Recombinant adeno-associated virus (rAAV) vectors for cartilage repair
Final Report Abstract
Damage to the articular cartilage remains a major unresolved problem for orthopaedic surgeons. None of the current interventions employed to treat disorders of this tissue can predictably restore an original articular surface. Gene transfer is a means to deliver potential therapeutic factors to sites of articular cartilage damage. Growth and transcription factors such as FGF-2, Sox9, IGF-I and its receptor are strong candidates for gene therapy strategies in the injured cartilage, as these molecules have been shown to regulate articular chondrocyte metabolism. Successful administration of gene sequences in human tissues requires that the gene vehicle allows for an elevated, sustained, and safe expression of the transgenes within the target celts in view of a clinical protocol. rAAV vectors are particularly well-suited to achieve these goals, as these small, non-pathogenic, non-immunogenic, and non-toxic vectors can directly, efficiently and persistently deliver reporter (marker) genes in articular chondrocytes (the cells forming the cartilage) in vitro, in cartilage explants in situ where the cells are embedded in their natural matrix, and in sites of cartilage injury in vivo. The goal of this project was to evaluate the potential of rAAV vectors to deliver or co-deliver the gene sequences for the candidates mentioned above in biologically active forms into human articular chondrocytes in vitro, within their dense extracellular matrix in situ, and in a clinically relevant animal model of cartilage injury in vivo. We tested the hypothesis that direct administration (transduction) and/or co-administration (cotransduction) of our constructs would lead to changes in articular chondrocyte metabolism in vitro and in situ, both in tissue from normal donors and osteoarthritic patients. We also hypothesized that overexpression or co-overexpression of the factors via direct rAAV injection would improve the properties of the repair tissue in an osteochondral defect model system in the rabbit knee joint in vivo. We successfully demonstrated that the combined gene transfer of the FGF-2 and sox9 sequences via rAAV vectors enhanced the proliferative, synthetic, and regenerative properties in all the systems established here (in vitro, in situ, and in vivo) to levels significantly higher than following application of each vector separately. The therapeutic effects reached with this strategy were relevant to further treat such cartilage lesions in larger animal models, and should allow in a close future to translate the methodology in human patients. This project has established a basis for direct, clinically relevant treatments of human articular cartilage lesions and other disorders of the cartilage (osteoarthritis) using gene-based approaches.
Publications
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Cucchiarini and Madry, Gene therapy for cartilage defects. J. Gene Med. 2005, 7(12):1495- 509.
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Cucchiarini et al. Improved tissue repair in articular cartilage defects in vivo by rAAV-mediated overexpression of human fibroblast growth factor 2. Mol. Ther. 2005, 12(2):229-38.
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Cucchiarini et al. Restoration of the extracellular matrix in human osteoarthritic articular cartilage by overexpression of the transcription factor Sox9. Arthritis Rheum. 2007, 56(1}:158-67.
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Madry et al In situ overexpression of human FGF-2 via rAAV stimulates cell proliferation in normal and osteoarthritic human articular cartilage. Trans. ORS 2006, 1007,
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Madry et al. rAAV-mediated co-overexpression of human FGF-2 and sox9 enhances the repair of articular cartilage defects in vivo. Trans. ORS 2007, 0229,
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Madry et al. rAAV-mediated overexpression of human sox9 enhances the repair of articular cartilage defects in vivo. Trans. ORS 2006, 0306.
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Weimer et al. Combined overexpression of human FGF-2 and sox9 via rAAV stimulates cell proliferation and extracellular matrix synthesis in human normal and osteoarthritic articular cartilage in situ. Trans. ORS 2007, 1467.
