Prospects of transplantation in human neurodegenerative diseases.

Over the past decade experimental data obtained from animals have suggested that restoration or preservation of function through cell transplantation into the CNS might be developed into a useful therapeutic approach in human neurodegenerative disorders. Clinical trials in patients with Parkinson's disease have provided evidence that grafts of fetal dopaminergic neurons can survive and induce functional effects in the human brain, but no treatment based on transplantation is available yet. Initiation of studies of patients with striatal neural grafts in Huntington's disease is supported by findings in animal models, and is motivated by the lack of therapy and the severity of the symptoms in this disorder. Application of cell transplantation to other neurodegenerative disorders such as Alzheimer's disease, amyotrophic lateral sclerosis, and hereditary ataxia is definitely premature. Further progress can be made only by systematic studies in animals of the scientific issues that can now be defined, but will also require clinical trials in a few well-monitored patients.