Growth kinetics of the endothelial cell progeny derived from cord and adult endothelial progenitor cell colonies. (A) Ex vivo expansion of adult peripheral blood (AB) and umbilical cord blood (CB) EPC-derived endothelial cells harvested from mononuclear cells. ▪ indicates the total cell number at each passage. Cells uniformly expressed the endothelial cell surface antigens shown in Figure 2A-B and not the hematopoietic cell-specific antigens, CD45 and CD14, at each passage (data not shown). A representative growth curve for cord blood and adult EPC-derived endothelial cells is shown. Eleven other cord blood and adult endothelial cell monolayers derived from different donors showed similar growth kinetics. (B-C) PDTs (B) and CPDLs (C) of cord (CB) and adult (AB) EPC-derived endothelial cells during 60 days of culture. Results represent the mean ± SEM PDTs and CPDLs of 6 independent experiments. ^*P < .01 by Student paired t test. (D) DNA synthesis of cord (CB) and adult (AB) EPC-derived endothelial cells. Early-passage (1-2) cord blood EPC-derived endothelial cells demonstrate increased DNA synthesis in response to 10% FBS, rhVEGF, and rhbFGF compared with adult cells. Results represent the average of 4 independent experiments using endothelial cells derived from different donors. ^*P < .01 by Student paired t test.