Visualization, direct isolation, and transplantation of midbrain dopaminergic neurons

To visualize and isolate live dopamine (DA)-producing neurons in the embryo nic ventral mesencephalon, we generated transgenic mice expressing green fl uorescent protein (GFP) under the control of the rat tyrosine hydroxylase g ene promoter. In the transgenic mice, GFP expression was observed in the de veloping DA neurons containing tyrosine hydroxylase. The outgrowth and cue- dependent guidance of GFP-labeled axons was monitored in vitro with brain c ulture systems. To isolate DA neurons expressing GFP from brain tissue, cel ls with GFP fluorescence were sorted by fluorescence-activated cell sorting . More than 60% of the sorted GFP(+) cells were positive for tyrosine hydro xylase, confirming that the population had been successfully enriched with DA neurons. The sorted GFP(+) cells were transplanted into a rat model of P arkinson's disease. Some of these cells survived and innervated the host st riatum, resulting in a recovery from Parkinsonian behavioral defects. This strategy for isolating an enriched population of DA neurons should be usefu l for cellular and molecular studies of these neurons and for clinical appl ications in the treatment of Parkinson's disease.