The objectives of this grant are to test the engraftment potential and biological activity of expanded purified human central nervous system neural stem cells (CNS-NSC) in a rodent model for Parkinson's disease. Recently, we have shown the identification and direct isolation of human CNS-NSC from primary fetal tissues using monoclonal antibodies (mAbs) directed toward surface markers and fluorescence activated cell (FACS) sorting. Clonaly derived populations of CNS-NSC were isolated and shown to self renew and maintain multilineage differentiative capacities. Moreover, the purified populations of CNS-NSC could be expanded using our long-term human neural cell culture system. Upon expansion and transplantation into neonatal NOD/SCID mice, these cells show a very robust engraftment and migration as well as differentiation. Here we propose to test the engraftment and differentiation of the in vitro expanded purified NSC in an MPTP mouse model. We will address sites for transplantation and differentiation to dopaminergic neurons. Additionally, we will continue testing in vitro conditions for the precommitment of these cells to the dopaminergic pathway by looking initially for tyrosine hydroxylase expression. PROPOSED COMMERCIAL APPLICATION: A source of highly defined engraftable human cells capable of extensive neuronal regeneration could be an effective therapeutic product for the treatment of neurodegenerative disorders. A defined reproducible method for the identification, enrichment, and expansion of either human NSCs or dopaminergic progenitors would be a potential cell based therapy product available to a broader patient base than current fetal nigral transplants as a treatment for Parkinson's disease.