AC133, an early hematopoietic stem cell marker is expressed on VEGFR-2⁺ CEPs but not on mature endothelial cells.

CD34⁺ cells derived from mobilized peripheral blood (A) and HUVEC monolayers were analyzed for the expression of AC133. Only the circulating CD34⁺ VEGFR-2⁺ cells express AC133, but not mature adherent HUVECs (B, C). CD34⁺ cells coexpressing VEGFR-2 and AC133 were present in different hematopoietic sources (D), with the highest percentage found in cytokine-mobilized peripheral blood (2 ± 0.5%) and the lowest in unmobilized peripheral blood (0.4 ± 0.2%). X-axis represents log fluorescence intensity.