This study will evaluate the clinical potential for the implantation of a concentration of bone marrow mononuclear cells which contain stem cells for therapeutic angiogenesis through the augmented formation of collateral vessels in the ischemic limb. It is a placebo-controlled, 1:1 randomized study with a total of 90 patients included. The placebo procedure consists of a sham bone marrow puncture where no bone marrow aspiration is done; instead, only a stab puncture of the skin is made.