Blood cells were collected for EPCs analysis after limb ischemia at day 3 and 21. Mice without limb ischemia were used as control. Flow cytometry analysis demonstrated that circulating Sca-1+/Flk-1+ cell population was initially increased significantly at day 3, then returned to baseline level at day 21 (B and D). CD34+/Flk-1+ cell population in blood was at low level at day 3, and only slightly increased at day 21 (A). The levels of all circulating EPCs were significantly increased by 2-3 folds at day 21 in mice treated with NAC compared to the control mice (A-D). On the other hand, NAC treatment resulted in a sustained elevation of circulating EPCs population (CD34+/Flk-1+, Sca-1+/Flk-1+, c-Kit+/CD31+ and CD34+/CD133+) in mice at day 21 of limb ischemia compared to the control, while leading to a significant reduction in the number of circulating Sca-1+/Flk-1+ cells and CD34+/CD133+ cells in mice at day 3 after limb ischemia. *Day 3 or 21 vs Ctrl, P <0.05, n≥8; $Day21 vs 3, P <0.05, n≥8; #ctrl vs NAC, P <0.05, n≥8.