U.S. patent application number 16/284565 was filed with the patent office on 2019-09-26 for photoreceptors and photoreceptor progenitors produced from pluripotent stem cells.
This patent application is currently assigned to Astellas Institute for Regenerative Medicine. The applicant listed for this patent is Astellas Institute for Regenerative Medicine. Invention is credited to Robert P. Lanza, Shi-Jiang Lu, Wei Wang.
Application Number | 20190290701 16/284565 |
Document ID | / |
Family ID | 51537881 |
Filed Date | 2019-09-26 |
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United States Patent
Application |
20190290701 |
Kind Code |
A1 |
Lanza; Robert P. ; et
al. |
September 26, 2019 |
PHOTORECEPTORS AND PHOTORECEPTOR PROGENITORS PRODUCED FROM
PLURIPOTENT STEM CELLS
Abstract
Methods are provided for the production of photoreceptor cells
and photoreceptor progenitor cells from pluripotent stem cells.
Additionally provided are compositions of photoreceptor cells and
photoreceptor cells, as well as methods for the therapeutic use
thereof. Exemplary methods may produce substantially pure cultures
of photoreceptor cells and/or photoreceptor cells.
Inventors: |
Lanza; Robert P.; (Clinton,
MA) ; Lu; Shi-Jiang; (Shrewsbury, MA) ; Wang;
Wei; (Rochester, MN) |
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Applicant: |
Name |
City |
State |
Country |
Type |
Astellas Institute for Regenerative Medicine |
Marlborough |
MA |
US |
|
|
Assignee: |
Astellas Institute for Regenerative
Medicine
Marlborough
MA
|
Family ID: |
51537881 |
Appl. No.: |
16/284565 |
Filed: |
February 25, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14774771 |
Sep 11, 2015 |
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PCT/US14/29790 |
Mar 14, 2014 |
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16284565 |
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61793168 |
Mar 15, 2013 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61P 27/06 20180101;
C12N 5/0623 20130101; A61K 35/545 20130101; A61P 27/02 20180101;
C12N 2501/155 20130101; A61K 35/30 20130101; C12N 2501/385
20130101; A61P 9/10 20180101; C12N 2501/33 20130101; C12N 2501/235
20130101; C12N 2500/33 20130101; C12N 2506/02 20130101; C12N 5/0696
20130101; C12N 5/062 20130101; C12N 5/0606 20130101; C12N 2501/13
20130101; C12N 2501/105 20130101 |
International
Class: |
A61K 35/545 20060101
A61K035/545; C12N 5/074 20060101 C12N005/074; C12N 5/0793 20060101
C12N005/0793; C12N 5/0735 20060101 C12N005/0735; C12N 5/0797
20060101 C12N005/0797; A61K 35/30 20060101 A61K035/30 |
Claims
1. A preparation of photoreceptor progenitor cells, comprising: a
plurality of photoreceptor progenitor cells, and a medium suitable
for maintaining the viability of the photoreceptor progenitor
cells, wherein greater than 90% of the cells in the preparation are
immunocytochemically PAX6+ and CHX10-, and mRNA transcript positive
for MASH1 as detected by qPCR.
2. (canceled)
3. The preparation of photoreceptor progenitor cells of claim 1,
wherein the plurality of photoreceptor progenitor cells is
substantially free of pluripotent stem cells, retinal ganglion
cells, mature photoreceptors, and/or amacrine cells.
4. (canceled)
5. The preparation of photoreceptor progenitor cells of claim 1,
wherein the preparation is a cryogenic cell preparation comprising
at least 10.sup.9 photoreceptor progenitor cells
6.-20. (canceled)
21. The preparation of claim 1, wherein the medium suitable for
maintaining the viability of the photoreceptor progenitor cells is
selected from the group consisting of a culture medium, a
cryopreservative, and a biocompatible injection medium suitable for
injection in a human patient.
22.-26. (canceled)
27. The preparation of photoreceptor progenitor cells of claim 1,
wherein greater than 90% of the cells are immunocytochemically
PAX6+, CHX10-, rhodopsin+, and opsin.
28. (canceled)
29. A method of treating a disease or disorder caused by loss of
photoreceptors in a patient, comprising administering the
pharmaceutical preparation of photoreceptor progenitor cells of
claim 1.
30. (canceled)
31. A method of producing photoreceptor progenitor cells,
comprising the steps of culturing eye field progenitor cells under
culture conditions alternating between low adherence or
non-adherent conditions for a period of time sufficient to form
individual cell spheres, and then adherent conditions, which
alternating culture conditions are continued until a majority of
the cells are photoreceptor progenitor cells, wherein the
photoreceptor progenitor cells are characterized as PAX6(+) and
CHX10(-), and wherein the photoreceptor progenitor cells
differentiate into photoreceptor cells upon treatment with retinoic
acid.
32. A method of producing photoreceptor progenitor cells,
comprising the steps of (a) culturing eye field progenitor cells,
preferably as cells clusters and preferably under low adherence or
non-adherent conditions, in a neural differentiation media for a
period of time sufficient for the cell clusters to form individual
cell spheres, wherein the eye field progenitor cells are
characterized as PAX6(+) and RX1(+) and OCT4(-) and NANOG(-), and
preferably are also characterized as SIX3(+), SIX6(+), LHX2(+),
TBX3(+), SOX2(+) and Nestin+, as determined by immunostaining
and/or flow cytometry; (b) culturing the cell spheres in a neural
differentiation media under adherent conditions, preferably on a
biomaterial scaffold such as gelatin, alginate, collagen type 1,
Matrigel.TM., polyglycolide, collagen, fibrin, or self-assembling
peptides, until a majority of cells in the culture are retinal
neural progenitor cells characterized as PAX6(+), CHX10(+) and
SOX2(-); (c) thereafter, alternating culture conditions one or more
times between low adherence or non-adherent conditions for a period
of time sufficient for the retinal neural progenitor cells to form
individual cell spheres, and then culturing the retinal neural
progenitor cell containing cell spheres under adherent conditions,
which alternating culture conditions are continued until a majority
of the cells are photoreceptor progenitor cells, wherein the
photoreceptor progenitor cells are characterized as PAX6(+) and
CHX10(-), and preferably are also characterized as mRNA transcript
positive for Mash1, Nr2e3, Tr.beta.2, ROR.beta. and NRO as detected
by qPCR, and wherein the photoreceptor progenitor cells
differentiate into photoreceptor cells upon treatment with retinoic
acid.
33.-37. (canceled)
38. A method for preparing a substantially pure culture of
pluripotent stem cell-derived photoreceptor progenitor cells
comprising: (a) culturing pluripotent stem cells in a feeder-free
system to produce one or more eye field progenitor cells; (b)
culturing said one or more eye field progenitor cells to produce
retinal neural progenitor cells that are PAX6+ and CHX10+; (c)
culturing said retinal neural progenitor cells to produce
photoreceptor progenitor cells (PRPCs) that are PAX6+ and CHX10-.
Description
RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser.
No. 14/774,771, filed Sep. 11, 2015, which is a national stage
filing under 35 U.S.C. .sctn. 371 of International Application No.
PCT/US2014/029790, filed Mar. 14, 2014, which was published under
PCT Article 21(2) in English, and which claims the benefit under 35
U.S.C. .sctn. 119(e) of U.S. Provisional Application Ser. No.
61/793,168, entitled "PHOTORECEPTORS AND PHOTORECEPTOR PROGENITORS
PRODUCED FROM PLURIPOTENT STEM CELLS" filed on Mar. 15, 2013, each
of which is herein incorporated by reference in its entirety.
BACKGROUND
[0002] Retinal diseases often result in blindness due to loss of
post-mitotic neuronal cells. Among the retinal diseases are rod or
cone dystrophies, retinal degeneration, retinitis pigmentosa,
diabetic retinopathy, macular degeneration, Leber congenital
amaurosis and Stargardt disease. In most retinal degenerations,
cell loss is primarily in the outer nuclear layer which includes
rod and cone photoreceptors. With the loss of post-mitotic neuronal
cell populations, an exogenous source of new cells as a replacement
for photoreceptor cells is needed.
[0003] A potential replacement source of photoreceptor cells
includes stem cells. Early studies incorporated the use of mouse
cells, mouse stem cells or heterogeneous populations of retinal
progenitor cells as a possible source of cells for replacement of
lost photoreceptors. These early studies described transplantation
of photoreceptor precursor cells from postnatal day 1 mouse retina
(Maclaren et al. Nature 444(9):203-207, 2006), in vitro generation
of retinal precursor cells from mouse embryonic stem cells (Ikeda
et al. Proc. Natl. Acad. Sci. 102(32):11331-11336, 2005),
generation of retinal progenitor cells from postnatal day 1 mouse
retinas (Klassen et al. Invest. Ophthal. Vis. Sci.
45(11):4167-4175, 2004), implantation of bone marrow mesenchymal
stem cells in an RCS rat model of retinal degeneration (Inoue et
al. Exp. Eye Res. 8(2):234-241, 2007), production of retinal
progenitor cells, including ganglion cells, amacrine cells,
photoreceptors wherein 0.01% of the total cells expressed S-opsin
or rhodopsin, bipolar cells and horizontal cells, from the H1 human
embryonic stem cell line (Lamba et al. Proc. Natl. Acad. Sci.
10(34):12769-12774, 2006) and induction of induced pluripotent stem
cells (iPS) from human fibroblasts to produce retinal progenitor
cells (Lamba et al. PLoS ONE 5(1):e8763.
doi:10.1371/journal.pone.0008763). None of these approaches
produced a homogeneous population of photoreceptor progenitor cells
or photoreceptor cells for implantation. None of these approaches
produced a homogeneous population of photoreceptor progenitor cells
or photoreceptor cells that showed in vivo rod or cone function
(e.g., detectable by conferring improvements in visual acuity).
Supplies of donor-derived tissue from which photoreceptors and
photoreceptor progenitors may be isolated (such as cadavers, fetal
tissue, and live animals) are limited. Stem cells can be propagated
and expanded in vitro indefinitely, providing a potentially
inexhaustible source of non-donor derived cells for human therapy.
Differentiation of stem cells into a homogeneous population of
photoreceptor progenitors or photoreceptors may provide an abundant
supply of non-donor derived cells for implantation and treatment of
retinal diseases.
BRIEF SUMMARY
[0004] In certain embodiments, the invention provides a
substantially pure preparation of photoreceptor progenitor cells,
comprising: a plurality of photoreceptor progenitor cells, and a
medium suitable for maintaining the viability of the photoreceptor
progenitor cells.
[0005] In certain embodiments, the invention provides a preparation
of photoreceptor progenitor cells, comprising a plurality of cells
containing at least 50% photoreceptor progenitor cells, and a
medium suitable for maintaining the viability of the photoreceptor
progenitor cells
[0006] In certain embodiments, the invention provides a preparation
of photoreceptor progenitor cells, comprising: a plurality of
photoreceptor progenitor cells substantially free of pluripotent
stem cells, retinal ganglion cells, mature photoreceptors, and/or
amacrine cells, i.e., include less than 10% or either of those
cells, and even more preferably less than less than 5%, 2%, 1%,
0.1% or even less than 0.01% eye field pluripotent stem cells,
retinal ganglion cells, mature photoreceptors, and/or amacrine
cells; and a medium suitable for maintaining the viability of the
photoreceptor progenitor cells.
[0007] In certain embodiments, the invention provides a
pharmaceutical preparation of photoreceptor progenitor cells that
is suitable for use in a mammalian patient, comprising: a plurality
of photoreceptor progenitor cells; and a pharmaceutically
acceptable carrier for maintaining the viability of the
photoreceptor progenitor cells for transplantation into a mammalian
patient.
[0008] In certain embodiments, the invention provides a cryogenic
cell preparation comprising at least 10.sup.9 photoreceptor
progenitor cells, and a cryopreservative system compatible the
photoreceptor progenitor cells and able to maintain the viability
of such cells after thawing.
[0009] In preferred embodiments of the above preparations, at least
70% of the cells in the preparation are immunocytochemically PAX6+
and CHX10-, and (though optionally) mRNA transcript positive for
MASH1 as detected by qPCR, and even more preferably at least 80%,
90%, 95% or 98% of the cells in the preparation are
immunocytochemically PAX6+ and CHX10-, and (though optionally) mRNA
transcript positive for MASH1 as detected by qPCR.
[0010] In certain embodiments, a majority of the photoreceptor
progenitor cells are mRNA transcript positive for Nr2e3, Tr.beta.2,
ROR.beta. and NRO as detected by qPCR.
[0011] In certain embodiments, the photoreceptor progenitor cells
express at least 2, 3, 4, 5 or even 10 fold more, relative to
retinal neural progenitor cells, of one or more proteins selected
from uPA, Tenascin-C, CXCL16, CX3CL1 and Chitinase 3 like-1, as
detected by immunoassay of secreted proteins or mRNA transcript
levels by qPCR,
[0012] In certain embodiments, the photoreceptor progenitor cells
have replicative capacity to undergo at least 10, 20, 30, 50 or
even 100 population doublings in cell culture with less than 25
percent of the cells undergoing cell death, senescing or
differentiating into phenotypically non-photoreceptor cells by the
10.sup.th, 20.sup.th, 30.sup.th, 50.sup.th or even 100.sup.th
doubling.
[0013] In certain embodiments, the photoreceptor progenitor cells
have transferrin protein and or transferrin mRNA levels which are
at least 10, 25, 50 or even 75 percent less than for glyceraldehyde
3-phosphate dehydrogenase.
[0014] In certain embodiments, the photoreceptor progenitor cells
are HLA-genotypically identical, and preferably are genomically
identical.
[0015] In certain embodiments, the photoreceptor progenitor cells
have a mean terminal restriction fragment length (TRF) that is
longer than 7 kb, 7.5 kb, 8 kb, 8.5 kb, 9 kb, 9.5 kb, 10 kb, 10.5
kb, 11 kb, 11.5 kb or even 12 kb.
[0016] In certain embodiments, the photoreceptor progenitor cells
have a statistically significant decreased content and/or enzymatic
activity, relative to fetal-derived photoreceptors, of proteins
involved in one or more of (i) cell cycle regulation and cellular
aging, (ii) cellular energy and/or lipid metabolism, (iii)
apoptosis.
[0017] In certain embodiments, the photoreceptor progenitor cells
have a statistically significant increased content and/or enzymatic
activity of proteins involved in cytoskeleton structure and
cellular dynamics relating thereto, relative to fetal derived
photoreceptors.
[0018] In certain embodiments, the photoreceptor progenitor cells
are suitable for administration to a human patient.
[0019] In certain embodiments, the photoreceptor progenitor cells
are suitable for administration to a non-human veterinarian
patient.
[0020] In preferred embodiments of the above preparations, the
photoreceptor progenitor cells are derived from mammalian
pluripotent stem cells, especially human pluripotent stem cells,
preferably selected from the group consisting of embryonic stem
cells and induced pluripotent stem cells.
[0021] In certain embodiments, the photoreceptor progenitor cells
are differentiated from a common pluripotent stem cell source.
[0022] In certain embodiments, the photoreceptor progenitor cells
maintain plasticity to differentiate into both rods and cones.
[0023] In certain embodiments, the photoreceptor progenitor cells
can be transplanted into the subretinal space of ELOVL4-TG2 mice,
will migrate to the outer nucleated layer and will improve scotopic
and photopic ERG responses in the ELOVL4-TG2 mice.
[0024] In certain embodiments, the photoreceptor progenitor cells
have phagocytic activity, such as the ability to phagocytose
isolated photoreceptor outer segments, pHrodo.TM. Red E. coli
BioParticles or both.
[0025] In certain embodiments, the photoreceptor progenitor cells
secrete one or more neuroprotective factors.
[0026] In certain embodiments, the medium suitable for maintaining
the viability of the photoreceptor progenitor cells is selected
from the group consisting of a culture medium, a cryopreservative,
and a biocompatible injection medium suitable for injection in a
human patient.
[0027] In certain embodiments, the photoreceptor progenitor cell
preparation is pyrogen and mycogen free.
[0028] Another aspect of the present invention provides a
pharmaceutical preparation of photoreceptors that is suitable for
use in a mammalian patient, comprising pluripotent stem cell
derived photoreceptor cells, wherein greater than 70%, 80%, 90%,
95% or even 98% of the cells are immunocytochemically PAX6+, CHX10-
and are rhodopsin+ and/or opsin+; and a pharmaceutically acceptable
carrier for maintaining the viability of the photoreceptor cells
for transplantation into a mammalian patient.
[0029] Still another aspect of the present invention provides a
pharmaceutical preparation comprising: retinal pigment epithelial
cells and either photoreceptor progenitor cells, photoreceptor
cells or both; and a pharmaceutically acceptable carrier for
maintaining the viability of the photoreceptor cells for
transplantation into a mammalian patient. The preparation of cells
can be provided as cells suspensions (either admixed together, or
in the form of a kit with separate doses of cells that be delivered
conjointly), or as a multi-layer cell graft (optionally disposed on
a biocompatible matrix or solid support). In the case of the
multi-layer cell graft, the RPE cells can be provided as a
monolayer, preferably a polarized monolayer.
[0030] Yet another aspect of the invention provides methods for
treating diseases and disorders caused by loss of photoreceptors in
a patient, comprising administering such pharmaceutical
preparations as described herein, such as preparations of
photoreceptor progenitor cells or photoreceptor cells, or both. The
preparations can be injected locally, such as into the subretinal
space of the patient's eye, into the vitreous of the patients, or
delivered systemically or into other body cavities where the cells
can persist.
[0031] The diseases or disorders caused by loss of photoreceptors
include macular degeneration such as age-related macular
degeneration, whether at early or late stage, and retinitis
pigmentosa.
[0032] In certain embodiments, the invention provides a method of
producing photoreceptor progenitor cells, comprising the steps
of
[0033] (a) culturing eye field progenitor cells, preferably as
cells clusters and preferably under low adherence or non-adherent
conditions, in a neural differentiation media for a period of time
sufficient for the cell clusters to form individual cell
spheres;
[0034] (b) culturing the cell spheres in a neural differentiation
media under adherent conditions, preferably on a matrix (such as a
biomaterial scaffold) until a majority of cells in the culture are
retinal neural progenitor cells characterized as PAX6+, CHX10+ and
SOX2-;
[0035] (c) thereafter, alternating culture conditions one or more
times between low adherence or non-adherent conditions for a period
of time sufficient for the retinal neural progenitor cells to form
individual cell spheres, and then culturing the retinal neural
progenitor cell containing cell spheres under adherent conditions,
which alternating culture conditions are continued until a majority
of the cells are photoreceptor progenitor cells.
[0036] In preferred embodiments, the eye field progenitor cells are
characterized, such as immunocytochemically, as PAX6+ and RX1+ and
OCT4- and NANOG-, and even more preferably are also characterized
as Six3+, Six6+, Lhx2+, Tbx3+, SOX2+ and Nestin+, such as may be
determined by immunostaining and/or flow cytometry or other
standard assay used characterized marker expression in cells.
[0037] In preferred embodiments, the photoreceptor progenitor cells
are characterized, such as immunocytochemically, as PAX6+ and
CHX10- (such as may be determined by immunostaining and/or flow
cytometry or other standard assay used characterized marker
expression in cells), and even more preferably are also
characterized as mRNA transcript positive for Mash1, Nr2e3,
Tr.beta.2, ROR.beta. and NRO as detected by qPCR,
[0038] In preferred embodiments, the photoreceptor progenitor cells
are characterized as able to differentiate into photoreceptor cells
upon treatment with retinoic acid.
[0039] In preferred embodiments, the photoreceptor progenitor cells
maintain plasticity to differentiate into both rods and cones.
[0040] In preferred embodiments, the photoreceptor progenitor
cells, when transplanted into the subretinal space of ELOVL4-TG2
mice, migrate to the outer nucleated layer and improve scotopic and
photopic ERG responses in the ELOVL4-TG2 mice relative to control
(no cells injected) ELOVL4-TG2 mice.
[0041] In certain embodiments, the adherent conditions include a
culture system having a surface to which the cells can adhere that
includes an adherent material, which may be, merely to illustrate,
comprises one or more of a polyester, a polypropylene, a
polyalkylene, a polyfluorochloroethylene, a polyvinyl chloride, a
polyvinyl fluoride resin, a polystyrene, a polysulfone, a
polyurethane, a polyethyene terephtalate, a cellulose, a glass
fiber, a ceramic particle, a biomaterial scaffold, a poly L lactic
acid, a dextran, an inert metal fiber, silica, natron glass,
borosilicate glass, chitosan, or a vegetable sponge. In some
embodiments, the adherent material is electrostatically charged. In
certain embodiments, the biomaterial scaffold is extracellular
matrix, such as collagen (such as collagent type IV or type I),
804G-derived matrix, fibronectin, vitronectin, chondronectin,
laminin or Matrigel.TM.. In other embodiments, the biomaterial is
gelatin, alginate, polyglycolide, fibrin, or self-assembling
peptides,
[0042] In certain embodiments, the eye field progenitor cells, and
as a consequence the retinal neural progenitor cells and
photoreceptor progenitor cells, are derived from pluripotent stem
cells, such as embryonic stem cells or induced pluripotent stem
cells.
[0043] In preferred embodiments, the resulting preparation of
photoreceptor progenitor cells, are provided substantially free of
pluripotent stem cells, i.e., include less than 10% pluripotent
stem cells, and even more preferably less than less than 5%, 2%,
1%, 0.1% or even less than 0.01% pluripotent stem cells.
[0044] In preferred embodiments, the resulting preparation of
photoreceptor progenitor cells, are provided substantially free of
eye field progenitor cells and retinal neural progenitor cells,
i.e., include less than 10% or either of those cells, and even more
preferably less than less than 5%, 2%, 1%, 0.1% or even less than
0.01% eye field progenitor cells and retinal neural progenitor
cells.
[0045] In preferred embodiments, cellular component of the
resulting preparation of photoreceptor progenitor cells is at least
50% pure with respect to other cell types (i.e., cells which are
not photoreceptor progenitor cells), and preferably at least 75%,
at least 85%, at least 95%, at least 99% or about 100% pure.
[0046] In certain embodiments, the method includes the further step
of cryopreserving the photoreceptor progenitor cells. The cells are
preferably frozen in a cryopreservative which is compatible with
ultimately thawing the frozen cells and, after optionally washing
the cells to remove the cryopreservative, the photoreceptors
retaining at least 25% cell viability (such as based on culture
efficiency), and more preferably at least 50%, 60%, 70%, 80% or
even at least 90% cell viability.
[0047] Various of the progenitor cells as well as the photoreceptor
cells may be cryopreserved. In some embodiments, the photoreceptor
progenitor cells are cryopreserved as spheres.
[0048] In certain embodiments, the neural differentiation media (or
medium as it is sometimes referred to herein) may comprise
D-glucose, penicillin, streptomycin, GlutaMAX.TM., N2 supplement,
B27 supplement, MEM Non-essential amino acids solution and
optionally including Noggin.
[0049] The neural differentiation media may include agents which
activate the Notch pathway, such as Notch ligands or
antibodies.
[0050] In certain embodiments, the neural differentiation media may
be an essentially serum free medium, such as a MEDII conditioned
medium. In certain embodiments, the neural differentiation media
comprises DMEM/F12, FGF-2 and a MEDII conditioned medium. In
certain embodiments, the neural differentiation media is between
approximately 10% to approximately 50%>MEDII conditioned medium.
In certain embodiments, the MEDII conditioned medium is a Hep G2
conditioned medium. The MEDII medium may comprise a large molecular
weight extracellular matrix protein. The MEDII medium may comprise
a low molecular weight component comprising proline.
[0051] In certain embodiments, the neural differentiation media is
essentially serum free cell differentiation environment comprises
less than 5% serum.
[0052] In certain embodiments, the neural differentiation media is
essentially LIF free.
[0053] The neural differentiation media may also comprise various
supplements such as B27 supplement (Invitrogen) and N2 supplement
(also from Invitrogen). B27 supplement contains, amongst other
constituents, SOD, catalase and other anti-oxidants (GSH), and
unique fatty acids, such as linoleic acid, linolenic acid, lipoic
acids. The N2 supplement can be replaced with, for example, the
following cocktail: transferrin (10 g/L), insulin (500 mg/L),
progesterone (0.63 mg/L), putrescine (1611 mg/L) and selenite (0.52
mg/L).
[0054] In certain embodiments of the foregoing aspects and
embodiments, the photoreceptor progenitor cells are differentiated
from a pluripotent stem cell source, such as a pluripotent stem
cell that expresses OCT4, alkaline phosphatase, SOX2, SSEA-3,
SSEA-4, TRA-1-60, and TRA-1-80 (such as, but not limited to, an
embryonic stem (ES) cell line or induced pluripotency stem (iPS)
cell line), and even more preferably from a common pluripotent stem
cell source.
[0055] In certain embodiments of the foregoing aspects and
embodiments, the photoreceptor progenitor cells have a mean
terminal restriction fragment length (TRF) that is longer than 7
kb, 7.5 kb, 8 kb, 8.5 kb, 9 kb, 9.5 kb, 10 kb, 10.5 kb, 11 kb, 11.5
kb or even 12 kb.
[0056] In certain embodiments of the foregoing aspects and
embodiments, a preparation is suitable for administration to a
human patient, and more preferably pyrogen-free and/or free of
non-human animal products.
[0057] In certain embodiments of the foregoing aspects and
embodiments, a preparation is suitable for administration to a
non-human veterinarian mammal, such as but not limited to a dog,
cat or horse.
[0058] In one aspect, the disclosure provides a method of producing
eye field progenitor cells, comprising (a) culturing pluripotent
stem cells in a retinal induction culture medium. Said pluripotent
stem cells may be human.
[0059] Said retinal induction culture medium may comprise insulin.
Said insulin may be human. Said insulin may be present in a
concentration of about 5-50 ug/ml human insulin or about 25 ug/ml.
Said retinal induction culture medium may comprise DMEM/F12,
DMEM/high glucose, or DMEM/knock-out.
[0060] Said retinal induction culture medium may comprise
D-glucose. The retinal induction culture medium may comprise about
450 mg/ml D-glucose or between about 400 and about 500 mg/ml
D-glucose.
[0061] The retinal induction culture medium may comprise one or
more antibiotics. Said antibiotics may include one or both of
penicillin and streptomycin, optionally in concentrations of about
0-100 units/ml of penicillin and optionally about 0-100 .mu.g/ml of
streptomycin, and further optionally in concentrations of about 100
units/ml of penicillin and optionally about 100 .mu.g/ml of
streptomycin.
[0062] The retinal induction culture medium may comprise N2
supplement. Said N2 supplement may be present in a concentration of
about 0.1 to 5% or about 1%.
[0063] The retinal induction culture medium may comprise B27
supplement. Said B27 supplement may be present in a concentration
of about 0.05-2.0% or about 0.2%.
[0064] The retinal induction culture medium may comprise
non-essential amino acids or MEM non-essential amino acids or
glutamine or GlutaMAX.TM.. Said non-essential amino acids or MEM
non-essential amino acids may be present in a concentration of
about 0.1 mM
[0065] The retinal induction culture medium may comprise a BMP
signaling inhibitor. Said BMP signaling inhibitor may be selected
from the group consisting of: Noggin such as Noggin polypeptide,
dorsomorphin, LDN-193189, and any combination thereof.
[0066] The retinal induction culture medium may comprise Noggin,
such as Noggin polypeptide. Said Noggin may be present at a
concentration of between about 5-100 ng/ml or about 10-100 ng/ml or
about 50 ng/ml.
[0067] In some embodiments, the medium may comprise Noggin, DKK1
and IGF-1. In some embodiments, the medium may comprise 5 ng/ml
Noggin, 5 ng/ml DKK1, and 5 ng/ml IGF-1.
[0068] Said pluripotent stem cells may comprise human ES cells,
human iPS cells, or human STAP cells. Said pluripotent stem cells
may be cultured under feeder-free and/or xeno-free conditions
and/or on a substrate optionally comprising Matrigel.TM. (a soluble
preparation from Engelbreth-Holm-Swarm (EHS) mouse sarcoma cells)
and optionally in mTESR1 medium, prior to being cultured in said
retinal induction culture medium comprising insulin.
[0069] Said retinal induction culture medium may be replaced with
fresh retinal induction culture medium daily. Said culturing in
step (a) may be continued for about 1-10 days or about 2-7 days, or
about 5-6 days.
[0070] The method may further comprise (b) culturing the cells in a
neural differentiation medium. Said neural differentiation medium
may comprise Neurobasal medium.
[0071] Said neural differentiation medium may comprise D-glucose.
The neural differentiation medium may comprise about 450 mg/ml
D-glucose or between about 400 and about 500 mg/ml D-glucose.
[0072] The neural differentiation medium may comprise one or more
antibiotics. Said antibiotics may include one or both of penicillin
and streptomycin, optionally in concentrations of about 0-100
units/ml of penicillin and optionally about 0-100 .mu.g/ml of
streptomycin, and further optionally in concentrations of about 100
units/ml of penicillin and optionally about 100 .mu.g/ml of
streptomycin.
[0073] The neural differentiation medium may comprise N2
supplement. Said N2 supplement may be present in a concentration of
about 0.1 to 5% or about 2%.
[0074] The neural differentiation medium may comprise B27
supplement. Said B27 supplement may be present in a concentration
of about 0.05-5.0%, about 0.05-2.0% or about 2%.
[0075] The neural differentiation medium may comprise non-essential
amino acids or MEM non-essential amino acids or glutamine or
GlutaMAX.TM.. Said non-essential amino acids or MEM non-essential
amino acids may be present in a concentration of about 0.1 mM
[0076] The neural differentiation culture medium may comprise a BMP
signaling inhibitor. Said BMP signaling inhibitor may be selected
from the group consisting of: Noggin such as Noggin polypeptide,
dorsomorphin, LDN-193189, and any combination thereof.
[0077] The neural differentiation culture medium may comprise
Noggin, such as Noggin polypeptide. Said Noggin may be present at a
concentration of between about 10-100 ng/ml or about 50 ng/ml.
[0078] Said cells may be cultured in said neural differentiation
medium for about 10-60 days or about 15-35 days or about 24
days.
[0079] Said eye field progenitor cells may comprise at least 50%,
at least 75%, at least 85%, at least 95%, at least 99% or about
100% of the cells in said culture.
[0080] Said eye field progenitor cells express one or both of the
markers PAX6 and RX1. Thus, the eye field progenitor cells may be
PAX6(+) and/or RX1(+). Said eye field progenitor cells may be one
or more of SIX3(+), SIX6(+), LHX2(+), TBX3(+), and/or Nestin(+).
Said eye field progenitor cells may be one or more of SOX2(+) and
OCT4(-) and Nanog (-). Said eye field progenitor cells may be
human.
[0081] The method may further comprise differentiating said eye
field progenitor cells into retinal neural progenitor cells.
[0082] In another aspect, the disclosure provides a composition
comprising eye field progenitor cells produced using a method as
described herein, e.g., as described in the preceding paragraphs.
In another aspect, the disclosure provides a composition comprising
eye field progenitor cells, which are optionally human.
[0083] Said eye field progenitor cells may be human. Said eye field
progenitor cells may comprise at least 50%, at least 75%, at least
85%, at least 95%, at least 99% or about 100% of the cells in said
culture. Said eye field progenitor cells express one or both of the
markers PAX6 and RX1. Thus, the eye field progenitor cells may be
PAX6(+) and/or RX1(+). Said eye field progenitor cells may be one
or more of SIX3(+), SIX6(+), LHX2(+), TBX3(+), and/or Nestin(+).
Said eye field progenitor cells may be one or more of SOX2(+) and
OCT4(-) and Nanog (-). Said eye field progenitor cells may be
cryopreserved.
[0084] In another aspect, the disclosure provides a method of
treatment of an individual in need thereof, comprising
administering a composition comprising eye field progenitor cells
(e.g., a composition as described herein or a composition produced
using a method as described herein) to said individual. Said
composition may be administered to the eye, subretinal space, or
intravenously. Such individuals may have macular degeneration
including age-related macular degeneration, and such macular
degeneration may be early or late stage. Such individuals may have
retinitis pigmentosa, retinal dysplasia, retinal degeneration,
diabetic retinopathy, congenital retinal dystrophy, Leber
congenital amaurosis, retinal detachment, glaucoma, or optic
neuropathy.
[0085] In another aspect, the disclosure provides a method of
producing retinal neural progenitor cells or photoreceptor
progenitor cells, comprising (a) culturing eye field progenitor
cells in a neural differentiation medium. Said neural
differentiation medium may comprise Neurobasal medium.
[0086] Said neural differentiation medium may comprise D-glucose.
The neural differentiation medium may comprise about 450 mg/ml
D-glucose or between about 400 and about 500 mg/ml D-glucose.
[0087] The neural differentiation medium may comprise one or more
antibiotics. Said antibiotics may include one or both of penicillin
and streptomycin, optionally in concentrations of about 0-100
units/ml of penicillin and optionally about 0-100 .mu.g/ml of
streptomycin, and further optionally in concentrations of about 100
units/ml of penicillin and optionally about 100 .mu.g/ml of
streptomycin.
[0088] The neural differentiation medium may comprise N2
supplement. Said N2 supplement may be present in a concentration of
about 0.1 to 5% or about 2%.
[0089] The neural differentiation medium may comprise B27
supplement. Said B27 supplement may be present in a concentration
of about 0.05-5.0%, about 0.05-2.0% or about 2%.
[0090] The neural differentiation medium may comprise non-essential
amino acids or MEM non-essential amino acids or glutamine or
GlutaMAX.TM.. Said non-essential amino acids or MEM non-essential
amino acids may be present in a concentration of about 0.1 mM
[0091] The neural differentiation culture medium optionally does
not comprises an exogenously added BMP signaling inhibitor. The
neural differentiation medium optionally does not contain
exogenously added Noggin, such as Noggin polypeptide.
[0092] Step (a) may comprise (i) culturing eye field progenitor
cells until the cells form spheres, and (ii) plating the spheres
under adherent conditions.
[0093] Step (i) may comprise culturing the cells on low-adherent
plates. Step (i) may comprise culturing the cells in a hanging
drop. The culture of step (i) may be formed by mechanically or
enzymatically breaking cultured cells into a single cell
suspension. Step (i) may be continued for 1-10, 3-8, or about 5
days.
[0094] Step (ii) may comprise plating the spheres on Matrigel.TM..
Step (ii) may comprise plating the spheres on laminin or collagen.
Step (ii) may be continued until said culture is confluent.
[0095] Steps (i) and (ii) may be repeated in an alternating
fashion.
[0096] Said cells may be cultured in said neural differentiation
medium for about 10-60 days or about 15-35 days or about 25
days.
[0097] Said retinal neural progenitor cells may differentiate from
said eye field progenitor cells and may be present in increasing
numbers in said culture. Said retinal neural progenitor cells may
comprise at least 50%, at least 75%, at least 85%, at least 95%, at
least 99% or about 100% of the cells in said culture.
[0098] Said retinal neural progenitor cells may express one or both
of the markers PAX6 and RX1. Thus, the neural progenitor cells may
be PAX6(+) and/or CHX10(+). Said retinal neural progenitor cells
may be SOX2(-). Said retinal neural progenitor cells may be Tuj1(+)
or Tuj1(-).
[0099] Said cells may be cultured in said neural differentiation
medium for about 10-330 days or about 15-300 days or about 10-100
days or about 15-100 days or about 100 days.
[0100] Said photoreceptor progenitor cells differentiate from said
retinal neural progenitor cells and may be present in increasing
numbers in said culture. Said photoreceptor progenitor cells may
comprise at least 50%, at least 75%, at least 85%, at least 95%, at
least 99% or about 100% of the cells in said culture.
[0101] Said photoreceptor progenitor cells may be PAX6(+) and/or
CHX10(-). Said photoreceptor progenitor cells may express one or
more of the markers Nr2e3, Tr.beta.2, Mash1, ROR.beta. and/or NRO,
and thus may be Nr2e3(+) and/or Tr.beta.2(+) and/or Mash1(+) and/or
ROR.beta.(+) and/or NRO(+).
[0102] Said cells may be cultured in said neural differentiation
medium for at least about 130 days, at least about 160 days, at
least about 190 days, or longer, whereby said photoreceptor
progenitor cells exhibit decreased or no ability to differentiate
into cones while retaining the ability to form rods.
[0103] The method may further comprise differentiating said
photoreceptor progenitor cells into photoreceptors.
[0104] Said eye field progenitor cells may be differentiated from a
pluripotent stem cell, such as an ES cell or iPS cell or a STAP
cell, which pluripotent stem cell, such as an ES cell or iPS cell
or STAP cell, may optionally be human.
[0105] In another aspect, said retinal neural progenitor cells may
be human.
[0106] In another aspect, the disclosure provides a composition
comprising retinal neural progenitor cells produced according to
any method described herein, e.g., the methods described in the
preceding paragraphs. In another aspect, the disclosure provides a
composition comprising retinal neural progenitor cells, which are
optionally human.
[0107] Said retinal neural progenitor cells may comprise at least
50%, at least 75%, at least 85%, at least 95%, at least 99% or
about 100% of the cells in said culture.
[0108] Said retinal neural progenitor cells may express one or both
of the PAX6 and CHX10 markers, and thus may be PAX6(+) and/or
CHX10(+). Said retinal neural progenitor cells may be SOX2(-). Said
retinal neural progenitor cells may be Tuj1(+) or Tuj1(-).
[0109] Said retinal neural progenitor cells may be
cryopreserved.
[0110] In another aspect, the disclosure provides a method of
treatment of an individual in need thereof, comprising
administering a composition comprising retinal neural progenitor
cells, e.g., a composition described herein or a composition
produced according to a method described herein, to said
individual. Said composition may be administered to the eye,
subretinal space, or intravenously. Said photoreceptor progenitor
cells may be human. Such individuals may have macular degeneration
including age-related macular degeneration, and such macular
degeneration may be early or late stage. Such individuals may have
retinitis pigmentosa, retinal dysplasia, retinal degeneration,
diabetic retinopathy, congenital retinal dystrophy, Leber
congenital amaurosis, retinal detachment, glaucoma, or optic
neuropathy.
[0111] In another aspect, the disclosure provides a composition
comprising photoreceptor progenitor cells produced according to a
method described herein, e.g., a method according to the preceding
paragraphs. In another aspect, the disclosure provides a
composition comprising photoreceptor progenitor cells, which are
optionally human.
[0112] Said photoreceptor progenitor cells may comprise at least
50%, at least 75%, at least 85%, at least 95%, at least 99% or
about 100% of the cells in said culture.
[0113] Said photoreceptor progenitor cells may be PAX6(+) and/or
CHX10(-). Said photoreceptor progenitor cells express one or more
of the Nr2e3, Tr.beta.2, Mash1, ROR.beta. and/or NRO markers, and
thus may be Nr2e3(+) and/or Tr.beta.2(+) and/or Mash1(+) and/or
ROR.beta.(+) and/or NRO(+).
[0114] Said photoreceptor progenitor cells may be
cryopreserved.
[0115] In another aspect, the disclosure provides a method of
treatment of an individual in need thereof, comprising
administering a composition comprising photoreceptor progenitor
cells, e.g., a composition as described herein e.g., in the
preceding paragraphs, or a composition produced according to the
methods described herein e.g., in the preceding paragraphs, to said
individual. Said composition may be administered to the eye,
subretinal space, or intravenously. Such individuals may have
macular degeneration including age-related macular degeneration,
and such macular degeneration may be early or late stage. Such
individuals may have retinitis pigmentosa, retinal dysplasia,
retinal degeneration, diabetic retinopathy, congenital retinal
dystrophy, Leber congenital amaurosis, retinal detachment,
glaucoma, or optic neuropathy.
[0116] In another aspect, the disclosure provides a method of
producing photoreceptor cells, comprising (a) culturing
photoreceptor progenitor cells in a photoreceptor differentiation
medium. Said photoreceptor differentiation medium may comprise
Neurobasal medium.
[0117] Said photoreceptor differentiation medium may comprise
D-glucose. The photoreceptor differentiation medium may comprise
about 450 mg/ml D-glucose or between about 400 and about 500 mg/ml
D-glucose.
[0118] The photoreceptor differentiation medium may comprise one or
more antibiotics. Said antibiotics may include one or more or all
of penicillin and streptomycin, optionally in concentrations of
about 0-100 units/ml of penicillin and optionally about 0-100
.mu.g/ml of streptomycin, and further optionally in concentrations
of about 100 units/ml of penicillin and optionally about 100
.mu.g/ml of streptomycin.
[0119] The photoreceptor differentiation medium may comprise N2
supplement. Said N2 supplement may be present in a concentration of
about 0.1 to 5% or about 2%.
[0120] The photoreceptor differentiation medium may comprise B27
supplement (e.g., formula number 080085-SA). Said B27 supplement
may be present in a concentration of about 0.05-5.0%, about
0.05-2.0% or about 2%.
[0121] The photoreceptor differentiation medium may comprise
non-essential amino acids or MEM non-essential amino acids or
glutamine or GlutaMAX.TM. GlutaMAX.TM. is L-alanyl-L-glutamine,
which is a stabilized form of L-glutamine. Said non-essential amino
acids or MEM non-essential amino acids may be present in a
concentration of about 0.1 mM
[0122] Said photoreceptor differentiation medium may comprise
forskolin. Said forskolin may be present in the photoreceptor
differentiation medium at a concentration between about 1-100 .mu.M
or about 5 .mu.M.
[0123] Said photoreceptor differentiation medium may comprise BDNF.
Said BDNF may be present in the photoreceptor differentiation
medium at a concentration between about 1-100 ng/ml or about 10
ng/ml.
[0124] Said photoreceptor differentiation medium may comprise CNTF.
Said CNTF may be present in the photoreceptor differentiation
medium at a concentration between about 1-100 ng/ml or about 10
ng/ml.
[0125] Said photoreceptor differentiation medium may comprise LIF.
Said LIF may be present in the photoreceptor differentiation medium
at a concentration between about 5-50 ng/ml or about 10 ng/ml.
[0126] Said photoreceptor differentiation medium may comprise DATP.
Said DATP may be present in the photoreceptor differentiation
medium at a concentration between about 1-100 M or about 10
.mu.M.
[0127] Said photoreceptor progenitor cells may be differentiated
from retinal neural progenitor cells, which are optionally human.
Said photoreceptor cells may be human.
[0128] In some embodiment, photoreceptor progenitor cells are
pre-treated with retinoic acid and taurine in ND medium, prior to
culture in the photoreceptor differentiation medium. The retinoic
acid may be used at a concentration of about 100-1000 ng/ml and
taurine may be used at a concentration of about 20-500 .mu.M. This
culture step may occur for about 1-2 weeks, in some embodiments.
The medium may be changed (e.g., half change) every 2 days, in some
instances. The medium may then be changed to ND medium lacking
retinoic acid and taurine, and the cells may be cultured for about
an additional 1-2 weeks, or until they become confluent.
[0129] In another aspect, the disclosure provides a composition
comprising photoreceptor cells produced according to a method as
described herein, e.g., in the preceding paragraphs, which are
optionally human.
[0130] Said photoreceptor cells may be PAX6(-). Said photoreceptor
cells may comprise at least 50%, at least 75%, at least 85%, at
least 95%, at least 99% or about 100% of the cells in said culture.
Said photoreceptor cells may be cryopreserved.
[0131] In another aspect, the disclosure provides a method of
treatment of an individual in need thereof, comprising
administering a composition comprising photoreceptor cells, e.g., a
composition as described herein such as in the preceding paragraphs
or a composition produced by a method as described herein e.g., in
the preceding paragraphs, to said individual. Said composition may
be administered to the eye, subretinal space, or intravenously.
Such individuals may have macular degeneration including
age-related macular degeneration, and such macular degeneration may
be early or late stage. Such individuals may have retinitis
pigmentosa, retinal dysplasia, retinal degeneration, diabetic
retinopathy, congenital retinal dystrophy, Leber congenital
amaurosis, retinal detachment, glaucoma, or optic neuropathy.
[0132] In another embodiment, the invention is directed to a
substantially pure preparation of photoreceptor progenitor cells
(PRPCs) or photoreceptor cells (PRs) of human origin, preferably
non-donor derived photoreceptor progenitor cells or photoreceptor
cells, originating from cells not grown on a mouse fibroblast
feeder platform. For example, the preparation may be 85%-95% pure.
In an embodiment, the invention is directed to a method of
preparing the substantially pure preparation of PRPCs or PRs of
human origin which omits the need for cells derived from a mouse
fibroblast feeder platform. Replacing a feeder system with the
methods of the present invention produces a greater homogeneity of
photoreceptors cells, e.g., at 75%-100% or 85%-95%. The
differentiation of the feeder-free stem cells can also occur in the
absence of the introduction of exogenous inducing factors, which is
a substantial improvement over the prior art. The optional addition
of Noggin, however, can accelerate differentiation of the stem
cells, even though it is not necessary for differentiation to
occur. The resultant photoreceptor progenitor cells are uniquely
characterized immunocytochemically as PAX6 positive (PAX6(+)) and
CHX10 negative (CHX10(-)).
BRIEF DESCRIPTION OF THE DRAWINGS
[0133] FIG. 1: Real-time PCR analysis of transcripts of eye field
transcription factors in cells differentiated under different
conditions.
[0134] FIGS. 2A-2C: Morphology of differentiating cells. (FIG. 2A)
At day 1 after cell differentiation, cells at the colony margin
were column-shaped (arrow). (FIG. 2B) At day 10 after
differentiation, the edge cells became big and flat (arrow head)
and the central cells were small and compact (arrow). (FIG. 2C)
Rosette like structures formed at day 21.
[0135] FIGS. 3A-3E: Cells cultured at 21 days after initiation of
differentiation expressed eye-field transcription factors. (FIG.
3A) Co-expression of PAX6 and RX1. (FIG. 3B) 93% of cells
co-expressed PAX6 and RX1 as shown by flow cytometric analysis.
(FIG. 3C) Cells expressed Nestin. (FIG. 3D) Cells expressed SOX2.
In both (FIG. 3C) and (FIG. 3D), DAPI labels cell nuclei. (FIG. 3E)
RT-PCR analysis of transcripts of eye field transcription factors:
RX1, PAX6, LHX2, SIX3, SIX6, TBX3 and SOX2.
[0136] FIGS. 4A-4C: Cells cultured at 30 days after initiation of
differentiation expressed retinal neural progenitor markers. (FIG.
4A) Morphology of cells. After plating on Matrigel.TM., neurons
migrated out from cell aggregates (arrow). A few epithelial-like
cells (arrow head) are observed around cell aggregates. (FIG. 4B)
Upper panel, phase contrast image of migrating neurons; Lower
panel, migrating neurons expressed Tuj1. (FIG. 4C) Cells
co-expressed PAX6 and CHX10.
[0137] FIGS. 5A-5D: Cells cultured at 3 months after initiation of
differentiation. (FIG. 5A) Morphology of cells. (FIG. 5B) Cells
express PAX6 but not CHX10. (FIG. 5C) The expression of Recoverin
was restricted to the cytoplasm of the cell body. (FIG. 5D),
Real-time RT-PCT analysis of transcripts of Rhodopsin, Opsin, and
Recoverin in retinal neural progenitors (RNPs) and photoreceptor
progenitor cells (indicated as PhRPs).
[0138] FIGS. 6A-6D: Differentiated cells express photoreceptor cell
markers. Cells expressed (FIG. 6A) Rhodopsin, (FIG. 6B) Rhodopsin
and Recoverin, (FIG. 6C) Opsin, and (FIG. 6D) phosphodiesterase 6A
alpha subunit (PDE6a). DAPI labels cell nuclei.
[0139] FIG. 7: Schematic diagram of animal studies in
ELOVL4-transgenic mice.
[0140] FIG. 8: Scotopic ERG intensity-response function recorded at
one month after subretinal cell injection. Stimulus intensity
curves for scotopic a-waves (upper panel) and b-waves (lower panel)
from ELOVL4-TG2 mice administered PBS (black line) or photoreceptor
progenitor cells (indicated as PhRPs, grey line). *, p<0.001
(vs. PBS).
[0141] FIG. 9: Scotopic ERG intensity-response function recorded at
one month after systemic cell injection. Stimulus intensity curves
for scotopic a-waves (upper panel) and b-waves (lower panel) from
ELOVL4-TG2 mice administered PBS, photoreceptor progenitor cells
(indicated as PhRPs) or retinoic acid treated photoreceptor
progenitor cells (PhRPs-RA). Blank represents untreated mice. #,
p<0.01 (vs. PBS).
[0142] FIGS. 10A-10B. Photoreceptor progenitor cell systemic
injection restores rod function between one month and two months
after cell transplantation. Scotopic ERG amplitude of a-waves (FIG.
10A) and b-waves (FIG. 10B) at one and two month after cell
injection from ELOVL4-TG2 mice administered PBS (PBS) or retinoic
acid treated photoreceptor progenitor cells (PhRPs-RA).
[0143] FIG. 10C: Scotopic ERG intensity-response function recorded
at two months after systemic cell injection. Stimulus intensity
curves for scotopic a-waves (upper panel) and b-waves (lower panel)
from ELOVL4-TG2 mice administered PBS or retinoic acid treated
photoreceptor progenitor cells (PhRPs-RA). Blank represents
untreated mice. Baseline is the level recorded at 4 weeks. *,
p<0.001 (vs. PBS).
[0144] FIG. 11: Photopic ERG amplitude of a-waves (upper panel) and
b-waves (lower panel) at one and two month after cell injection
from ELOVL4-TG2 mice administered with PBS or retinoic acid treated
Photoreceptor progenitors (PhRPs-RA). *, p<0.001 (vs. PBS 2
month).
[0145] FIG. 12: Whole central retina thickness measured by OCT at
one and two months after cell injection from untreated ELOVL4-TG2
mice (blank) and mice administered PBS, photoreceptor progenitor
cells (PhRPs), or retinoic acid treated photoreceptor progenitor
cells (PhRPs-RA).
[0146] FIGS. 13A-13B: (FIG. 13A) Representative images of retina HE
staining at two months after cell injection from ELOVL4-TG2 mice
administered PBS (Left panel) and retinoic acid treated
photoreceptor progenitor cells (Right panel). ONL, outer nuclear
layer. INL, internal nuclear layer. (FIG. 13B), Quantification of
the thickness of ONL of retina at two month after cell injection
from untreated ELOVL4-TG2 mice (blank) and mice administered PBS or
retinoic acid treated Photoreceptor progenitors (PhRPs-RA).
[0147] FIG. 14: Schematic diagram of animal studies in RCS
rats.
[0148] FIGS. 15A-15C: Preservation of host photoreceptor cells
after transplantation of human ES cell-derived photoreceptor
progenitor cells. Retinal sections at P90 stained with DAPI: (FIG.
15A) Outer nuclear layer (ONL) is reduced to 0-1 layer in control
rats. (FIG. 15B) Rescued ONL cells in RCS rat after intravenous
cell injection, which is 2-4 cells deep. (FIG. 15C) Rescued ONL
cells in RCS rat receiving intravitreal cell injection, which is
3-5 cells deep. INL, inner nuclear layer; GL, ganglion cell
layer.
[0149] FIGS. 16A-16C: Preservation of host rod photoreceptor cell
outer segment (OS) after transplantation of human ES cell-derived
photoreceptor progenitor cells. Retinal sections at P90 stained for
Rhodopsin. (FIG. 16A) Complete loss of rod OS in control rats
(arrow). (FIG. 16B) Expression of Rhodopsin in the OS of host rod
photoreceptor cells in RCS rat retina after intravenous injection
of photoreceptor progenitor cells (arrow). (FIG. 16C) Expression of
Rhodopsin in the OS of host rod photoreceptor cells in RCS rat
retina after intravitreal transplantation of photoreceptor
progenitor cells (arrow). Expression of Rhodopsin is apparent in
the Figure.
[0150] FIGS. 17A-17C: Preservation of host cone photoreceptor cell
outer segment (OS) after transplantation of human ES cell-derived
photoreceptor progenitor cells. Retinal sections at P90 stained for
Opsin. (FIG. 17A) Complete loss of cone OS in control rats (arrow).
(FIG. 17B) Expression of Opsin in the OS of host cone photoreceptor
cells in RCS rat retina after intravenous injection of
photoreceptor progenitor cells (arrow). (FIG. 17C) Expression of
Opsin in the OS of host cone photoreceptor cells in RCS rat retina
after intravitreal transplantation of photoreceptor progenitors
(arrow). Expression of Opsin is apparent in the Figure.
[0151] FIGS. 18A-18B: Human ES cell-derived photoreceptor
progenitor cells transplanted into the vitreous of RCS rats
differentiated into mature rod photoreceptor cells. Retinal
sections at P90 stained for rhodopsin (FIG. 18A), Recoverin FIG.
18B. Human cells were labeled with anti-HuNU antibody. DAPI labeled
all nuclei. Expression of rhodopsin and recoverin and staining with
DAPI is apparent in the Figure.
[0152] FIG. 19 illustrates the overall method used for
photoreceptor development in Examples 1-2 and further illustrates
the media used at each step of the process.
[0153] FIG. 20 illustrates the timing of photoreceptor cell and
photoreceptor progenitor cell development in Examples 1-2.
[0154] FIGS. 21A-21E show the components of culture media and media
supplements used in the Examples.
[0155] FIG. 22 illustrates the gene expression pattern of ESC, eye
field progenitor cells, retinal neural progenitor cells,
photoreceptor progenitor cells, and photoreceptor cells during in
vitro differentiation from human pluripotent stem cells.
[0156] FIG. 23 provides flow cytometry histograms showing relative
degrees of phagocytosis of pHrodo.TM. Red E. coli BioParticles
(Invitrogen) fluorescent bioparticles by hES-RPE and
hES-photoreceptor progenitors at 37.degree. C. and at 4.degree. C.,
compared to control (no bioparticles). The histogram for the
photoreceptor progenitor cells illustrate that, like RPE cells, the
intensity of the fluorescence signal increases upon shifting the
cells from a relatively non-permissive temperature of 4.degree. C.
to a physiologically relevant temperature of 37.degree. C.,
indicating that photoreceptor progenitor cells are capable of
phagocytosing the bioparticles. The bioparticles are a surrogate
for shed outer segments and drusen in the eye.
DETAILED DESCRIPTION
[0157] The invention provides methods for generating photoreceptor
cells (PRC) and photoreceptor progenitor cells (PRPC). These
methods involve in vitro differentiation from earlier progenitors
including pluripotent stem cells, eye field (EF) progenitors, and
retinal neural progenitor cells. The methods provided herein may
use as a starting material any of the foregoing progenitor
(including stem cell) populations.
[0158] The invention further contemplates generating photoreceptor
cells (PRC) and photoreceptor progenitor cells (PRPC) in vitro from
primary eye field (EF) progenitors and retinal neural progenitors
cells (i.e., primary cells referring to cells obtained from a
subject rather than from in vitro differentiation of a more
immature progenitor.
[0159] Photoreceptor development occurs through a number of
developmental stages, each of which can be defined phenotypically
(e.g., by way of marker expression profile) and/or functionally.
This development is illustrated schematically in FIG. 22. In vitro
pluripotent stem cells differentiate into EF progenitors, which in
turn differentiate into retinal neural progenitor cells, which in
turn differentiate into photoreceptor progenitor cells, which in
turn differentiate into photoreceptor cells.
[0160] Progenitor cells, as used herein, refer to cells that remain
mitotic and can produce more progenitor cells, of the same or of
more limited differentiative capacity, or can differentiate to an
end fate cell lineage. The terms progenitor and precursor are used
interchangeably. Cells at each of these stages will be discussed in
greater detail herein.
[0161] The photoreceptor progenitor cells (also referred to as
photoreceptor progenitors) and photoreceptor cells provided herein
may be used in a variety of in vivo and in vitro methods. For
example, the photoreceptor progenitor cells may be used in vivo to
treat conditions of the retina, including but not limited to
macular degeneration and retinitis pigmentosa. The photoreceptor
progenitor cells and photoreceptor cells may be used in vitro in
screening assays to identify putative therapeutic or prophylactic
treatment candidates.
[0162] The invention further provides photoreceptor progenitor
cells and photoreceptor cells obtained by the methods described
herein. Photoreceptor progenitor cells and photoreceptor cells
obtained by in vitro differentiation of pluripotent stem cells or
their differentiated progeny such as eye field progenitor cells.
Eye field progenitor cells may themselves be obtained from in vitro
differentiation of pluripotent stem cells, or they may be primary
eye field progenitors obtained from a subject.
[0163] The invention provides populations of photoreceptor
progenitor cells and populations of photoreceptor cells that have
not been attained or are not attainable from primary sources. These
populations may be homogenous or near homogeneous in their cell
content. For example, at least 50%, at least 60%, at least 70%, at
least 80%, at least 90%, at least 95%, at least 99%, or about 100%
of the cells in such a population may be photoreceptor progenitor
cells. As another example, at least 50%, at least 60%, at least
70%, at least 80%, at least 90%, at least 95%, at least 99%, or
about 100% of the cells in such a population may be photoreceptor
cells. These cells in these populations may be of a single
haplotype. For example, they may be HLA-matched. These cells in
these populations may be genetically identical.
[0164] The disclosure provides substantially pure (or homogeneous)
preparations of various cell populations based on the ability of
the disclosed methods to directly differentiate progenitor cells
such as but not limited to pluripotent stem cells. As used herein,
directed differentiation intends that the progenitor cell
population differentiates into or towards a desired lineage, due in
part to the factors or other stimuli provided to such progenitor
cells, thereby avoiding differentiation into other undesired, and
thus potentially contaminating, lineages. The methods provided
herein drive differentiation of for example pluripotent stem cells
to eye field progenitors without generating embryoid bodies (EB).
EBs, as described below, are three dimensional cell clusters that
can form during differentiation of pluripotent stem cells including
but not limited to embryonic stem (ES) cells, and that typically
contain cells, including progenitors, of mesodermal, ectodermal and
endodermal lineages. The three dimensional nature of the EB may
create a different environment, including different cell-cell
interactions and different cell-cell signaling, than occurs in the
non-EB based methods described herein. In addition, cells within
EBs may not all receive a similar dose of an exogenously added
agent, such as a differentiation factor present in the surrounding
medium, and this can result in various differentiation events and
decisions during development of the EB.
[0165] In contrast, the culture methods of the invention culture
progenitor cells do not require and preferably avoid EB formation.
Instead, these methods culture cells in conditions that provide the
cells with equal contact with the surrounding medium, including
factors in such medium. The cells may grow as a monolayer or near
monolayer attached to a culture surface, as an example.
[0166] The ability of all or a majority of the progenitor cells to
be in contact with their surrounding medium and thus the factors in
such medium to an approximately equal degree results in those
progenitor cells differentiating at similar times and to similar
degrees. This similar differentiation timeline for a population of
progenitor cells indicates that such cells are synchronized. The
cells may be cell cycle synchronized in some instances also. Such
synchronicity results in populations of cells that are homogeneous
or near homogeneous in their cellular make-up. As an example, the
methods described herein can produce cellular populations wherein
at least 50%, at least 60%, at least 70%, at least 80%, at least
90%, at least 95%, or about 100% of cells are a particular cell of
interest. The cell of interest may be defined phenotypically, for
example by intracellular or extracellular marker expression. The
cell of interest may be an eye field progenitor cell, a neural
retinal progenitor cell, a photoreceptor progenitor cell, or a
photoreceptor cell.
[0167] As used herein, a majority of cells means at least 50%, and
depending on the embodiment may include at least 60%, at least 70%,
at least 80%, at least 90%, at least 95%, or about 100% of
cells.
[0168] The degree of purity that may be achieved using the methods
of the invention are particularly important where such cell
populations are to be used in vivo for therapeutic or prophylactic
purposes. The ability to obtain populations of high cellular purity
avoids performing another manipulation such as an enrichment or
selection step, which may result in unnecessary cell loss. This is
particularly important where the cell population may be small or
the cell number may be limited.
Definitions
[0169] As defined here, singular forms are provided for
illustrative purposes, but may also apply to plural versions of the
phrase. The following definitions are meant to supplement
conventional definitions of the terms as they would be understood
by persons of ordinary skill.
[0170] "Substantially pure preparation of photoreceptor progenitor
cells (PRPCs)." As used herein, this phrase refers to a preparation
of cells (e.g., a composition comprising cells) wherein the cells
are at least 75% pure or preferably at least 85% pure, at least 95%
pure, or are about 85% to 95% pure. For example, the level of
purity may be quantified by determining the proportion of cells in
the preparation that express one or more markers, such as those
markers of PRPCs (including those markers identified in this
application or others known in the art), relative to the total
number of cells in the preparation, e.g., by detecting cells that
do or do not express said one or more markers. Optionally
expression of markers indicative of non-PRPC cells may also be
detected, thereby facilitating detection and/or quantitation of
said cells. Exemplary methods that may be utilized to include,
without limitation, Fluorescence Activated Cell Sorting (FACS),
immunohistochemistry, in situ hybridization, and other suitable
methods known in the art. Optionally the determination of purity
may be performed disregarding non-viable cells present in the
preparation.
[0171] "Substantially pure preparation of photoreceptor cells (PRs)
of human origin." As used herein, this phrase refers to a
preparation of cells (e.g., a composition comprising cells) wherein
the cells are at least 75% pure or preferably at least 85% pure, at
least 95% pure, or are about 85% to 95% pure. For example, the
level of purity may be quantified by determining the proportion of
cells in the preparation that express one or more markers, such as
those markers of PRs (including those markers identified in this
application or others known in the art), relative to the total
number of cells in the preparation, e.g., by detecting cells that
do or do not express said one or more markers. Optionally
expression of markers indicative of non-PR cells may also be
detected, thereby facilitating detection and/or quantitation of
said cells. Exemplary methods that may be utilized to include,
without limitation, Fluorescence Activated Cell Sorting (FACS),
immunohistochemistry, in situ hybridization, and other suitable
methods known in the art. Optionally the determination of purity
may be performed disregarding non-viable cells present in the
preparation.
[0172] "Embryoid bodies" refers to clumps or clusters of
pluripotent cells (e.g., iPSC or ESC) which may be formed by
culturing pluripotent cells under non-attached conditions, e.g., on
a low-adherent substrate or in a "hanging drop." In these cultures,
pluripotent cells can form clumps or clusters of cells denominated
as embryoid bodies. See Itskovitz-Eldor et al., Mol Med. 2000
February; 6(2):88-95, which is hereby incorporated by reference in
its entirety. Typically, embryoid bodies initially form as solid
clumps or clusters of pluripotent cells, and over time some of the
embryoid bodies come to include fluid filled cavities, the latter
former being referred to in the literature as "simple" EBs and the
latter as "cystic" embryoid bodies.
[0173] The term "embryonic stem cell" (ES cell or ESC) is used
herein as it is used in the art. This term includes cells derived
from the inner cell mass of human blastocysts or morulae, including
those that have been serially passaged as cell lines. The ES cells
may be derived from fertilization of an egg cell with sperm, as
well as using DNA, nuclear transfer, parthenogenesis, or by means
to generate ES cells with homozygosity in the HLA region. ES cells
are also cells derived from a zygote, blastomeres, or
blastocyst-staged mammalian embryo produced by the fusion of a
sperm and egg cell, nuclear transfer, parthenogenesis,
androgenesis, or the reprogramming of chromatin and subsequent
incorporation of the reprogrammed chromatin into a plasma membrane
to produce a cell. Embryonic stem cells, regardless of their source
or the particular method used to produce them, can be identified
based on (i) the ability to differentiate into cells of all three
germ layers, (ii) expression of at least OCT 4 and alkaline
phosphatase, and (iii) ability to produce teratomas when
transplanted into immunodeficient animals. Embryonic stem cells
that may be used in embodiments of the present invention include,
but are not limited to, human ES cells ("ESC" or "hES cells") such
as MA01, MA09, ACT-4, No. 3, H1, H7, H9, H14 and ACT30 embryonic
stem cells. Additional exemplary cell lines include NED1, NED2,
NED3, NED4, NED5, and NED7. See also NIH Human Embryonic Stem Cell
Registry. An exemplary human embryonic stem cell line that may be
used is MA09 cells. The isolation and preparation of MA09 cells was
previously described in Klimanskaya, et al. (2006) "Human Embryonic
Stem Cell lines Derived from Single Blastomeres." Nature 444:
481-485. The human ES cells used in accordance with exemplary
embodiments of the present invention may be derived and maintained
in accordance with GMP standards.
[0174] The term "ES cells" does not infer, and should not be
inferred to mean, that the cells were generated through the
destruction of an embryo. To the contrary, various methods are
available and can be used to generate ES cells without destruction
of an embryo, such as a human embryo. As an example, ES cells may
be generated from single blastomeres derived from an embryo, in a
manner similar to the extraction of blastomeres for
pre-implantation genetic diagnosis (PGD). Examples of such cell
lines include NED1, NED2, NED3, NED4, NED5, and NED7. An exemplary
human embryonic stem cell line that may be used is MA09 cells. The
isolation and preparation of MA09 cells was previously described in
Klimanskaya, et al. (2006) "Human Embryonic Stem Cell lines Derived
from Single Blastomeres." Nature 444: 481-485. See also Chung et
al. 2008, Cell Stem Cell, 2:113. All of these lines were generated
without embryo destruction.
As used herein, the term "pluripotent stem cells" includes but is
not limited to tissue-derived stem cells, embryonic stem cells,
embryo-derived stem cells, induced pluripotent stem cells, and
stimulus-triggered acquisition of pluripotency (STAP) cells,
regardless of the method by which the pluripotent stem cells are
derived. The term also includes pluripotent stem cells having the
functional and phenotypic characteristics of the afore-mentioned
cells, regardless of the method used to generate such cells.
Pluripotent stem cells are defined functionally as stem cells that
are: (a) capable of inducing teratomas when transplanted in
immunodeficient (SCID) mice; (b) capable of differentiating to cell
types of all three germ layers (e.g., can differentiate to
ectodermal, mesodermal, and endodermal cell types); and (c) express
one or more markers of embryonic stem cells (e.g., express OCT4,
alkaline phosphatase, SSEA-3 surface antigen, SSEA-4 surface
antigen, Nanog, TRA-1-60, TRA-1-81, SOX2, REX1, etc). In certain
embodiments, pluripotent stem cells express one or more markers
selected from the group consisting of: OCT4, alkaline phosphatase,
SSEA-3, SSEA-4, TRA-1-60, and TRA-1-81. Exemplary pluripotent stem
cells can be generated using, for example, methods known in the
art. Exemplary pluripotent stem cells include embryonic stem cells
derived from the ICM of blastocyst stage embryos, as well as
embryonic stem cells derived from one or more blastomeres of a
cleavage stage or morula stage embryo (optionally without
destroying the remainder of the embryo). Such embryonic stem cells
can be generated from embryonic material produced by fertilization
or by asexual means, including somatic cell nuclear transfer
(SCNT), parthenogenesis, and androgenesis. Further exemplary
pluripotent stem cells include induced pluripotent stem cells
(iPSCs) generated by reprogramming a somatic cell by expressing a
combination of factors (herein referred to as reprogramming
factors). The iPSCs can be generated using fetal, postnatal,
newborn, juvenile, or adult somatic cells.
[0175] In certain embodiments, factors that can be used to
reprogram somatic cells to pluripotent stem cells include, for
example, a combination of OCT 4 (sometimes referred to as OCT 3/4),
SOX2, c-Myc, and KLF4. In other embodiments, factors that can be
used to reprogram somatic cells to pluripotent stem cells include,
for example, a combination of OCT 4, SOX2, Nanog, and Lin28. In
certain embodiments, at least two reprogramming factors are
expressed in a somatic cell to successfully reprogram the somatic
cell. In other embodiments, at least three reprogramming factors
are expressed in a somatic cell to successfully reprogram the
somatic cell. In other embodiments, at least four reprogramming
factors are expressed in a somatic cell to successfully reprogram
the somatic cell. In other embodiments, additional reprogramming
factors are identified and used alone or in combination with one or
more known reprogramming factors to reprogram a somatic cell to a
pluripotent stem cell. Induced pluripotent stem cells are defined
functionally and include cells that are reprogrammed using any of a
variety of methods (integrative vectors, non-integrative vectors,
chemical means, etc). Pluripotent stem cells may be genetically
modified or otherwise modified to increase longevity, potency,
homing, to prevent or reduce alloimmune responses or to deliver a
desired factor in cells that are differentiated from such
pluripotent cells (for example, photoreceptors, photoreceptor
progenitor cells, rods, cones, etc. and other cell types described
herein, e.g., in the examples).
[0176] "Induced pluripotent stem cells" (iPS cells or iPSC) can be
produced by protein transduction of reprogramming factors in a
somatic cell. In certain embodiments, at least two reprogramming
proteins are transduced into a somatic cell to successfully
reprogram the somatic cell. In other embodiments, at least three
reprogramming proteins are transduced into a somatic cell to
successfully reprogram the somatic cell. In other embodiments, at
least four reprogramming proteins are transduced into a somatic
cell to successfully reprogram the somatic cell.
[0177] The pluripotent stem cells can be from any species.
Embryonic stem cells have been successfully derived in, for
example, mice, multiple species of non-human primates, and humans,
and embryonic stem-like cells have been generated from numerous
additional species. Thus, one of skill in the art can generate
embryonic stem cells and embryo-derived stem cells from any
species, including but not limited to, human, non-human primates,
rodents (mice, rats), ungulates (cows, sheep, etc.), dogs (domestic
and wild dogs), cats (domestic and wild cats such as lions, tigers,
cheetahs), rabbits, hamsters, gerbils, squirrel, guinea pig, goats,
elephants, panda (including giant panda), pigs, raccoon, horse,
zebra, marine mammals (dolphin, whales, etc.) and the like. In
certain embodiments, the species is an endangered species. In
certain embodiments, the species is a currently extinct
species.
[0178] Similarly, iPS cells can be from any species. These iPS
cells have been successfully generated using mouse and human cells.
Furthermore, iPS cells have been successfully generated using
embryonic, fetal, newborn, and adult tissue. Accordingly, one can
readily generate iPS cells using a donor cell from any species.
Thus, one can generate iPS cells from any species, including but
not limited to, human, non-human primates, rodents (mice, rats),
ungulates (cows, sheep, etc), dogs (domestic and wild dogs), cats
(domestic and wild cats such as lions, tigers, cheetahs), rabbits,
hamsters, goats, elephants, panda (including giant panda), pigs,
raccoon, horse, zebra, marine mammals (dolphin, whales, etc.) and
the like. In certain embodiments, the species is an endangered
species. In certain embodiments, the species is a currently extinct
species.
[0179] Induced pluripotent stem cells can be generated using, as a
starting point, virtually any somatic cell of any developmental
stage. For example, the cell can be from an embryo, fetus, neonate,
juvenile, or adult donor. Exemplary somatic cells that can be used
include fibroblasts, such as dermal fibroblasts obtained by a skin
sample or biopsy, synoviocytes from synovial tissue, foreskin
cells, cheek cells, or lung fibroblasts. Although skin and cheek
provide a readily available and easily attainable source of
appropriate cells, virtually any cell can be used. In certain
embodiments, the somatic cell is not a fibroblast.
[0180] The induced pluripotent stem cell may be produced by
expressing or inducing the expression of one or more reprogramming
factors in a somatic cell. The somatic cell may be a fibroblast,
such as a dermal fibroblast, synovial fibroblast, or lung
fibroblast, or a non-fibroblastic somatic cell. The somatic cell
may be reprogrammed through causing expression of (such as through
viral transduction, integrating or non-integrating vectors, etc.)
and/or contact with (e.g., using protein transduction domains,
electroporation, microinjection, cationic amphiphiles, fusion with
lipid bilayers containing, detergent permeabilization, etc.) at
least 1, 2, 3, 4, 5 reprogramming factors. The reprogramming
factors may be selected from OCT 3/4, SOX2, NANOG, LIN28, C-MYC,
and KLF4. Expression of the reprogramming factors may be induced by
contacting the somatic cells with at least one agent, such as a
small organic molecule agents, that induce expression of
reprogramming factors.
[0181] Further exemplary pluripotent stem cells include induced
pluripotent stem cells generated by reprogramming a somatic cell by
expressing or inducing expression of a combination of factors
("reprogramming factors"). iPS cells may be obtained from a cell
bank. The making of iPS cells may be an initial step in the
production of differentiated cells. iPS cells may be specifically
generated using material from a particular patient or matched donor
with the goal of generating tissue-matched PHRPS or photoreceptor
cells. iPSCs can be produced from cells that are not substantially
immunogenic in an intended recipient, e.g., produced from
autologous cells or from cells histocompatible to an intended
recipient.
[0182] The somatic cell may also be reprogrammed using a
combinatorial approach wherein the reprogramming factor is
expressed (e.g., using a viral vector, plasmid, and the like) and
the expression of the reprogramming factor is induced (e.g., using
a small organic molecule.) For example, reprogramming factors may
be expressed in the somatic cell by infection using a viral vector,
such as a retroviral vector or a lentiviral vector. Also,
reprogramming factors may be expressed in the somatic cell using a
non-integrative vector, such as an episomal plasmid. See, e.g., Yu
et al., Science. 2009 May 8; 324(5928):797-801, which is hereby
incorporated by reference in its entirety. When reprogramming
factors are expressed using non-integrative vectors, the factors
may be expressed in the cells using electroporation, transfection,
or transformation of the somatic cells with the vectors. For
example, in mouse cells, expression of four factors (OCT3/4, SOX2,
C-MYC, and KLF4) using integrative viral vectors is sufficient to
reprogram a somatic cell. In human cells, expression of four
factors (OCT3/4, SOX2, NANOG, and LIN28) using integrative viral
vectors is sufficient to reprogram a somatic cell.
[0183] Once the reprogramming factors are expressed in the cells,
the cells may be cultured. Over time, cells with ES characteristics
appear in the culture dish. The cells may be chosen and subcultured
based on, for example, ES morphology, or based on expression of a
selectable or detectable marker. The cells may be cultured to
produce a culture of cells that resemble ES cells--these are
putative iPS cells.
[0184] To confirm the pluripotency of the iPS cells, the cells may
be tested in one or more assays of pluripotency. For example, the
cells may be tested for expression of ES cell markers; the cells
may be evaluated for ability to produce teratomas when transplanted
into SCID mice; the cells may be evaluated for ability to
differentiate to produce cell types of all three germ layers. Once
a pluripotent iPSC is obtained it may be used to produce cell types
disclosed herein, e.g., photoreceptor progenitor cells,
photoreceptor cells, rods, cones, etc. and other cell types
described herein, e.g., in the examples.
[0185] Stimulus-triggered acquisition of pluripotency (STAP) cells
are pluripotent stem cells produced by reprogramming somatic cells
with sublethal stimuli such as low-pH exposure. The reprogramming
does not require nuclear transfer into or genetic manipulation of
the somatic cells. Reference can be made to Obokata et al., Nature,
505:676-680, 2014.
[0186] "Stem cell" is used here to refer to a pluripotent cell
which can proliferate and/or differentiate into a mature cell and
is optionally of human origin.
[0187] "Adult stem cell" refers to a multipotent cell isolated from
adult tissue and can include bone marrow stem cells, cord blood
stem cells and adipose stem cells and is of human origin.
[0188] "Retina" refers to the neural cells of the eye, which are
layered into three nuclear layers comprised of photoreceptors,
horizontal cells, bipolar cells, amacrine cells, Muller glial cells
and ganglion cells.
[0189] "Precursor cell" refers to a cell capable of differentiating
to an end fate cell lineage. In embodiments of the invention, an
"eye field progenitor cell" is differentiated from embryonic stem
cells or induced pluripotent stem cells and expresses the markers
PAX6 and RX1. In embodiments of the invention, a "retinal neural
progenitor cell" refers to a cell differentiated from embryonic
stem cells or induced pluripotent stem cells, that expresses the
cell markers PAX6 and CHX10. In embodiments of the invention,
"photoreceptor progenitor" refers to cells differentiated from
embryonic stem cells or induced pluripotent stem cells and that
expresses the marker PAX6 while not expressing the marker CHX10
(i.e. CHX10(-)). These cells transiently express CHX10 at retinal
neural progenitor stage, but the CHX10 expression is turned off
when cells differentiate into the photoreceptor progenitor stage.
Also, "photoreceptor" may refer to post-mitotic cells
differentiated from embryonic stem cells or induced pluripotent
stem cells and that expresses the cell marker rhodopsin or any of
the three cone opsins, and optionally express the rod or cone cGMP
phosphodiesterase. The photoreceptors may also express the marker
recoverin, which is found in photoreceptors. The photoreceptors may
be rod and/or cone photoreceptors.
[0190] "Signs" of disease, as used herein, refers broadly to any
abnormality indicative of disease, discoverable on examination of
the patient; an objective indication of disease, in contrast to a
symptom, which is a subjective indication of disease.
[0191] "Symptoms" of disease as used herein, refers broadly to any
morbid phenomenon or departure from the normal in structure,
function, or sensation, experienced by the patient and indicative
of disease.
[0192] "Therapy," "therapeutic," "treating," "treat" or
"treatment", as used herein, refers broadly to treating a disease,
arresting or reducing the development of the disease or its
clinical symptoms, and/or relieving the disease, causing regression
of the disease or its clinical symptoms. Therapy encompasses
prophylaxis, prevention, treatment, cure, remedy, reduction,
alleviation, and/or providing relief from a disease, signs, and/or
symptoms of a disease. Therapy encompasses an alleviation of signs
and/or symptoms in patients with ongoing disease signs and/or
symptoms. Therapy also encompasses "prophylaxis" and "prevention".
Prophylaxis includes preventing disease occurring subsequent to
treatment of a disease in a patient or reducing the incidence or
severity of the disease in a patient. The term "reduced", for
purpose of therapy, refers broadly to the clinical significant
reduction in signs and/or symptoms. Therapy includes treating
relapses or recurrent signs and/or symptoms. Therapy encompasses
but is not limited to precluding the appearance of signs and/or
symptoms anytime as well as reducing existing signs and/or symptoms
and eliminating existing signs and/or symptoms. Therapy includes
treating chronic disease ("maintenance") and acute disease. For
example, treatment includes treating or preventing relapses or the
recurrence of signs and/or symptoms.
[0193] Conditions to be treated according to the invention and thus
using one or more of the preparations provided herein include but
are not limited macular degeneration including age-related macular
degeneration, and such macular degeneration may be early or late
stage. Other conditions to be treated include but are not limited
to retinitis pigmentosa, retinal dysplasia, retinal degeneration,
diabetic retinopathy, congenital retinal dystrophy, Leber
congenital amaurosis, retinal detachment, glaucoma, optic
neuropathy, and trauma that affects the eye.
[0194] Cell Markers:
[0195] Exemplary cell markers that may be assessed for expression
include the following: PAX6, RX1, SIX3, SIX6, LHX2, TBX3, SOX2,
CHX10, Nestin, TRbeta2, NR2E3, NRL, MASH1, RORbeta, Recoverin,
Opsin, Rhodopsin, rod and cone cGMP Phosphodiesterase, which may be
assessed at the protein and/or mRNA (see Fischer A J, Reh T A, Dev
Neurosci. 2001; 23(4-5):268-76; Baumer et al., Development. 2003
July; 130(13):2903-15, Swaroop et al., Nat Rev Neurosci. 2010
August; 11(8):563-76, Agathocleous and Harris, Annu. Rev. Cell Dev.
Biol. 2009. 25:45-69, each of which is hereby incorporated by
reference in its entirety). Said marker identifiers are generally
used as in the literature and in the art, particular in the fields
of art in related to the contexts in which those gene identifiers
are recited herein, which may include literature related to
photoreceptors, rods, cones, photoreceptor differentiation,
photoreceptor progenitors, neural differentiation, neural stem
cells, pluripotent stem cells, and other fields as indicated by
context. Additionally, the markers are generally human, e.g.,
except where the context indicates otherwise. The cell markers can
be identified using conventional immunocytochemical methods or
conventional PCR methods which techniques are well known to those
of ordinary skill in the art.
[0196] Cell Culture Media:
[0197] In embodiments of the invention, the cells are stored,
proliferated or differentiated in various cell culture media.
Retinal induction medium is utilized for the stem cell production
into Eye Field Progenitor Cells. The retinal induction medium may
comprise D-glucose, penicillin, streptomycin, N2 supplement (e.g.
0.1-5%), B27 supplement (e.g., 0.005 to 0.2%), MEM Non-essential
amino acids solution and optionally including insulin and/or
Noggin, and may be in a DMEM/F12 (Invitrogen) or similar base
medium. For example, the Retinal induction medium may include at
least insulin. Additionally, the insulin concentration may be
varied or increased which may promote cell survival and/or yield of
differentiated cells. For example, the insulin concentration may be
varied across a range and survival and/or differentiation monitored
in order to identify an insulin concentration with improves either
or both of these attributes. The addition of Noggin is believed not
to be necessary but was observed to increase the expression of eye
field transcription factors.
[0198] The components of DMEM/F12, Neurobasal medium, N2 serum
supplement, and B27 serum supplement are provided in FIGS. 21A-21E.
It is to be understood that the invention contemplates the use of
these particular media and supplements or media or supplements
comprising, consisting essentially of, or consisting of these
components.
[0199] The methods described herein may use human factors such as
human Noggin, human insulin, and the like.
[0200] Noggin is a secreted BMP inhibitor that reportedly binds
BMP2, BMP4, and BMP7 with high affinity to block TGF.beta. family
activity. SB431542 is a small molecule that reportedly inhibits
TGF.beta./Activin/Nodal by blocking phosphorylation of ACTRIB,
TGF.beta.R1, and ACTRIC receptors. SB431542 is thought to
destabilize the Activin- and Nanog-mediated pluripotency network as
well as suppress BMP induced trophoblast, mesoderm, and endodermal
cell fates by blocking endogenous Activin and BMP signals. It is
expected that agents having one or more of the aforementioned
activities could replace or augment the functions of one or both of
Noggin and SB431542, e.g., as they are used in the context of the
disclosed methods. For example, applicants envision that the
protein Noggin and/or the small molecule SB4312542 could be
replaced or augmented by one or more inhibitors that affect any or
all of the following three target areas: 1) preventing the binding
of the ligand to the receptor; 2) blocking activation of receptor
(e.g., dorsomorphin), and 3) inhibition of SMAD intracellular
proteins/transcription factors. Exemplary potentially suitable
factors include the natural secreted BMP inhibitors Chordin (which
blocks BMP4) and Follistatin (which blocks Activin), as well as
analogs or mimetics thereof. Additional exemplary factors that may
mimic the effect of Noggin include use of dominant negative
receptors or blocking antibodies that would sequester BMP2, BMP4,
and/or BMP7. Additionally, with respect to blocking receptor
phosphorylation, dorsomorphin (or Compound C) has been reported to
have similar effects on stem cells. Inhibition of SMAD proteins may
also be effected using soluble inhibitors such as SIS3
(6,7-Dimethoxy-2-((2E)-3-(1-methyl-2-phenyl-1H-pyrrolo[2,3-b]pyridin-3-yl-
-prop-2-enoyl))-1,2,3,4-tetrahydroisoquinoline, Specific Inhibitor
of Smad3, SIS3), overexpression of one or more of the inhibitor
SMADs (e.g., SMAD6, SMAD7, SMAD10) or RNAi for one of the receptor
SMADs (SMAD1, SMAD2, SMAD3, SMAD5, SMAD8/9). Another combination of
factors expected to be suitable for generating neural progenitors
comprises a cocktail of Leukemia Inhibitory Factor (LIF), GSK3
inhibitor (CHIR 99021), Compound E (.gamma. secretase inhibitor
XXI) and the TGF.beta. inhibitor SB431542 which has been previously
shown to be efficacious for generating neural crest stem cells (Li
et al., Proc Natl Acad Sci USA. 2011 May 17; 108(20):8299-304).
Additional exemplary factors may include derivatives of SB431542,
e.g., molecules that include one or more added or different
substituents, analogous functional groups, etc. and that have a
similar inhibitory effect on one or more SMAD proteins. Suitable
factors or combinations of factors may be identified, for example,
by contacting pluripotent cells with said factor(s) and monitoring
for adoption of eye field progenitor cell phenotypes, such as
characteristic gene expression (including expression of the markers
described herein, expression of a reporter gene coupled to an eye
field progenitor cell promoter, or the like) or the ability to form
a cell type disclosed herein such as retinal neural progenitor
cells, photoreceptor progenitors, rod progenitors, cones, and/or
rods.
[0201] Preferably the cells are treated with or cultured in a
retinal induction medium prior to culture with a neural
differentiation medium. A neural differentiation medium is utilized
for Eye Field Progenitor Cell production into Retinal Neural
Progenitor Cells. The neural differentiation medium may comprise
D-glucose, penicillin, streptomycin, GlutaMAX.TM., N2 supplement,
B27 supplement, MEM Non-essential amino acids solution and
optionally including Noggin. The neural differentiation medium may
also be utilized for Retinal Neural Progenitor Cell production into
Photoreceptor Progenitor Cells but without the inclusion of Noggin.
The use of a neural differentiation medium, optionally supplemented
with retinoic acid and taurine, followed by utilization of a
photoreceptor differentiation medium (Invitrogen) which optionally
may comprise D-glucose, penicillin, streptomycin, GlutaMAX.TM., N2
supplement, B27 supplement (e.g., formula number 080085-SA) with
the addition of Forskolin, BDNF, CNTF, LIF and DATP is utilized for
Photoreceptor Progenitor Cells production into Photoreceptor Cells.
For example the photoreceptor differentiation medium may comprise
thyroid hormone, e.g., in an amount that is present in the
foregoing medium, or in a different or greater amount. For example
said medium may comprise exogenously added thyroid hormone. In
exemplary embodiments the photoreceptor differentiation medium may
comprise one, two, or all three BDNF, CNTF and DATP, e.g., BDNF,
CNTF, DATP, BDNF and CNTF, CNTF and DATP, BDNF and DATP, or all
three of BDNF, CNTF and DATP, which medium may optionally comprise
Neurobasal Medium and/or may optionally comprise thyroid
hormone.
[0202] The neural differentiation medium constituents are as
follows: N2: 1% (1 ml of N2 per 100 ml), B27: 2% (2 ml of B27 per
100 ml), and Noggin: 50 ng/ml.
[0203] Noggin is not needed after cells have all become eye field
progenitors.
[0204] Embryonic Stem Cells (ESCs) or Adult Stem Cells or Induced
Pluripotent Stem Cells (iPS):
[0205] The ESCs, or Adult Stem Cells or iPS cells utilized herein
may be propagated on a feeder-free system, such as in Matrigel.TM.
(a soluble preparation from Engelbreth-Holm-Swarm (EHS) mouse
sarcoma cells) or another matrix. Additionally, or alternatively,
said pluripotent cells may be cultured on a matrix which may be
selected from the group consisting of laminin, fibronectin,
vitronectin, proteoglycan, entactin, collagen, collagen I, collagen
IV, collagen VIII, heparan sulfate, Matrigel.TM. (a soluble
preparation from Engelbreth-Holm-Swarm (EHS) mouse sarcoma cells),
CellStart, a human basement membrane extract, and any combination
thereof. Said matrix may comprise, consist of, or consist
essentially of Matrigel.TM. (a soluble preparation from
Engelbreth-Holm-Swarm (EHS) mouse sarcoma cells). The stem cells do
not form embryoid bodies in culture, which is an improvement over
the prior art. The cells differentiate into eye field progenitor
cells in the absence of exogenous factors. In an embodiment, ESCs
differentiate into eye field progenitor cells in the presence of
Noggin.
[0206] Eye Field Progenitor Cells (EFPCs):
[0207] The EFPCs differentiate from ESCs, Adult stem cells or
induced pluripotent cells (iPCs) into cells that are PAX6(+) and
RX1(+). The EFPCs can also be SIX3(+), SIX6(+), LHX2(+), TBX3(+)
Nestin(+) and/or SOX2(+) and OCT4(-) and NANOG(-). The
differentiation into EFPCs occurs in a retinal induction medium
which may comprise DMEM/F12, D-glucose, penicillin, streptomycin,
N2 supplement, B27 supplement, MEM non-essential amino acid and
insulin. On day 5, when cells reach confluence, cells are changed
to neural differentiation medium. Preferably the step of producing
EFPCs is performed prior to culturing pluripotent cells in the
neural differentiation medium described below, as it has been
observed that such culture conditions may adversely affect
pluripotent cell viability.
[0208] Retinal Neural Progenitor Cells (RNPCs):
[0209] The RNPCs differentiate from the EFPCs in the absence of
exogenous factors. The RNPCs are PAX6(+) and CHX10(+). The cells at
this state may be Tuj1+ or Tuj1-. Optionally the method may include
enriching or purifying Tuj1+ or Tuj1- cells at this stage, and/or
purifying or removing strongly Tuj1+ cells and/or purifying or
removing strongly Tuj1- cells (e.g., cells lacking even low level
detectable expression thereof) and proceeding with the subsequent
method steps with one or the other of these populations. In an
embodiment, Noggin is added to accelerate the differentiation from
EFPCs to RNPCs The differentiation into RNPCs occurs in a neural
differentiation media which may comprise Neurobasal Medium
(Invitrogen), D-glucose, penicillin, streptomycin, GlutaMAX.TM., N2
supplement, B27 supplement and MEM non-essential amino acid
solution. Noggin may be added at a final concentration of 5-100
.mu.g/ml.
[0210] Photoreceptor Progenitor Cells (PhRPCs):
[0211] The PhRPCs may be differentiated from the RNPCs in the
absence of Noggin and in neural differentiation medium). The PRPCs
are PAX6(+) and CHX10(-). In embodiment, 60%, 70%, 80%, 85%, 90%,
or 95% of the PRPCs are PAX6(+) and CHX10(-) The PRPCs can also be
Nr2e3(+), Tr.beta.2(+), Mash1(+), ROR.beta.(+) and/or NRO(+). The
presence of CHX10 would suggest a bipolar cell lineage, but in the
present method, the PRPCs have differentiated to a photoreceptor
lineage, and therefore do not possess CHX10 at this stage. The
cells may be grown as spheres or neurospheres (e.g., on low
attachment plates or optionally on hanging drop cultures, in a
low-gravity environment, or other suitable culture condition).
[0212] Photoreceptors (PRs):
[0213] The PRs may differentiate from the PhRPCs in a two-step
differentiation process 1) Adding neural differentiation medium
with retinoic acid and taurine for 2 weeks and 2) addition of the
photoreceptor differentiation medium.--see Example 2.
[0214] The PRs may be rhodopsin(+), recoverin(+), PE6a(+) or
opsin(+). The opsin may be any of the cone opsins. The PRs may be
bipotential for cones or rods. Exemplary photoreceptors produced by
this method may be PAX6-, which may be in contrast to some
previously described purported photoreceptor cells. As described
below in exemplary embodiments there is a 2 step differentiation
process 1) adding ND medium and retinoic acid and taurine for 2
weeks and 2) use of the photoreceptor differentiation medium, which
methods are further exemplified in the working examples below.
[0215] In exemplary embodiments the method may produce 40-60
million EFPCs, 60-90 million RNPCs, or 0.5-1 billion PhRPCs per
starting 1 million pluripotent cells.
[0216] In an exemplary embodiment, the cells may be transplanted
into a rat in need thereof, e.g., an RCS rat, or other animal model
of disease (e.g. for night blindness or for color blindness), and
the resulting effect on visual function may be detected by the
Optomotor response test, ERG, luminance threshold recording and/or
the visual center blood flow assay.
[0217] Applications and Uses
[0218] Screening Assays
[0219] The present invention provides methods for screening various
agents that modulate the differentiation of a retinal progenitor
cell. It could also be used to discover therapeutic agents that
support and/or rescue mature photoreceptors that are generated in
culture from retinal progenitor cells. For the purposes of this
invention, an "agent" is intended to include, but not be limited
to, a biological or chemical compound such as a simple or complex
organic or inorganic molecule, a peptide, a protein (e.g.
antibody), a polynucleotide (e.g. anti-sense) or a ribozyme. A vast
array of compounds can be synthesized, for example polymers, such
as polypeptides and polynucleotides, and synthetic organic
compounds based on various core structures, and these are also
included in the term "agent." In addition, various natural sources
can provide compounds for screening, such as plant or animal
extracts, and the like. It should be understood, although not
always explicitly stated, that the agent is used alone or in
combination with another agent, having the same or different
biological activity as the agents identified by the inventive
screen.
[0220] To practice the screening method in vitro, an isolated
population of cells can be obtained as described herein. When the
agent is a composition other than a DNA or RNA, such as a small
molecule as described above, the agent can be directly added to the
cells or added to culture medium for addition. As is apparent to
those skilled in the art, an "effective" amount must be added which
can be empirically determined. When the agent is a polynucleotide,
it can be directly added by use of a gene gun or electroporation.
Alternatively, it can be inserted into the cell using a gene
delivery vehicle or other method as described above. Positive and
negative controls can be assayed to confirm the purported activity
of the drug or other agent.
[0221] Neurosensory Retinal Structures
[0222] The photoreceptor progenitor cells, and optionally the
photoreceptor cells differentiated therefrom, can be used to
generate neurosensory retinal structures. For instance, the
invention contemplates the generation of multilayer cellular
structures comprised of retinal pigment epithelial (RPE) cells and
photoreceptor cells (or photoreceptor progenitor cells). These
structures can be used for drug screening, as models for diseases,
or as or in a pharmaceutical preparation. In the latter case, the
pharmaceutical preparation can be an RPE-photoreceptor graft, which
may be disposed on a biocompatible solid support or matrix
(preferably a bioresorbable matrix or support) that can be
implanted like a "patch".
[0223] To further illustrate, the biocompatible support for the
cells can be a biodegradable polyester film support for retinal
progenitor cells. The biodegradable polyester can be any
biodegradable polyester suitable for use as a substrate or scaffold
for supporting the proliferation and differentiation of retinal
progenitor cells. The polyester should be capable of forming a thin
film, preferably a micro-textured film, and should be biodegradable
if used for tissue or cell transplantation. Suitable biodegradable
polyesters for use in the invention include polylactic acid (PLA),
polylactides, polyhydroxyalkanoates, both homopolymers and
co-polymers, such as polyhydoxybutyrate (PHB), polyhydroxybutyrate
co-hydroxyvalerate (PHBV), polyhydroxybutyrate co-hydroxyhexanote
(PHBHx), polyhydroxybutyrate co-hydroxyoctonoate (PHBO) and
polyhydroxybutyrate co-hydroxyoctadecanoate (PHBOd),
polycaprolactone (PCL), polyesteramide (PEA), aliphatic
copolyesters, such as polybutylene succinate (PBS) and polybutylene
succinate/adipate (PBSA), aromatic copolyesters. Both high and low
molecular weight polyesters, substituted and unsubstituted
polyester, block, branched or random, and polyester mixtures and
blends can be used. Preferably the biodegradable polyester is
polycaprolactone (PCL).
[0224] In certain embodiments, the biocompatible support is a
poly(p-xylylene) polymer, such as parylene N, parylene D,
parylene-C, parylene AF-4, parylene SF, parylene HT, parylene VT-4
and Parylene CF, and most preferably parylene-C.
[0225] The polymeric support can typically be formed into a thin
film using known techniques. The film thickness is advantageously
from about 1 micron to about 50 microns, and preferably about 5
microns in thickness. The surface of the film can be smooth, or the
film surface can be partially or completely micro-textured.
Suitable surface textures include micro-grooves or micro-posts, for
instance. The film can be cut and shaped to form a suitable shape
for implantation.
[0226] The RPE and/or photoreceptor cells or photoreceptor
progenitor cells can be plated directly--together or sequentially
(e.g., photoreceptor cells or photoreceptor progenitor cells after
an RPE layer is formed)--onto the film to form a biocompatible
scaffold. Alternatively, the polymer film can be coated with a
suitable coating material such as poly-D-lysine, poly-L-lysine,
fibronectin, laminin, collagen I, collagen IV, vitronectin and
Matrigel.TM.. The cells can be plated to any desired density, but a
single layer of RPE cells (an RPE monolayer) is preferred.
[0227] Therapeutic Uses
[0228] This invention also provides methods for replacing or
repairing photoreceptor cells in a patient in need of this
treatment comprising administering a pharmaceutical preparation
including the photoreceptor progenitor cells of the present
invention, or photoreceptors derived therefrom or a combination
thereof, to a patient. As described herein, the pharmaceutical
preparation can be a suspension of cells or cells which are formed
into transplantable tissue in vitro. In many instances, the cells
will be administered to the subretinal space of a diseased or
degenerated retina. However, as the photoreceptor progenitor cells
of the present invention also have a neuroprotective effect, the
cells can be administered locally but outside of the retina (such
as in the vitreous) or by depot or systemic delivery to other parts
of the body.
[0229] The pharmaceutical preparations of the present invention can
be used in a wide range of diseases and disorders that result in
visual system deterioration, including retinal degeneration-related
disease. Such diseases and disorders may be caused by aging, such
that there appears to be an absence of an injury or disease that is
identifiable as a substantial source of the deterioration. Skilled
artisans will understand the established methods for diagnosing
such disease states, and/or inspecting for known signs of such
injuries. In addition, the literature is replete with information
on age-related decline or deterioration in aspects of the visual
systems of animals. The term "retinal degeneration-related disease"
is intended to refer to any disease resulting from innate or
postnatal retinal degeneration or abnormalities. Examples of
retinal degeneration-related diseases include retinal dysplasia,
retinal degeneration, aged macular degeneration, diabetic
retinopathy, retinitis pigmentosa, congenital retinal dystrophy,
Leber congenital amaurosis, retinal detachment, glaucoma, optic
neuropathy, and trauma.
[0230] Additionally or alternatively, the deterioration of the
visual system components, such as the neurosensory retina can be
caused by injury, for example trauma to the visual system itself
(e.g., an eye), to the head or brain, or the body more generally.
Certain such injuries are known to be age-related injuries, i.e.,
their likelihood, or frequency increases with age. Examples of such
injuries include retinal tears, macular holes, epiretinal membrane,
and retinal detachments, each of which might occur in an animal of
any age, but which are more likely to occur, or occur with greater
frequency in aging animals, including otherwise healthy aging
animals.
[0231] The deterioration of the visual system or components thereof
also can be caused by disease. Included among the diseases are
various age-related diseases that impact the visual system. Such
diseases occur with greater likelihood and/or frequency in older
animals than in the young. Examples of diseases which may affect
the visual system, including for example the neurosensory retinal
layers, and cause deterioration thereof are various forms of
retinitis, optic neuritis, macular degeneration, proliferative or
nonproliferative diabetic retinopathy, diabetic macular edema,
progressive retinal atrophy, progressive retinal degeneration,
sudden acquired retinal degeneration, immune-mediated retinopathy,
retinal dysplasia, chorioretinitis, retinal ischemia, retinal
hemorrhage (preretinal, intraretinal and/or subretinal),
hypertensive retinopathy, retinal inflammation, retinal edema,
retinoblastoma, or retinitis pigmentosa.
[0232] Some of the foregoing diseases tend to be specific to
certain animals such as companion animals, e.g., dogs and/or cats.
Some of the diseases are listed generically, i.e., there may be
many types of retinitis, or retinal hemorrhage; thus some of the
disease are not caused by one specific etiologic agent, but are
more descriptive of the type of disease or the result. Many of the
diseases that can cause decline or deterioration of one or more
components of the visual system can have both primary and secondary
or more remote effects on an animal's visual system.
[0233] Advantageously, the pharmaceutical preparations of the
present invention may be used to compensate for a lack or
diminution of photoreceptor cell function. Examples of retinal
dysfunction that can be treated by the retinal stem cell
populations and methods of the invention include but are not
limited to: photoreceptor degeneration (as occurs in, e.g.,
retinitis pigmentosa, cone dystrophies, cone-rod and/or rod-cone
dystrophies, and macular degeneration); retina detachment and
retinal trauma; photic lesions caused by laser or sunlight; a
macular hole; a macular edema; night blindness and color blindness;
ischemic retinopathy as caused by diabetes or vascular occlusion;
retinopathy due to prematurity/premature birth; infectious
conditions, such as, e.g., CMV retinitis and toxoplasmosis;
inflammatory conditions, such as the uveitidies; tumors, such as
retinoblastoma and ocular melanoma; and for the replacement of
inner retinal neurons, which are affected in ocular neuropathies
including glaucoma, traumatic optic neuropathy, and radiation optic
neuropathy and retinopathy.
[0234] In one aspect, the cells can treat or alleviate the symptoms
of retinitis pigmentosa in a patient in need of the treatment. In
another aspect, the cells can treat or alleviate the symptoms of
macular degeneration, such as age-related macular degeneration (wet
or dry), Stargardt's disease, myopic macular degeneration or the
like, in a patient in need of this treatment. For all of these
treatments, the cells can be autologous or allogeneic to the
patient. In a further aspect, the cells of the invention can be
administered in combination with other treatments.
[0235] Retinitis pigmentosa (RP) refers to a heterogeneous group of
hereditary eye disorders characterized by progressive vision loss
due to a gradual degeneration of photoreceptors. An estimated
100,000 people in the United States have RP. Classification of this
group of disorders under one rubric is based on the clinical
features most commonly observed in these patients. The hallmarks of
RP are night blindness and reduction of peripheral vision,
narrowing of the retinal vessels, and the migration of pigment from
disrupted retinal pigment epithelium into the retina, forming
clumps of various sizes, often next to the retinal blood
vessels.
[0236] Typically, patients first notice difficulty seeing at night
due to the loss of rod photoreceptors; the remaining cone
photoreceptors then become the mainstay of visual function. Over
years and decades, however, the cones also degenerate, leading to a
progressive loss of vision. In most RP patients, visual field
defects begin in the midperiphery, between 30.degree. and
50.degree. from fixation. The defective regions gradually enlarge,
leaving islands of vision in the periphery and a constricted
central field (called tunnel vision). When the visual field
contracts to 200 or less and/or central vision is 20/200 or worse,
the patient becomes legally blind.
[0237] Inheritance patterns indicate that RP can be transmitted in
X-linked (XLRP), autosomal dominant (ADRP), or recessive (ARRP)
modes. Among the three genetic types of RP, ADRP is the mildest.
These patients often retain good central vision to 60 years of age
and beyond. In contrast, patients with the XLRP form of the disease
are usually legally blind by 30 to 40 years of age. However, the
severity and the age of onset of the symptoms varies greatly among
patients with the same genetic type of RP. This variation is
apparent even within the same family when presumably all the
affected members have the same genetic mutation. Many RP-inducing
mutations have now been described. Of the genes identified so far,
many encode photoreceptor-specific proteins, several being
associated with phototransduction in the rods, such as rhodopsin,
subunits of the cGMP phosphodiesterase, and the cGMP-gated
Ca.sup.2+ channel. Multiple mutations in each of the cloned genes
have been found. For example, in the case of the rhodopsin gene, 90
different mutations have been identified among ADRP patients.
[0238] Regardless of the specific mutation, the vision loss that is
most critical to RP patients is due to the gradual degeneration of
cones. In many cases, the protein that the RP-causing mutation
affects is not even expressed in the cones; the prime example is
rhodopsin--the rod-specific visual pigment. Therefore, the loss of
cones may be an indirect consequence of a rod-specific mutation.
The ability to replace damaged photoreceptors provides an approach
to the treatment of this disease.
[0239] Age-related macular degeneration (AMD) causes a progressive
loss of central vision, and is the most common cause of vision loss
in people over age 55. The underlying pathology is degeneration of
the photoreceptors. Various studies have implicated hereditary
factors, cardiovascular disease, environmental factors such as
smoking and light exposure, and nutritional causes as contributing
to the risk of developing AMD. RPE degeneration is accompanied by
variable loss of both the overlying photoreceptors and the
underlying choroidal perfusion. Visual acuity loss or visual field
loss occurs when the RPE atrophies and results in secondary loss of
the overlying photoreceptor cells that it supplies. The ability to
replace RPE and photoreceptor cells provides a means of treating
established AMD.
[0240] Macular degeneration is broadly divided into two types. In
the exudative-neovascular form, or "wet" AMD, which accounts for
10% of all cases, abnormal blood vessel growth occurs under the
macula. There is formation of a subretinal network of choroidal
neovascularization often associated with intraretinal hemorrhage,
subretinal fluid, pigment epithelial detachment, and
hyperpigmentation. Eventually, this complex contracts and leaves a
distinct elevated scar at the posterior pole. These blood vessels
leak fluid and blood into the retina and thus cause damage to the
photoreceptors. Wet AMD tends to progress rapidly and can cause
severe damage; rapid loss of central vision may occur over just a
few months.
[0241] The remaining 90% of AMD cases are atrophic macular
degeneration (dry form), where there is pigmentary disturbance in
the macular region but no elevated macular scar and no hemorrhage
or exudation in the region of the macula. In these patients there
is a gradual disappearance of the retinal pigment epithelium (RPE),
resulting in circumscribed areas of atrophy. Since photoreceptor
loss follows the disappearance of RPE, the affected retinal areas
have little or no visual function. Vision loss from dry AMD occurs
more gradually over the course of many years. These patients
usually retain some central vision, although the loss can be severe
enough to compromise performance of tasks that require seeing
details.
[0242] When the appropriate age and clinical findings are
accompanied by the loss of visual acuity, visual field, or other
visual functions, the condition often is classified as AMD. At
times, the step prior to the onset of visual loss has been
classified as AMD if the patient has characteristic drusen and
relevant family history.
[0243] Occasionally, macular degeneration occurs at a much earlier
age. Many of these cases are caused by genetic mutations. There are
many forms of hereditary macular degeneration, each with its own
clinical manifestations and genetic cause. The most common form of
juvenile macular degeneration is known as Stargardt disease, which
is inherited as an autosomal recessive. Patients are usually
diagnosed under the age of 20. Although the progression of vision
loss is variable, most of these patients are legally blind by age
50. Mutations that cause Stargardt disease have been identified in
the ABCR gene, which codes for a protein that transports retinoids
across the photoreceptor membrane.
[0244] The photoreceptor progenitor cells of the present invention
find use in the treatment of degenerative diseases, and may be
delivered as progenitor cells; as the differentiated progeny (rods
and cones) thereof, e.g. after commitment to a photoreceptor
lineage of interest. The cells are administered in a manner that
permits them to graft or migrate to the intended retinal site, such
as in the outer nucleated layer, and reconstitute or regenerate the
functionally deficient area.
[0245] Genetically engineered progenitor cells or photoreceptors
can also be used to target gene products to sites of degeneration.
These gene products can include survival-promoting factors to
rescue native degenerating neurons, factors that can act in an
autocrine manner to promote survival and differentiation of grafted
cells into site-specific neurons or to deliver neurotransmitter(s)
to permit functional recovery. Ex vivo gene therapy, e.g., the
recombinantly engineering the progenitor cells or the
photoreceptors in culture, could be used effectively as a
neuroprotective strategy to prevent retinal cell loss in RP, AMD,
and glaucoma and in diseases that cause retinal detachment, by the
delivery of growth factors and neurotrophins such as FGF2, NGF,
ciliary neurotrophic factor (CNTF), and brain derived neurotrophic
factor (BDNF), which factors have been shown to significantly slow
the process of cell death in models of retinal degeneration.
Therapy using photoreceptor progenitor and/or photoreceptor cells
engineered to synthesize a growth factor or a combination of growth
factors can not only ensure sustained delivery of neuroprotectants,
but may also reconstruct damaged retina.
[0246] In the methods of the invention, cells to be transplanted
are transferred to a recipient in any physiologically acceptable
excipient comprising an isotonic excipient prepared under
sufficiently sterile conditions for human administration. For
general principles in medicinal formulation, the reader is referred
to Cell Therapy: Stem Cell Transplantation, Gene Therapy, and
Cellular Immunotherapy, by G. Morstyn & W. Sheridan eds,
Cambridge University Press, 1996. Choice of the cellular excipient
and any accompanying elements of the composition will be adapted in
accordance with the route and device used for administration. The
cells may be introduced by injection, catheter, or the like. The
cells may be frozen at liquid nitrogen temperatures and stored for
long periods of time, being capable of use on thawing. If frozen,
the cells will usually be stored in a 10% DMSO, 50% FCS, 40% RPMI
1640 medium.
[0247] The pharmaceutical preparations of the invention are
optionally packaged in a suitable container with written
instructions for a desired purpose. Such formulations may comprise
a cocktail of retinal differentiation and/or trophic factors, in a
form suitable for combining with photoreceptor progenitor or
photoreceptor cells. Such a composition may further comprise
suitable buffers and/or excipients appropriate for transfer into an
animal. Such compositions may further comprise the cells to be
engrafted.
[0248] Pharmaceutical Preparations
[0249] The PRPCs or photoreceptor cells may be formulated with a
pharmaceutically acceptable carrier. For example, PRPCs or
photoreceptor cells may be administered alone or as a component of
a pharmaceutical formulation. The subject compounds may be
formulated for administration in any convenient way for use in
medicine. Pharmaceutical preparations suitable for administration
may comprise the PRPCs or photoreceptor cells, in combination with
one or more pharmaceutically acceptable sterile isotonic aqueous or
nonaqueous solutions (e.g., balanced salt solution (BSS)),
dispersions, suspensions or emulsions, or sterile powders which may
be reconstituted into sterile injectable solutions or dispersions
just prior to use, which may contain antioxidants, buffers,
bacteriostats, solutes or suspending or thickening agents.
Exemplary pharmaceutical preparations comprises the PRPCs or
photoreceptor cells in combination with ALCON.RTM. BSS PLUS.RTM. (a
balanced salt solution containing, in each mL, sodium chloride 7.14
mg, potassium chloride 0.38 mg, calcium chloride dihydrate 0.154
mg, magnesium chloride hexahydrate 0.2 mg, dibasic sodium phosphate
0.42 mg, sodium bicarbonate 2.1 mg, dextrose 0.92 mg, glutathione
disulfide (oxidized glutathione) 0.184 mg, hydrochloric acid and/or
sodium hydroxide (to adjust pH to approximately 7.4) in water).
[0250] When administered, the pharmaceutical preparations for use
in this disclosure may be in a pyrogen-free, physiologically
acceptable form.
[0251] The preparation comprising PRPCS or photoreceptor cells used
in the methods described herein may be transplanted in a
suspension, gel, colloid, slurry, or mixture. Further, the
preparation may desirably be encapsulated or injected in a viscous
form into the vitreous humor for delivery to the site of retinal or
choroidal damage. Also, at the time of injection, cryopreserved
PRPCS photoreceptor cells may be resuspended with commercially
available balanced salt solution to achieve the desired osmolality
and concentration for administration by subretinal injection. The
preparation may be administered to an area of the pericentral
macula that was not completely lost to disease, which may promote
attachment and/or survival of the administered cells.
[0252] The PRPCS and/or photoreceptor cells may be frozen
(cryopreserved) as described herein. Upon thawing, the viability of
such cells may be at least 20%, at least 30%, at least 40%, at
least 50%, at least 60%, at least 70%, at least 80%, at least 90%
at least 95% or about 100% (e.g., at least 20%, at least 30%, at
least 40%, at least 50%, at least 60%, at least 70%, at least 80%,
at least 90% at least 95% or about 100% of the cells harvested
after thawing are viable or at least 20%, at least 30%, at least
40%, at least 50%, at least 60%, at least 70%, at least 80%, at
least 90% at least 95% or about 100% of the cell number initially
frozen are harvested in a viable state after thawing).
[0253] The PRPCS or photoreceptor cells of the disclosure may be
delivered in a pharmaceutically acceptable ophthalmic formulation
by intraocular injection. When administering the formulation by
intravitreal injection, for example, the solution may be
concentrated so that minimized volumes may be delivered.
Concentrations for injections may be at any amount that is
effective and non-toxic, depending upon the factors described
herein. The pharmaceutical preparations of PRPCS or photoreceptor
cells for treatment of a patient may be formulated at doses of at
least about 10.sup.4 cells/mL. The PRPCS or photoreceptor cell
preparations for treatment of a patient are formulated at doses of
at least about 10.sup.3, 10.sup.4, 10.sup.5, 10.sup.6, 10.sup.7,
10.sup.8, 10.sup.9, or 10.sup.10 PRPCS or photoreceptor cells/mL.
For example, the PRPCS or photoreceptor cells may be formulated in
a pharmaceutically acceptable carrier or excipient.
[0254] The pharmaceutical preparations of PRPCS or photoreceptor
cells described herein may comprise at least about 1,000; 2,000;
3,000; 4,000; 5,000; 6,000; 7,000; 8,000; or 9,000 PRPCS or
photoreceptor cells. The pharmaceutical preparations of PRPCS or
photoreceptor cells may comprise at least about 1.times.10.sup.4,
2.times.10.sup.4, 3.times.10.sup.4, 4.times.10.sup.4,
5.times.10.sup.4, 6.times.104, 7.times.10.sup.4, 8.times.10.sup.4,
9.times.10.sup.4, 1.times.10.sup.5, 2.times.10.sup.5,
3.times.10.sup.5, 4.times.10.sup.5, 5.times.10.sup.5, 6.times.105,
7.times.10.sup.5, 8.times.105, 9.times.10.sup.5, 1.times.10.sup.6,
2.times.10.sup.6, 3.times.10.sup.6, 4.times.10.sup.6,
5.times.10.sup.6, 6.times.10.sup.6, 7.times.106, 8.times.106,
9.times.106, 1.times.107, 2.times.10.sup.7, 3.times.107,
4.times.10.sup.7, 5.times.10.sup.7, 6.times.107, 7.times.10.sup.7,
8.times.10.sup.7, 9.times.10.sup.7, 1.times.10.sup.8,
2.times.10.sup.8, 3.times.10.sup.8, 4.times.10.sup.8,
5.times.10.sup.8, 6.times.10.sup.8, 7.times.10.sup.8,
8.times.10.sup.8, 9.times.10.sup.8, 1.times.10.sup.9,
2.times.10.sup.9, 3.times.10.sup.9, 4.times.10.sup.9,
5.times.10.sup.9, 6.times.10.sup.9, 7.times.10.sup.9,
8.times.10.sup.9, 9.times.10.sup.9, 1.times.10.sup.10,
2.times.1010, 3.times.10.sup.10, 4.times.10.sup.10,
5.times.10.sup.10, 6.times.10.sup.10, 7.times.10.sup.10,
8.times.10.sup.10, or 9.times.10.sup.10 PRPCS or photoreceptor
cells. The pharmaceutical preparations of PRPCS or photoreceptor
cells may comprise at least about
1.times.10.sup.2-1.times.10.sup.3,
1.times.10.sup.2-1.times.10.sup.4,
1.times.10.sup.4-1.times.10.sup.5, or
1.times.10.sup.3-1.times.10.sup.6 PRPCS OR PRPCS or photoreceptor
cells. The pharmaceutical preparations of PRPCS or photoreceptor
cells may comprise at least about 10,000, 20,000, 25,000, 50,000,
75,000, 100,000, 125,000, 150,000, 175,000, 180,000, 185,000,
190,000, or 200,000 PRPCS or photoreceptor cells. For example, the
pharmaceutical preparation of PRPCS or photoreceptor cells may
comprise at least about 20,000-200,000 PRPCS or photoreceptor cells
in a volume at least about 50-200 .mu.L. Further, the
pharmaceutical preparation of PRPCS or photoreceptor cells may
comprise about 50,000 PRPCS or photoreceptor is in a volume of 150
.mu.L, about 200,000 PRPCS or photoreceptor cells in a volume of
150 .mu.L, or at least about 180,000 PRPCS or photoreceptor cells
in a volume at least about 150 .mu.L.
[0255] In the aforesaid pharmaceutical preparations and
compositions, the number of PRPCS or photoreceptor cells or
concentration of PRPCS or photoreceptor cells may be determined by
counting viable cells and excluding non-viable cells. For example,
non-viable PRPCS or photoreceptor may be detected by failure to
exclude a vital dye (such as Trypan Blue), or using a functional
assay (such as the ability to adhere to a culture substrate,
phagocytosis, etc.). Additionally, the number of PRPCS or
photoreceptor cells or concentration of PRPCS or photoreceptor
cells may be determined by counting cells that express one or more
PRPCS or photoreceptor cell markers and/or excluding cells that
express one or more markers indicative of a cell type other than
PRPCS or photoreceptor.
[0256] The PRPCS or photoreceptor cells may be formulated for
delivery in a pharmaceutically acceptable ophthalmic vehicle, such
that the preparation is maintained in contact with the ocular
surface for a sufficient time period to allow the cells to
penetrate the affected regions of the eye, as for example, the
anterior chamber, posterior chamber, vitreous body, aqueous humor,
vitreous humor, cornea, iris/ciliary, lens, choroid, retina,
sclera, suprachoridal space, conjunctiva, subconjunctival space,
episcleral space, intracorneal space, epicorneal space, pars plana,
surgically-induced avascular regions, or the macula.
[0257] The PRPCS or photoreceptor cells may be contained in a sheet
of cells. For example, a sheet of cells comprising PRPCS or
photoreceptor cells may be prepared by culturing PRPCS or
photoreceptor cells on a substrate from which an intact sheet of
cells can be released, e.g., a thermoresponsive polymer such as a
thermoresponsive poly(N-isopropylacrylamide) (PNIPAAm)-grafted
surface, upon which cells adhere and proliferate at the culture
temperature, and then upon a temperature shift, the surface
characteristics are altered causing release the cultured sheet of
cells (e.g., by cooling to below the lower critical solution
temperature (LCST) (see da Silva et al., Trends Biotechnol. 2007
December; 25(12):577-83; Hsiue et al., Transplantation. 2006 Feb.
15; 81(3):473-6; Ide, T. et al. (2006); Biomaterials 27, 607-614,
Sumide, T. et al. (2005), FASEB J. 20, 392-394; Nishida, K. et al.
(2004), Transplantation 77, 379-385; and Nishida, K. et al. (2004),
N. Engl. J. Med. 351, 1187-1196 each of which is incorporated by
reference herein in its entirety). The sheet of cells may be
adherent to a substrate suitable for transplantation, such as a
substrate that may dissolve in vivo when the sheet is transplanted
into a host organism, e.g., prepared by culturing the cells on a
substrate suitable for transplantation, or releasing the cells from
another substrate (such as a thermoresponsive polymer) onto a
substrate suitable for transplantation. An exemplary substrate
potentially suitable for transplantation may comprise gelatin (see
Hsiue et al., supra). Alternative substrates that may be suitable
for transplantation include fibrin-based matrixes and others. The
sheet of cells may be used in the manufacture of a medicament for
the prevention or treatment of a disease of retinal degeneration.
The sheet of PRPCS OR photoreceptor cells may be formulated for
introduction into the eye of a subject in need thereof. For
example, the sheet of cells may be introduced into an eye in need
thereof by subfoveal membranectomy with transplantation the sheet
of PRPCS or photoreceptor cells, or may be used for the manufacture
of a medicament for transplantation after subfoveal
membranectomy.
[0258] The volume of preparation administered according to the
methods described herein may be dependent on factors such as the
mode of administration, number of P PRPCS or photoreceptor cells,
age and weight of the patient, and type and severity of the disease
being treated. If administered by injection, the volume of a
pharmaceutical preparations of PRPCS or photoreceptor cells of the
disclosure may be from at least about 1, 1.5, 2, 2.5, 3, 4, or 5
mL. The volume may be at least about 1-2 mL. For example, if
administered by injection, the volume of a pharmaceutical
preparation of PRPCS or photoreceptor cells of the disclosure may
be at least about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31,
32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48,
49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65,
66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82,
83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99,
100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 100, 111, 112,
113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125,
126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138,
139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151,
152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164,
165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177,
178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190,
191, 192, 193, 194, 195, 196, 197, 198, 199, or 200 .mu.L
(microliters). For example, the volume of a preparation of the
disclosure may be from at least about 10-50, 20-50, 25-50, or 1-200
.mu.L. The volume of a preparation of the disclosure may be at
least about 10, 20, 30, 40, 50, 100, 110, 120, 130, 140, 150, 160,
170, 180, 190, or 200 .mu.L, or higher.
[0259] For example, the preparation may comprise at least about
1.times.103, 2.times.103, 3.times.103, 4.times.103, 5.times.103,
6.times.103, 7.times.103, 8.times.103, 9.times.103, 1.times.104,
2.times.104, 3.times.104, 4.times.104, 5.times.104, 6.times.104,
7.times.104, 8.times.104, or 9.times.104 PRPCS or photoreceptor
cells per .mu.L. The preparation may comprise 2000 PRPCS or
photoreceptor cells per .mu.L, for example, 100,000 PRPCS or
photoreceptor cells per 50 .mu.L or 180,000 PRPCS or photoreceptor
cells per 90 .mu.L.
[0260] The method of treating retinal degeneration may further
comprise administration of an immunosuppressant. Immunosuppressants
that may be used include but are not limited to anti-lymphocyte
globulin (ALG) polyclonal antibody, anti-thymocyte globulin (ATG)
polyclonal antibody, azathioprine, BASILIXIMAB.RTM.
(anti-IL-2R.alpha. receptor antibody), cyclosporin (cyclosporin A),
DACLIZUMAB.RTM. (anti-IL-2R.alpha. receptor antibody), everolimus,
mycophenolic acid, RITUXIMAB.RTM. (anti-CD20 antibody), sirolimus,
and tacrolimus. The immunosuppressants may be dosed at least about
1, 2, 4, 5, 6, 7, 8, 9, or 10 mg/kg. When immunosuppressants are
used, they may be administered systemically or locally, and they
may be administered prior to, concomitantly with, or following
administration of the PRPCS or photoreceptor cells.
Immunosuppressive therapy may continue for weeks, months, years, or
indefinitely following administration of PRPCS or photoreceptor
cells. For example, the patient may be administered 5 mg/kg
cyclosporin for 6 weeks following administration of the PRPCS or
photoreceptor cells.
[0261] The method of treatment of retinal degeneration may comprise
the administration of a single dose of PRPCS or photoreceptor
cells. Also, the methods of treatment described herein may comprise
a course of therapy where PRPCS or photoreceptor cells are
administered multiple times over some period. Exemplary courses of
treatment may comprise weekly, biweekly, monthly, quarterly,
biannually, or yearly treatments. Alternatively, treatment may
proceed in phases whereby multiple doses are administered initially
(e.g., daily doses for the first week), and subsequently fewer and
less frequent doses are needed.
[0262] If administered by intraocular injection, the PRPCS or
photoreceptor cells may be delivered one or more times periodically
throughout the life of a patient. For example, the PRPCS or
photoreceptor cells may be delivered once per year, once every 6-12
months, once every 3-6 months, once every 1-3 months, or once every
1-4 weeks. Alternatively, more frequent administration may be
desirable for certain conditions or disorders. If administered by
an implant or device, the PRPCS or photoreceptor cells may be
administered one time, or one or more times periodically throughout
the lifetime of the patient, as necessary for the particular
patient and disorder or condition being treated. Similarly
contemplated is a therapeutic regimen that changes over time. For
example, more frequent treatment may be needed at the outset (e.g.,
daily or weekly treatment). Over time, as the patient's condition
improves, less frequent treatment or even no further treatment may
be needed.
[0263] The methods described herein may further comprise the step
of monitoring the efficacy of treatment or prevention by measuring
electroretinogram responses, optomotor acuity threshold, or
luminance threshold in the subject. The method may also comprise
monitoring the efficacy of treatment or prevention by monitoring
immunogenicity of the cells or migration of the cells in the
eye.
[0264] The PRPCs or PRs may be used in the manufacture of a
medicament to treat retinal degeneration. The disclosure also
encompasses the use of the preparation comprising PRPCs or PRs in
the treatment of blindness. For example, the preparations
comprising human PRPCs or PRs may be used to treat retinal
degeneration associated with a number of vision-altering ailments
that result in photoreceptor damage and blindness, such as,
diabetic retinopathy, macular degeneration (including age related
macular degeneration, e.g., wet age related macular degeneration
and dry age related macular degeneration), retinitis pigmentosa,
and Stargardt's Disease (fundus flavimaculatus), night blindness
and color blindness. The preparation may comprise at least about
5,000-500,000 PRPCs or PRs (e.g., 100,00 PRPCs or PRs) which may be
administered to the retina to treat retinal degeneration associated
with a number of vision-altering ailments that result in
photoreceptor damage and blindness, such as, diabetic retinopathy,
macular degeneration (including age related macular degeneration),
retinitis pigmentosa, and Stargardt's Disease (fundus
flavimaculatus).
[0265] The PRPCs or PRs provided herein may be PRPCs or PRs. Note,
however, that the human cells may be used in human patients, as
well as in animal models or animal patients. For example, the human
cells may be tested in mouse, rat, cat, dog, or non-human primate
models of retinal degeneration. Additionally, the human cells may
be used therapeutically to treat animals in need thereof, such as
in veterinary medicine. Examples of veterinary subjects or patients
include without limitation dogs, cats, and other companion animals,
and economically valuable animals such as livestock and horses.
[0266] The following are examples to illustrate the invention and
should not be viewed as limiting the scope of the invention.
EXAMPLES
Example 1: Generation of Photoreceptor Progenitor Cells
[0267] Human embryonic stem cells were cultured under feeder free
conditions in mTESR1 media (Stem Cell Technology) on a Matrigel.TM.
(a soluble preparation from Engelbreth-Holm-Swarm (EHS) mouse
sarcoma cells, BD Biosciences) surface. Upon 80-90% confluence,
cells were passaged or frozen. Passaging of stem cells was
performed using enzymatic (dispase) or non-enzymatic (EDTA-based
cell dissociation buffer, Invitrogen) techniques.
[0268] Direct differentiation methods were used for generation of
eye field progenitor cells, retinal neural progenitor cells,
photoreceptor progenitor cells and retinal photoreceptor cells.
Formation of embryoid bodies was not required.
[0269] The overall method used for photoreceptor development in
these examples is schematically illustrated in FIG. 19, which
further illustrates the media used at each step of the process.
[0270] Based on staining data it was determined that the cells
become EFPC between day 7-day 30 (indicated by staining done at day
20 which confirmed this cell identity), they become RNPC between
day 21-day 45 (indicated by staining done at day 30), and they
become PhRPC between 1-4 month (based on staining done at day
90).
[0271] Additionally it was estimated that the timing at which
different cell types arose using the methods described in Example 1
were as follows:
[0272] Eye Field Progenitors (EFPC): 7-30 days/65%-98% purity
[0273] Retinal Neural Progenitors (RNPC): 21-45 days/70%-95%
purity
[0274] Photoreceptor Progenitors (PhRPs) capable of becoming both
rod photoreceptors and cone photoreceptors: 1-4 months/85%-95%
purity
[0275] Photoreceptor Progenitors (PhRPs) thought to have lost or
experienced reduction in their capability of becoming rod
photoreceptors (but not cone photoreceptors): 5-12 months/85%-95%
purity.
[0276] Day 0: Cell differentiation of human pluripotent stem cells
was induced at 15-20% confluence. Culture media was changed to
retinal induction (RI) medium: DMEM/F12 supplied with 450 mg/ml
D-glucose, 100 unit/ml of penicillin, 100 .mu.g/ml of streptomycin,
1% (or optionally 0.1 to 5%) N2 supplement (Invitrogen), 0.2% (or
optionally 0.05-2.0%) B27 supplement, 0.1 mM MEM Non-essential
amino acids solution, 25 .mu.g/ml (or optionally 5-50 g/ml) human
insulin was added to the RI medium. The Smad inhibitor Noggin was
also included and increased the expression of eye field
transcription factors when included at a concentration of 10-100
ng/ml or preferably 50 ng/ml. As shown in FIG. 1, inclusion of
different factors including 50 ng/ml Noggin, 5 ng/ml Dkk1, 5 ng/ml
IGF-1, or a combination of 5 ng/ml Noggin, 5 ng/ml Dkk1, and 5
ng/ml IGF-1 affected the level of expression of eye field
transcription factors in differentiated eye field progenitor cells
at day 21. Among those conditions, inclusion of 50 ng/ml Noggin
greatly induced the expression of eye field progenitor markers.
[0277] The RI medium composition included the following:
[0278] N2: 1% (1 ml of N2 per 100 ml media)
[0279] B27: 0.2% (0.2 ml of b27 per 100 ml)
[0280] Human insulin: 20 .mu.g/ml (in addition to the 5 .mu.g/ml
insulin supplied by N2). The final concentration of insulin was 25
.mu.g/ml.
[0281] Noggin: 50 ng/ml final concentration.
[0282] Day 1-Day 4: A complete media change was done on every day.
Though this frequency is preferred, it is thought that changing the
medium less often, e.g., every 2-3 days, may be suitable
particularly if a larger volume of media is used. Cell colonies
continued to grow in the RI media with insulin and Noggin in the
same concentrations as in the previous step. After 1 day exposure
to RI media, cells located at the colony margin were elongated and
column-shaped, as shown in FIG. 2A.
[0283] Day 5: Cell cultures became 80-90% confluent on day 5. Media
was changed to neural differentiation (ND) medium: Neurobasal
Medium (components listed in FIGS. 21A-21E, Invitrogen) supplied
with 450 mg/ml D-glucose, 100 unit/ml of penicillin, 100 .mu.g/ml
of streptomycin, lx GlutaMAX.TM. (a stabilized form dipeptide from
L-glutamine, L-alanyl-L-glutamine), 1% (or optionally 0.1 to 5%) N2
supplement (a chemically defined, serum-free supplement based on
Bottenstein's N-1 formulation comprising 1 mM Human Transferrin
(Holo), 0.0861 mM Insulin Recombinant Full Chain, 0.002
Progesterone, 10.01 mM Putrescine, and 0.00301 mM Selenite,
Invitrogen), 2% (or optionally 0.05-2.0%) B27 supplement
(components listed in FIGS. 21A-21E), 0.1 mM MEM Non-essential
amino acids solution. Noggin was also added to the ND media at the
final concentration of 50 ng/ml (or optionally 10-100 ng/ml).
[0284] Day 6-Day 20: Cells were maintained in the ND medium. Half
the amount of medium was changed every 2 days. Cell colonies
continued to grow in the ND medium. The edge cells become flat and
large, while the central cells were smaller and formed compact cell
clusters (FIG. 2B). Around Day 14, cells located at the center of
colonies began to form Rosette-like structures (FIG. 2C). At day
21, over 90% of the cells co-expressed PAX6 and RX1 (FIG. 3A-3B) as
revealed by immunostaining and flow cytometry. By immunostaining,
cells were positive for Nestin and SOX2 (FIG. 3C-3D). Cells were
negative for an ES cell marker (specifically OCT4) and a retinal
neural progenitor marker (specifically CHX10). By RT-PCR, cells
expressed eye field transcription factors: PAX6, RX1, LHX2, SIX3,
SIX6, TBX3 and SOX2 (FIG. 3E). These results indicate that the
cells were eye-field progenitor cells.
[0285] The cells become eye field progenitors after they are
cultured with neural differentiation media, from about day 7-8
(about 2-3 days culture in ND media). At these time points
detectable pax6/rx1 double positive cells arise. After about day 14
(between days 14-30), high purity (>90%) of eye field progenitor
are generated.
[0286] Between about days 7-30 "Eye Field Progenitor Cells" or
"EFPCs" are formed.
[0287] Day 21-Day 24: At Day 21, cells were lifted off from the
growth surface and mechanically fragmented into clusters in ND
medium without Noggin. Cell clusters were transferred to 100 mm
ultra-low attachment culture dishes. Cell clusters rounded up and
formed individual spheres (solid clusters) in the suspension
culture. At Day 23, half of the culture medium was replaced.
[0288] At Day 25, spheres were collected and dead cells and debris
were removed by washing the spheres with the ND media. Cell spheres
were plated onto Matrigel.TM. coated glass chamber slide (for
immunostaining) or tissue culture dishes in the ND medium. Spheres
attached within 12 hours. They continued to grow and show neuronal
phenotypes, specifically exhibiting cell aggregates within the
spheres that extended axon-like neurites with some cells migrating
out from aggregates (FIG. 4A). There were few big epithelial-like
cells which could be eliminated during cell passage (see "Month
2-Month 3" below). The cultures were maintained with half of the
culture medium changed every two days until the cell cultures
become confluent It was observed that balls of spheres attached to
the plate.
[0289] At Day 30, the migrating cells were positive for Tuj1, which
labels immature and mature neurons (FIG. 4B). Cells in the
aggregates were negative for Tuj1. Over 95% cells (including cells
in the aggregates or migrating out from aggregates) co-expressed
PAX6 and CHX10 suggesting that they had become retinal neural
progenitors (FIG. 4C).
[0290] Month 2-Month 3: Growth and passaging cells in the ND media.
The cells from the previous step were passaged when they became
confluent. A two-step successive passaging technique was used to
produce high-purity neural cultures by eliminating the majority of
non-neuronal phenotype cells. The first step: neural sphere
culture. Cells were enzymatically (e.g., using Accutase) or
mechanically dissociated into a mixture of single cells and cell
clusters. Cells were transferred to ultra-low attachment dishes in
ND medium. All cells with neuronal phenotype form neural spheres in
the suspension culture. On day 3, half of the medium was changed
and the cells were maintained until day 5. The second step:
adherent culture. Neural spheres were collected on day 5 and dead
cells and debris were removed by washing the spheres with ND
medium. Spheres were plated on Matrigel.TM.-coated tissue culture
dishes until confluent. The first and second steps were alternated
and the cells were so maintained until the end of the third
month.
[0291] At the end of the 3rd month, the cells showed neural
phenotype. Specifically, the cells formed neurites in culture (FIG.
5A). They were capable of proliferation. They expressed PAX6 but
were negative for CHX10 as assessed by immunostaining (FIG. 5B). By
immunostaining, the cells were positive for Recoverin, which was
expressed in the cytoplasm of the cell body (FIG. 5C). The cells
also expressed Rhodopsin, Opsin and Recoverin mRNA (FIG. 5D).
Real-time PCR analyses revealed that the expressions of
transcription factors controlling rod and/or cone photoreceptor
differentiation are highly expressed (Table 1). These results
indicate that the cells were photoreceptor progenitors.
Additionally, at this time-point it was through based on
observations that all or essentially all of the cells in the
culture are photoreceptor progenitors.
TABLE-US-00001 TABLE 1 Quantitative RT-PCT analyses of
transcription factors controlling photoreceptor differentiation and
regeneration. Transcription Factors Rod/Cone Fold change (vs. ESC)
TR.beta.2 Cone 3.5-5.sup. NR2E3 Rod 7-11 NRL Rod 4-8 MASH1 Rod
1000-1200 CRX Rod, Cone -- ROR.beta. Rod, Cone 40-60 OTX2 Rod, Cone
--
[0292] Month 4-Month 9/or longer: In vitro expansion of
photoreceptor progenitors. In some experiments the cells were
further expanded using the two-step successive passaging technique
described above ("Month 2-Month 3"). However, it was observed that
over time the cells lose their capability to differentiate into
cone photoreceptors (though they retain the ability to
differentiate into rod photoreceptors). Specifically, after
photoreceptor progenitors were maintained by the two-step
successive passaging technique for 9 months in culture and then
induced to differentiate, they only produced cells that expressed
rod photoreceptor markers and not cells that expressed cone
photoreceptor markers. This property could potentially be put to
advantageous use, as progenitor cells that preferentially produce
rod photoreceptors may be useful in the treatment of diseases
wherein rod formation is desirable, or as a reagent for the study
of factors involved in photoreceptor progenitor fate
determination.
Example 2: Differentiation of Photoreceptor Progenitor Cells: Cell
Treatment with Retinoic Acid and Taurine
[0293] Attached photoreceptor progenitors were treated with
retinoic acid in the following conditions for two weeks: ND medium
supplied with 100 ng/ml (or optionally 10-1000 ng/ml) retinoic acid
and 100 .mu.M (or optionally 20-500 .mu.M) taurine. Half of the
culture medium was changed every 2 days.
[0294] Differentiate cells in Photoreceptor differentiation media:
The medium was changed to Photoreceptor Differentiation Medium
comprising Neurobasal Medium (Invitrogen) supplied with 450 mg/ml
D-glucose, 100 unit/ml of penicillin, 100 .mu.g/ml of streptomycin,
lx GlutaMAX.TM., 1% N2 supplement (Invitrogen), 2% B27 supplement
(formula number 080085-SA), with the addition of 5 .mu.M (or
optionally 1-100 .mu.M) Forskolin, 10 ng/ml (or optionally 1-100
ng/ml) BDNF, 10 ng/ml (or optionally 1-100 ng/ml) CNTF, 10 ng/ml
(or optionally 5-50 ng/ml) LIF and 10 .mu.M (or optionally 1-100
.mu.M) DATP. Half of the medium was changed every 2 days.
Specifically the amounts of each factor were as follows: Forskolin
(5 .mu.M), BDNF (10 ng/ml), CNTF (10 ng/ml), LIF (10 ng/ml) and
DATP (10 .mu.M). LIF was determined not to be necessary and can be
left out.
[0295] At two weeks after initiating cell differentiation, the
expressions of Rhodopsin, Opsin (green/red), Recoverin and
phosphodiesterase 6A alpha subunit (PDE6a) were detected in the
cytoplasm of the cell body and neurites (FIG. 6A-6D). These gene
expression results indicate that these are photoreceptor cells.
Example 3: Cryopreservation of Human ESC-Derived Retinal Neural
Progenitors
[0296] Retinal neural progenitors of the invention, photoreceptor
progenitors of the invention and retinoic acid treated
photoreceptor progenitors of the invention can be frozen down in an
animal-free cryopreservation buffer, such as Cryostor CS 10, or
another cryopreservation buffer such as 90% FBS and 10% DMSO. With
respect to the photoreceptor progenitors, it was observed that
freezing cells as neurospheres was beneficial, which may be due to
the benefits of cell-cell contact. Preferably the neurospheres were
frozen down at a size that was not too large, such as 50-250
cells.
Example 4: Animal Studies in Stargardt Macular Dystrophy Animal
Model
[0297] Animal studies were carried out in a Stargardt macular
dystrophy animal model, ELOVL4 transgenic 2 (TG2) mice (FIG.
7).
[0298] Photoreceptor progenitors (produced as described in in
Example 1) and separately, retinoic acid and taurine treated
photoreceptor progenitors (i.e., immature photoreceptor cells,
produced as described in Example 2) were dissociated into single
cells using Accutase. Cells were re-suspended in PBS buffer.
[0299] 28 days-old TG2 mice received an injection of 1 al of cell
suspension containing 5.times.10.sup.5 cells into the subretinal
space or 150 al of cell suspension containing 1.times.10.sup.6
cells into the tail vein. All mice underwent baseline ERG and OCT
tests before cell injection.
[0300] Mice were fed with water supplied with Cyclosporin A (USP
modified).
[0301] At one month after cell injection, mice that received a
subretinal injection of photoreceptor progenitors showed a
significant improvement of the rod photoreceptor function revealed
by a significant increase of the scotopic ERG amplitude of both the
a- and b-wave (FIG. 8). Mice that received a tail vein injection of
photoreceptor progenitors and retinoic acid and taurine-treated
photoreceptor progenitors showed a significant improvement of the
Rod photoreceptor function revealed by a significant increase of
the scotopic ERG amplitude of both a- and b-wave (FIG. 9).
[0302] At two months after cell injection, mice that received a
tail vein injection of retinoic acid treated photoreceptor
progenitors showed a further improvement of the rod photoreceptor
function revealed by a further increase of the amplitude of both a-
and b-wave of scotopic ERG responsive curve (FIG. 10A-10C). The
function of cone photoreceptors was significantly improved as
revealed by a significant increase of the photopic ERG amplitude of
both a- and b-wave (FIG. 11).
[0303] At two months after injection, mice that received a tail
vein injection of immature photoreceptor cells treated with
retinoic acid and taurine showed a significant increase of whole
retina thickness revealed by OCT (FIG. 12).
[0304] At two months after cell transplantation, there was a
significant preservation of photoreceptor neurons in the ONL of
retina in mice that received retinoic acid and taurine-treated
photoreceptor progenitors (FIG. 13).
Example 5: Animal Models of Achromatopsia (Color Blindness) and
Improving Night Vision
[0305] Cells produced according to the methods described in Example
1 or Example 2 are tested in mouse, sheep, and/or dog models of
Achromatopsia (color blindness). The following models are used:
[0306] Mouse: (1) the cpfl5 mouse: a naturally occurring mouse
model of achromatopsia with a CNGA3 mutation; (2) CNGA3 knockout
mice; (3) GNAT2cpfl3 mice: mutation related to GNAT2; (4)
PDE6C-cpfl1: mutation related to pde6c.
[0307] Sheep: Awassi Sheep Lambs: Mutation in CNGA3
[0308] Dog: Two natural occurring canines for mutation in CNGA3
have been identified: the autosomal recessive canine cone
degeneration in the Alaskan malamute and the German shorthaired
pointer.
[0309] Photoreceptor progenitors (produced as described in Example
1) are dissociated into single cells using accutase. Cells and are
re-suspended in PBS buffer. The animals receive injections of
2.times.10.sup.5 cells or more into the vitreous cavity or
5.times.10.sup.6 cells or more into a tail vein (e.g., the tail
vein). Control animals receive an injection with PBS buffer. After
one or two months or at other time points, the animals are given
optomotor responsiveness tests to check visual function in order to
detect possible improvements thereto. Additionally, histological
analysis is performed to determine whether there is any significant
preservation of photoreceptor neurons or growth of photoreceptor
neurons, and additionally to detect whether cells transplanted into
the vitreous cavity showed good survival after injection, and
whether the cells differentiated into rod or cone photoreceptor
cells expressing markers thereof.
Example 6: Animal Studies in a Photoreceptor Degeneration Rat
Model, Royal College of Surgeons (RCS) Rat
[0310] Photoreceptor progenitors (produced as described in Example
1) were dissociated into single cells using accutase. Cells were
re-suspended in PBS buffer.
[0311] On postnatal day 30, RCS rats received injections of
2.times.10.sup.5 cells into the vitreous cavity or 5.times.10.sup.6
cells into the tail vein. Control rats received an injection with
PBS buffer.
[0312] RCS rats were fed with water supplied with Cyclosporin A
(USP modified).
[0313] At one month and two months after cell injection, rats were
given optomotor responsive tests to check visual function. There
was no significant improvement in visual function in treated rats
(data not shown).
[0314] The resulting effect on visual function may be detected by
the Optomotor response test, ERG, luminance threshold recording
and/or visual center blood flow assay.
[0315] At two months after cell injection, Histology revealed a
significant preservation of photoreceptor neurons in the ONL of
retina in RCS rats administered with cell treatment (FIG. 15).
[0316] Preservation of rod and cone photoreceptor outer segment
revealed by immunostaining of Rhodopsin (rod) and Opsin (cone) was
observed in cell treated groups (both intravitreal and tail vein
injection, FIG. 16 and FIG. 17).
[0317] Cells transplanted into the vitreous cavity showed good
survival at 2 months after injection, then further differentiated
into rod photoreceptor cells expressing rod photoreceptor markers
(FIG. 18).
* * * * *