U.S. patent application number 10/635658 was filed with the patent office on 2004-02-12 for implantable substrates for the healing and protection of connective tissue, preferably cartilage.
This patent application is currently assigned to TRANSTISSUE TECHNOLOGIES, GmbH. Invention is credited to Burmester, Gerd-Rudiger, Schultz, Olaf, Sittinger, Michael.
Application Number | 20040028717 10/635658 |
Document ID | / |
Family ID | 7930715 |
Filed Date | 2004-02-12 |
United States Patent
Application |
20040028717 |
Kind Code |
A1 |
Sittinger, Michael ; et
al. |
February 12, 2004 |
Implantable substrates for the healing and protection of connective
tissue, preferably cartilage
Abstract
Implantable substrate for the healing and/or protection of
connective tissue, preferably cartilage, comprising at least one
composition for the activation of locally present cells for tissue
regeneration and at least one structure for cell invasion in vivo
and/or for the formation of cell matrix and/or for the release of
constituents of the employed composition.
Inventors: |
Sittinger, Michael;
(Grobetaziethen, DE) ; Schultz, Olaf; (Berlin,
DE) ; Burmester, Gerd-Rudiger; (Berlin, DE) |
Correspondence
Address: |
JONES DAY
555 WEST FIFTH STREET, SUITE 4600
LOS ANGELES
CA
90013-1025
US
|
Assignee: |
TRANSTISSUE TECHNOLOGIES,
GmbH
Berlin
DE
|
Family ID: |
7930715 |
Appl. No.: |
10/635658 |
Filed: |
August 5, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10635658 |
Aug 5, 2003 |
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09718801 |
Nov 22, 2000 |
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6602294 |
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Current U.S.
Class: |
424/423 ;
623/23.75 |
Current CPC
Class: |
A61F 2002/30677
20130101; A61L 27/227 20130101; A61B 17/00491 20130101; A61F
2/30756 20130101; A61F 2002/30929 20130101; A61F 2002/2817
20130101; A61K 38/00 20130101; A61F 2310/00377 20130101 |
Class at
Publication: |
424/423 ;
623/23.75 |
International
Class: |
A61F 002/02 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 24, 1999 |
DE |
19957388.3 |
Claims
1. Implantable substrate for the healing and/or protection of
connecting tissue, preferably cartilage, comprising at least one
means for the activation of locally present cells for tissue
regeneration and at least one structure for cell invasion in vivo
and/or for the formation of cell matrix and/or for the release of
constituents of the employed means.
2. Substrate according to claim 1 in which the at least one means
contains chemotactic factors or differentiating factors and
chemotactic factors.
3. Implantable substrate for the healing and/or protection of
connecting tissue, preferably cartilage, comprising at least one
means which contains differentiating factors and chemotactic
factors.
4. Substrate according to claim 1, characterized in that it
comprises at least one covering material.
5. Substrate according to claim 2, characterized in that it
comprises at least one covering material.
6. Substrate according to claim 1, characterized in that structures
comprise at least one constituent (a) to (g): a) hydrogels b)
sponges, collagen sponges c) wool/cotton wool made of
polysaccharides, cellulose wool, cellulose cotton wool d) natural
or synthetic polypeptides, fibrin, polylysine e) plaitings, knitted
fabrics or woolen structures made of fibers, preferably fibers
comprising resorbable polymers f) cement pastes, acrylate cements,
bonding sheets, fibrinogen-covered hyaluronic acid foil, or g)
ceramic materials.
7. Substrate according to claim 2, characterized in that structures
comprise at least one constituent (a) to (g): a) hydrogels b)
sponges, collagen sponges c) wool/cotton wool made of
polysaccharides, cellulose wool, cellulose cotton wool d) natural
or synthetic polypeptides, fibrin, polylysine e) plaitings, knitted
fabrics or woolen structures made of fibers, preferably fibers
comprising resorbable polymers f) cement pastes, acrylate cements,
bonding sheets, fibrinogen-covered hyaluronic acid foil, or g)
ceramic materials.
8. Substrate according to claim 1, characterized in that the at
least one means contains a biologically active factor, chosen from
the group consisting of: growth and differentiating factors,
cellular adhesion molecules, synthetic peptides, cytokines,
chemotactic factors and extracellular matrix components.
9. Substrate according to claim 3, characterized in that the at
least one means contains a biologically active factor, chosen from
the group consisting of: growth and differentiating factors,
cellular adhesion molecules, synthetic peptides, cytokines,
chemotactic factors and extracellular matrix components.
10. Substrate according to claim 7, characterized in that the at
least one means contains a biologically active factor, chosen from
the group consisting of: growth and differentiating factors,
cellular adhesion molecules, synthetic peptides, cytokines,
chemotactic factors and extracellular matrix components.
11. Substrate according to claim 1, characterized in that it
further comprises an anchoring structure for the anchoring of the
substrates in or on the location to be treated.
12. Substrate according to claim 3, characterized in that it
further comprises an anchoring structure for the anchoring of the
substrates in or on the location to be treated.
13. Substrate according to claim 8, characterized in that it
further comprises an anchoring structure for the anchoring of the
substrates in or on the location to be treated.
14. Method for the manufacture of implantable substrates for the
healing and/or protection of connecting tissue, preferably
cartilage, according to claim 1, characterized in that a structure
for the formation of cell matrix and at least one means for the
activation of locally present cells for the regeneration of tissue
are contacted with each other or that differentiating factors and
chemotactic factors are contacted with each other.
15. Method for the manufacture of implantable substrates for the
healing and/or protection of connecting tissue, preferably
cartilage, according to claim 3, characterized in that a structure
for the formation of cell matrix and at least one means for the
activation of locally present cells for the regeneration of tissue
are contacted with each other or that differentiating factors and
chemotactic factors are contacted with each other.
16. Method for the manufacture of implantable substrates for the
healing and/or protection of connecting tissue, preferably
cartilage, according to claim 6, characterized in that a structure
for the formation of cell matrix and at least one means for the
activation of locally present cells for the regeneration of tissue
are contacted with each other or that differentiating factors and
chemotactic factors are contacted with each other.
17. Method for the manufacture of implantable substrates for the
healing and/or protection of connecting tissue, preferably
cartilage, according to claim 8, characterized in that a structure
for the formation of cell matrix and at least one means for the
activation of locally present cells for the regeneration of tissue
are contacted with each other or that differentiating factors and
chemotactic factors are contacted with each other.
18. Method for the healing of connective tissue and/or protection
thereof, characterized in that the connective tissue is contacted
with a substrate according to claim 14.
19. Method for the healing of connective tissue and/or protection
thereof, characterized in that the connective tissue is contacted
with a substrate according to claim 15.
20. Method for the healing of connective tissue and/or protection
thereof, characterized in that the connective tissue is contacted
with a substrate according to claim 16.
21. Method according to claim 17, characterized in that the
connective tissue is cartilage and that before contacting the
cartilage with the substrate, connecting channels into the
subchondral space of the cartilage are produced.
22. Method according to claim 18, characterized in that the
connective tissue is cartilage and that before contacting the
cartilage with the substrate, connecting channels into the
subchondral space of the cartilage are produced.
23. Method according to claim 19, characterized in that the
connective tissue is cartilage and that before contacting the
cartilage with the substrate, connecting channels into the
subchondral space of the cartilage are produced.
24. Use of a substrate obtained by a method according to claim 14,
in surgical medicine and tissue engineering.
25. Use of a substrate obtained by a method according to claim 15,
in surgical medicine and tissue engineering.
26. Use of a substrate obtained by a method according to claim 16,
in surgical medicine and tissue engineering.
27. A method for the manufacture of implantable substrates for the
healing and/or protection of connecting tissue, said substrate
comprising: a composition comprising biologically active factors
(i), (ii), and (iii), wherein (i) is a growth and differentiating
factor, (ii) is a chemotactic factor, and (iii) is a cellular
adhesion molecule; and at least one structure for cell invasion in
vivo and/or for the formation of cell matrix and/or for the release
of constituents of the employed composition, wherein said structure
comprises at least one constituent (a) to (f): (a) a hydrogel, (b)
a compound selected from the group consisting of sponges, collagen
sponges, (c) a compound selected from the group consisting of wool,
a cotton wool-like structure, wool made of polysaccharides,
cellulose wool, and cellulose cotton wool, (d) a compound selected
from the group consisting of natural or synthetic polypeptides,
fibrin, and polylysine, (e) a compound selected from the group
consisting of plaitings, knitted fabrics, woolen structures made of
fibers, and fibers comprising resorbable polymers, (f) a compound
selected from the group consisting of cement pastes, acrylate
cements, bonding sheets, and fibrinogen-covered hyaluronic acid
foil, comprising at least one of the following steps: (i) bringing
said structure into contact with at least said above defined
composition or (ii) bringing said biologically active factors (i),
(ii), and (iii) of said composition into contact with said above
defined structure.
28. The method of claim 27, wherein said connecting tissue
comprises cartilage.
29. The method according to claim 27, wherein the step of bringing
said substrate into contact with said composition comprises
bringing said structure into contact with at least one biologically
active factor chosen from the group consisting of synthetic
peptides, cytokines, and extra cellular matrix components.
30. The method of claim 29, characterized in that said connecting
tissue comprises cartilage.
31. A method of healing and/or protection of connective tissue,
comprising contacting said connective tissue with a substrate
manufactured according to the method of claim 27.
32. A method of healing and/or protection of connective tissue,
comprising contacting said connective tissue with a substrate
manufactured according to the method of claim 29.
33. The method according to claim 31, wherein said connective
tissue comprises cartilage, and the method further includes the
step of producing connecting channels into the subchondral space of
the cartilage before contacting said connective tissue with said
substrate.
34. The method according to claim 32, wherein said connective
tissue comprises cartilage, and the method further includes the
step of producing connecting channels into the subchondral space of
the cartilage before contacting said cartilage with said substrate.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This is a divisional application, based on prior U.S.
application Ser. No. 09/718,801, filed on Nov. 22, 2000, which is
hereby incorporated by reference in its entirety as if set forth
fully herein.
FIELD OF THE INVENTION
[0002] The invention relates to implantable substrates for the
healing and protection of connective tissue, preferably cartilage
in the state of arthrosis. More specifically, the invention relates
to an implantable substrate for the healing and protection of
connective tissue, preferably cartilage, comprising at least one
structure for the invasion of cells in vivo, for the formation of
cell matrix, and/or for the release of constituents of the employed
means and at least one means for the activation of locally present
cells for the regeneration of tissue. The invention also relates to
a method for the production of the implantable substrate, a method
for the healing and/or protection of connective tissue, preferably
cartilage in the state of arthrosis, employing the implantable
substrates according to the invention, as well as the use of the
implantable substrates in the field of surgical medicine and tissue
engineering.
BACKGROUND OF THE INVENTION
[0003] Osteoarthrosis is the most common joint disease worldwide,
affecting the majority of humans older than 65 years. As a
necessary consequence, there is an enormous clinical,
health-political and economical relevancy of methods directed to
the treatment of osteoarthrosis. During the course of this
primarily degenerative joint disease, which is dependent on the
age, a stepwise focal destruction of the surface of the joint
occurs, and, as a result, a misregulated regional growth of the
neighboring and subchondral bone structures (osteophytes) follows.
The consequences are pain and restricted function and mobility.
Systemic factors which influence the emergence of osteoarthrosis
are age, gender, weight, osteoporosis, hereditary factors and an
excess of mechanical stress. Local factors comprise the specific
shape of the joint, distortions, trauma, as well as specifically
acting biomechanical factors. Although the primary genesis is
degenerative, during the course of osteoarthrosis, there are
inflammatory degenerations to be observed, such as synovitis
(inflammation of the endothelium of the joint) and the production
of biological messenger substances (cytokines and growth factors),
which promote inflammation. These ongoing changes embody an
ill-regulation of tissue homeostasis, which occurs in the area of
load-carrying cartilage and bone structures, i.e., there is a lack
of balance between degenerative processes and repair processes. (WB
van den Berg: The role of cytokines and growth factors in cartilage
destruction in osteoarthritis, Z Rheumatol. 58:136-141, 1999.)
[0004] The disease is a consequence of malfunctions in the area of
the entire joint including the bone, the muscle and the innervation
of the joint, which finally leads to an excessive mechanical stress
and a biochemically mediated destruction of the affected joints.
Furthermore, there has not yet been any possibility of healing this
disease. Very often, physiotherapeutic measures and pain-reducing,
anti-inflammatory medication, such as non-steroidal anti-rheumatic
drugs, are insufficient symptomatic kinds of treatments.
Conventional orthopedic measures, such as debridement,
joint-shaving, microfracture, drilling, are also insufficient to
treat the disease. If extensive degenerations occur, often a
surgical reconstructive measure, with endoprothetic exchange of the
joint, remains as the only option. (J A Buckwalter, H J Mankin:
Articular Cartilage Repair and Transplantation: Arthritis &
Rheumatism 41:1131-1342, 1998.)
[0005] Tissue engineering offers promising new technologies for the
transplantation of functionally active autologous cells and
optionally for biomaterials creating a desired shape of the
material.
[0006] Using tissue engineering technology, new cartilage and bone
tissue are actively built up or bred, respectively. Usually, tissue
engineering is based on the breeding of autologous cells which are
subsequently transplanted into the patient, for example, as a
solution or as a matured graft. Unfortunately, the proliferative
potential of these cells is limited and the breeding over many cell
passages in vitro substantially reduces the functional quality of
the cells.
[0007] Another approach in tissue engineering is embodied by the
stimulation of tissue regeneration itself, or at least the
differentiation of cells which were yielded from the patient
beforehand, for example, by addition of growth factors. In this
context, the factors of the TGF-.beta.-superfamily are of interest
because they play a major role during the development of tissues
and organs.
[0008] There are substantially different principles to employ these
growth factors. For example, a part of the cells may be transfected
with the genes of the TGF-.beta.-family to achieve an improved
maturation, but also in order to protect the tissue of, e.g., a
chronically inflamed joint from being destroyed again. (Evans C H,
Robbins P D: Gene therapy for arthritis, Gene therapeutics: Methods
and applications of direct gene transfer, edited by J A Wolff,
Boston, Birkhuser, 321, (1994); Kalden J R, Geiler T, Hermann M,
Bertling W: Gentherapie der rheumatoiden Arthritis--ein bereits,
anwendbares Therapieprinzip?--Z Rheumatol 57:139-47, (1988);
Herndon J H, Robbins P D, Evans C H: Arthritis: is the cure in your
genes? J Bone Joint Surg Am, 81:152-7, (1999).)
[0009] Another possibility lies in the use of release systems, such
as the transient release of factors from resorbable microparticles
or cell carriers, e.g., to stabilize a graft during the critical
phase of wound healing. (U.S. Pat. No. 5,910,489). Finally, the
direct regeneration of tissue may be achieved without cells by
using growth factors and biomaterials. (Kubler, Osteoinduktion und
-reparation, Mund-Kiefer-Gesichtschir., 1, 2-25, (1997).)
[0010] The discovery and characterization of new factors, which are
capable of influencing the maturation and differentiation of
somatic cells, are available tools which allow for the manufacture
of a full-fledged replacement cartilage or bone, starting with only
a few autologous cells.
[0011] However, the major disadvantage of the latter technology is
the necessity of obtaining a tissue sample from the patient and
also the comparably sophisticated cultivation of the cells.
[0012] During a naturally-occurring tissue healing process, cells
from the area surrounding a defect or lesion are normally attracted
in order to fill that lesion. The attracted cells are mainly
precursor cells which, at a later stage, develop into tissue cells
with their particular properties. Accordingly, when a bone fracture
occurs, precursor cells from the periostium and the bone marrow
migrate into the defect and form new bones via the "detour" of a
cartilage tissue. By contrast, natural regeneration of cartilage by
means of invading precursor cells does finally not work in humans
at all. Certain methods of treatment, such as methods of
microfracture, are aimed at opening the way into the joint space
for cells originating from bone marrow.
[0013] In the art of cartilage healing, bioactive substances have
been developed that possess chemotactic, anti-inflammatory,
anti-angiogenetic, differentiating or anti-adhesive properties.
(See, i.e., U.S. Pat. No. 5,853,746, entitled "Methods and
compositions for the treatment and repair of defects or lesions in
cartilage or bone using functional barrier"; U.S. Pat. No.
5,817,773, entitled "Stimulation, production, culturing and
transplantation of stem cells by fibroblast growth factors"; and
U.S. Pat. No. 5,910,489, entitled "Topical composition containing
hyaluronic acid and NSAIDs".)
SUMMARY OF THE INVENTION
[0014] The invention is based on the problem of developing a
substrate which can be used in the process of healing and/or
protecting connective tissue, preferably cartilage. The problem was
solved by the provision of implantable substrates for the healing
and/or protection of connective tissue, particularly for the
healing and/or protection of cartilage in the state of
arthrosis.
[0015] The present invention is particularly based on the use or
stimulation, respectively, of pluripotent precursor cells or
mesenchymal stem cells for the regeneration of tissue. The
potential of these cells for proliferation and differentiation is
of major interest for the healing of cartilage and bone. Precursors
and stem cells may be used in a comparable manner to the adult
cells. In doing so, the differentiation behavior may be influenced
by using different morphogenic factors, such as, for example, FGF
(fibroblast growth factor) or TGF-.beta. (transforming growth
factor .beta.)-superfamily under defined culture parameters. (U.S.
Pat. No. 5,817,773.)
[0016] Hence, the present invention relates to an implantable
substrate for the healing and/or protection of connective tissue,
preferably cartilage, comprising at least one means for the
activation of locally present cells to achieve tissue generation
and at least one structure for the invasion of cells in vivo and/or
for the formation of a cell matrix and/or for the release of
constituents of the means employed.
[0017] The invention further relates to a substrate for the
protection and/or healing of connective tissue, preferably
cartilage, comprising at least one means containing differentiating
and chemotactic factors, preferably in combination with a structure
such as described herein.
[0018] The present invention also provides methods for producing an
implantable substrate for the healing and/or protection of
connective tissue, wherein the implantable substrate comprises at
least one means for the activation of locally present cells to
achieve tissue generation and at least one structure for the
invasion of cells in vivo and/or for the formation of a cell matrix
and/or for the release of constituents of the means employed.
[0019] In the present context, the term "substrate" denominates the
entirety of the subject matter according to the invention. For
example, the substrate according to the invention may be a
spreadable or adhesive "cell attraction paste" or a kind of
"bioactive cartilage covering." One embodiment of the substrate
according to the invention is shown in FIG. 1.
[0020] The phrase "structure for cell invasion in vivo and/or for
the formation of cell matrix and/or for the release of constituents
of the means employed" (also sometimes referred to herein as
"structure") comprises the matrix in which the means according to
the invention is present.
[0021] The term "means" comprises the entirety of usable
biologically active and inactive constituents which may be used in
the scope of the present invention which in their entirety
contribute to the activation of locally present cells for the
purpose of tissue regeneration.
[0022] "Chemotactic factors" are biologically active factors which
are capable of "attracting" cells, for example cartilage precursor
cells from bone marrow, autologous mesenchymal cells, progenitor
cells and stem cells, to the area of treatment or to the location
where the substrate according to the invention is located.
[0023] "Differentiating factors" are biologically active factors,
which are capable of inducing cell growth, in particular of the
cells mentioned herein, and, concomitantly, the formation of new
tissue.
[0024] Surprisingly, it was possible to provide a substrate with
means, which allows for the induction and control of invasion of
tissue precursor cells from the surrounding tissues--in the case of
the joint cartilage, this means from the bone marrow or synovium.
This occurs by releasing the means contained in the substrate
during treatment.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1 shows a preferred embodiment of a substrate according
to the invention, which is constructed in a sandwich-like manner.
The reference numbers in FIG. 1 refer to the following items:
1--substance spread, 2--connecting channels to the bone marrow,
3--migration of precursor cells out of the bone marrow, 4--release
of bioactive factors, 5--mesenchymal cells which are optionally
genetically modified, 6--particles with bioactive factors,
7--covering layer, 8--layer composed of differentiating or
tissue-forming factors, respectively, and 9--layer with chemotactic
factors.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0026] For ease of reference, some of the common abbreviations used
throughout the detailed description of the preferred embodiments
and claims are listed in Table 1.
Means
[0027] The means used in the scope of the substrate according to
the invention are capable of inducing and controlling the invasion
of tissue precursor cells from surrounding tissues to the area of
treatment. Normally, the means are substances which are capable of
mobilizing, activating and/or attracting autologous mesenchymal
cells, progenitor cells and stem cells. In particular, the means
contain biologically active factors, such as, for example,
chemotactic or chemotactic and differentiating factors. Preferred
biologically active factors useful in the present invention include
the following: growth and differentiation factors, including, for
example, factors from the TGF-superfamily, FGF-family, PDGF, IGF,
and EGF; cellular adhesion molecules, including, for example,
integrin, CD44, selecting, and proteoglycans; synthetic peptides,
including, for example, RGD-sequences, such as,
arginine-glycine-aspartic acid; cytokines; chemotactic factors,
including, for example, CDMP, CTGF, osteopontin, and NO-synthase
blockers; or components of the extracellular matrix, including, for
example, proteoglycans, fibronectin, and collagen.
[0028] Furthermore, the means used according to the invention may
comprise--depending on the purpose of use--the following
components: enzymes or precursors thereof, including, for example,
proteases, metalloproteinases, and cathepsins; inhibitors of
enzymes, including, for example, THVIP, antibodies or synthetic
blockers of the catalytic center; and anti-inflammatory additives
including, for example, anti-inflammatory medications and/or
factors.
[0029] Further, the means may also contain autologous and
non-autologous cells, such as, for example, mesenchymal cells,
progenitor cells, stem cells and/or precursor cells, which may, in
turn, release the corresponding factors.
[0030] In a further embodiment, genes or bioactive factors may be
transfected into the cells.
[0031] In this context, the release of two or more components of
the employed means according to the invention may occur
simultaneously or sequentially and/or from two or more phases,
components, and/or layers of the substrate or the structure,
respectively. Further, the used means according to the invention
and/or the structure used according to the invention may comprise
facilities for a delayed release of the components.
Structures
[0032] Further, the substrates according to the invention
contain--in one embodiment necessarily and in a further embodiment
optionally--suitable structures to allow for cell invasion in vivo
and/or for the formation of a cell matrix and/or for the release of
constituents of the used means, especially of the factors contained
therein.
[0033] The structures for in vivo cell invasion according to the
invention and/or for the formation of cell matrix and/or for the
release of constituents of the used means, especially of the
chemotactic and/or differentiating factors preferably comprise
hydrogels; sponges (e.g., made of collagen); wool or cotton
wool-like materials made of polysaccharides (e.g., cellulose wool,
cellulose cotton wool); natural or synthetic polypeptides (fibrin,
polylysine); plaitings, tissues, or knitted fabrics made of fibers
(e.g., fibers of resorbable polymers); cements (e.g., acrylate
cement); bonding sheets (e.g., fibrinogen, coated hyaluronic acid
sheets); ceramic materials; or a combination of one or more of
these structures.
[0034] The structures employed according to the invention and,
hence, also the substrates according to the invention--may possess
resorbable or non-resorbable properties. Structures showing
resorbable properties, for example, comprise hyaluronic acids,
preferably such with a molecular weight of 400-600 kD,
poly-alpha-hydroxy acids, collagens, alginates, agaroses, fibrins,
biological glass materials or combinations thereof. Structures with
non-resorbable properties comprise, for example, ceramic materials
or combinations of ceramic materials with structures which exhibit
resorbable properties.
[0035] Further, the substrate according to the invention may
comprise a structure having several substructures. The
substructures, which are able to store and release the means
employed according to the invention or particular constituents of
these means, comprise layers, droplets, spherelets, or surface
coatings. Accordingly, it is, for example, possible that within a
grid structure made of ceramic material, a hydrogel comprising a
means according to the invention is implemented.
[0036] Hence, the substrate according to the invention may be
constructed as a structure in the shape of a sponge, in the form of
beads, membranes, grids, cotton wools, bags and/or cushions, as a
liquid, gel or as a multi-layered material. In the latter case, the
substrate comprises, e.g., a wool-like polymer construction, such
as, for example, polyglycolid, combined with hyaluronic acid and
chemotactic growth factors, as, for example, osteopontin.
[0037] In general, the substrates exhibit formable, spreadable or
paste-like properties with elastic or plastic mechanical
properties, and they are injectable.
[0038] The substrate or, respectively, the structure contained
therein, if present, may also comprise several phases and/or
components and/or layers, which, in turn, may release two or more
means.
[0039] In a preferred embodiment, mesenchymal stem cells may be
mixed with hyaluronic acid and are injected at the place of
treatment.
[0040] In a particular embodiment, the substrates may exhibit a
structure in the form of a multi-layered material for the coverage
of the joint surface, which at the underside is fitted with pins,
hollow needles or an anchoring structure, such as a velcro
fastener. Further, they may be constructed in a way that, at the
underside, they release for example, cartilage-digesting
enzymes--metalloproteinases, hyaluronidases, cathepsins. The pins,
hollow needles or anchoring structure are preferably such that they
are resorbable.
[0041] In a further embodiment, mesenchymal stem cells and/or other
connective tissue precursor cells, e.g., cells of the periostium
and of the perichondrium, are injected with hyaluronic acid in a
twin-syringe simultaneously or subsequently with separate
syringes.
[0042] The implantable substrates according to the invention have
the capability to mobilize, activate and/or attract autologous
mesenchymal cells, progenitor cells and/or stem cells and to
stimulate these cells in a way that lets them proliferate,
differentiate and/or mature. Genes or the above-mentioned bioactive
factors may also be transfected into these cells.
Method of Production
[0043] The manufacture of an implantable substrate for the healing
and/or protection of connective tissue, preferably cartilage,
according to the invention is achieved by contacting a structure
for the purpose of forming a cell matrix and/or the purpose of cell
invasion in vivo and/or the purpose of release of constituents of
the used means with at least one means for the activation of
locally present cells for the regeneration of tissue, or by
contacting differentiating factors and chemotactic factors, if the
substrate according to the invention does not comprise a structure
in the scope of the invention.
Methods of Treatment
[0044] The present invention also relates to a method of healing
and/or protecting connective tissue, especially in the state of
arthrosis, characterized in that the connective tissue is contacted
with a substrate according to the invention.
[0045] The term "connective tissue" in the scope-of the present
invention comprises cartilage, bone, tendons and meniscus. In a
preferred embodiment, when the method according to the invention is
used for the healing and/or protection of cartilage, connecting
channels within the subchrondal space of the cartilage are
generated before the cartilage is contacted with the substrate.
[0046] For example, when a cartilage healing and protection
treatment takes place, such substrates may be cemented onto the
surface to the joint by using fibrin or acrylate cement and the
substrates may be fitted accordingly. The fibrin and acrylate
cements employed are preferably administered with stored
chemotactic growth factors, such as cartilage derived morphogenic
protein or connective tissue growth factor. The substrates are
brought in contact with the joint surface and are preferably
cemented to form an artificial superclot using thrombin.
Alternatively, the substrate according to the invention comprises,
when using a twin-syringe, in one chamber the means according to
the invention, e.g., differentiating and/or chemotactic factors
and, in a second chamber, thrombin. In particular, the latter
variant is used after a microfracture treatment was performed at
the location to be treated, with the possibility of bringing the
biologically active substances (means) into the superclot.
[0047] The induction of the means and/or the release of the factors
are preferably achieved from outside, for example, by magnetic
fields, electrical impulses such as current or voltage, movement or
the injection of substances.
[0048] The substrates according to the invention are preferably
implemented after the generation of channels, for example, into the
subchondral space, for example by microfractures, drillings,
stitches. The connecting channels or drillings between the marrow
space and the joint space itself may be generated by a grid of
needles which may be a constituent of the structure, or by a velcro
fitting-like anchoring structure employed with a grid of needles
lying underneath.
[0049] The latter method in a preferred embodiment is characterized
by the fact that when the connecting channels between joint space
and bone marrow space are produced, a sticky cartilage-friendly
layer is brought onto the arthrotic cartilage, and cells from the
bone marrow are attracted and are developed into cartilage tissue
in the surrounding area, which temporarily provides nutrition and
positive influence within the cemented layer. By doing so,
substrates which are capable of providing connections between the
joint space and the bone marrow space by multiple preformed tiny
drillings and/or channels are employed, by means of which the
invasion of tissue precursor cells from the surrounding tissues is
induced and structures for the formation of cell matrix are
enabled. It is a property of the above-mentioned method that the
substrate comprises structures and/or means which are able to cover
a joint's surface, preferably in several layers, thereby inducing
the growth and maturation of cartilage precursor cells from bone
marrow.
[0050] The substrate according to the invention exhibits a
combination of known elements (mesenchymal cells, progenitor cells,
stem cells, precursor cells from bone marrow and/or bioactive
factors) and new elements (connecting channels between bone marrow
space and joint space; multi-layered materials for covering the
joint to induce growth and maturation of cartilage precursor cells
from bone marrow; and artificial superclot) which mutually
influence and, by means of their new effect, provide a synergistic
effect and the desired success, which lies in the fact that cells
from bone marrow can now be attracted and develop into cartilage
tissue within the substrate according to the invention, e.g., in
multi-layered substrates for the coverage of the joint surface. By
using the substrate according to the invention, it is possible to
minimize the external breeding and subsequent transplantation of
the bred cells into the patients, preferably the latter process can
be completely replaced.
[0051] The use of the substrates according to the invention is
embodied by their employment in surgical medicine and tissue
engineering, in particular in the field of cartilage healing and
protection in the state of arthrosis, as well as their use for the
purpose of proliferation, differentiation and maturation of
cells.
[0052] The invention shall be further explained by means of working
examples.
EXAMPLE 1
[0053] In order to treat a substantially arthrotically deformed
joint surface, first small connections between the bone marrow
space and the joint space are generated by using multiple tiny
drillings of 1 to 2 mm. Subsequently, a wool-like polymer construct
(polyglycolid) combined with hyaluronic acid and chemotactic growth
factors (osteopontin) are glued onto the joint surface using fibrin
or acrylate cement.
EXAMPLE 2
[0054] In order to treat the joint surface shown in Example 1,
after the generation of the connections to the bone marrow space,
fibrin cement with stored chemotactic growth factors (cartilage
derived morphogenetic protein or connective tissue growth factor)
is spread over the joint's surface and is cemented using thrombin
(artificial superclot).
1TABLE 1 List of abbreviations CD44 cluster of differentiation CDMP
cartilage derived morphogenetic protein CTGF connective tissue
growth factor EGF epidermal growth factor FGF fibroblast growth
factor IGF insulin-like growth factor NO-synthase-inhibitor
nitrogen oxide synthase inhibitor NSAID non-steroidal
anti-inflammatory drugs PDGF platelet derived growth factor (growth
factor formed by thrombocytes RGD-sequences
arginine-glycine-aspartic acid sequences PVC polyvinyl chloride
TGF-.beta.-superfamily transforming growth factor beta superfamily
TIMP tissue inhibitor of metalloproteinases.
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