ISOLATION AND MANIPULATION OF ROSTRAL MESENCEPHALIC TEGMENTAL PROGENITOR CELLS FROM RAT

A technique for isolating mitotic progenitor cells from the embryonic rostral mesencephalon is described. Culture of the progenitor cells in complete media with subsequent staining for neuron specific enolase ( NSE) revealed that only 0.6% of the cells were NSE immunoreactive. Coc ulturing the progenitor cells with established striatal cultures did n ot result in conversion of any of the cells to the dopamine neuron phe notype (tyrosine hydroxylase immunoreactive (THir) neurons). In contra st, co-culture of progenitor cells with established mesencephalic cult ures produced a statistically significant, and in some cases (three of twelve), dramatic increase in the number of THir cells. The THir cell s that were present had more pronounced process extension than those o bserved in mesencephalic mono-cultures. Culturing progenitor cells in transwell baskets that were continuously exposed to media but physical ly separated from established mesencephalic cultures growing underneat h the baskets led to the conversion of only a few progenitor cells to THir neurons in four of twelve transwell studies suggesting that cell- cell contact between progenitor cells and mesencephalic cells is requi red for the conversion. This co-culture technique also increased the n umber of THir neurons in the mesencephalic cultures although the incre ase was not profound enough to explain the increase observed in tradit ional co-culture. These data suggest that mitotic progenitor cells can be isolated from fetal rat tissue and successfully converted to the d opamine neuron phenotype. Progenitor-mesencephalic co-culture appears to increase the number of THir cells in both tissue sources mediated i n part by soluble factor(s) although cell-cell contact and presumably extracellular matrix proteins play a more substantial role. These prog enitor cells may prove useful as a tissue source for transplantation p rocedures in Parkinson's disease.