[Future views and challenges to the peripheral nerve regeneration by cell based therapy]

Chronic degenerative diseases and traumatic injuries are responsible for a decline in neuronal function. Cell transplantation is one of the strategies with potential for treatment of such neural disorders, and many kinds of cells including embryonic stem cells and neural stem cells have been considered as candidates for transplantation therapy. Bone marrow stromal cells (MSCs) have great potential as therapeutic agents since they are easy to isolate and can be expanded from patients without serious ethical and technical problems. We found a method for the highly efficient and specific induction of functional neurons, skeletal muscle cells and Schwann cells from both rat and human MSCs. Induced neurons and Schwann cells were transplanted to animal models of Parkinson's disease, stroke, peripheral nerve injury, and spinal cord injury, resulting in the successful integration of transplanted cells and improvement in behavior of transplanted animals. Induced skeletal muscle cells differentiate into muscle fibers upon transplantation into degenerated muscles of rats and mdx-nude mice. The induced population contained Pax7-positive cells that contribute to subsequent regeneration of muscle upon repetitive damage without additional transplantation of cells. Here we focus on the respective potentials of MSC-derived cells and discuss the possibility of clinical application in neurodegenerative and muscle degenerative diseases.