Gene therapy for meniscal injury: enhanced synthesis of proteoglycan and collagen by meniscal cells transduced with a TGFβ1gene

Abstract

Objective To determine whether meniscal cells can express a TGFβ1transgene 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 TGFβ1cDNA or marker genes. Conditioned media were assayed for the presence of TGFβ1. 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 TGFβ1gene, accumulated several nanograms/106cells of TGFβ1during a 48h incubation. Media conditioned by control cells contained very little TGFβ1. Transduction with the TGFβ1gene, 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 TGFβ1gene 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 TGFβ1cDNA by greatly increasing matrix synthesis. These findings encourage the further development of genetic approaches to the healing of meniscal lesions.