Concepts in gene therapy for cartilage repair (original) (raw)
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Gene therapy and the future of cartilage repair
Operative Techniques in Orthopaedics, 2001
Articular cartilage has a very limited intrinsic healing capacity because of its avascular status. Although numerous attempts to repair full-thickness articular cartilage defects have been conducted, no methods have successfully regenerated long-lasting hyaline cartilage. One of the most promising procedures for cartilage repair is tissue engineering accompanied by gene therapy. With gene therapy, genes encoding therapeutic growth factors can be expressed at a high level in the injured site for an extended period of time. Chondrocytes have been intensively studied for cell transplantation for articular cartilage defects. However, recent studies have shown that chondrocytes are not the only candidate for cartilage repair. Muscle-derived cells have been found capable of delivering genes and represent a good vehicle to deliver therapeutic genes to improve cartilage repair. More importantly, recent studies have suggested the presence of pluripotent stem cells in muscle-derived cells. This article summarizes the current status of gene therapy for cartilage repair and its future application.
Two rapidly progressing areas of research will likely contribute to cartilage repair procedures in the foreseeable future: gene therapy and synthetic scaffolds. Gene therapy refers to the transfer of new genetic information to cells that contribute to the cartilage repair process. This approach allows for manipulation of cartilage repair at the cellular and molecular level. Scaffolds are the core technology for the next generation of autologous cartilage implantation procedures in which synthetic matrices are used in conjunction with chondrocytes. This approach can be improved further using bioreactor technologies to enhance the production of extracellular matrix proteins by chondrocytes seeded onto a scaffold. The resulting ''neo-cartilage implant'' matures within the bioreactor, and can then be used to fill cartilage defects.
Gene therapy for cartilage healing
Arthritis Research & Therapy, 2001
There is increasing interest in adeno-associated virus (AAV) vectors for a wide variety of gene therapy applications. AAV is a nonpathogenic human parvovirus that can mediate long-term transduction of a number of cell types without provoking a significant immune response. These properties make AAV especially attractive for use in gene therapy of rheumatoid arthritis (RA), a chronic inflammatory disease. To investigate the potential of AAV in gene therapy of arthritis, the ability of AAV to infect synovium in vitro and in vivo was tested. Three human RA synovial fibroblast cell lines and two murine (one DBA/1J and one DBA1J×C3H F1) synovial fibroblast cell lines were used to test AAV transduction in vitro. The cell lines (2 × 10 5 cells) were infected with 10 4 particles/cell of a murine IL-10-encoding vector (AAV-mIL-10) alone or with the addition of a low titer (100 particles/cell) of an E1-, E3-deleted recombinant adenovirus to provide E4orf6 activity to enhance second-strand synthesis. The supernatants were harvested from the wells at various time points and assayed for mIL-10 expression by ELISA. Both human synovial cell lines infected with AAV alone demonstrated low-level transgene expression throughout the course of the study. However, by day 10, all human cultures coinfected with adenovirus showed a 16-to 56-fold increase in mIL-10 compared to cultures infected with AAV-mIL10 alone. By day 30, a 31-to 135-fold increase was observed. No such increase was observed in any of the mouse cell lines. To determine the AAV transduction efficiency for synovium in vivo, human RA synovial tissues obtained from patients undergoing joint-replacement surgery were implanted subcutaneously on the backs of NOD.CB17-Prkdc SCID mice. After allowing a 2-week period for engraftment, tissues were injected with 3.4 × 10 11 particles of AAV-luciferase alone or in combination with 1.0 × 10 11 particles of adenovirus. Two weeks following AAV administration, the tissues were homogenized and assayed for expression of luciferase. Only the tissues coinfected with adenovirus had luciferase levels above background. A similar experiment with AAV-LacZ demonstrated X-gal staining only of synovial tissues coinfected with adenovirus. These findings demonstrate a preferential ability of AAV to transduce human, compared to mouse, synovial tissue and suggest that second strand synthesis may be a limiting factor in gene transduction. Further studies to elucidate the mechanisms limiting gene transduction in human synovium may allow optimization of this vector for the treatment of arthritis.
The Journal of rheumatology, 2002
To evaluate the effectiveness of transplanted allogeneic muscle derived cells (MDC) embedded in collagen gels for the treatment of full thickness articular cartilage defects, to compare the results to those from chondrocyte transplantation, and to evaluate the feasibility of MDC based ex vivo gene therapy for cartilage repair. Rabbit MDC and chondrocytes were transduced with a retrovirus encoding for the beta-galactosidase gene (LacZ). The cells were embedded in type I collagen gels, and the cell proliferation and transgene expression were investigated in vitro. In vivo, collagen gels containing transduced cells were grafted to the experimental full thickness osteochondral defects. The repaired tissues were evaluated histologically and histochemically, and collagen typing of the tissue was performed. The MDC and chondrocyte cell numbers at 4 weeks of culture were 305 +/- 25% and 199 +/- 25% of the initial cell number, respectively. The initial percentages of LacZ positive cells in t...
Genetically engineered stem cell-based strategies for articular cartilage regeneration
Biotechnology and Applied Biochemistry, 2012
Cartilage is frequently injured, often as a result of inflammatory rheumatic diseases or sports-related trauma. Given its nonvascular nature, articular cartilage has a limited capability for self-repair and currently the few therapeutic options still have uncertain long-term outcomes. Cell-based surgical therapies using autologous chondrocytes to repair cartilage injury have been used in the clinic for over a decade, but this approach has shown mixed results mainly due to the low number of harvested chondrocytes and the loss of cartilage-related phenotype and functionality after several passages of in vitro culture. A wide range of cell sources have been tested to circumvent chondrocyte limitations in cartilage repair, and stem cells have been presented as those that offer the greatest potential for clinical application. This review will focus on recent advances in stem cell-based strategies for articular cartilage repair, specifically focusing on the use of genetically engineered adult stem cells by conventional gene delivery methods and by gene-activated matrices. Perspectives in cartilage engineering are also addressed.
Gene Transfer Approaches to the Healing of Bone and Cartilage
Molecular Therapy, 2002
Gene therapy is traditionally considered a treatment modality for genetic diseases and a limited number of complex, life-threatening disorders, such as cancer. However, gene therapy also holds promise as a novel means of treating more mundane conditions, including broken bones and damaged cartilages [1-3]. These injuries frequently present enormous clinical challenges to both orthopedic surgeons and rheumatologists, and can result in considerable human suffering and economic loss. Various gene products, particularly growth factors, show remarkable promise as agents that can improve the healing of bone, cartilage, and other connective tissues. Their clinical utility, however, is limited by delivery problems. The attraction of gene transfer approaches is the unique ability to deliver authentically processed gene products to precise anatomical locations at therapeutic levels for sustained periods of time. However, unlike the treatment of chronic disease, it is neither necessary nor desirable for transgene expression to persist beyond the few weeks or months needed to achieve healing. It is also unlikely that the level of transgene expression will need to be closely regulated. Moreover, achieving targeted delivery is not an issue, because the same orthopedic procedures that are already used when operating on bones and joints can be adapted for the purposes of targeted gene transfer. Thus, the applications proposed in this review represent several of the few examples in which gene therapy has a good chance of clinical success using existing technology.
Advanced Strategies for Articular Cartilage Defect Repair
Articular cartilage is a unique tissue owing to its ability to withstand repetitive compressive stress throughout an individual’s lifetime. However, its major limitation is the inability to heal even the most minor injuries. There still remains an inherent lack of strategies that stimulate hyaline-like articular cartilage growth with appropriate functional properties. Recent scientific advances in tissue engineering have made significant steps towards development of constructs for articular cartilage repair. In particular, research has shown the potential of biomaterial physico-chemical properties significantly influencing the proliferation, differentiation and matrix deposition by progenitor cells. Accordingly, this highlights the potential of using such properties to direct the lineage towards which such cells follow. Moreover, the use of soluble growth factors to enhance the bioactivity and regenerative capacity of biomaterials has recently been adopted by researchers in the field of tissue engineering. In addition, gene therapy is a growing area that has found noteworthy use in tissue engineering partly due to the potential to overcome some drawbacks associated with current growth factor delivery systems. In this context, such advanced strategies in biomaterial science, cell-based and growth factor-based therapies that have been employed in the restoration and repair of damaged articular cartilage will be the focus of this review article.
Journal of Orthopaedic Research, 2006
A novel gene therapy approach for treating damaged cartilage is proposed that involves placing endotoxin-free cDNA containing the gene for bone morphogenetic protein-2 (BMP-2) in type I collagen sponges and then transferring the naked plasmid DNA construct to the injury site. A fullthickness cartilaginous defect in rabbits implanted with plasmid containing a marker gene (bgalactosidase) showed expressed protein as detected by immunostaining. At 1 week postimplantation, mesenchymal cells subjacent to the defect had incorporated the implanted naked plasmid DNA and, once transfected, served as local bioreactors, transiently producing the gene product. Plasmids containing the gene for BMP-2 implanted in collagen sponges in cartilage lesions stimulated hyalinelike articular cartilage repair at 12 weeks postimplantation, nearly equivalent in quality to that induced by collagen sponges with recombinant BMP-2 protein. Our approach circumvents the risks of inflammation and immunogenic response associated with the use of viral vectors. Naked plasmid DNA as a vehicle for transferring therapeutic genes has been shown to be effective in a therapeutic model within rabbit articular cartilage and appears to be safe and cost effective. ß
Cell Therapy and Tissue Engineering Approaches for Cartilage Repair and/or Regeneration
International Journal of Stem Cells, 2015
Articular cartilage injuries caused by traumatic, mechanical and/or by progressive degeneration result in pain, swelling, subsequent loss of joint function and finally osteoarthritis. Due to the peculiar structure of the tissue (no blood supply), chondrocytes, the unique cellular phenotype in cartilage, receive their nutrition through diffusion from the synovial fluid and this limits their intrinsic capacity for healing. The first cellular avenue explored for cartilage repair involved the in situ transplantation of isolated chondrocytes. Latterly, an improved alternative for the above reparative strategy involved the infusion of mesenchymal stem cells (MSC), which in addition to a self-renewal capacity exhibit a differentiation potential to chondrocytes, as well as a capability to produce a vast array of growth factors, cytokines and extracellular matrix compounds involved in cartilage development. In addition to the above and foremost reparative options up till now in use, other therapeutic options have been developed, comprising the design of biomaterial substrates (scaffolds) capable of sustaining MSC attachment, proliferation and differentiation. The implantation of these engineered platforms, closely to the site of cartilage damage, may well facilitate the initiation of an 'in situ' cartilage reparation process. In this mini-review, we examined the timely and conceptual development of several cell-based methods, designed to repair/regenerate a damaged cartilage. In addition to the above described cartilage reparative options, other therapeutic alternatives still in progress are portrayed.