CD31 (PECAM-1)-bright cells derived from AC133-positive cells in human peripheral blood as endothelial-precursor cells

To clarify the process of endothelial differentiation, we isolated AC133(+) cells and induced the in vitro differentiation of these cells into endothelial cells. AC133(+) cells efficiently differentiated into endothelial cells when the cells were cultured on fibronectin-coated dishes in the presence of vascular endothelial growth factor. Time-course analysis of the alteration of endothelial markers on cultured AC133(+) cells revealed that the expression of CD31 (PECAM-1) on AC133(+) cells was the earliest marker among all of the tested markers. Based on the hypothesis that CD31 is an early indicator during the endothelial differentiation, we examined the relationship between CD31 expression and the ability to differentiate into endothelial cells in cells derived from AC133(+) cells. CD31-bright cells, which were sorted from cultured AC133(+) cells, differentiated more efficiently into endothelial cells than had CD31-positive or CD31-negative cells, suggesting that CD31-bright cells maybe precursor cells for endothelial cells. In the present study, we identified CD31(+) cells derived from cultured AC133(+) cells that are able to differentiate to endothelial cells as precursor cells. (C) 2003 Wiley-Liss, Inc.