An immortalized, type-1 astrocyte of mesencephalic origin source of a dopaminergic neurotrophic factor

Rat embryonic d 14 (E14) mesencephalic cells, 2.5% of which are glioblasts, were incubated in medium containing 10% of fetal bovine serum for 12 h and subsequently expanded in a serum-free medium using basic fibroblast growth factor (bFGF) as the mitogen. On a single occasion, after more than 15 d i n culture, several islets of proliferating, glial-like cells were observed in one dish. The cells, when isolated and passaged, proliferated rapidly in either a serum-free or serum-containing growth medium. Subsequent immunocy tochemical analysis showed that they stained positive for GFAP and vimentin , and negative for A2B5, O4, GalC, and MAP2. Serum-free conditioned medium (CM) prepared from these cells caused a fivefold increase in survival and p romoted neuritic expansion of E14 mesencephalic dopaminergic neurons in cul ture. These actions are similar to those exerted by CM derived from primary , mesencephalic type-1 astrocytes. The pattern of expression of the region- selective genes; wnt-1, en-1, sis showed that 70% of the cells were heterop loid, and of these, 50% were tetraploid. No apparent decline in proliferati ve capacity has been observed after 25 passages. The properties of this cel l line, named ventral mesencephalic cell line one (VMCL1), are consistent w ith those of an immortalized, type-1 astrocyte. The mesencephalic origin of the cell line, and the pattern and potency of the neurotrophic activity ex erted by the CM, strongly suggest that the neurotrophic factor(s) identifie d are novel, and will likely be strong candidates with clinical utility for the treatment of Parkinson's disease.