BM cells were collected for EPCs analysis at day 3 and 21 after limb ischemia. Mice without limb ischemia were used as control. Flow cytometry analysis showed that BM cells positive for CD34+/Flk-1+ and Sca-1+/Flk-1+ (EPCs) were significantly increased up to 7 and 4 folds, respectively, at day 3 after ischemia, and remained at the same level at day 21 after ischemia (A and B). However, BM c-Kit+/CD31+ cell population did not change at day 3 after ischemia, but increased at day 21 (C). BM CD34+/CD133+ cell population slightly increased at day 3, and remained at this level at day 21 (D). No significant difference in the population of BM CD34+/Flk-1+, Sca-1+/Flk-1+, c-Kit+/CD31+ and CD34+/CD133+ cell population were observed between the mice treated with NAC at day 21 after limb ischemia and the control mice; however, NAC treatment significantly prevented ischemia-induced increases in the populations of BM Sca-1+/Flk-1+ cells, c-Kit+/CD31+ cells, and CD34+/CD133+ cells in mice at day 3 after limb ischemia (A-D). BM: bone marrow; Ctrl: mice without limb ischemia; Day3: 3 days after limb ischemia; Day 21: 21 days after limb ischemia. *Day3 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.