This is a randomized and single blinded study aimed to compare the efficacy between intramuscular autologous bone marrow mononuclear cells plus mesenchymal stem cell implantation and intramuscular autologous bone marrow mononuclear cells implantation only in patients with chronic critical limb ischemia. Patients will be randomized into two groups of equal number; patients in one group will be implanted with mononuclear cells and mesenchymal stem cells, and the other implanted with mononuclear cells only in the area of affected limb.