Clinical studies have established that implantation of bone marrow mononuclear cells (BM-MNCs) or peripheral blood mononuclear cells (PB-MNCs) into ischaemic limbs increases collateral vessel formation. We, the investigators at Nagoya University, further investigated the efficacy and safety of autologous implantation of BM-MNCs or PB-MNCs in patients with severe ischaemic limbs who have no other alternative therapeutic options. We also examined a potential limiting factor which reduced the efficacy of therapeutic angiogenesis using cell transplantation (TACT).