Central nervous system grafting in the treatment of parkinsonism

Central nervous system transplantation currently is being investigated in numerous centers throughout the world. The concept of restoring lost neurological function by grafting neuronal or neuronal-like tissue into the CNS has the potential for revolutionizing the treatment of numerous neurological disorders. Parkinson's disease is the subject of the majority of CNS transplantation studies although the first human studies were disappointing. However, further refinements of technique and patient selection, and animal research using a newly developed primate model of parkinsonism, led to promising results reported from several centers. Despite this, numerous fundamental issues have yet to be resolved: (1) age of patient? (2) degree of disability of patient? (3) use of fetal or adrenal tissue? (4) caudate or putamen placement? and (5) open or stereotactic surgery? This report reviews the clinically significant results of nonhuman primate research and clinical studies, and addresses these unresolved issues.