Survival of intracerebrally grafted rat dopamine neurons previously cultured in vitro.

Fetal rat dopamine (DA) neurons were cultured in vitro for a 6-day period and transported, after redissociation, for 2 days prior to being grafted to the neostriatum of adult rats with 6-hydroxydopamine lesions of the ascending nigrostriatal pathway. In 2 of the 5 graft recipients that were tested for amphetamine-induced motor asymmetry, the grafts eliminated the lesion-induced turning behaviour within 3-6 weeks after transplantation. Fluorescence histochemistry revealed surviving grafts in all 6 recipients at 7 weeks after transplantation, containing between 42 and 125 DA neurons. The number of surviving DA neurons in the 3 non-compensated rats was below the minimum number of cells previously found to be necessary for functional effects on turning behaviour to occur.