The promise of stem cells for neural repair.

The realization that the adult nervous system develops from multipotential stem cells and that cells with stem-like properties are retained in the adult CNS has provoked an intense search for ways to utilize their potential for therapeutic treatments of multiple neurological disorders. Transplantation of neural stem cells or more restricted progenitors to replace cells lost to injury or disease may facilitate functional recovery in a spectrum of neurological disorders. Alternatively, expansion and recruitment of endogenous progenitors may be effective in treating widespread cell loss in the adult CNS. A major challenge to the development of effective stem cell therapies is to direct the fate of the newly generated cells to specifically replace those lost to disease. Insights from developmental research are providing molecular targets for regulating the differentiation of neural stem cells and their progeny in areas of injury to the adult CNS. Given the commonality of processes mediating the assembly of multicellular systems, the approaches developed in the CNS will likely be applicable for selective cell replacement in the auditory system.