Transplantation of neural progenitor and stem cells: developmental insights may suggest new therapies for spinal cord and other CNS dysfunction.

Multipotent neural progenitors and stem cells may integrate appropriately into the developing and degenerating central nervous system. They may also be effective in the replacement of genes, cells, and nondiffusible factors in either a widespread or a more circumscribed manner, depending on the therapeutic demands of the clinical situation. In addition, they may be uniquely responsive to some types of neurodegenerative conditions. We believe that these various appealing capabilities are the normal expression of basic biologic properties and attributes of a stem cell. The therapeutic utility of some of those properties is illustrated in this review of ongoing work in our laboratory, particularly with regard to spinal dysfunction. In these examples, we believe we have tapped into a mechanism that underlies a remarkable degree of natural plasticity programmed into the nervous system at the cellular level, and we have now exploited those properties for therapeutic ends.