Conclusions: Endothelial progenitor cells were related with endothelial dysfunction, whereas a higher baseline number of the subpopulation CD45+CD34+KDR+, as well as an impaired reactivity of subpopulation CD45+CD34+CD133+CD184+ after angioplasty, showed a predictive ability for major limb amputation in patients with critical limb ischemia. This evidence concerns the gene CXCR4 and endothelial dysfunction.