Intranigral transplantation of fetal substantia nigra allograft in the hemiparkinsonian rhesus monkey

Current clinical protocols for fetal cell transplantation for Parkinson's d isease (PD) have focused on restoring dopamine in the striatum. However, th ere are now a number of human transplant recipients who have had robust inn ervation of the striatum by dopaminergic grafts (documented by positron emi ssion tomography or by autopsy), but only a partial improvement in parkinso nian motor signs. Thus, there is a need for improved transplant strategies. In animal models of PD, there is recent evidence that restoring dopamine i n the substantia nigra, instead of or in addition to the striatum, may be i mportant to correct abnormal motor behavior. This pilot study examined the morphological features and behavioral effects of fetal dopaminergic neurona l allografts placed into the substantia nigra of three 1-methyl-4-phenyl-1, 2,3,6-tetrahydropyridine (MPTP)treated hemiparkinsonian rhesus monkeys. We show that grafts can survive in host substantia nigra. Characteristics of t he graft-host interface were variable. In one animal, reinnervation of host substantia nigra was observed, and this animal showed behavioral improveme nt in a reach-and-retrieval task.