Effect of two types of endothelial progenitor cell colony-forming units (EPC-CFUs) on neovascularization. (a) Macroscopical observation of ischemic hindlimb 28 days after transplantation of large-EPCs and small-EPCs, which are derived from bone marrow c-Kit+/Sca-1+ lineage-negative (BM-KSL) cells, and murine endothelial cells (mECs) into hindlimb ischemia. (b) The ratios of the above outcomes in each group. (c) Laser Doppler perfusion imaging showing reduction of blood flow at day 28 after surgery. Quantification data of blood flow as the ratio of perfusion in ischemic hindlimb to that in normal hindlimb are shown. In hindlimb ischemic mice, blood flow of hindlimb kept to be low in small-EPCs transplanted and other control groups at day 28 after surgery. Transplantation of large-EPCs recovered the limb perfusion in hindlimb ischemic mice. **P < 0.01 versus mice transplanted with large-EPCs (n = 8). (d) Representative images of iso-lectin B4-positive tissue 28 days after transplantation of large-EPCs, small-EPCs, and mECs into hindlimb ischemia. (e) The statistical data of (a). Transplantation of large-EPC-CFUs into hindlimb ischemia model enhanced neovascularization. ***P < 0.001 versus mice transplanted with large-EPCs (n = 8). HPF, high-powered field; PBS, phosphate-buffered saline.