FETAL VENTRAL MESENCEPHALON OF HUMAN AND RAT ORIGIN MAINTAINED IN-VITRO AND TRANSPLANTED TO 6-HYDROXYDOPAMINE-LESIONED RATS GIVES RISE TO GRAFTS RICH IN DOPAMINERGIC-NEURONS

Free-floating roller tube cultures of human fetal (embryonic age 6-10 weeks post-conception) and rat fetal (embryonic day 13) ventral mesenc ephalon were prepared. After 7-15 days in vitro, the mesencephalic tis sue cultures were transplanted into the striatum of adult rats that ha d received unilateral injections of 6-hydroxydopamine into the nigrost riatal bundle 3-5 weeks prior to transplantation. Graft survival was a ssessed in tyrosine hydroxylase (TH)-immunostained serial sections of the grafted brains up to post-transplantation week 4 for the human fet al xenografts and post-transplantation week 11 for the rat fetal allog rafts. D-amphetamine-induced rotation was monitored up to 10 weeks aft er transplantation in the allografted animals and compared with that o f lesioned-only control animals. All transplanted animals showed large , viable grafts containing TH-immunoreactive (ir) neurons. The density of TH-ir neurons in the human fetal xenografts and in rat fetal allog rafts was similar. A significant amelioration of the amphetamine-induc ed rotation was observed in the animals that received cultured tissue allografts. These results promote the feasibility of in vitro maintena nce of fetal human and rat nigral tissue prior to transplantation usin g the free-floating roller tube technique.