR or FGFR3
is an anti-LIFR antibody or an anti-FGFR3 antibody, such as a
monoclonal antibody. In another embodiment, the agent reactive with
LIFR or FGFR3 is a soluble LIFR ligand or FGFR3 ligand, such as a
LIFR ligand fusion protein or a FGFR3 ligand fusion protein. For
example, the agent reactive with LIFR can comprise the LIFR ligand
leukemia inhibitor factor (LIF), such as a soluble LIF fusion
protein (e.g., a LIF/Ig fusion protein). Similarly, the agent
reactive with FGFR3 can comprise the FGFR3 ligand fibroblast growth
factor (FGF), such as a soluble FGF fusion protein (e.g., a FGF/Ig
fusion protein).
In the methods for isolating human cardiac ventricular progenitor
cells, various types of separation methods can be used to separate
LIFR and/or FGFR3 reactive positive cells (or LIFR/Islet 1 or
FGFR3/Islet 1 reactive positive cells) from non-reactive cells. For
example, in one embodiment, the reactive positive cells are
separated from the non-reactive cells by fluorescence activated
cell sorting (FACS). In another embodiment, the reactive positive
cells are separated from the non-reactive cells by magnetic
activated cells sorting (MACS).
[0027] In yet another aspect, the invention pertains to a method of
obtaining a clonal population of human cardiac ventricular
progenitor cells, the method comprising:
[0028] isolating a single LIFR+ and/or FGFR3+ human cardiac
ventricular progenitor cell; and
[0029] culturing the single LIFR+ and/or FGFR3+ human cardiac
ventricular progenitor cell under conditions such that the cell is
expanded to at least 1.times.10.sup.9 cells to thereby obtain a
clonal population of human cardiac ventricular progenitor
cells.
[0030] In one embodiment, the single LIFR+ and/or FGFR3+ human
cardiac ventricular progenitor cell is Islet 1 positive, Nkx2.5
negative and flk1 negative at the time of initial culture. The
single LIFR+ or FGFR3+ human cardiac ventricular progenitor cell
can be isolated by methods such as those described above (e.g.,
FACS or MACS). The single LIFR+ and/or FGFR3+ human cardiac
ventricular progenitor cell can be isolated using a reagent(s)
reactive with LIFR and/or FGFR3, such as those described above
(e.g., anti-LIFR antibodies, anti-FGFR3 antibodies, soluble LIFR
ligands or soluble FGFR3 ligands, such as ligand fusion proteins).
Upon further culture and differentiation, the clonal population of
human cardiac ventricular progenitor cells can express the
ventricular marker MLCV2.
[0031] In a preferred embodiment, the single LIFR+ and/or FGFR3+
human cardiac ventricular progenitor cell is cultured in vitro
under conditions such that the cell is biased toward ventricular
differentiation. For example, the single LIFR+ and/or FGFR3+ human
cardiac ventricular progenitor cell can be cultured in Cardiac
Progenitor Culture (CPC) medium (80% advanced DMEM/F12 supplemented
with 20% KnockOut Serum Replacement, 2.5 mM GlutaMax and 100
.mu.g/ml Vitamin C), which allows for differentiation of the cells
into ventricular cells expressing the MLC2v ventricular marker. In
various embodiments, the single LIFR+ and/or FGFR3+ human cardiac
ventricular progenitor cell is expanded to a clonal population of,
for example, at least 1.times.10.sup.9 cells, at least
2.times.10.sup.9 cells, at least 5.times.10.sup.9 cells or at least
10.times.10.sup.9 cells.
[0032] Accordingly in another aspect, the invention pertains to a
clonal population of isolated LIFR+ and/or FGFR3+ human cardiac
ventricular progenitor cells. In various embodiments, this clonal
population comprises, for example, at least 1.times.10.sup.9 cells,
at least 2.times.10.sup.9 cells, at least 5.times.10.sup.9 cells or
at least 10.times.10.sup.9 cells. In a preferred embodiment, this
clonal population comprises at least 1.times.10.sup.9 LIFR+ human
cardiac ventricular progenitor cells or at least 1.times.10.sup.9
FGFR3+ human cardiac ventricular progenitor cells.
[0033] In yet another aspect, the invention pertains to a method of
enhancing cardiac function in a subject using the LIFR+ and/or
FGFR3+ human cardiac ventricular progenitor cells described herein.
For example, in one embodiment, the invention provides a method of
enhancing cardiac function in a subject, the method comprising
administering a pharmaceutical composition comprising a clonal
population LIFR+ and/or FGFR3+ human cardiac ventricular progenitor
cells, such as a clonal population of at least at least
1.times.10.sup.9 cells, at least 2.times.10.sup.9 cells, at least
5.times.10.sup.9 cells or at least 10.times.10.sup.9 cells. In one
embodiment, the clonal population is administered directly into the
heart of the subject. For example, the clonal population can be
administered directly into a ventricular region of the heart of the
subject. In one embodiment, the pharmaceutical composition
administered to the subject comprises the clonal population
formulated onto a three dimensional matrix, such as a heart muscle
patch comprising ventricular muscle cells. The subject is one in
need of enhancement of cardiac function, for example someone who
has suffered a myocardial infarction or someone who has a
congenital heart disorder.
[0034] In yet another aspect, the invention pertains to a method
for generating human ventricular tissue comprising
[0035] transplanting LIFR+ and/or FGFR3+ human cardiac ventricular
progenitor cells into an organ of a non-human animal; and
[0036] allowing the progenitor cells to grow in vivo such that
human ventricular tissue is generated.
The non-human animal can be, for example, an immunodeficient mouse.
The organ can be, for example, the kidney (e.g., the cells are
transplanted under the kidney capsule) or the heart. In one
embodiment, the cells are transplanted at a time when one, two,
three, four or five of the following cell marker patterns are
present: (i) after peak of cardiac mesoderm formation; (ii) at time
of peak Islet-1 expression; (iii) before peak of NKX2.5 expression;
(iv) before peak expression of downstream genes MEF-2 and TBX-1;
and (v) before expression of differentiated contractile protein
genes. In one embodiment, the cells are transplanted between day 5
and day 7 (inclusive) of in vitro culture of human pluripotent stem
cells under conditions to generate human ventricular progenitor
cells. In another embodiment, the cells are transplanted on day 6
of in vitro culture of human pluripotent stem cells under
conditions to generate human ventricular progenitor cells. The
method can further include harvesting the human ventricular tissue
generated in the non-human animal.
[0037] In still another aspect of the invention, the human cardiac
ventricular progenitor cells described herein can be used in
screening assays to evaluate the cardiac toxicity of a test
compound. Accordingly, the invention provides a method of screening
for cardiac toxicity of test compound, the method comprising
[0038] providing LIFR+ and/or FGFR3+ cardiac ventricular progenitor
cells;
[0039] contacting the cells with the test compound; and
[0040] measuring toxicity of the test compound for the cells,
[0041] wherein toxicity of the test compound for the cells
indicates cardiac toxicity of the test compound. The toxicity of
the test compound for the cells can be measured, for example, by
assessing cell viability or other physiological parameters of the
cell.
[0042] Culturing methods for generating human ventricular
progenitor cells are also provided. For example, in one embodiment,
the invention pertains to a method of generating human ventricular
progenitors (HVPs) comprising: [0043] culturing human pluripotent
stems cells (hPSCs) in a medium comprising CHIR98014 such that
cells expressing cardiac mesodermal markers are generated, and
[0044] culturing the cells expressing cardiac mesodermal markers in
a medium comprising Wnt-C59 such that HVPs are generated.
[0045] Other features and advantages of the invention will be
apparent from the following detailed description and claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0046] FIG. 1 is a schematic diagram of an exemplary culturing
protocol for generating human Isl1+ cardiomyogenic progenitor cells
from human pluripotent stem cells (hPSCs).
[0047] FIG. 2 shows the results of Western blot analysis of protein
expression during cardiac differentiation of hPSCs, showing
expression of Isl1, Nkx2.5 and cTn1. GAPDH was used as a
control.
[0048] FIG. 3 shows the results of flow cytometry analysis of
cardiomyogenic progenitor cells, showing expression of Isl1 on
cells at day 6 of differentiation.
[0049] FIG. 4 shows the results of double staining flow cytometry
analysis of cardiomyogenic progenitor cells, showing coexpression
of Isl1 and Jag1 on cells at day 6 of differentiation.
[0050] FIG. 5 shows the results of Western blot analysis of protein
expression during cardiac differentiation of hPSCs, showing
expression of FZD4. GAPDH was used as a control.
[0051] FIG. 6 shows the results of double staining flow cytometry
analysis of cardiomyogenic progenitor cells, showing coexpression
of Isl1 and FZD4 on cells at day 5 of differentiation.
[0052] FIG. 7 is a schematic diagram of the generation of human
ventricular progenitor (HVP) cells, their ultimate differentiation
into ventricular myocytes, their antibody purification and their
use in transplantation.
[0053] FIGS. 8A-B is a schematic diagram of the transplantation of
HPVs into the renal capsule (FIG. 8A) or intra-myocardially (FIG.
8B) for organ-on-organ tissue engineering.
[0054] FIG. 9 shows the results of double staining flow cytometry
analysis of human ventricular progenitor (HVP) cells, showing
coexpression of Isl1 and LIFR on the cells.
[0055] FIGS. 10A-B show the results of flow cytometry analysis of
the expression of LIFR and FGFR3 on human ventricular progenitor
cells (FIG. 10B) as compared to undifferentiated embryonic stem
(ES) cells (FIG. 10A).
DETAILED DESCRIPTION OF THE INVENTION
[0056] The invention provides methods of isolating human
cardiomyogenic progenitor cells, in particular cells that are
biased to the ventricular lineage, as well as isolated clonal
populations of such progenitor cells, based on the discovery that
LIFR and FGFR3 are cell surface markers for cardiac ventricular
progenitor cells. In vitro and in vivo uses for these cardiac
ventricular progenitor cells are also provided.
[0057] In order that the present invention may be more readily
understood, certain terms are first defined. Additional definitions
are set forth throughout the detailed description.
[0058] As used herein, the terms "Leukemia Inhibitor Factor
Receptor", "LIF Receptor" and "LIFR" are used interchangeably to
refer to a protein known in the art that has been described in, for
example, Gearing, D. et al. (1991) EMBO J. 10:2839-2848; Gearing,
D. and Bruce, A. G. (1992) New. Biol. 4:61-65; and Schiemann, W. P.
et al. (1995) Proc. Natl. Acad. Sci. USA 92:5361-5365. LIFR is also
referred to in the art as Leukemia Inhibitor Factor Receptor Alpha,
CD118, CD118 antigen, SJS2, STWS and SWS. A non-limiting example of
a LILFR protein is the human protein having the amino acid sequence
set forth in Genbank Accession Number NP_001121143.1.
[0059] As used herein, the terms "Fibroblast Growth Factor Receptor
3", "FGF Receptor 3" and "FGFR3" are used interchangeably to refer
to a protein known in the art that has been described in, for
example, Keegan, K. et al. (1991) Proc. Natl. Acad. Sci. USA
88:1095-1099; Thompson, L. M. et al. (1991) Genomics 11:1133-1142;
and Shiang, R. et al. (1994) Cell 78:335-343. FGFR3 is also
referred to in the art as CD333, CD333 antigen, EC 2.7.10.1, JTK4,
ACH, CEK2 and HSFGFR3EX. A non-limiting example of an FGFR3 protein
is the human protein having the amino acid sequence set forth in
Genbank Accession Number NP 000133.1.
[0060] As used herein, the term "stem cells" is used in a broad
sense and includes traditional stem cells, progenitor cells,
pre-progenitor cells, reserve cells, and the like. The term "stem
cell" or "progenitor" are used interchangeably herein, and refer to
an undifferentiated cell which is capable of proliferation and
giving rise to more progenitor cells having the ability to generate
a large number of mother cells that can in turn give rise to
differentiated, or differentiable daughter cells. The daughter
cells themselves can be induced to proliferate and produce progeny
that subsequently differentiate into one or more mature cell types,
while also retaining one or more cells with parental developmental
potential. The term "stem cell" refers then, to a cell with the
capacity or potential, under particular circumstances, to
differentiate to a more specialized or differentiated phenotype,
and which retains the capacity, under certain circumstances, to
proliferate without substantially differentiating. In one
embodiment, the term progenitor or stem cell refers to a
generalized mother cell whose descendants (progeny) specialize,
often in different directions, by differentiation, e.g., by
acquiring completely individual characters, as occurs in
progressive diversification of embryonic cells and tissues.
Cellular differentiation is a complex process typically occurring
through many cell divisions. A differentiated cell may derive from
a multipotent cell which itself is derived from a multipotent cell,
and so on. While each of these multipotent cells may be considered
stem cells, the range of cell types each can give rise to may vary
considerably. Some differentiated cells also have the capacity to
give rise to cells of greater developmental potential. Such
capacity may be natural or may be induced artificially upon
treatment with various factors. In many biological instances, stem
cells are also "multipotent" because they can produce progeny of
more than one distinct cell type, but this is not required for
"stem-ness." Self-renewal is the other classical part of the stem
cell definition, and it is essential as used in this document. In
theory, self-renewal can occur by either of two major mechanisms.
Stem cells may divide asymmetrically, with one daughter retaining
the stem state and the other daughter expressing some distinct
other specific function and phenotype. Alternatively, some of the
stem cells in a population can divide symmetrically into two stems,
thus maintaining some stem cells in the population as a whole,
while other cells in the population give rise to differentiated
progeny only. Formally, it is possible that cells that begin as
stem cells might proceed toward a differentiated phenotype, but
then "reverse" and re-express the stem cell phenotype, a term often
referred to as "dedifferentiation".
[0061] The term "progenitor cell" is used herein to refer to cells
that have a cellular phenotype that is more primitive (e.g., is at
an earlier step along a developmental pathway or progression than
is a fully differentiated cell) relative to a cell which it can
give rise to by differentiation. Often, progenitor cells also have
significant or very high proliferative potential. Progenitor cells
can give rise to multiple distinct differentiated cell types or to
a single differentiated cell type, depending on the developmental
pathway and on the environment in which the cells develop and
differentiate.
[0062] The term "pluripotent" as used herein refers to a cell with
the capacity, under different conditions, to differentiate to cell
types characteristic of all three germ cell layers (endoderm,
mesoderm and ectoderm). Pluripotent cells are characterized
primarily by their ability to differentiate to all three germ
layers, using, for example, a nude mouse and teratomas formation
assay. Pluripotency is also evidenced by the expression of
embryonic stem (ES) cell markers, although the preferred test for
pluripotency is the demonstration of the capacity to differentiate
into cells of each of the three germ layers. In some embodiments, a
pluripotent cell is an undifferentiated cell.
[0063] The term "pluripotency" or a "pluripotent state" as used
herein refers to a cell with the ability to differentiate into all
three embryonic germ layers: endoderm (gut tissue), mesoderm
(including blood, muscle, and vessels), and ectoderm (such as skin
and nerve), and typically has the potential to divide in vitro for
a long period of time, e.g., greater than one year or more than 30
passages.
[0064] The term "multipotent" when used in reference to a
"multipotent cell" refers to a cell that is able to differentiate
into some but not all of the cells derived from all three germ
layers. Thus, a multipotent cell is a partially differentiated
cell. Multipotent cells are well known in the art, and examples of
multipotent cells include adult stem cells, such as for example,
hematopoietic stem cells and neural stem cells. Multipotent means a
stem cell may form many types of cells in a given lineage, but not
cells of other lineages. For example, a multipotent blood stem cell
can form the many different types of blood cells (red, white,
platelets, etc.), but it cannot form neurons.
[0065] The term "embryonic stem cell" or "ES cell" or "ESC" are
used interchangeably herein and refer to the pluripotent stem cells
of the inner cell mass of the embryonic blastocyst (see U.S. Pat.
Nos. 5,843,780, 6,200,806, which are incorporated herein by
reference). Such cells can similarly be obtained from the inner
cell mass of blastocysts derived from somatic cell nuclear transfer
(see, for example, U.S. Pat. Nos. 5,945,577, 5,994,619, 6,235,970,
which are incorporated herein by reference). The distinguishing
characteristics of an embryonic stem cell define an embryonic stem
cell phenotype. Accordingly, a cell has the phenotype of an
embryonic stem cell if it possesses one or more of the unique
characteristics of an embryonic stem cell such that that cell can
be distinguished from other cells. Exemplary distinguishing
embryonic stem cell characteristics include, without limitation,
gene expression profile, proliferative capacity, differentiation
capacity, karyotype, responsiveness to particular culture
conditions, and the like. In some embodiments, an ES cell can be
obtained without destroying the embryo, for example, without
destroying a human embryo.
[0066] The term "adult stem cell" or "ASC" is used to refer to any
multipotent stem cell derived from non-embryonic tissue, including
fetal, juvenile, and adult tissue. Stem cells have been isolated
from a wide variety of adult tissues including blood, bone marrow,
brain, olfactory epithelium, skin, pancreas, skeletal muscle, and
cardiac muscle. Each of these stem cells can be characterized based
on gene expression, factor responsiveness, and morphology in
culture. Exemplary adult stem cells include neural stem cells,
neural crest stem cells, mesenchymal stem cells, hematopoietic stem
cells, and pancreatic stem cells. As indicated above, stem cells
have been found resident in virtually every tissue. Accordingly,
the present invention appreciates that stem cell populations can be
isolated from virtually any animal tissue.
[0067] The term "human pluripotent stem cell" (abbreviated as
hPSC), as used herein, refers to a human cell that has the capacity
to differentiate into a variety of different cell types as
discussed above regarding stem cells and pluripotency. Human
pluripotent human stem cells include, for example, induced
pluripotent stem cells (iPSC) and human embryonic stem cells, such
as ES cell lines.
[0068] The term "human cardiac progenitor cell", as used herein,
refers to a human progenitor cell that is committed to the cardiac
lineage and that has the capacity to differentiate into all three
cardiac lineage cells (cardiac muscle cells, endothelial cells and
smooth muscle cells).
[0069] The term "human cardiomyogenic progenitor cell", as used
herein, refers to a human progenitor cell that is committed to the
cardiac lineage and that predominantly differentiates into cardiac
muscle cells (i.e., more than 50% of the differentiated cells,
preferably more than 60%, 70%, 80% or 90% of the differentiated
cells, derived from the progenitor cells are cardiac muscle
cells).
[0070] The term "cardiac ventricular progenitor cell", as used
herein, refers to a progenitor cell that is committed to the
cardiac lineage and that predominantly differentiates into cardiac
ventricular muscle cells (i.e., more than 50% of the differentiated
cells, preferably more than 60%, 70%, 80% or 90% of the
differentiated cells, derived from the progenitor cells are cardiac
ventricular muscle cells). This type of cell is also referred to
herein as a human ventricular progenitor, or HVP, cell.
[0071] The term "cardiomyocyte" refers to a muscle cell of the
heart (e.g. a cardiac muscle cell). A cardiomyocyte will generally
express on its cell surface and/or in the cytoplasm one or more
cardiac-specific marker. Suitable cardiomyocyte-specific markers
include, but are not limited to, cardiac troponin I, cardiac
troponin-C, tropomyosin, caveolin-3, GATA-4, myosin heavy chain,
myosin light chain-2a, myosin light chain-2v, ryanodine receptor,
and atrial natriuretic factor.
[0072] The term "derived from" used in the context of a cell
derived from another cell means that a cell has stemmed (e.g.
changed from or produced by) a cell that is a different cell type.
The term "derived from" also refers to cells that have been
differentiated from a progenitor cell.
[0073] The term "Isl1+ cardiac progenitor cell", as used herein,
refers to a human progenitor cell that is committed to the cardiac
lineage and that expresses Islet 1.
[0074] The term "Isl1+ LIFR+ cardiac progenitor cell", as used
herein, refers to a human progenitor cell that is committed to the
cardiac lineage and that expresses both Islet 1 and LIFR.
[0075] The term "Isl1+ FGFR3+ cardiac progenitor cell", as used
herein, refers to a human progenitor cell that is committed to the
cardiac lineage and that expresses both Islet 1 and FGFR3.
[0076] The term "Isl1+ LIFR+ FGFR3+ cardiac progenitor cell", as
used herein, refers to a human progenitor cell that is committed to
the cardiac lineage and that expresses Islet 1, LIFR and FGFR3.
[0077] With respect to cells in cell cultures or in cell
populations, the term "substantially free of" means that the
specified cell type of which the cell culture or cell population is
free, is present in an amount of less than about 10%, less than
about 9%, less than about 8%, less than about 7%, less than about
6%, less than about 5%, less than about 4%, less than about 3%,
less than about 2% or less than about 1% of the total number of
cells present in the cell culture or cell population.
[0078] In the context of cell ontogeny, the adjective
"differentiated", or "differentiating" is a relative term. A
"differentiated cell" is a cell that has progressed further down
the developmental pathway than the cell it is being compared with.
Thus, stem cells can differentiate to lineage-restricted precursor
cells (such as a mesodermal stem cell), which in turn can
differentiate into other types of precursor cells further down the
pathway (such as an cardiomyocyte precursor), and then to an
end-stage differentiated cell, which plays a characteristic role in
a certain tissue type, and may or may not retain the capacity to
proliferate further.
[0079] The term "differentiation" in the present context means the
formation of cells expressing markers known to be associated with
cells that are more specialized and closer to becoming terminally
differentiated cells incapable of further differentiation. The
pathway along which cells progress from a less committed cell, to a
cell that is increasingly committed to a particular cell type, and
eventually to a terminally differentiated cell is referred to as
progressive differentiation or progressive commitment. Cell which
are more specialized (e.g., have begun to progress along a path of
progressive differentiation) but not yet terminally differentiated
are referred to as partially differentiated. Differentiation is a
developmental process whereby cells assume a specialized phenotype,
e.g., acquire one or more characteristics or functions distinct
from other cell types. In some cases, the differentiated phenotype
refers to a cell phenotype that is at the mature endpoint in some
developmental pathway (a so called terminally differentiated cell).
In many, but not all tissues, the process of differentiation is
coupled with exit from the cell cycle. In these cases, the
terminally differentiated cells lose or greatly restrict their
capacity to proliferate. However, we note that in the context of
this specification, the terms "differentiation" or "differentiated"
refer to cells that are more specialized in their fate or function
than at a previous point in their development, and includes both
cells that are terminally differentiated and cells that, although
not terminally differentiated, are more specialized than at a
previous point in their development. The development of a cell from
an uncommitted cell (for example, a stem cell), to a cell with an
increasing degree of commitment to a particular differentiated cell
type, and finally to a terminally differentiated cell is known as
progressive differentiation or progressive commitment. A cell that
is "differentiated" relative to a progenitor cell has one or more
phenotypic differences relative to that progenitor cell. Phenotypic
differences include, but are not limited to morphologic differences
and differences in gene expression and biological activity,
including not only the presence or absence of an expressed marker,
but also differences in the amount of a marker and differences in
the co-expression patterns of a set of markers.
[0080] The term "differentiation" as used herein refers to the
cellular development of a cell from a primitive stage towards a
more mature (i.e. less primitive) cell.
[0081] As used herein, "proliferating" and "proliferation" refers
to an increase in the number of cells in a population (growth) by
means of cell division. Cell proliferation is generally understood
to result from the coordinated activation of multiple signal
transduction pathways in response to the environment, including
growth factors and other mitogens. Cell proliferation may also be
promoted by release from the actions of intra- or extracellular
signals and mechanisms that block or negatively affect cell
proliferation.
[0082] The terms "renewal" or "self-renewal" or "proliferation" are
used interchangeably herein, and refers to a process of a cell
making more copies of itself (e.g. duplication) of the cell. In
some embodiments, cells are capable of renewal of themselves by
dividing into the same undifferentiated cells (e.g. progenitor cell
type) over long periods, and/or many months to years. In some
instances, proliferation refers to the expansion of cells by the
repeated division of single cells into two identical daughter
cells.
[0083] The term "lineages" as used herein refers to a term to
describe cells with a common ancestry or cells with a common
developmental fate, for example cells that have a developmental
fate to develop into ventricular cardiomyocytes.
[0084] The term "clonal population", as used herein, refers to a
population of cells that is derived from the outgrowth of a single
cell. That is, the cells within the clonal population are all
progeny of a single cell that was used to seed the clonal
population.
[0085] The term "media" as referred to herein is a medium for
maintaining a tissue or cell population, or culturing a cell
population (e.g. "culture media") containing nutrients that
maintain cell viability and support proliferation. The cell culture
medium may contain any of the following in an appropriate
combination: salt(s), buffer(s), amino acids, glucose or other
sugar(s), antibiotics, serum or serum replacement, and other
components such as peptide growth factors, etc. Cell culture media
ordinarily used for particular cell types are known to those
skilled in the art.
[0086] The term "phenotype" refers to one or a number of total
biological characteristics that define the cell or organism under a
particular set of environmental conditions and factors, regardless
of the actual genotype.
[0087] A "marker" as used herein describes the characteristics
and/or phenotype of a cell. Markers can be used for selection of
cells comprising characteristics of interest. Markers will vary
with specific cells. Markers are characteristics, whether
morphological, functional or biochemical (enzymatic)
characteristics particular to a cell type, or molecules expressed
by the cell type. Preferably, such markers are proteins, and more
preferably, possess an epitope for antibodies or other binding
molecules available in the art. However, a marker may consist of
any molecule found in a cell including, but not limited to,
proteins (peptides and polypeptides), lipids, polysaccharides,
nucleic acids and steroids. Examples of morphological
characteristics or traits include, but are not limited to, shape,
size, and nuclear to cytoplasmic ratio. Examples of functional
characteristics or traits include, but are not limited to, the
ability to adhere to particular substrates, ability to incorporate
or exclude particular dyes, ability to migrate under particular
conditions, and the ability to differentiate along particular
lineages. Markers may be detected by any method available to one of
skill in the art.
[0088] The term "isolated cell" as used herein refers to a cell
that has been removed from an organism in which it was originally
found or a descendant of such a cell. Optionally the cell has been
cultured in vitro, e.g., in the presence of other cells. Optionally
the cell is later introduced into a second organism or
re-introduced into the organism from which it (or the cell from
which it is descended) was isolated.
[0089] The term "isolated population" with respect to an isolated
population of cells as used herein refers to a population of cells
that has been removed and separated from a mixed or heterogeneous
population of cells. In some embodiments, an isolated population is
a substantially pure population of cells as compared to the
heterogeneous population from which the cells were isolated or
enriched from.
[0090] The term "substantially pure", with respect to a particular
cell population, refers to a population of cells that is at least
about 75%, preferably at least about 85%, more preferably at least
about 90%, and most preferably at least about 95% pure, with
respect to the cells making up a total cell population.
[0091] The terms "subject" and "individual" are used
interchangeably herein, and refer to an animal, for example a
human, to whom cardiac ventricular progenitor cells as disclosed
herein can be implanted into, for e.g. treatment, which in some
embodiments encompasses prophylactic treatment or for a disease
model, with methods and compositions described herein, is or are
provided. For treatment of disease states that are specific for a
specific animal such as a human subject, the term "subject" refers
to that specific animal. The terms "non-human animals" and
"non-human mammals" are used interchangeably herein, and include
mammals such as rats, mice, rabbits, sheep, cats, dogs, cows, pigs,
and non-human primates. The term "subject" also encompasses any
vertebrate including but not limited to mammals, reptiles,
amphibians and fish. However, advantageously, the subject is a
mammal such as a human, or other mammals such as a domesticated
mammal, e.g. dog, cat, horse, and the like, or production mammal,
e.g. cow, sheep, pig, and the like are also encompassed in the term
subject.
[0092] As used herein, the term "recipient" refers to a subject
that will receive a transplanted organ, tissue or cell.
[0093] The term "three-dimensional matrix" or "scaffold" or
"matrices" as used herein refers in the broad sense to a
composition comprising a biocompatible matrix, scaffold, or the
like. The three-dimensional matrix may be liquid, gel, semi-solid,
or solid at 25.degree. C. The three-dimensional matrix may be
biodegradable or non-biodegradable. In some embodiments, the
three-dimensional matrix is biocompatible, or bioresorbable or
bioreplacable. Exemplary three-dimensional matrices include
polymers and hydrogels comprising collagen, fibrin, chitosan,
MATRIGEL.TM., polyethylene glycol, dextrans including chemically
crosslinkable or photocrosslinkable dextrans, processed tissue
matrix such as submucosal tissue and the like. In certain
embodiments, the three-dimensional matrix comprises allogeneic
components, autologous components, or both allogeneic components
and autologous components. In certain embodiments, the
three-dimensional matrix comprises synthetic or semi-synthetic
materials. In certain embodiments, the three-dimensional matrix
comprises a framework or support, such as a fibrin-derived
scaffold.
[0094] As used herein, the terms "administering," "introducing" and
"transplanting" are used interchangeably and refer to the placement
of cardiomyogenic progenitor cells and/or cardiomyocytes
differentiated as described herein into a subject by a method or
route which results in at least partial localization of the cells
at a desired site. The cells can be administered by any appropriate
route that results in delivery to a desired location in the subject
where at least a portion of the cells remain viable. The period of
viability of the cells after administration to a subject can be as
short as a few hours, e.g. twenty-four hours, to a few days, to as
long as several years.
[0095] The term "statistically significant" or "significantly"
refers to statistical significance and generally means a two
standard deviation (2SD) below normal, or lower, concentration of
the marker. The term refers to statistical evidence that there is a
difference. It is defined as the probability of making a decision
to reject the null hypothesis when the null hypothesis is actually
true. The decision is often made using the p-value. The term
"substantially" or "predominantly" as used herein means a
proportion of at least about 60%, or preferably at least about 70%
or at least about 80%, or at least about 90%, at least about 95%,
at least about 97% or at least about 99% or more, or any integer
between 70% and 100%.
[0096] The term "disease" or "disorder" is used interchangeably
herein, and refers to any alternation in state of the body or of
some of the organs, interrupting or disturbing the performance of
the functions and/or causing symptoms such as discomfort,
dysfunction, distress, or even death to the person afflicted or
those in contact with a person. A disease or disorder can also
related to a distemper, ailing, ailment, malady, disorder,
sickness, illness, complaint, indisposition or affection.
[0097] As used herein, the phrase "cardiovascular condition,
disease or disorder" is intended to include all disorders
characterized by insufficient, undesired or abnormal cardiac
function, e.g. ischemic heart disease, hypertensive heart disease
and pulmonary hypertensive heart disease, valvular disease,
congenital heart disease and any condition which leads to
congestive heart failure in a subject, particularly a human
subject. Insufficient or abnormal cardiac function can be the
result of disease, injury and/or aging. By way of background, a
response to myocardial injury follows a well-defined path in which
some cells die while others enter a state of hibernation where they
are not yet dead but are dysfunctional. This is followed by
infiltration of inflammatory cells, deposition of collagen as part
of scarring, all of which happen in parallel with in-growth of new
blood vessels and a degree of continued cell death. As used herein,
the term "ischemia" refers to any localized tissue ischemia due to
reduction of the inflow of blood. The term "myocardial ischemia"
refers to circulatory disturbances caused by coronary
atherosclerosis and/or inadequate oxygen supply to the myocardium.
For example, an acute myocardial infarction represents an
irreversible ischemic insult to myocardial tissue. This insult
results in an occlusive (e.g., thrombotic or embolic) event in the
coronary circulation and produces an environment in which the
myocardial metabolic demands exceed the supply of oxygen to the
myocardial tissue.
[0098] As used herein, the term "treating" or "treatment" are used
interchangeably herein and refers to reducing or decreasing or
alleviating or halting at least one adverse effect or symptom of a
cardiovascular condition, disease or disorder, i.e., any disorder
characterized by insufficient or undesired cardiac function.
Adverse effects or symptoms of cardiac disorders are well-known in
the art and include, but are not limited to, dyspnea, chest pain,
palpitations, dizziness, syncope, edema, cyanosis, pallor, fatigue
and death. In some embodiments, the term "treatment" as used herein
refers to prophylactic treatment or preventative treatment to
prevent the development of a symptom of a cardiovascular condition
in a subject.
[0099] Treatment is generally "effective" if one or more symptoms
or clinical markers are reduced as that term is defined herein.
Alternatively, a treatment is "effective" if the progression of a
disease is reduced or halted. That is, "treatment" includes not
just the improvement of symptoms or decrease of markers of the
disease, but also a cessation or slowing of progress or worsening
of a symptom that would be expected in absence of treatment.
Beneficial or desired clinical results include, but are not limited
to, alleviation of one or more symptom(s), diminishment of extent
of disease, stabilized (i.e., not worsening) state of disease,
delay or slowing of disease progression, amelioration or palliation
of the disease state, and remission (whether partial or total),
whether detectable or undetectable. "Treatment" can also mean
prolonging survival as compared to expected survival if not
receiving treatment. Those in need of treatment include those
already diagnosed with a cardiac condition, as well as those likely
to develop a cardiac condition due to genetic susceptibility or
other factors such as weight, diet and health. In some embodiments,
the term to treat also encompasses preventative measures and/or
prophylactic treatment, which includes administering a
pharmaceutical composition as disclosed herein to prevent the onset
of a disease or disorder.
[0100] A therapeutically significant reduction in a symptom is,
e.g. at least about 10%, at least about 20%, at least about 30%, at
least about 40%, at least about 50%, at least about 60%, at least
about 70%, at least about 80%, at least about 90%, at least about
100%, at least about 125%, at least about 150% or more in a
measured parameter as compared to a control or non-treated subject.
Measured or measurable parameters include clinically detectable
markers of disease, for example, elevated or depressed levels of a
biological marker, as well as parameters related to a clinically
accepted scale of symptoms or markers for a disease or disorder. It
will be understood, that the total daily usage of the compositions
and formulations as disclosed herein will be decided by the
attending physician within the scope of sound medical judgment. The
exact amount required will vary depending on factors such as the
type of disease being treated.
[0101] With reference to the treatment of a cardiovascular
condition or disease in a subject, the term "therapeutically
effective amount" refers to the amount that is safe and sufficient
to prevent or delay the development or a cardiovascular disease or
disorder. The amount can thus cure or cause the cardiovascular
disease or disorder to go into remission, slow the course of
cardiovascular disease progression, slow or inhibit a symptom of a
cardiovascular disease or disorder, slow or inhibit the
establishment of secondary symptoms of a cardiovascular disease or
disorder or inhibit the development of a secondary symptom of a
cardiovascular disease or disorder. The effective amount for the
treatment of the cardiovascular disease or disorder depends on the
type of cardiovascular disease to be treated, the severity of the
symptoms, the subject being treated, the age and general condition
of the subject, the mode of administration and so forth. Thus, it
is not possible to specify the exact "effective amount". However,
for any given case, an appropriate "effective amount" can be
determined by one of ordinary skill in the art using only routine
experimentation. The efficacy of treatment can be judged by an
ordinarily skilled practitioner, for example, efficacy can be
assessed in animal models of a cardiovascular disease or disorder
as discussed herein, for example treatment of a rodent with acute
myocardial infarction or ischemia-reperfusion injury, and any
treatment or administration of the compositions or formulations
that leads to a decrease of at least one symptom of the
cardiovascular disease or disorder as disclosed herein, for
example, increased heart ejection fraction, decreased rate of heart
failure, decreased infarct size, decreased associated morbidity
(pulmonary edema, renal failure, arrhythmias) improved exercise
tolerance or other quality of life measures, and decreased
mortality indicates effective treatment. In embodiments where the
compositions are used for the treatment of a cardiovascular disease
or disorder, the efficacy of the composition can be judged using an
experimental animal model of cardiovascular disease, e.g., animal
models of ischemia-reperfusion injury (Headrick J P, Am J Physiol
Heart circ Physiol 285; H1797; 2003) and animal models acute
myocardial infarction. (Yang Z, Am J Physiol Heart Circ. Physiol
282:H949:2002; Guo Y, J Mol Cell Cardiol 33; 825-830, 2001). When
using an experimental animal model, efficacy of treatment is
evidenced when a reduction in a symptom of the cardiovascular
disease or disorder, for example, a reduction in one or more
symptom of dyspnea, chest pain, palpitations, dizziness, syncope,
edema, cyanosis, pallor, fatigue and high blood pressure which
occurs earlier in treated, versus untreated animals. By "earlier"
is meant that a decrease, for example in the size of the tumor
occurs at least 5% earlier, but preferably more, e.g., one day
earlier, two days earlier, 3 days earlier, or more.
[0102] As used herein, the term "treating" when used in reference
to a treatment of a cardiovascular disease or disorder is used to
refer to the reduction of a symptom and/or a biochemical marker of
a cardiovascular disease or disorder, for example a reduction in at
least one biochemical marker of a cardiovascular disease by at
least about 10% would be considered an effective treatment.
Examples of such biochemical markers of cardiovascular disease
include a reduction of, for example, creatine phosphokinase (CPK),
aspartate aminotransferase (AST), lactate dehydrogenase (LDH) in
the blood, and/or a decrease in a symptom of cardiovascular disease
and/or an improvement in blood flow and cardiac function as
determined by someone of ordinary skill in the art as measured by
electrocardiogram (ECG or EKG), or echocardiogram (heart
ultrasound), Doppler ultrasound and nuclear medicine imaging. A
reduction in a symptom of a cardiovascular disease by at least
about 10% would also be considered effective treatment by the
methods as disclosed herein. As alternative examples, a reduction
in a symptom of cardiovascular disease, for example a reduction of
at least one of the following; dyspnea, chest pain, palpitations,
dizziness, syncope, edema, cyanosis etc. by at least about 10% or a
cessation of such systems, or a reduction in the size one such
symptom of a cardiovascular disease by at least about 10% would
also be considered as affective treatments by the methods as
disclosed herein. In some embodiments, it is preferred, but not
required that the therapeutic agent actually eliminate the
cardiovascular disease or disorder, rather just reduce a symptom to
a manageable extent.
[0103] Subjects amenable to treatment by the methods as disclosed
herein can be identified by any method to diagnose myocardial
infarction (commonly referred to as a heart attack) commonly known
by persons of ordinary skill in the art are amenable to treatment
using the methods as disclosed herein, and such diagnostic methods
include, for example but are not limited to; (i) blood tests to
detect levels of creatine phosphokinase (CPK), aspartate
aminotransferase (AST), lactate dehydrogenase (LDH) and other
enzymes released during myocardial infarction; (ii)
electrocardiogram (ECG or EKG) which is a graphic recordation of
cardiac activity, either on paper or a computer monitor. An ECG can
be beneficial in detecting disease and/or damage; (iii)
echocardiogram (heart ultrasound) used to investigate congenital
heart disease and assessing abnormalities of the heart wall,
including functional abnormalities of the heart wall, valves and
blood vessels; (iv) Doppler ultrasound can be used to measure blood
flow across a heart valve; (v) nuclear medicine imaging (also
referred to as radionuclide scanning in the art) allows
visualization of the anatomy and function of an organ, and can be
used to detect coronary artery disease, myocardial infarction,
valve disease, heart transplant rejection, check the effectiveness
of bypass surgery, or to select patients for angioplasty or
coronary bypass graft.
[0104] The terms "coronary artery disease" and "acute coronary
syndrome" as used interchangeably herein, and refer to myocardial
infarction refer to a cardiovascular condition, disease or
disorder, include all disorders characterized by insufficient,
undesired or abnormal cardiac function, e.g. ischemic heart
disease, hypertensive heart disease and pulmonary hypertensive
heart disease, valvular disease, congenital heart disease and any
condition which leads to congestive heart failure in a subject,
particularly a human subject. Insufficient or abnormal cardiac
function can be the result of disease, injury and/or aging. By way
of background, a response to myocardial injury follows a
well-defined path in which some cells die while others enter a
state of hibernation where they are not yet dead but are
dysfunctional. This is followed by infiltration of inflammatory
cells, deposition of collagen as part of scarring, all of which
happen in parallel with in-growth of new blood vessels and a degree
of continued cell death.
[0105] As used herein, the term "ischemia" refers to any localized
tissue ischemia due to reduction of the inflow of blood. The term
"myocardial ischemia" refers to circulatory disturbances caused by
coronary atherosclerosis and/or inadequate oxygen supply to the
myocardium. For example, an acute myocardial infarction represents
an irreversible ischemic insult to myocardial tissue. This insult
results in an occlusive (e.g., thrombotic or embolic) event in the
coronary circulation and produces an environment in which the
myocardial metabolic demands exceed the supply of oxygen to the
myocardial tissue.
[0106] The terms "composition" or "pharmaceutical composition" used
interchangeably herein refer to compositions or formulations that
usually comprise an excipient, such as a pharmaceutically
acceptable carrier that is conventional in the art and that is
suitable for administration to mammals, and preferably humans or
human cells. In some embodiments, pharmaceutical compositions can
be specifically formulated for direct delivery to a target tissue
or organ, for example, by direct injection or via catheter
injection to a target tissue. In other embodiments, compositions
can be specifically formulated for administration via one or more
of a number of routes, including but not limited to, oral, ocular
parenteral, intravenous, intraarterial, subcutaneous, intranasal,
sublingual, intraspinal, intracerebroventricular, and the like. In
addition, compositions for topical (e.g., oral mucosa, respiratory
mucosa) and/or oral administration can form solutions, suspensions,
tablets, pills, capsules, sustained-release formulations, oral
rinses, or powders, as known in the art are described herein. The
compositions also can include stabilizers and preservatives. For
examples of carriers, stabilizers and adjuvants, University of the
Sciences in Philadelphia (2005) Remington: The Science and Practice
of Pharmacy with Facts and Comparisons, 21st Ed.
[0107] As used herein, the terms "administering," "introducing" and
"transplanting" are used interchangeably and refer to the placement
of a pharmaceutical composition comprising cardiomyogenic
progenitor cells, or a composition comprising a population of
differentiated cardiomyocytes (e.g., ventricular cardiomyocytes) as
described herein, into a subject by a method or route which results
in at least partial localization of the pharmaceutical composition,
at a desired site or tissue location. In some embodiments, the
pharmaceutical composition can be administered by any appropriate
route which results in effective treatment in the subject, i.e.
administration results in delivery to a desired location or tissue
in the subject where at least a portion of the cells are located at
a desired target tissue or target cell location.
[0108] The phrases "parenteral administration" and "administered
parenterally" as used herein mean modes of administration other
than enteral and topical administration, usually by injection, and
includes, without limitation, intravenous, intramuscular,
intraarterial, intrathecal, intraventricular, intracapsular,
intraorbital, intracardiac, intradermal, intraperitoneal,
transtracheal, subcutaneous, subcuticular, intraarticular, sub
capsular, subarachnoid, intraspinal, intracerebro spinal, and
intrasternal injection and infusion. The phrases "systemic
administration," "administered systemically", "peripheral
administration" and "administered peripherally" as used herein mean
the administration of cardiovascular stem cells and/or their
progeny and/or compound and/or other material other than directly
into the cardiac tissue, such that it enters the animal's system
and, thus, is subject to metabolism and other like processes, for
example, subcutaneous or intravenous administration.
[0109] The phrase "pharmaceutically acceptable" is employed herein
to refer to those compounds, materials, compositions, and/or dosage
forms which are, within the scope of sound medical judgment,
suitable for use in contact with the tissues of human beings and
animals without excessive toxicity, irritation, allergic response,
or other problem or complication, commensurate with a reasonable
benefit/risk ratio.
[0110] The phrase "pharmaceutically acceptable carrier" as used
herein means a pharmaceutically acceptable material, composition or
vehicle, such as a liquid or solid filler, diluent, excipient,
solvent or encapsulating material, involved in carrying or
transporting the subject agents from one organ, or portion of the
body, to another organ, or portion of the body. Each carrier must
be "acceptable" in the sense of being compatible with the other
ingredients of the formulation.
[0111] The term "drug" or "compound" or "test compound" as used
herein refers to a chemical entity or biological product, or
combination of chemical entities or biological products,
administered to a subject to treat or prevent or control a disease
or condition. The chemical entity or biological product is
preferably, but not necessarily a low molecular weight compound,
but may also be a larger compound, for example, an oligomer of
nucleic acids, amino acids, or carbohydrates including without
limitation proteins, oligonucleotides, ribozymes, DNAzymes,
glycoproteins, siRNAs, lipoproteins, aptamers, and modifications
and combinations thereof.
[0112] The term "transplantation" as used herein refers to
introduction of new cells (e.g. reprogrammed cells), tissues (such
as differentiated cells produced from reprogrammed cells), or
organs into a host (i.e. transplant recipient or transplant
subject)
[0113] The term "agent reactive with LIFR", as used herein, refers
to an agent that binds to or otherwise interacts with LIFR.
Preferably, the agent "specifically" binds or otherwise interacts
with LIFR such that it does not bind or interact with other
non-LIFR proteins.
[0114] The term "agent reactive with FGFR3", as used herein, refers
to an agent that binds to or otherwise interacts with FGFR3.
Preferably, the agent "specifically" binds or otherwise interacts
with FGFR3 such that it does not bind or interact with other
non-FGFR3 proteins.
[0115] The term "agent reactive with Islet 1", as used herein,
refers to an agent that binds to or otherwise interacts with Islet
1. Preferably, the agent "specifically" binds or otherwise
interacts with Islet 1 such that it does not bind or interact with
other non-Islet 1 proteins.
[0116] The term "antibody", as used herein, includes whole
antibodies and any antigen binding fragment (i.e., "antigen-binding
portion") or single chain thereof. An "antibody" refers, in one
preferred embodiment, to a glycoprotein comprising at least two
heavy (H) chains and two light (L) chains inter-connected by
disulfide bonds, or an antigen binding portion thereof. Each heavy
chain is comprised of a heavy chain variable region (abbreviated
herein as VH) and a heavy chain constant region. The heavy chain
constant region is comprised of three domains, CH1, CH2 and CH3.
Each light chain is comprised of a light chain variable region
(abbreviated herein as V.sub.L) and a light chain constant region.
The light chain constant region is comprised of one domain, CL. The
term "antigen-binding portion" of an antibody (or simply "antibody
portion"), as used herein, refers to one or more fragments of an
antibody that retain the ability to specifically bind to an
antigen.
[0117] The term "monoclonal antibody," as used herein, refers to an
antibody that displays a single binding specificity and affinity
for a particular epitope.
[0118] The term "human monoclonal antibody", as used herein, refers
to an antibody which displays a single binding specificity and
which has variable and optional constant regions derived from human
germline immunoglobulin sequences.
[0119] The term "humanized monoclonal antibody", as used herein,
refers to an antibody which displays a single binding specificity
and which has heavy and light chain CDR1, 2 and 3 from a non-human
antibody (e.g., a mouse monoclonal antibody) grafted into human
framework and constant regions.
[0120] The term "chimeric monoclonal antibody", as used herein,
refers to an antibody which displays a single binding specificity
and which has heavy and light chain variable regions from one
species linked to constant regions from another species.
[0121] The term "fusion protein", as used herein, refers to a
composite protein, typically made using recombinant DNA technology,
in which two different proteins, or portions thereof, are
operatively linked together. A non-limiting example is an Fc fusion
protein in which a non-immunoglobulin protein is operatively linked
to an immunoglobulin Fc region.
[0122] Various aspects of the invention are described in further
detail in the following subsections.
Methods of Isolating Human Cardiac Ventricular Progenitor Cells
[0123] In one aspect, the invention pertains to methods of
isolating human cardiac ventricular progenitor cells. As described
in the Examples, LIFR and FGFR3 have now been identified as a cell
surface marker of human cardiac ventricular progenitor cells and
thus these markers can be used to facilitate isolation of these
progenitor cells. Accordingly, in one embodiment, the invention
provides a method for isolating human cardiac ventricular
progenitor cells, the method comprising:
[0124] contacting a culture of human cells containing cardiac
progenitor cells with one or more agents reactive with LIFR and/or
FGFR3; and
[0125] separating LIFR and/or FGFR3 reactive positive cells from
non-reactive cells to thereby isolate human cardiac ventricular
progenitor cells.
[0126] Alternatively, after the contacting step, the method can
comprise isolating LIFR and/or FGFR3 reactive positive cells from
non-reactive cells to thereby isolate human cardiac ventricular
progenitor cells.
[0127] Also as described in the Examples, Islet 1 is a marker that
is co-expressed with LIFR and/or FGFR3 by the cardiac ventricular
progenitor cells and thus both markers can be used to facilitate
isolation of these progenitor cells. Accordingly, in another
embodiment of the above method, the culture of human cells is also
contacted with an agent reactive with Islet 1; and LIFR
reactive/Islet 1 reactive positive cells, FGFR3 reactive/Islet 1
reactive positive cells or LIFR reactive/FGFR3 reactive/Islet 1
reactive positive cells are separated from non-reactive cells to
thereby isolate human cardiac ventricular progenitor cells. The
culture of human cells can be simultaneously contacted with the
agent(s) reactive with LIFR and/or FGFR3 and the agent reactive
with Islet 1. Alternatively, the culture of human cells can be
contacted with the agent reactive with Islet 1 before contacting
with the agent(s) reactive with LIFR and/or FGFR3. Alternatively,
the culture of human cells can be contacted with the agent(s)
reactive with LIFR and/or FGFR3 before contacting with the agent
reactive with Islet 1.
[0128] In yet another embodiment, the culture of human cells can be
contacted with an agent reactive with LIFR and an agent reactive
with FGFR3, and cells that are LIFR+/FGFR3+ can be separated. In
yet another embodiment, the culture of human cells can be contacted
with an agent reactive with LIFR, an agent reactive with FGFR3 and
an agent reactive with Islet 1, and cells that are
LIFR+/FGFR3+/Islet 1+ can be separated.
[0129] In another embodiment, the invention provides a method for
isolating human cardiac ventricular progenitor cells, the method
comprising:
[0130] culturing human pluripotent stem cells under conditions that
generate cardiac progenitor cells to obtain a culture of cells;
[0131] contacting the culture of cells with one or more agents
reactive with LIFR and/or FGFR3; and
[0132] separating LIFR reactive positive cells and/or FGFR3
reactive positive cells from non-reactive cells to thereby isolate
human cardiac ventricular progenitor cells.
[0133] Alternatively, after the culturing and contacting steps, the
method can comprise isolating LIFR and/or FGFR3 reactive positive
cells from non-reactive cells to thereby isolate human cardiac
ventricular progenitor cells.
[0134] In one embodiment of the above method, the culture of human
cells is also contacted with an agent reactive with Islet 1; and
LIFR reactive/Islet 1 reactive, FGFR3 reactive/Islet 1 reactive
positive cells or LIFR reactive/FGFR3 reactive/Islet 1 reactive
positive cells are separated from non-reactive cells to thereby
isolate human cardiac ventricular progenitor cells. The culture of
human cells can be simultaneously contacted with the agent(s)
reactive with LIFR and/or FGFR3 and the agent(s) reactive with
Islet 1. Alternatively, the culture of human cells can be contacted
with the agent(s) reactive with Islet 1 before contacting with the
agent reactive with LIFR and/or FGFR3. Alternatively, the culture
of human cells can be contacted with the agent(s) reactive with
LIFR and/or FGFR3 before contacting with the agent reactive with
Islet 1.
[0135] In yet another embodiment, the culture of human cells can be
contacted with an agent reactive with LIFR and an agent reactive
with FGFR3, and cells that are LIFR+/FGFR3+ can be separated. In
yet another embodiment, the culture of human cells can be contacted
with an agent reactive with LIFR, an agent reactive with FGFR3 and
an agent reactive with Islet 1, and cells that are
LIFR+/FGFR3+/Islet 1+ can be separated.
[0136] In a preferred embodiment, the agent reactive with LIFR is
an anti-LIFRantibody, such as a monoclonal antibody. Non-limiting
examples include murine, rabbit, human, humanized or chimeric
monoclonal antibodies with binding specificity for LIFR. Anti-LIFR
monoclonal antibodies are commercially available in the art (e.g.,
R&D Systems, Santa Cruz Biotechnology). Moreover, anti-LIFR
antibodies can be prepared using standard techniques well
established in the art using LIFR as the antigen.
[0137] In another embodiment, the agent reactive with LIFR is a
LIFR ligand, such as a soluble LIFR ligand or a soluble LIFR ligand
fusion protein. Non-limiting examples of LIFR ligands include
leukemia inhibitory factor (LIF), oncostatin M (OSM) and
cardiotrophin-1 (CT-1). Preferably, the LIFR ligand is LIF. Soluble
LIFR ligands can be prepared using standard recombinant DNA
techniques, for example by deletion of the transmembrane and
cytoplasmic domains. A soluble ligand can be transformed into a
soluble ligand fusion protein also using standard recombinant DNA
techniques. A fusion protein can be prepared in which fusion
partner can comprise a binding moiety that facilitates separation
of the fusion protein.
[0138] Similarly, the agent reactive with FGFR3 can be, for
example, an anti-FGFR3 antibody (e.g., monoclonal antibody) or a
FGFR3 ligand, such as a FGFR3 ligand fusion protein. Non-limiting
examples include murine, rabbit, human, humanized or chimeric
monoclonal antibodies with binding specificity for FGFR3.
Anti-FGFR3 monoclonal antibodies are commercially available in the
art (e.g., R&D Systems, Santa Cruz Biotechnology). Moreover,
anti-FGFR3 antibodies can be prepared using standard techniques
well established in the art using FGFR3 as the antigen.
Non-limiting examples of FGFR3 ligands include Fibroblast Growth
Factor 1 (FGF1), Fibroblast Growth Factor 2 (FGF2) and Fibroblast
Growth Factor 9 (FGF9).
[0139] Similarly, the agent reactive with Islet 1 can be, for
example, an anti-Islet 1 antibody (e.g., monoclonal antibody) or an
Islet 1 ligand, such as an Islet 1 ligand fusion protein.
[0140] In order to separate the LIFR and/or FGFR3 reactive positive
cells from non-reactive cells, one of a variety of different cell
separation techniques known in the art can be used. Preferably, the
LIFR and/or FGFR3 reactive positive cells are separated from
non-reactive cells by fluorescence activated cell sorting (FACS).
The FACS technology, and apparatuses for carrying it out to
separate cells, is well established in the art. When FACS is used
for cell separation, preferably the agent(s) reactive with LIFR
and/or FGFR3 that is used is a fluorescently-labeled anti-LIFR
and/or anti-FGFR3 monoclonal antibody. Alternatively, cell
separation can be achieved by, for example, magnetic activated cell
sorting (MACS). When MACS is used for cell separation, preferably
the agent reactive with LIFR or FGFR3 that is used is magnetic
nanoparticles coated with anti-LIFR or anti-FGFR3 monoclonal
antibody. Alternatively, other single cell sorting methodologies
known in the art can be applied to the methods of isolating cardiac
ventricular progenitor cells of the invention, including but not
limited to IsoRaft array and DEPArray technologies.
[0141] Prior to contact with the agent(s) reactive with LIFR and/or
FGFR3, and separation of LIFR and/or FGFR3 reactive cells, human
pluripotent stem cells can be cultured under conditions that lead
to the generation of cardiac progenitor cells. Culture conditions
for generating cardiac progenitor cells have been described in the
art (see e.g., Lian, X. et al. (2012) Proc. Natl. Acad. Sci. USA
109:E1848-1857; U.S. Patent Publication No. 20130189785) and also
are described in detail in Example 1 and FIG. 1, as well as in
Example 10. Typically, Wnt/.beta.-catenin signaling is first
activated in the hPSCs, followed by an incubation period, followed
by inhibition of Wnt/.beta.-catenin signaling. Activation of
Wnt/.beta.-catenin signaling is achieved by incubation with a Gsk3
inhibitor, preferably CHIR98014 (CAS 556813-39-9). Inhibition of
Wnt/.beta.-catenin signaling is achieved by incubation with a Porcn
inhibitor, preferably Wnt-C59 (CAS 1243243-89-1). Suitable hPSCs
for use in the methods of the invention include induced pluripotent
stem cells (iPSC), such as 19-11-1, 19-9-7 or 6-9-9 cells (Yu, J.
et al. (2009) Science 324:797-801), and human embryonic stem cell
lines, such as ES03 cells (WiCell Research Institute) or H9 cells
(Thomson, J. A. et al. (1998) Science 282:1145-1147). Suitable
culture media for generating cardiomyogenic progenitors include E8
medium, mTeSR1 medium and RPMI/B27 minus insulin, each described
further in Example 1 and/or Example 10.
[0142] Preferably, the human cardiomyogenic progenitor cells are
ventricular progenitor cells. Culture conditions have now been
determined that bias the cardiomyogenic progenitor cells to the
ventricular lineage. These ventricular cardiomyogenic progenitor
cells can be cultured in RPMI/B27 medium and they can further
differentiate into ventricular muscle cells. A preferred medium for
culturing the cardiac ventricular progenitor cells in vitro such
that they differentiation into ventricular cells in vitro (e.g.,
expressing the MLC2v marker described below) is the Cardiac
Progenitor Culture (CPC) medium (advanced DMEM/F12 supplemented
with 20% KnockOut Serum Replacement, 2.5 mM GlutaMAX and 100
.mu.g/ml Vitamin C).
[0143] Known markers of differentiated cardiac cells can be used to
identify the type(s) of cells that are generated by differentiation
of the cardiac progenitor cells. For example, cardiac troponin I
(cTnI) can be used as a marker of cardiomyocyte differentiation.
CD144 (VE-cadherin) can be used as a marker of endothelial cells.
Smooth muscle actin (SMA) can be used as a marker of smooth muscle
cells. MLC2v can be used as a marker of ventricular muscle cells.
MLC2a, which is expressed on both immature ventricular muscle cells
and atrial muscle cells, can be used as a marker for those cell
types. Additionally, sarcolipin, which is specifically expressed in
atrial muscle cells, can be used as a marker for atrial muscle
cells. Phospholamban, which is expressed predominantly in the
ventricles and, to a lesser extent, in the atria, can also be used
as a marker. Hairy-related transcription factor 1 (HRT1), also
called Hey1, which is expressed in atrial cardiomyocytes, can be
used as a marker for atrial cardiomyocytes. HRT2 (Hey2), which is
expressed in ventricular cardiomyocytes, can be used as a marker
for ventricular cardiomyocytes. In addition, IRX4 has a
ventricular-restricted expression pattern during all stages of
development, and thus can be used as a ventricular lineage marker.
In summary, the genes expressed in the ventricles, and thus which
are appropriate ventricular markers, are: MLC2v, IRX4 and HRT2,
while genes expressed in the atria, and thus which are appropriate
atrial markers are: MLC2a, HRT1, Sarcolipin and ANF (atrial
natriuretic factor). The preferred marker of ventricular
differentiation is MLC2v.
Clonal Populations of Human Cardiac Ventricular Progenitor
Cells
[0144] In another aspect, the invention provides methods for
obtaining a clonal population of human cardiac ventricular
progenitor cells, as well as isolated clonal populations of such
progenitors. The invention allows for the expansion and propagation
of the cardiac ventricular progenitor cells such that a clonal
population of a billion or more cells can be achieved. The ability
to clonally expand the LIFR+ and/or FGFR3+ cardiac ventricular
progenitor cells to such large numbers is a necessary feature for
successful use of these cells in vivo to enhance cardiac function,
since such a use requires on the order of a billion or more
cells.
[0145] Accordingly, in another aspect, the invention provides a
method for obtaining a clonal population of human cardiac
ventricular progenitor cells, the method comprising:
[0146] isolating a single LIFR+ and/or FGFR3+ human cardiac
ventricular progenitor cell; and
[0147] culturing the single LIFR+ and/or FGFR3+ human cardiac
ventricular progenitor cell under conditions such that the cell is
expanded to at least 1.times.10.sup.9 cells to thereby obtain a
clonal population of human cardiac ventricular progenitor
cells.
[0148] In a preferred embodiment, the single LIFR+ and/or FGFR3+
human cardiac ventricular progenitor cell is Islet 1 positive,
Nkx2.5 negative and flk1 negative at the time of initial culture.
As described further in the Examples, such a single cell can be
obtained at approximately day 6 of the culture under conditions
that promote the generation of cardiomyogenic progenitors. The
clonal population of human cardiac ventricular progenitors can be
further cultured and differentiated in vitro such that the cells
express the ventricular maker MLC2v.
[0149] Preferably, the single LIFR+ and/or FGFR3+ human cardiac
ventricular progenitor cell is isolated by fluorescence activated
cell sorting. Alternatively, the cell can be isolated by MACS or by
other cell sorting methods known in the art and/or described
herein.
[0150] Preferably, the single LIFR+ and/or FGFR3+ human cardiac
ventricular progenitor cell is isolated using one or more agents
reactive with LIFR and/or FGFR3, such as an anti-LIFR antibody or
other agent reactive with LIFR as described hereinbefore, or an
anti-FGFR3 antibody or other agent reactive with FGFR3 as described
hereinbefore.
[0151] In other embodiments, the clonal population of human cardiac
ventricular progenitor cells is LIFR+ and FGFR3+. Such
double-positive cells can be isolated and clonally expanded as
described herein before using both an agent reactive with LIFR and
an agent reactive with FGFR3.
[0152] In a preferred embodiment, the single LIFR+ and/or FGFR3+
human cardiac ventricular progenitor cell is cultured in Cardiac
Progenitor Culture (CPC) medium, as described hereinbefore
[0153] In a preferred embodiment, the single LIFR+ and/or FGFR3+
human cardiac ventricular progenitor cell is cultured under
conditions such that the cell is biased toward ventricular
differentiation. Preferred culture conditions include culture in
CPC medium.
[0154] In various embodiments, the single LIFR+ and/or FGFR3+ human
cardiac ventricular progenitor cell can be expanded to at least
1.times.10.sup.9 cells, at least 2.times.10.sup.9 cells, at least
3.times.10.sup.9 cells, at least 4.times.10.sup.9 cells, at least
5.times.10.sup.9 cells, at least 6.times.10.sup.9 cells, at least
7.times.10.sup.9 cells, at least 8.times.10.sup.9 cells, at least
9.times.10.sup.9 cells or at least 10.times.10.sup.9 cells.
[0155] Accordingly, the invention also provides a clonal population
of at least 1.times.10.sup.9 LIFR+ and/or FGFR3+ human cardiac
ventricular progenitor cells, which are obtainable or obtained by
the methods of the invention for obtaining a clonal population of
human cardiac ventricular progenitor cells. In various embodiments,
the clonal population of LIFR+ and/or FGFR3+ human cardiac
ventricular progenitor cells comprises at least 1.times.10.sup.9
cells, at least 2.times.10.sup.9 cells, at least 3.times.10.sup.9
cells, at least 4.times.10.sup.9 cells, at least 5.times.10.sup.9
cells, at least 6.times.10.sup.9 cells, at least 7.times.10.sup.9
cells, at least 8.times.10.sup.9 cells, at least 9.times.10.sup.9
cells or at least 10.times.10.sup.9 cells. Differentiation of the
progenitor cells to the ventricular lineage in vitro can be
achieved by culture under conditions described herein for biasing
toward the ventricular lineage. Furthermore, transplantation of the
cardiac ventricular progenitor cells in vivo leads to ventricular
differentiation in vivo.
[0156] The invention also provides pharmaceutical compositions
comprising the clonal population of cardiac ventricular progenitor
cells. The pharmaceutical compositions typically are sterile and
can comprise buffers, media, excipients and the like suitable for
pharmaceutical administration. In one embodiment, the
pharmaceutical composition comprising the clonal population is
formulated onto a three dimensional (3D) matrix. Compositions
formulated onto a 3D matrix are particularly preferred for
formation of a heart muscle cell patch that can be transplanted in
vivo for heart muscle repair. Furthermore, the compositions can be
formulated into two dimensional (2D) sheets of cells, such as a
muscular thin film (MTF) as described in Domian, I. J. et al.
(2009) Science 326:426-429. Such 2D sheets of cell tissue also can
be used in the formation of a heart muscle cell patch that can be
transplanted in vivo for heart muscle repair.
Generation of Human Ventricular Progenitors (HVPs)
[0157] Prior to isolation by the aforementioned methods, and
optionally obtaining a clonal population by the aforementioned
methods, a non-clonal population of human ventricular progenitors
(HVPs) can be obtained by culture of human pluripotent stem cells
(hPSCs) under appropriate culture conditions to generate the HVPs.
An exemplary set of culture conditions, and suitable starting
cells, is described in detail in Example 1 and Example 10, also
referred to herein as the Human Ventricular Progenitor Generation
(HVPG) protocol. Suitable hPSC starting cells include induced
pluripotent stem cells (iPSC) and human embryonic stem cells, such
as ES cell lines. For the protocol, Wnt/.beta.-catenin signaling
first is activated in the hPSCs, followed by an incubation period,
followed by inhibition of Wnt/.beta.-catenin signaling.
Wnt/.beta.-catenin signaling activation is achieved by incubation
with a Gsk3 inhibitor, preferably CHIR98014 (CAS 556813-39-9;
commercially available from, e.g., Selleckchem). Wnt/.beta.-catenin
signaling inhibition is achieved by incubation with a Porcn
inhibitor, preferably Wnt-C59 (CAS 1243243-89-1; commercially
available from, e.g., Selleckchem or Tocris). The Gsk3 inhibitor is
used to promote cardiac mesodermal differentiation, whereas the
Porcn inhibitor is used to enhance ventricular progenitor
differentiation from mesoderm cells.
[0158] Accordingly, in another aspect, the invention provides a
method of generating human ventricular progenitors (HVPs)
comprising culturing human pluripotent stems cells (hPSCs) in a
medium comprising a Gsk3 inhibitor, preferably CHIR98014, for at
least 24 hours, more preferably for 2 days or 3 days, followed by
culturing the hPSCs in a medium comprising a Porcn inhibitor,
preferably Wnt-C59 (and lacking the Gsk3 inhibitor), for at least
48 hours such that HVPs are generated. Experiments showed that
after 24-hour treatment with CHIR-98014, more than 99% of hPSCs
expressed the mesoderm marker Brachyury, and three days later after
treatment with CHIR-98014, more than 95% of differentiated cells
expressed Mesp1, which marks the cardiac mesoderm. Furthermore,
48-hour treatment with Wnt-C59 enhanced ventricular progenitor
differentiation from mesoderm cells.
[0159] Accordingly, with regard to timing of the use of the Gsk3
and Porcn inhibitors, typically, at day 0 of culture, the hPSCs are
cultured with the Gsk3 inhibitor, at day 3 of culture the medium is
changed to remove the Gsk3 inhibitor and the cells are then
cultured with media containing the Porcn inhibitor through day 5 of
culture. HVP generation is optimal between days 5 and 7 (inclusive)
in culture and peaks at day 6 of culture. Other non-limiting,
exemplary details on culture conditions and timing of the use of
the Gsk3 and Porcn inhibitors are described in detail in Examples 1
and 10.
In Vivo Tissue Engineering
[0160] In vivo transplantation studies described in Example 6 and 7
in which the human ventricular progenitors (HVPs) were transplanted
under the kidney capsule in nude mice document the ability of the
HVPs to spontaneously assemble into a large wall of mature,
functional, human ventricular muscle on the surface of the kidney
capsule. Vascularization occurs via a paracrine pathway by calling
the murine vasculature to the ventricular muscle wall, while a
matrix is generated via a cell autonomous pathway from the
progenitors themselves. In vivo intra-myocardial transplantation
studies described in Example 8 in which the HVPs were transplanted
into the normal murine heart document that the HVPs spontaneously
migrate to the epicardial surface, where they expand, subsequently
differentiate, and mature into a wall of human ventricular muscle
on the surface of the epicardium. Taken together, these studies
show that human ventriculogenesis can occur via a completely cell
autonomous pathway in vivo via purified HVPs, thereby allowing
their use in organ-on-organ in vivo tissue engineering.
[0161] The human ventricular myocardium has a limited capacity for
regeneration, most of which is lost after 10 years of age
(Bergmann, O. et al. (2015) Cell 161:1566-1575). As such, new
strategies to generate heart muscle repair, regeneration, and
tissue engineering approaches during cardiac injury have been a
subject of intense investigation in regenerative biology and
medicine (Sahara, M. et al. (2015) EMBO J. 34:710-738; Segers, V.
F. M. and Lee, R. T. (2008) Nature 451:937-942). Given the need to
achieve coordinated vascularization and matrix formation during
tissue engineering of any solid organ, the assumption has been that
the formation of an intact 3-D solid organ in vivo will ultimately
require the addition of vascular cells and/or conduits, as well as
biomaterials and/or decellularized matrix that will allow alignment
and the generation of contractile force (Forbes, S. J. and
Rosenthal, N. (2014) Nature Med. 20:857-869; Harrison, R. H. et al.
(2014) Tissue Eng. Part B Rev. 20:1-16). The complexity of adding
these various components to achieve the formation of a functional
solid organ has confounded attempts to reduce this to clinical
practice (Webber, M. J. et al. (2014) Ann. Biomed. Eng.
43:641-656). Although hPSCs hold great promise, to date, it has not
been possible to build a pure, vascularized, fully functional, and
mature 3-D human ventricular muscle organ in vivo on the surface of
a heart in any mammalian system (Vunjak-Novakovic, G. et al. (2011)
Annu. Rev. Biomed. Eng. 13:245-267).
[0162] The ability of generate billions of purified HVPs from a
renewable source of either human ES or iPS cell lines represent a
new approach to the generation of functional ventricular muscle in
the setting of advanced heart failure. The progenitors can be
delivered by intramyocardial injection and then self-migrate to the
epicardial surface where they expand and differentiate, losing
progenitor markers. Over the course of several week, the cells exit
the cell cycle, and proceed to form adult rod-shaped cells that
display several independent markers of mature ventricular
myocardium including the formation of T tubules, catecholamine
responsiveness, loss of automaticity, adult rod shaped conformation
with aligned sarcomenric structures, and the ability to generate
force that is comparable to other heart muscle patches derived from
hPSCs differentiated cardiomyocytes (Tulloch, N. L. et al. (2011)
Circ. Res. 109:47-59). The scalability of this cell autonomous
pathway has allowed the ectopic generation of human ventricular
muscle that has a combined thickness in excess of 1.5 cm in
thickness, approaching levels that correspond to the human
ventricular free wall (Basavarajaiah, S. et al. (2007) Br. J.
Sports Med. 41:784-788).
[0163] The ability to migrate to the epicardial niche, the site of
most of the adult heart progenitors at later stages, is a unique
feature of HVPs, and mimics the normal niche of these cells during
expansion of the ventricular compact zone during ventriculogenesis.
Previous studies have shown that the generation of acute ischemic
injury and a breakdown in vascular permeability are a pre-requisite
for the grafting of relatively small numbers of ES cell derived
cardiomyocytes into injured myocardium (van Laake, L. W. et al.
(2007) Stem Cell Res. 1:9-24; Laflamme, M. A. et al. (2007) Nat.
Biotechnol. 25:1015-1024), and even then the survival rate is low
(<5%) (Laflamme, M. A. and Murry, C. E. (2011) Nature
473:326-335; Laflamme, M. A. et al. (2005) Am. J. Pathol.
167:663-671). The ability of intra-myocardial HVPs to form an
extensive ventricular patch on the epicardial surface in the
absence of acute ischemic injury provides a new therapeutic
strategy for dilated cardiomyopathy without the need for additional
biomaterials, cells, or transfer of exogenous genes and/or
RNAs.
[0164] The ability to form a 3-D ventricular muscle wall on the
epicardial surface of the in vivo normal heart is a unique feature
of the ISL1/FZD4/JAG1 ventricular progenitors as later stage
progenitors do not display the ability for the formation of
three-dimensional ventricular tissue in either the cardiac or
non-cardiac context, emphasizing the importance of generating a
committed ventricular lineage as well as purifying the specific
ventricular progenitor at a specific stage of
ventriculogenesis.
[0165] Accordingly, the invention provides methods for generating
human ventricular tissue in vivo using the HVPs described herein.
In one embodiment, the method comprises transplanting the LIFR+
and/or FGFR3+ progenitors into an organ of a non-human animal and
allowing the progenitors to grow in vivo such that human
ventricular tissue is generated. Preferably, the non-human animal
is immunodeficient such that it cannot mount an immune response
against the human progenitor cells. In one embodiment, the
non-human animal is a mouse, such as an immunodeficient NOD.
Cg-Prkdcscid Il2rgtm1Wjl/SzJ mouse or an immunodeficient SCID-beige
mouse (commercially available from Charles River France). In one
embodiment, the organ is a kidney (e.g., the cells are transplanted
under the kidney capsule). In another embodiment, the organ is a
heart. In various embodiments, at least 1.times.10.sup.6 cells, at
least 2.times.10.sup.6 cells, at least 3.times.10.sup.6 cells, at
least 4.times.10.sup.6 cells, at least 5.times.10.sup.6 cells, at
least 1.times.10.sup.7 cells, at least 5.times.10.sup.7 cells, at
least 1.times.10.sup.8 cells, at least 1.times.10.sup.9 cells are
transplanted.
[0166] To obtain HVPs for transplantation, human pluripotent stem
cells (hPSCs) can be cultured in vitro under conditions leading to
the generation of HVPs, as described herein (referred to herein as
the HVPG protocol). Regarding the timing of transplanting HVPs post
in-vitro culture, for optimal ventricular tissue generation the
cells should be transplanted at a stage that can be defined based
on the cellular markers expressed by the HVPs at the time of
transplantation, determined at days post the start of culture,
which is defined as day 0 of the HVPG protocol. In one embodiment,
the cells are transplanted after the peak of cardiac mesoderm
formation, which can be defined as peak expression of the
mesodermal marker MESP1. Typically, MESP1 expression is between day
2 and day 4 of culture (inclusive) and peaks at day 3. In one
embodiment, the cells are transplanted at the time corresponding to
peak Islet-1 expression. Typically, Islet 1 is expressed between
day 4 to day 8 of culture (inclusive) and peaks at day 6 of
culture. In one embodiment, the cells are transplanted before the
peak of NKX2.5 expression. Typically, NKX2.5 expression starts at
day 6 of culture, peaks at day 10 of culture and is then maintained
afterwards. In one embodiment, the cells are transplanted prior to
the peak expression of the downstream genes MEF-2 and TBX-1.
Typically, these downstream genes are expressed between day 5 and
day 15 of culture (inclusive) and peaks at day 8 of culture. In one
embodiment, the cells are transplanted prior to the expression of
differentiated contractile protein genes. Typically, the expression
of contractile protein genes (including TNNT2 and MYH6) starts from
day 10 of culture onward. In certain embodiments, the cells are
transplanted at a time when two, three or four of the
aforementioned marker patterns are present. In another embodiment,
the cells are transplanted at a time when all five of the
aforementioned marker patterns are present. In one embodiment, the
cells are transplanted between day 4 to day 8 (inclusive) of
culture. In a more preferred embodiment, the cells are transplanted
between day 5 to day 7 (inclusive) of culture. In the most
preferred embodiment, the cells are transplanted on day 6 of
culture.
[0167] The transplanted cells can be allowed to grow in the
non-human animal for a suitable period time to allow for the
generation of the desired size, amount or thickness of ventricular
tissue. In various embodiments, the cells are allowed to grow for
one week, two weeks, one month, two months, three months, four
months, five months or six months. The method can further comprise
harvesting ventricular tissue from the non-human animal after
growth of the cells and differentiation into ventricular
tissue.
Methods of Enhancing Cardiac Function
[0168] The cardiac ventricular progenitor cells of the invention
can be used in vivo to enhance cardiac function by transplanting
the cells directly into the heart. It has now been shown that the
LIFR+ and/or FGFR3+ progenitors have the capacity to differentiate
into all three types of cardiac lineage cells (cardiac myocytes,
endothelial cells and smooth muscle cells) (see Example 3).
Furthermore, when cultured under conditions that bias toward the
ventricular lineage, the LIFR+ and/or FGFR3+ progenitors have now
been shown to adopt a predominantly ventricular muscle phenotype
when transplanted into the natural ventricle environment in vivo,
demonstrating that these progenitor cells "recognize" the
ventricular environment and respond and differentiate appropriately
in vivo. Since damage to the ventricular environment is largely
responsible for the impaired cardiac function in cardiac diseases
and disorders, the ability to restore ventricular muscle cells
using the ventricular progenitor cells of the invention represents
a significant advance in the art.
[0169] Accordingly, in another aspect, the invention provides a
method of enhancing cardiac function in a subject, the method
comprising administering a pharmaceutical composition comprising
the clonal population of LIFR+ and/or FGFR3+ cardiac ventricular
progenitor cells of the invention to the subject. Preferably, the
clonal population is administered directly into the heart of the
subject. More preferably, the clonal population is administered
directly into a ventricular region of the heart of the subject. In
one embodiment, the pharmaceutical composition administered to the
subject comprises the clonal population formulated onto a three
dimensional matrix.
[0170] The methods of the invention for enhancing cardiac function
in a subject can be used in a variety of clinical situations
involving damage to the heart or reduced or impaired cardiac
function. Non-limiting examples of such clinical situations include
a subject who has suffered a myocardial infarction and a subject
who has a congenital heart disorder. Thus, in another aspect, the
invention provides a method of treating a cardiovascular condition,
disease or disorder in a subject, the method comprising
administering a pharmaceutical composition comprising the clonal
population of LIFR+ and/or FGFR3+ cardiac ventricular progenitor
cells of the invention to the subject. A therapeutically effective
amount of cardiac ventricular progenitor cells can be administered
for the treatment of a cardiovascular condition, disease or
disorder. Examples of preferred cardiovascular conditions, diseases
or disorders include coronary artery disease and acute coronary
syndrome.
Methods of Use of Cardiac Ventricular Progenitor Cells In Vitro
[0171] The cardiac ventricular progenitor cells of the invention
can be used in vitro in the study of various aspects of cardiac
maturation and differentiation, in particular in identifying the
cells signaling pathways and biological mediators involved in the
process of cardiac maturation and differentiation.
[0172] Furthermore, since the LIFR+ and/or FGFR3+ cardiac
ventricular progenitor cells of the invention are committed to the
cardiac lineage and, moreover, are biased toward ventricular
differentiation, these progenitor cells also are useful for
evaluating the cardiac toxicity of test compounds. All potential
new drugs and therapeutics must be evaluated for their toxicity to
cardiac cells, before they can be deemed safe for use in humans.
Thus, the ability to assess cardiac toxicity in an in vitro culture
system is very advantageous. Accordingly, in another aspect, the
invention provides a method of screening for cardiac toxicity of
test compound, the method comprising
[0173] providing LIFR+ and/or FGFR3+ human cardiac ventricular
progenitor cells;
[0174] contacting the cells with the test compound; and
[0175] measuring toxicity of the test compound for the cells,
[0176] wherein toxicity of the test compound for the cells
indicates cardiac toxicity of the test compound.
[0177] In a preferred embodiment, the LIFR+ and/or FGFR3+ human
cardiac ventricular progenitor cells are provided by isolating the
cells according to the methods described herein. In a particularly
preferred embodiment, the cells are isolated by separating LIFR+
and/or FGFR3+ cells from a cell culture comprising cardiac
progenitor cells using an anti-LIFR and/or anti-FGFR3 antibody.
Preferably, the cells are isolated using FACS or MACS as described
herein. In yet another embodiment, the LIFR+ and/or FGFR3+ human
cardiac ventricular progenitor cells are further cultured and
differentiation into MLC2v+ ventricular cells prior to contacting
with the test compound.
[0178] The toxicity of the test compound for the cells can be
measured by one or more of a variety of different methods for
assessing cell viability or other physiological functions.
Preferably, the effect of the test compound on cell viability is
measured using a standard cell viability assay, wherein reduced
cell viability in the presence of the test compound is indicative
of cardiac toxicity of the test compound. Additionally or
alternatively, cell growth can be measured. Additionally or
alternatively, other indicators of physiological functions can be
measured, such as cell adhesion, cell signaling, surface marker
expression, gene expression and the like. Similarly, a negative
effect of the test compound on any of these indicators of
physiological function is indicative of cardiac toxicity of the
test compound.
[0179] The invention further provides a method of identifying a
compound that modulates human cardiac ventricular progenitor cell
differentiation, the method comprising
[0180] providing LIFR+ and/or FGFR3+ human cardiac ventricular
progenitor cells;
[0181] culturing the cells in the presence or absence of a test
compound;
[0182] measuring differentiation of the cells in the presence or
absence of the test compound; and
[0183] selecting a test compound that modulates human cardiac
ventricular progenitor cell differentiation, as compared to
differentiation in the absence of the test compound, to thereby
identify a compound that modulates human cardiac ventricular
progenitor cell differentiation.
[0184] In one embodiment, the test compound stimulates human
cardiac ventricular progenitor cell differentiation. In another
embodiment, the test compound inhibits human cardiac ventricular
progenitor cell differentiation. Differentiation of the cells can
be measured by, for example, measurement of the expression of
differentiation markers appearing on the cultured cells over time,
as described herein. In a preferred embodiment, the LIFR+ and/or
FGFR3+ human cardiac ventricular progenitor cells are provided by
isolating the cells according to the methods described herein. In a
particularly preferred embodiment, the cells are isolated by
separating LIFR+ and/or FGFR3+ cells from a cell culture comprising
cardiac progenitor cells using an anti-LIFR and/or anti-FGFR3
antibody. Preferably, the cells are isolated using FACS or MACS as
described herein.
[0185] The invention further provides a method of identifying a
compound that modulates human ventricular cardiomyocyte function,
the method comprising
[0186] providing LIFR+ and/or FGFR3+ human cardiac ventricular
progenitor cells;
[0187] culturing the cells in the presence or absence of a test
compound under conditions that generate human ventricular
cardiomyocytes;
[0188] measuring function of the human ventricular cardiomyocytes
in the presence or absence of the test compound; and
[0189] selecting a test compound that modulates human ventricular
cardiomyocyte function, as compared to function in the absence of
the test compound, to thereby identify a compound that modulates
human ventricular cardiomyocyte function.
[0190] In one embodiment, the test compound stimulates human
ventricular cardiomyocyte function. In another embodiment, the test
compound inhibits human ventricular cardiomyocyte function.
Function of the cells can be measured by measurement of any
suitable indicator of ventricular cell function, including but not
limited to, for example, formation of T tubules, acquisition of
adult-rod shaped ventricular cardiomyocytes, and ability to
generate force in response to electrical stimulation. Suitable
assays for measuring such indicators of ventricular cell function
are known in the art. In a preferred embodiment, the LIFR+ and/or
FGFR3+ human cardiac ventricular progenitor cells are provided by
isolating the cells according to the methods described herein. In a
particularly preferred embodiment, the cells are isolated by
separating LIFR+ and/or FGFR3+ cells from a cell culture comprising
cardiac progenitor cells using an anti-LIFR and/or anti-FGFR3
antibody. Preferably, the cells are isolated using FACS or MACS as
described herein.
In Vivo Animal Models Using Human Ventricular Progenitor Cells
[0191] The development of human iPS and ES cell based models of
cardiac disease has opened new horizons in cardiovascular drug
development and discovery. However, to date, these systems have had
the limitations of being based on 2D structures in cultured cell
systems. In addition, the fetal and immature properties of the
cells limit their utility and fidelity to the adult heart. Human
cardiac disease, in particular heart failure, is a complex,
multifactorial, multi-organ disease, that is influenced by
environmental, hormonal, and other key organs that are known sites
for therapeutic targets, such as the kidney. The ability to build a
mature functional human ventricular organ either ectopically or on
the surface of the intact normal murine heart opens up a new in
vivo model system to allow studies that normally could only be
assayed on a mature human ventricular muscle chamber, such as
ventricular arrhythmias, generation of contractile force, fibrosis,
and the potential for regeneration. Accordingly, the option to
study human cardiac disease outside of the in vitro tissue culture
systems, and directly in the context of heart failure in vivo, is
now clearly possible.
[0192] Thus, the human ventricular progenitor cells also can be
used to create animal models that allow for in vivo assessment of
human cardiac tissue function and for in vivo screening of
compounds, such as to determine the cardiac toxicity of a test
compound in vivo or to identify compounds that modulate human
cardiac tissue differentiation or function in vivo. Accordingly,
the invention provides methods for testing the effects of test
compounds on human ventricular tissue in vivo using the HVPs
described herein. In one embodiment, the method comprises:
[0193] transplanting LIFR+ and/or FGFR3+ human ventricular
progenitors into an organ of a non-human animal;
[0194] allowing the progenitors to grow in vivo such that human
ventricular tissue is generated;
[0195] administering a test compound to the non-human animal;
and
[0196] evaluating the effect of the test compound on the human
ventricular tissue in the non-human animal.
[0197] In another embodiment, the method comprises:
[0198] administering a test compound to a non-human animal, wherein
the non-human animal comprises LIFR+ and/or FGFR3+ human
ventricular progenitors transplanted into an organ of the non-human
animal; and
[0199] evaluating the effect of the test compound on the LIFR+
and/or FGFR3+ human ventricular progenitors in the non-human
animal.
[0200] In one embodiment, the cardiac toxicity of the test compound
is evaluated, for example by measuring the effect of the test
compound on the viability of the human ventricular tissue or the
LIFR+ and/or FGFR3+ human ventricular progenitors in the non-human
animal (as compared to the viability of the tissue or progenitors
in the absence of the test compound). Cell viability can be
assessed by standard methods known in the art.
[0201] In another embodiment, the ability of a test compound to
modulate cardiac differentiation can be evaluated, for example by
measuring the effect of the test compound on the differentiation of
the human ventricular tissue or LIFR+ and/or FGFR3+ progenitors in
the non-human animal (as compared to the differentiation of the
tissue or progenitors in the absence of the test compound).
Differentiation of the cells can be measured by, for example,
measurement of the expression of differentiation markers appearing
on the cells over time.
[0202] In another embodiment, the ability of a test compound to
modulate cardiac function can be evaluated, for example by
measuring the effect of the test compound on the function of the
human ventricular tissue or LIFR+ and/or FGFR3+ human progenitors
in the non-human animal (as compared to the function of the tissue
or progenitors in the absence of the test compound). Function of
the tissue or progenitors can be measured by measurement of any
suitable indicator of ventricular cell function, including but not
limited to, for example, formation of T tubules, acquisition of
adult-rod shaped ventricular cardiomyocytes, and ability to
generate force in response to electrical stimulation. Suitable
assays for measuring such indicators of ventricular cell function
are known in the art.
[0203] Preferably, the non-human animal is immunodeficient such
that it cannot mount an immune response against the human
progenitor cells. In one embodiment, the non-human animal is a
mouse, such as an immunodeficient NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ
mouse or an immunodeficient SCID-beige mouse (commercially
available from Charles River France). In one embodiment, the organ
is a kidney (e.g., the cells are transplanted under the kidney
capsule). In another embodiment, the organ is a heart. In various
embodiments, at least 1.times.10.sup.6 cells, at least
2.times.10.sup.6 cells, at least 3.times.10.sup.6 cells, at least
4.times.10.sup.6 cells, at least 5.times.10.sup.6 cells, at least
1.times.10.sup.7 cells, at least 5.times.10.sup.7 cells, at least
1.times.10.sup.8 cells, at least 1.times.10.sup.9 cells are
transplanted.
[0204] To create the animal models, HVPs for transplantation can be
obtained as described above by culturing of hPSCs in vitro under
conditions leading to the generation of HVPs. Regarding the timing
of transplanting HVPs post in-vitro culture, for optimal
ventricular tissue generation the cells should be transplanted at a
stage that can be defined based on the cellular markers expressed
by the HVPs at the time of transplantation, determined at days post
the start of culture, which is defined as day 0 of the HVPG
protocol. In one embodiment, the cells are transplanted after the
peak of cardiac mesoderm formation, which can be defined as peak
expression of the mesodermal marker MESP1. Typically, MESP1
expression is between day 2 and day 4 of culture (inclusive) and
peaks at day 3. In one embodiment, the cells are transplanted at
the time corresponding to peak Islet-1 expression. Typically, Islet
1 is expressed between day 4 to day 8 of culture (inclusive) and
peaks at day 6 of culture. In one embodiment, the cells are
transplanted before the peak of NKX2.5 expression. Typically,
NKX2.5 expression starts at day 6 of culture, peaks at day 10 of
culture and is then maintained afterwards. In one embodiment, the
cells are transplanted prior to the peak expression of the
downstream genes MEF-2 and TBX-1. Typically, these downstream genes
are expressed between day 5 and day 15 of culture (inclusive) and
peaks at day 8 of culture. In one embodiment, the cells are
transplanted prior to the expression of differentiated contractile
protein genes. Typically, the expression of contractile protein
genes (including TNNT2 and MYH6) starts from day 10 of culture
onward. In certain embodiments, the cells are transplanted at a
time when two, three or four of the aforementioned marker patterns
are present. In another embodiment, the cells are transplanted at a
time when all five of the aforementioned marker patterns are
present. In one embodiment, the cells are transplanted between day
4 to day 8 (inclusive) of culture. In a more preferred embodiment,
the cells are transplanted between day 5 to day 7 (inclusive) of
culture. In the most preferred embodiment, the cells are
transplanted on day 6 of culture.
[0205] The transplanted cells can be allowed to grow in the
non-human animal for a suitable period time to allow for the
generation of the desired size, amount or thickness of ventricular
tissue, prior to administration of the test compound(s). In various
embodiments, the cells are allowed to grow for one week, two weeks.
one month, two months, three months, four months, five months or
six months.
[0206] The present invention is further illustrated by the
following examples, which should not be construed as further
limiting. The contents of figures and all references, patents and
published patent applications cited throughout this application are
expressly incorporated herein by reference.
EXAMPLES
Example 1: Generation of Human Isl1+ Cardiomyogenic Progenitor
Cells by Modulation of Wnt Signaling in Human Pluripotent Stem
Cells
[0207] Temporal modulation of canonical Wnt signaling has been
shown to be sufficient to generate functional cardiomyocytes at
high yield and purity from numerous hPSC lines (Lian, X. et al.
(2012) Proc. Natl. Acad. Sci. USA 109:E1848-1857; Lian, X. et al.
(2013) Nat. Protoc. 8:162-175). In this approach,
Wnt/.beta.-catenin signaling first is activated in the hPSCs,
followed by an incubation period, followed by inhibition of
Wnt/.beta.-catenin signaling. In the originally published protocol,
Wnt/.beta.-catenin signaling activation was achieved by incubation
with the Gsk3 inhibitor CHIR99021 (GSK-3 .alpha., IC.sub.50=10 nM;
GSK-3, .beta. IC.sub.50=6.7 nM) and Wnt/.beta.-catenin signaling
inhibition was achieved by incubation with the Porcn inhibitor IWP2
(IC.sub.50=27 nM). Because we used Gsk3 inhibitor and Wnt
production inhibitor for cardiac differentiation, this protocol was
termed GiWi protocol. To improve the efficiency of the original
protocol and reduce the potential side effects of the small
molecules used in the original protocol, a second generation
protocol was developed that uses another set of small molecules
with higher inhibition potency. In this second generation GiWi
protocol, Wnt/.beta.-catenin signaling activation was achieved by
incubation with the Gsk3 inhibitor CHIR98014 (CAS 556813-39-9;
commercially available from, e.g., Selleckchem) (GSK-3 .alpha.,
IC.sub.50=0.65 nM; GSK-3, .beta. IC.sub.50=0.58 nM) and
Wnt/.beta.-catenin signaling inhibition was achieved by incubation
with the Porcn inhibitor Wnt-C59 (CAS 1243243-89-1; commercially
available from, e.g., Selleckchem or Tocris) (IC.sub.50=74 pM). The
Gsk3 inhibitor CHIR98014 was used to promote cardiac mesodermal
differentiation, whereas the Porcn inhibitor Wnt-C59 was used to
enhance ventricular progenitor differentiation from mesoderm
cells.
[0208] For cardiomyocyte differentiation via the use of these small
molecules, hPSCs were maintained on Matrigel (BD Biosciences)
coated plates (Corning) in E8 medium (described in Chen, G. et al.
(2011) Nature Methods, 8:424-429; commercially available; STEMCELL
Technologies) or mTeSR1 medium (commercially available; STEMCELL
Technologies). Suitable hPSCs include induced pluripotent stem
cells (iPSCs) such as 19-11-1, 19-9-7 or 6-9-9 cells (Yu, J. et al.
(2009) Science, 324:797-801) and human embryonic stem cells
(hESCs), such as ES03 (WiCell Research Institute) and H9 cells
(Thomson, J. A. et al. (1998) Science, 282:1145-1147).
[0209] hPSCs maintained on a Matrigel-coated surface in mTeSR1
medium were dissociated into single cells with Accutase (Life
Technologies) at 37.degree. C. for 5 minutes and then seeded onto a
Matrigel-coated cell culture dish at 100,000-200,000 cells/cm.sup.2
in mTeSR1 medium supplemented with 5 .mu.M ROCK inhibitor Y-27632
(Selleckchem)(day -2) for 24 hours. Cells were then cultured in
mTeSR1, changed daily. At day 0, cells were then treated with 1
.mu.M Gsk3 inhibitor CHIR98014 (Selleckchem) for 24 hours (day 0 to
day 1) in RPMFB27-ins (500 ml RPMI with 10 ml B27 supplement
without insulin). The medium was then changed to the corresponding
medium containing 2 .mu.M the Porcn inhibitor Wnt-C59 (Selleckchem)
at day 3, which was then removed during the medium change on day 5.
Cells were maintained in RPMFB27 (stock solution: 500 ml RMPI
medium+10 ml B27 supplement) starting from day 7, with the medium
changed every three days. This exemplary culturing protocol for
generating cardiomyogenic progenitor cells is illustrated
schematically in FIG. 1.
[0210] Flow cytometry and immunostaining were performed to examine
the expression of particular lineage markers. After 24 hour
treatment with CHIR-98014, more than 99% of the hPSCs expressed the
mesoderm marker Brachyury. Three days after treatment with
CHIR-98014, more than 95% of differentiated cells expressed Mesp1,
which marks the cardiac mesoderm. The culture protocol not only
allowed the cells to synchronously differentiate into the cardiac
mesodermal lineage, but also reproducibly generated more than 90%
of ventricular myocytes after 14 days of differentiation, as
determined by cTnT flow cytometry and electrophysiology
analysis.
[0211] To further assess cardiac differentiation of the hPSCs over
time, Western blot analysis was performed on days 0-7 and d11 to
examine the expression of Isl1 and Nkx2.5 (cardiomyogenic
progenitor markers) and cTnI (a cardiac myocyte marker). Cells were
lysed in M-PER Mammalian Protein Extraction Reagent (Pierce) in the
presence of Halt Protease and Phosphatase Inhibitor Cocktail
(Pierce). Proteins were separated by 10% Tris-Glycine SDS/PAGE
(Invitrogen) under denaturing conditions and transferred to a
nitrocellulose membrane. After blocking with 5% dried milk in TBST,
the membrane was incubated with primary antibody overnight at
4.degree. C. The membrane was then washed, incubated with an
anti-mouse/rabbit peroxidase-conjugated secondary antibody at room
temperature for 1 hour, and developed by SuperSignal
chemiluminescence (Pierce). The results are shown in FIG. 2. During
cardiac differentiation of hPSCs, Isl1 expression started on day 4
and increased to its maximum expression on day 6, whereas NKx2.5
only started to express on day 6 and reached its maximum expression
after day 10. Cardiomyocytes (cTnI+ cells) were not induced until
day 11 of differentiation.
[0212] In addition, immunostaining of the day 6 cells was performed
for Isl1 expression. Cells were fixed with 4% formaldehyde for 15
minutes at room temperature and then stained with primary
(anti-Isl1) and secondary antibodies in PBS plus 0.4% Triton X-100
and 5% non-fat dry milk (Bio-Rad). Nuclei were stained with Gold
Anti-fade Reagent with DAPI (Invitrogen). An epifluorescence
microscope (Leica DM IRB) with a QImaging.RTM. Retiga 4000R camera
was used for imaging analysis. The results showed substantial
numbers of Isl1+ cells.
[0213] Flow cytometry analysis of day 6 cells for Isl1 expression
also was performed. Cells were dissociated into single cells with
Accutase for 10 minutes and then fixed with 1% paraformaldehyde for
20 minutes at room temperature and stained with primary and
secondary antibodies in PBS 0.1% Triton X-100 and 0.5% BSA. Data
were collected on a FACSCaliber flow cytometer (Beckton Dickinson)
and analyzed using FloJo. The results, shown in FIG. 3, showed that
more than 95% of cells expressed Isl1 at this stage.
[0214] In summary, this example provides a protocol for human
ventricular progenitor generation (HVPG protocol) that allows for
the large-scale production of billions of Isl1+ human HPVs
efficiently within 6 days.
Example 2: Identification of Jagged 1 as a Cell Surface Marker of
Cardiac Progenitor Cells
[0215] To profile the transcriptional changes that occur during the
cardiac differentiation process at a genome-scale level, RNA
sequencing (RNA-seq) was performed at different time points
following differentiation to build cardiac development
transcriptional landscapes. We performed RNA-seq experiments on day
0 to day 7 samples, as well as day 19 and day 35 samples (two
independent biological replicates per time point). Two batches of
RNA-seq (100 bp and 50 bp read length) were performed using the
illumine Hiseq 2000 platform. In total, 20 samples were examined.
Bowtie and Tophat were used to map our reads into a reference human
genome (hg19) and we calculate each gene expression (annotation of
the genes according to Refseq) using RPKM method (Reads per
kilobase transcript per million reads). Differentiation of hPSCs to
cardiomyocytes involves five major cell types: pluripotent stem
cells (day 0), mesoderm progenitors (day 1 to day 2), cardiac
mesoderm cells (day 3 to day 4), heart field progenitors (day 5,
day 6 and day 7), and cardiomyocytes (day 10 after).
[0216] Molecular mRNA analysis of cardiac differentiation from
hPSCs using the HVPG protocol revealed dynamic changes in gene
expression, with down-regulation of the pluripotency markers OCT4,
NANOG and SOX2 during differentiation. Induction of the primitive
streak-like genes T and MIXL1 occurred within the first 24 hours
following CHIR-98014 addition, and was followed by upregulation of
the cardiac mesodermal marker MESP1 on day 2 and day 3. Expression
of the cardiac muscle markers TNNT2, TNNC1, MYL2, MYL7, MYH6, MYH7
and IRX4 was detected at later stage of differentiation (after day
10).
[0217] By this analysis, genes enriched at each differentiation
stage, including mesoderm cells, cardiac progenitors and
cardiomyocytes, were identified. Mesoderm cells, which are related
to day 1 differentiated cells, express brachyury. We identified
potential surface markers for mesoderm cells, including: FZD10,
CD48, CD1D, CD8B, IL15RA, TNFRSF1B, TNFSF13, ICOSLG, SEMA7A,
SLC3A2, SDC1, HLA-A. Through similar analysis, we also identified
surface markers for cardiac mesoderm mesp1 positive cells,
including: CXCR4, ANPEP, ITGA5, TNFRSF9, FZD2, CD1D, CD177, ACVRL1,
ICAM1, L1 CAM, NGFR, ABCG2, FZD7, TNFRSF13C, TNFRSF1B.
[0218] Consistent with western blot analysis, ISL1 mRNA was
expressed as early as day 4 and peaked on day 5, one day before its
protein expression reached its peak. On day 5 of differentiation
(the cardiac progenitor stage, isl1 mRNA expression maximum on day
5, isl1 protein expression maximum on day 6), the day 5 enriched
genes were compared with an anti-CD antibody array (a panel of 350
known CD antibodies) and a number of potential cell-surface protein
markers were identified. We identified many cell-surface proteins
expressed at this stage, including: FZD4, JAG1, PDGFRA, LIFR
(CD118), TNFSF9, FGFR3.
[0219] The cell surface protein Jagged 1 (JAG1) and Frizzled 4
(FZD4) were selected for further analysis. Jagged 1 expression was
further studied as described below and in Examples 3 and 4.
Frizzled 4 expression was further studied as described in Example
5.
[0220] Firstly, the expression of Isl1 and Jag1 was profiled using
the double staining flow cytometry technique. Flow cytometric
analysis was carried out essentially as described in Example 1,
using anti-Isl1 and anti-Jag1 antibodies for double staining. The
results are shown in FIG. 4. Jagged 1 expression was found to trace
the expression of Islet 1 and on day 6 of differentiation, all of
the Islet 1 positive cells also expressed Jagged 1, and vice versa.
Because of the co-expression pattern of these two markers, a Jagged
1 antibody was used to enrich the 94.1% Islet 1+ cells
differentiated population to 99.8% purity of Islet1+Jagged1+
cells.
[0221] It also was confirmed that Islet 1 is an earlier
developmental gene than the Nkx2.5 gene using double immunostaining
of ISL1 and NKX2.5 expression in HVPs. The purified HVPs uniformly
express the ISL1 gene, but at this stage, only a few of the cells
started to express Nkx2.5.
[0222] Furthermore, immunostaining with both anti-Isl1 and anti-Jag
1 was performed, essentially as described in Example 1, on week 4
human fetal heart tissue, neonatal heart tissue and 8-year old
heart tissue. The results revealed that in the in vivo fetal heart,
all of the Islet 1 positive cells also expressed Jagged 1. However,
the neonatal heart and 8-year old heart did not express Islet 1 or
Jagged 1. In the ventricle of week 4 human fetal heart, cardiac
Troponin T (cTnT) staining revealed visible sarcomere structures.
In addition, over 50% of ventricular cells in the week 4 fetal
heart expressed both Islet1 and Jagged1, which was markedly
decreased during subsequent maturation, with the loss of expression
of both Islet1 and Jagged1 in the ventricular muscle cells of the
human neonatal hearts.
[0223] The above-described experiments demonstrate that Jagged 1 is
a cell surface marker for Islet 1 positive cardiomyogenic
progenitor cells.
Example 3: Clonal Differentiation of Isl1+Jag1+ Cardiac Progenitor
Cells
[0224] To characterize the clonal differentiation potential of
Isl1+Jag1+ cells, cardiomyogenic progenitor cells were generated by
the culturing protocol described in Example 1, and one single
Isl1+Jag1+ cell was seeded into one well of a Matrigel-coated
48-well plate. Cells were purified with antibody of Jag1 and then
one single cell was seeded into one well. The single cells were
then cultured for 3 weeks in Cardiac Progenitor Culture (CPC)
medium (advanced DMEM/F12 supplemented with 2.5 mM GlutaMAX, 100
.mu.g/ml Vitamin C, 20% Knockout Serum Replacement).
[0225] Immunostaining of the 3-week differentiation cell population
was then performed with three antibodies: cardiac troponin 1 (cTn1)
for cardiomyocytes, CD144 (VE-cadherin) for endothelial cells and
smooth muscle actin (SMA) for smooth muscle cells. The results
showed that the single cell-cultured, Isl1+Jag1+ cells gave rise to
cTn1 positive and SMA positive cells, but not VE-cadherin positive
endothelial cells, indicating these generated Islet1+ cells are
heart muscle progenitors that have limited differentiation
potential to endothelial lineages. Purified Islet1+Jagged1+ cells
differentiated with the HVPG protocol from human induced
pluripotent stem cells (iPSC 19-9-11 line) also showed similar in
vitro differentiation potential and predominantly differentiate to
cTnI+SMA+ cells, but not VE-cadherin+ cells. Over the course of
several weeks, the cells expressed the ventricular specific marker
MLC2v, indicating that the initial ISL1+ subset was already
committed to the ventricular cell fate. Because of the limited
vascular differentiation potential of Islet1+ cells generated using
the HVPG protocol, these generated Islet1+ cells might represent a
distinct progenitor population from the previously reported KDR+
population (Yang, L. et al. (2008) Nature 453:524-528) or
multipotent ISL1+ cells (Bu, L. et al. (2009) Nature 460:113-117;
Moretti, A. et al. (2006) Cell 127:1151-1165), which can give rise
to all three lineages of cardiovascular cells.
[0226] These results demonstrated that the Isl1+Jag1+
cardiomyogenic progenitor cells can be successfully cultured in
vitro from a single cell to a significantly expanded cell
population (1.times.10.sup.9 cells or greater) that contains all
three types of cardiac lineage cells, with a predominance of
cardiomyocytes. Furthermore, these cells can be cultured in vitro
for extended periods of time, for at least 2-3 weeks, and even for
months (e.g., six months or more). Since the cardiomyogenic
progenitor cells gradually differentiate into cardiomyocytes, which
do not proliferate, a culture period of approximately 2-3 weeks is
preferred.
Example 4: In Vivo Developmental Potential of Isl1+Jag1+ Cardiac
Progenitor Cells'
[0227] The ES03 human embryonic stem cell (hESC) line (obtained
from WiCell Research Institute) expresses green fluorescent protein
(GFP) driven by the cardiac-specific cTnT promoter. ES03 cells were
used to generate Isl1+Jag1+ cardiomyogenic progenitor cells using
the culturing protocol described in Example 1. The Isl1+Jag1+
cardiomyogenic progenitor cells were transplanted into the hearts
of severe combined immunodeficient (SCID) beige mice to document
their developmental potential in vivo.
[0228] Briefly, Isl1+Jag1+ cells were injected (1,000,000 cells per
recipient) directly into the left ventricular wall of
NOD/SCID-gamma mice in an open-chest procedure. Hearts were
harvested 2-3 weeks post surgery, fixed in 1% PFA and sectioned at
10 .mu.m (n=12). Histological analyses of the hearts of the
transplanted mice revealed the presence of GFP+ donor cells,
detected by epifluorescence and by staining with an anti-GFP
antibody, demonstrating that the Isl1+Jag1+ cardiomyogenic
progenitor cells were capable of differentiating into
cardiomyocytes when transplanted in vivo.
[0229] The Isl1+Jag1+ cardiomyogenic progenitor cells were also
transplanted directly into infarcted hearts of SCID beige mice
("injured mice"), as compared to similarly transplanted normal
mice. When analyzed two weeks later, injured mice transplanted with
the Isl1+Jag1+ cardiomyogenic progenitor cells had a larger graft
size than the normal mice similarly transplanted, demonstrating the
cardiomyocyte regeneration capacity of the Isl1+Jag1+
cardiomyogenic progenitor cells in vivo.
Example 5: Identification of Frizzled 4 as a Cell Surface Marker of
Cardiac Progenitor Cells
[0230] As described in Example 2, Frizzled 4 (FZD4) was identified
by RNA-seq analysis as being expressed in cardiac progenitor cells.
Thus, to confirm FZD4 as a cell surface marker of cardiac
progenitor cells, FZD4 expression was assessed during cardiac
differentiation via Western blot analysis. The results, as shown in
FIG. 5, demonstrated that FZD4 was not express in pluripotent stem
cells and the first 3 days differentiated cells. However, FZD4
started to express on day 4 and maximize its expression on day 5 of
expression.
[0231] In order to quantify the co-expression pattern of FZD4 and
Isl1 at the single cell level, FACS analysis was performed. As
shown in FIG. 6, on day 5 of differentiation, more than 83% of
cells express both isl1 and FZD4, demonstrating that FZD4 is a cell
surface marker for isl1 positive cells during cardiac progenitor
differentiation using the GiWi protocol.
[0232] In order to confirm that both JAG1 and FZD4 were indeed
co-expressed with ISL1 on the human ventricular progenitor cells,
triple immunofluorescence analysis of day 6 differentiated cells
from hPSCs was performed with antibodies to Islet 1, Jagged 1 and
Frizzled 4. The triple staining experiment demonstrated that Isl1+
cells expressed both Jagged 1 and Frizzled 4.
Example 6: Human Ventricular Progenitors (HPVs) Generate a 3-D
Ventricular Heart Muscle Organ In Vivo
[0233] The building of the ventricular heart muscle chamber is one
of the most critical and earliest steps during human organogenesis,
and requires a series of coordinated steps, including migration,
proliferation, vascularization, assembly, and matrix alignment. To
test the capacity of HVPs to drive ventriculogenesis in vivo, we
transplanted purified HVPs or unpurified HVPs (92.0.+-.1.9% ISL+)
under the kidney capsule of immunocompromised mice. After 2 months
post-transplantation, animals transplanted with unpurified HVPs
formed tumors, resulting in a tumor formation efficiency of 100%
(100%, 4/4), whereas animals transplanted with purified HVPs did
not form any tumors (0%, 0/10).
[0234] The engrafted kidneys with purified HVPs were further
assayed for histological analysis. Hematoxylin and Eosin (H&E)
staining revealed an organ that exceeded 0.5 cm in length with more
than 1 mm thickness on the surface of the mouse kidney, and that
uniformly expressed the ventricular specific marker MLC2v (O'Brien,
T. X. et al. (1993) Proc. Natl. Acad. Sci. USA 90:5157-5161). The
resulting human muscle organ was fully vascularized and red blood
cells could be detected in the blood vessels. Analysis of cTnT,
MLC2v, and MLC2a immunostaining further revealed that the
transplanted HVPs not only differentiated into cardiac muscle cells
(cTnT+ cells), but also further mature to become MLC2v+ ventricular
myocytes that are negative for MLC2a expression. The resulting
ventricular muscle organ is fully vascularized by murine derived
vascular cells, consistent with the notion that its vascularization
occurred via paracrine cues derived from the HVPs.
[0235] The blood vessel structured was revealed by immunostaining
analysis of antibodies directed against VE-cadherin and smooth
muscle actin expression. In addition, using a human specific
monoclonal laminin antibody targeting laminin .gamma.-1 chain, the
HVPs secreted their own human laminin as their extracellular matrix
(the mouse kidney region is negative for human laminin
immunostaining). In addition, we found human fibronectin expression
is restricted to areas near the blood vessels using a monoclonal
human fibronectin antibody.
[0236] To assess the capacity of late stage cardiac cells to drive
ventriculogenesis, NKX2.5+ cells (day 10 after differentiation)
were transplanted under the kidney capsule of immunocompromised NSG
mice. At three weeks post-transplantation, animals transplanted
with NKX2.5+ cells did not form any visible human muscle graft,
indicating that HVPs lose their ability for in vivo
ventriculogenesis following peak Islet-1 expression.
[0237] Taken together, these studies indicate that the HVPs can
synthesize and release their own cardiac laminin-derived matrix, as
well as fibronectin which serves to stabilize the vasculature to
the nascent ventricular organ.
Example 7: HVPs Create a Mature, Functioning Ventricular Muscle
Organ In Vivo Via a Cell Autonomous Pathway
[0238] One of the critical limitations for the utility of hPSCs for
studies of human cardiac biology and disease is their lack of
maturity and persistence of expression of fetal isoforms. To
determine if the HVP derived organs could become functional mature
ventricular muscle, long term transplantation studies were
performed followed by detailed analyses of a panel of well accepted
features of adult ventricular myocardium including formation of T
tubules (Brette, F. and Orchard, C. (2003) Circ. Res. 92:1182-1192;
Marks, A. R. (2013) J. Clin. Invest. 123:46-52), ability to
generate force comparable to other studies of engineered
ventricular tissue, loss of automaticity, and acquisition of
adult-rod shaped ventricular cardiomyocytes.
[0239] After 5 months post-transplantation of purified HVPs, no
tumors formed in all of our animals. Animals were sacrificed and
the engrafted kidneys were removed for further analysis. The
5-month human graft was a hemisphere structure with the radius of
0.4 cm (diameter of 0.8 cm). The volume for the 5-month human graft
was around 0.13 cm.sup.3 for one kidney, a volume that suggests
feasibility for generating human ventricular muscle that achieves a
thickness comparable to the in vivo human adult heart. Rod-shaped
mature human ventricular myocytes were observed in the human muscle
organ. In addition, muscle trips taken from our mature human muscle
organ generated forces (0.36.+-.0.04 mN) in response to electric
stimulation and increased their force generation after treatment
with a .beta.-adrenergic agonist isoprenaline (0.51.+-.0.02 mN,
p<0.05 compared to control). Taken together, these studies
indicate that the HVPs are capable of generating a fully
functional, mature human ventricular muscle organ in vivo via a
cell autonomous pathway, i.e., without the addition of other cells,
genes, matrix proteins, or biomaterials.
Example 8: HVPs Migrate Towards an Epicardial Niche and
Spontaneously Form a Human Ventricular Muscle Patch on the Surface
of a Normal Murine Heart In Vivo
[0240] The epicardium is a known niche for heart progenitors,
driving the growth of the ventricular chamber during compact zone
expansion, as well as serving as a home to adult epicardial
progenitors that can expand after myocardial injury and that can
drive vasculogenesis in response to known vascular cell fate
switches, such as VEGF (Giordano, F. J. et al. (2001) Proc. Natl.
Acad. Sci. USA 98:5780-5785; Masters, M. and Riley, P. R. (2014)
Stem Cell Res. 13:683-692; Zangi, L. et al. (2013) Nat. Biotechnol.
31:898-907). To determine if the HVPs might migrate spontaneously
to the epicardial surface of the normal heart, purified green
fluorescent protein (GFP)-labeled HVPs were injected
intra-myocardially into the hearts of immunocompromised mice. After
one week or one month post-transplantation, animals were sacrificed
and the engrafted hearts were removed for histology. After one week
post-transplantation, the majority of GFP+ cells were retained in
the myocardium. However, almost all the GFP+ cells migrated to the
epicardium after one month post-transplantation. In addition, GFP+
cells were ISL1+ and Ki67+ after one week post-transplantation.
[0241] In order to trace the differentiation potential of Islet1+
cells, the purified ISL1+JAG1+ cells generated from a cTnT promoter
driven green fluorescent protein (GFP)-expressing hESC line
(H9-cTnT-GFP) were transplanted into the hearts of severe combined
immunodeficient (SCID) beige mice to document their developmental
potential in vivo. One month after transplantation of Isl1+Jag1+
cells directly into the ventricle of the hearts of SCID beige mice,
Hematoxylin and eosin staining revealed a human muscle strip graft
present in the epicardium of the murine heart. In addition,
immunohistological analyses revealed the presence of GFP+ donor
cells detected by epifluorescence and by staining with an anti-GFP
antibody. More importantly, when analysed with antibodies of MLC2v
and MLC2a, the grafted human muscle strip is positive for MLC2v
(100% of cells +), and negative for the atrial marker MLC2a,
indicating the transplanted ISL1+ cells not only further
differentiated to cardiac muscle cells, but also became ventricular
muscle cells.
[0242] Taken together, these studies indicate that the HYPs can
migrate to an epicardial niche, where they expand, and subsequently
differentiate in to a homogenous ventricular muscle patch, again
without the addition of exogenous cells, genes, matrices, or
biomaterials.
Example 9: Additional Experimental Materials and Methods
[0243] In this example, additional details on the experimental
materials and methods used in Examples 1-8 are provided.
Maintenance of hPSCs
[0244] hESCs (ES03, H9) and human iPSCs (19-9-11) were maintained
on Matrigel (BD Biosciences) coated plates in mTeSR1 medium
(STEMCELL Technologies) according to previous published methods
(Lian, X. et al. (2013) Nat. Proc. 8:162-175; Lian, X. et al.
(2013) Stem Cells 31:447-457).
Human Ventricular Progenitor Generation (HVPG) Protocol
[0245] hPSCs maintained on a Matrigel-coated surface in mTeSR1 were
dissociated into single cells with Accutase at 37.degree. C. for 10
min and then seeded onto a Matrigel-coated cell culture dish at
100,000-200,000 cell/cm.sup.2 in mTeSR1 supplemented with 5 .mu.M
ROCK inhibitor Y-27632 (day -2) for 24 hours. At day -1, cells were
cultured in mTeSR1. At day 0, cells were treated with 1 .mu.M
CHIR-98014 (Selleckchem) in RPMI supplemented with B27 minus
insulin (RPMFB27-ins) for 24 hours (day 0 to day 1), which was then
removed during the medium change on day 1. At day 3, half of the
medium was changed to the RPMFB27-ins medium containing 2 .mu.M
Wnt-C59 (Selleckchem), which was then removed during the medium
change on day 5. At day 6, cells were dissociated into single cells
and purified with anti-JAG1 or anti-FZD4 antibody.
RNA-Seq Library Construction
[0246] RNA was isolated (RNeasy Mini kit, Qiagen), quantified
(Qubit RNA Assay Kit, Life Technologies) and quality controlled
(BioAnalyzer 2100, Agilent). RNA (800 ng) from each sample was used
as input for the Illumina TruSeq mRNA Sample Prep Kit v2 (Illumina)
and sequencing libraries were created according to the
manufacturer's protocol. Briefly, poly-A containing mRNA molecules
were purified using poly-T oligo-attached magnetic beads. Following
purification, the mRNA was fragmented and copied into first strand
complementary DNA using random primers and reverse transcriptase.
Second strand cDNA synthesis was then done using DNA polymerase I
and RNase H. The cDNA was ligated to adapters and enriched with PCR
to create the final cDNA library. The library was pooled and
sequenced on a HiSeq 2000 (Illumina) instrument per the
manufacturer's instructions.
RNA-Seq Data Processing
[0247] The RNA-seq reads were trimmed and mapped to the hg19
reference using Tophat 2. On average, approximately 23 million
reads were generated per sample, and 76% of these reads were
uniquely mapped. Expression levels for each gene were quantified
using the python script rpkmforgenes and annotated using RefSeq.
Genes without at least one sample with at least ten reads were
removed from the analysis. Principle Component Analysis and
heatmaps were constructed using the R and Gene-E respectively.
Transplantation
[0248] Aliquots of 2 million purified HVPs were collected into an
eppendorf tube. Cells were spun down, and the supernatant was
discarded. Each tube of cells was transplanted under the kidney
capsule, or intra-myocardially injected into the heart of the
immunodeficient mice, NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ or
SCID-Beige respectively (Charles River France), following a
previously described protocol (Shultz, L. D. et al. (2005) J.
Immunol. 174:6477-6489). Engrafted Kidneys or hearts are harvested
at various time intervals for histological and physiological
analysis.
Flow Cytometry
[0249] Cells were dissociated into single cells with Accutase for
10 min and then fixed with 1% paraformaldehyde for 20 min at room
temperature and stained with primary and secondary antibodies in
PBS plus 0.1% Triton X-100 and 0.5% BSA. Data were collected on a
FACSCaliber flow cytometer (Beckton Dickinson) and analyzed using
FlowJo.
Immunostaining
[0250] Cells were fixed with 4% paraformaldehyde for 15 min at room
temperature and then stained with primary and secondary antibodies
in PBS plus 0.4% Triton X-100 and 5% non-fat dry milk (Bio-Rad).
Nuclei were stained with Gold Anti-fade Reagent with DAPI
(Invitrogen). An epifluorescence microscope and a confocal
microscope (ZEISS, LSM 700) were used for imaging analysis.
Western Blot Analysis
[0251] Cells were lysed in M-PER Mammalian Protein Extraction
Reagent (Pierce) in the presence of Halt Protease and Phosphatase
Inhibitor Cocktail (Pierce). Proteins were separated by 10%
Tris-Glycine SDS/PAGE (Invitrogen) under denaturing conditions and
transferred to a nitrocellulose membrane. After blocking with 5%
dried milk in TBST, the membrane was incubated with primary
antibody overnight at 4.degree. C. The membrane was then washed,
incubated with an anti-mouse/rabbit peroxidase-conjugated secondary
antibody at room temperature for 1 hour, and developed by
SuperSignal chemiluminescence (Pierce).
Electrophysiology (Patch Clamping)
[0252] Beating ventricular myocyte clusters were microdissected and
replated onto glass coverslips before recording. Action potential
activity was assessed using borosilicate glass pipettes (4-5 M Ohm
resistance) filled with intracellular solution consisting of 120 mM
K D-gluconate, 25 mM KCl, 4 mM MgATP, 2 mM NaGTP, 4 mM
Na2-phospho-creatin, 10 mM EGTA, 1 mM CaCl2, and 10 mM HEPES (pH
7.4 adjusted with HCl at 25.degree. C.). Cultured cardiomyocytes
seeded on coverslip dishes were submerged in extracellular solution
(Tyrode's solution) containing 140 mM NaCl, 5.4 mM KCl, 1 mM MgCl2,
10 mM glucose, 1.8 mM CaCl2, and 10 mM HEPES (pH 7.4 adjusted with
NaOH at 25.degree. C.). Spontaneous action potentials were recorded
at 37.degree. C. using patch clamp technique (whole-cell, current
clamp configuration) performed using a Multiclamp 700B amplifier
(Molecular Devices, CA, USA) software low-pass filtered at 1 kHz,
digitized and stored using a Digidata 1322A and Clampex 9.6
software (Molecular Devices, CA, USA).
Statistics
[0253] Data are presented as mean.+-.standard error of the mean
(SEM). Statistical significance was determined by Student's t-test
(two-tail) between two groups. P<0.05 was considered
statistically significant.
Example 10: Xeno-Free Human Ventricular Progenitor Differentiation
Protocol
[0254] In this example, an alternative differentiation protocol for
differentiation of human ventricular progenitors is provided, which
utilizes a defined, xeno-free culture medium, Essential 8. The
Essential 8 medium was developed for growth and expansion of human
pluripotent stem cells (hPSCs) and is described further in Chen, G.
et al. (2011) Nat. Methods 8:424-429 (referred to therein as "E8"
medium).
[0255] hPSCs maintained on a Vitronectin (or Laminin 521)-coated
surface in Essential 8 medium were dissociated into single cells
with Versene solution at 37.degree. C. for 10 min and then seeded
onto a Vitronectin (or Laminin 521)-coated cell culture dish at
100,000-200,000 cell/cm.sup.2 in Essential 8 medium supplemented
with 5 .mu.M ROCK inhibitor Y-27632 (day -2) for 24 hours. At day
-1, cells were cultured in Essential 8 medium. At day 0, cells were
treated with 0.5 .mu.M CHIR-98014 in RPMI for 24 hours (day 0 to
day 1), which was then removed during the medium change on day 1.
At day 3, half of the medium was changed to the RPMI medium
containing 0.5 .mu.M Wnt-C59, which was then removed during the
medium change on day 5. At day 6, cells (human ventricular
progenitors) were dissociated into single cells and purified with
anti-JAG1 or anti-FZD4 antibody. Alternatively cells are purified
with anti-LIFR or anti-FGFR3 antibody.
Example 11: Identification of Leukemia Inhibitor Factor Receptor
(LIFR) and Fibroblast Growth Factor Receptor 3 (FGFR3) as Cell
Surface Markers of Cardiac Progenitor Cells
[0256] In this example, expression of additional cell surface
markers for the cardiac progenitor cells described in Examples 1-8
(i.e., human ventricular progenitor cells) was confirmed by flow
cytometry analysis. Human ventricular progenitor (HVP) cells were
generated as described in Example 1 or 10 and day 6 cells were
analyzed by standard flow cytometry.
[0257] FIG. 9 shows the results of a double staining flow cytometry
experiment using anti-Islet 1 and anti-Leukemia Inhibitory Factor
Receptor (LIFR) antibodies. The results demonstrate that the HVP
cells co-express Islet 1 and LIFR, thereby confirming that LIFR is
a cell surface marker for the HVP cells.
[0258] FIGS. 10A-B show the results of flow cytometry experiments
comparing the expression of LIFR and Fibroblast Growth Factor
Receptor 3 (FGFR3) on day 6 HVP cells to undifferentiated embryonic
stem (ES) cells. The results demonstrate that LIFR and FGFR3 are
both highly enriched for expression on the HVP cells, thereby
confirming that LIFR and FGFR3 are both cell surface markers for
the HVP cells.
EQUIVALENTS
[0259] Those skilled in the art will recognize, or be able to
ascertain using no more than routine experimentation, many
equivalents of the specific embodiments of the invention described
herein. Such equivalents are intended to be encompassed by the
following claims.
* * * * *