Implantation of human fetal ventral mesencephalon to the right caudate nucleus in advanced Parkinson's disease.

Disaggregated ventral mesencephalic tissue from single aborted human fetuses of 11 to 18 weeks' gestation was implanted stereotaxically into a consistent striatal site in 12 patients with advanced Parkinson's disease. All were receiving optimum levodopa therapy and were examined preoperatively and at 3,6,9, and 12 months postoperatively. Immunosuppression was not used. There were significant sustained improvements at 12 months in three patients; motor fluctuations were absent in two. There were modest group improvements up to 6 months, with increased quality of "on" and "off" phases, quantity of on times, and specific improvements in contralateral upper limb bradykinesia. Preoperative levodopa requirements were reduced to a mean of 64% at 6 months and 61% at 12 months. Deterioration below baseline ratings occurred in three of nine patients who had consistent follow-up to 12 months. Grafting of midgestational human fetal tissue can lead to improvement in Parkinson's disease. Individual disease severity may be critical, and further trials are needed to identify host factors influencing outcome.