Objective To determine whether meniscal cells can express a TGFbeta(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 TGFbeta(1)cDNA or marker genes. Conditioned media were assayed for the presence of TGFbeta(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 TGFbeta(1)gene, accumulated several nanograms/10(6)cells of TGFbeta(1)during a 48 h incubation. Media conditioned by control cells contained very little TGFbeta(1). Transduction with the TGFbeta(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 TGFbeta(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 TGFbeta(1)cDNA by greatly increasing matrix synthesis. These findings encourage the further development of genetic approaches to the healing of meniscal lesions.