New strategies for disc repair: novel preclinical trials.

Degeneration of lumbar intervertebral discs is a major cause of low back complaints, an irreversible occurrence with no currently available treatment. Furthermore, various surgical procedures can accelerate disc degeneration. On the other hand, recent experimental studies on disc cells have demonstrated an important role for the nucleus pulposus in preserving overall disc structure. The author's group has already found that nucleus pulposus cells activated annulus fibrous cells, and reinsertion of nucleus pulposus cells slowed further disc degeneration. We have designed three subsequent studies that were designed to examine further possibilities for clinical transplantation: (1) activation of nucleus pulposus cells by mesenchymal stem cells; (2) focus on the multilineage differentiation potential of mesenchymal stem cells as an alternative cell source for cell transplantation therapy of disc degeneration; (3) the possibility of a human nucleus pulposus cell line as a cell source for cell transplantation therapy. Activation of nucleus pulposus could be achieved by co-culture with autogenous mesenchymal stem cells allowed to have direct cellular interaction. This would be a useful clinical cell source. Induction of nucleus pulposus cells by autogenous mesenchymal stem cells also would be an important subject for a clinical trial. Clinical application of the cells derived from a human nucleus pulposus cell line is an important project to be undertaken in the near future.