The present invention concerns methods and compositions for differentiating cells, including human fibroblasts, into chondrocyte-like cells via in vivo mechanical strain. In particular aspects, fibroblasts are delivered to a joint, such as an intervertebral disc, following which the fibroblasts differentiate into chondrocyte-like cells to treat dysfunction of cartilage therein, including to repair degenerated discs, for example. The fibroblasts that do not differentiate to chondrocytic cells because of the location of the cells, as in the fissures of annulus, or other biomechanical and biochemical micro-environment factors, may produce fibrous matrix molecule(s) in aiding tissue repair and regeneration in both nucleus pulposus and annulus fibrosus. In certain aspects, the fibroblasts prior to delivery to the individual are managed in the absence of growth factors, in vitro mechanical strain, and/or matrix molecules, for example.
