There is growing evidence that certain areas of the adult central nervous system retain the capacity to generate new neurons from endogenous immature progenitor cells. Our preliminary results show that the adult substantia nigra (SN) region of the brain contains progenitor cells with the potential to differentiate into neurons. We have been able to isolate and to propagate these SN progenitor cells. In this grant we propose to a) investigate the characteristics of adult SN progenitor cells; b) define conditions that will stimulate differentiation of adult SN progenitor cells into the type of dopaminergic neurons lost in Parkinson's disease; and c) test the effect of grafted SN progenitor cells in animal models for Parkinson's disease. The suggested experiments will not only explore the suitability of adult SN progenitor cells for therapeutic transplantation strategies, but also lay the groundwork for possible future approaches in which we will try to stimulate the endogenous SN progenitor cells to replace degenerating SN dopaminergic neurons, and thus possibly negate the need for transplantation in some patients. We are now defining these neurons in greater detail to determine whether they synthesize and send the chemical signal that is deficient in Parkinson's disease. Based on these studies, we will maximize utility for Parkinson's disease by growing the BMSCs or neurons under different conditions and by inserting genes to enhance function. The adult bone marrow cells are particularly advantageous since they divide rapidly, are extremely flexible, and accept new genes without difficulty. We have already transplanted the differentiated neurons to various regions of animal brains, including those affected in Parkinson's disease, and the cells survive for at least one and a half months-the longest time examined. Utility of the BMSCs and neurons will be tested in animal models of Parkinson's disease. Successful approaches will be applied to human cells from the animal prototypes. Our overall goal is to develop human lines for use in Parkinson's disease.