Transfer of genes to chondrocytic cells of the lumbar spine: Proposal for a treatment strategy of spinal disorders by local gene therapy

Study Design. In the current study, chondrocytic cells from bovine intervertebral end plates were cultivated in vitro end modified genetically. Objective. The authors intended to perform isolation and cultivation of cells from bovine end plates of the spine. They also intended to show, in principle, the feasibility of introducing exogenous genes into chondrocytic cells from bovine intervertebral end plates by way of retroviral vectors. Summary of Background Data. The involvement of cytokines in the destruction of articular cartilage is established. It appears possible that similar mechanisms may play a role in intervertebral disc degeneration and other spinal disorders. Conventional medication and surgery of intervertebral disc degeneration addresses neither the pathophysiology nor the chronicity of the disease. Therapeutic proteins carry great potential as locally produced drugs after transfer of their cognate genes to the sites of interest. Methods. Vertebral end plate tissue was obtained from bovine os coccygis. Chondrocytic cells were isolated and cultured in vitro. The bacterial β-galactosidase (LacZ) gene and, alternatively, the complementary DNA (DNA copy of the mRNA) of the human interleukin-1 receptor antagonist were introduced into the isolated cells by retrovirus mediated gene transfer. β-galactosidase activity was determined by staining, and interleukin-1 receptor antagonist protein was quantitated by enzyme-linked immunosorbent assay. Results. Isolation and cultivation of chondrocytic end plate cells is possible. Native cells continue to grow in culture for more than 2 months. Transfer of the β- galactosidase gene to cultured cells resulted in ~1% β-galactosidase positive cells. Transfer of the interleukin-1 receptor antagonist complementary DNA resulted in the production of 24 ng/ml/10⁶ cells interleukin-1 receptor antagonist protein in 48 hours. Conclusions. The introduction of exogenous therapeutic genes into cells from the intervertebral end plate opens the possibility for s local gene-based treatment of intervertebral disc degeneration. This approach avoids some of the shortcomings of conventional drug- and surgery-based treatments and has the potential to be specific, effective, and appropriate to the chronicity of the disease.