EPCs exhibit a higher resistance to oxidative stress as compared with HUVECs or CD14⁺ monocytes. (A) EPCs, HUVECs, and CD14⁺ monocytes were stained with the fluorescent dye CM-H₂DCF-DA to measure ROS levels by FACS analysis. A histogram representative of 3 independent experiments is shown. (B) Data are mean ± SD, n = 3. *P < .05 versus EPCs.