Gene therapy for meniscal injury:: enhanced synthesis of proteoglycan and collagen by meniscal cells transduced with a TGFβ1 gene

Objective: To determine whether meniscal cells can express a TGF beta(1) transgene delivered by a retroviral vector, and respond to the gene product by increasing matrix synthesis. Methods: Monolayer cultures of human and canine meniscal cells were infected with retroviruses carrying either a human TGF beta(1) cDNA or marker genes. Conditioned media were assayed for the presence of TGF beta(1). Biosynthesis assays using radiolabeled precursors were employed to determine the effects of the transgenes on the synthesis of proteoglycan, collagen and noncollagenous proteins. Collagen phenotyping was performed by SDS-PAGE. Results: Media conditioned by canine and human meniscal cells transduced with the TGF beta(1) gene, accumulated several nanograms/10(6) cells of TGF beta(1) during a 48 h incubation. Media conditioned by control cells contained very little TGF beta(1). Transduction with the TGF beta(1) gene, but not marker genes, increased the synthesis of collagen and proteoglycan by 8-15-fold. The synthesis of noncollagenous proteins was enhanced more modestly. Monolayers of meniscal cells synthesized types I, III, V and VI collagen. The TGF beta(1) gene increased the synthesis of all types of collagen without altering the ratios between them. Conclusions: Meniscal cells are readily transduced by retroviral vectors and respond to the transfer of a TGF beta(1) cDNA by greatly increasing matrix synthesis. These findings encourage the further development of genetic approaches to the healing of meniscal lesions. (C) 2000 OsteoArthritis Research Society International.