In conclusion, EPCs were related with endothelial dysfunction, whereas a higher baseline number of EPCs CD45+CD34+KDR+, obtained from blood flow at the proximity of vascular lesion, as well as an impaired reactivity of EPCs CD45+CD34+CD133+CD184+ after angioplasty, showed a predictive ability for major limb amputation in patients with critical limb ischemia. The gene discussed is CXCR4; the disease is endothelial dysfunction.