Functional characterization of EPCs isolated from PBMCs. (A) A typical EPC colony formed after culturing PBMCs on fibronectin in Endocult medium followed by EGM-2 medium and appearance after staining cells with the endothelial markers DiI-acetylated LDL and FITC-Ulex-lectin. Both endothelial markers are colocalized in the majority of cells. (B) Expression of the eNOS mRNA in the isolated colony-forming cells and HUVECs. (C) NO production in the cells within the colonies monitored by live imaging of NO with the NO-specific fluorescent probe DAF-FM diacetate (top panel). Fluorescence of NO-specific probe was sensitive to L-NAME, an inhibitor of nitric oxide synthase. Values are means ± SD (n = 3). **P < .01 compared with untreated cells.