Brain repair.

Diseases of the human brain and spinal cord are common and often progressive since, unlike peripheral nerve, the adult human central nervous system does not spontaneously repair itself. Studies on development and cell lineages in the nervous system have started to elucidate the scientific basis for this lack of regeneration, and have suggested ways of enhancing repair. At the same time, improved understanding of neurodegenerative processes has provided a rationale for treatments which limit neuronal and glial damage. Cell implantation has been tested, experimentally and in man, and with some prospects for successful restoration of normal cell arrangements in the central nervous system. Taken together, a coherent strategy for limiting the damage and repairing the brain is beginning to emerge. The translation of these ideas into clinical practice is timely and eagerly awaited.