[Functional differentiation of neural stem cells into endothelial cells]

Neural stem cells (NSCs) were isolated from mouse embryonic day 12.5 (E12.5) cortex and cultured by neurosphere formation in serum-free medium in the presence of 20 ng/ml basic fibroblast growth factor (bFGF). To examine whether NSCs give rise to endothelial cells, differentiation was induced by the addition of 10% fetal bovine serum (FBS) after bFGF withdrawal. Most of the differentiated cells displayed a cobblestone-like morphology. Immunological analyses and RT-PCR indicated that NSCs expressed endothelial cell-specific marker proteins such as PECAM-1, VE-cadherin, and Flk-1, and these expressions were up-regulated during differentiation. When the differentiated cells were inoculated in collagen gels with 10% FBS and bFGF and incubated for 5 days, vessel-like tube structures consisting of PECAM-1- or VE-cadherin-immunoreactive cells were formed in the gels. These results suggested that NSCs give rise to endothelial cells in vitro, which have the ability to form vascular tubes.