Allogeneic Mesenchymal Stromal Cells for Angiogenesis and Neovascularization in No-option Ischemic Limbs

The primary objective of this trial is to investigate whether intramuscular administration of allogeneic mesenchymal stromal cells (MSC) is safe and potentially effective, assessed as a composite outcome of mortality, limb status, clinical status (Rutherford classification) and pain score (visual analogue scale), in patients with no-option severe limb ischemia (SLI). The investigators will conduct a double-blind, placebo-controlled randomized clinical trial to investigate the effect of allogeneic bone marrow(BM)-derived MSC in patients with SLI, who are not eligible for conventional surgical or endovascular therapies. The investigators intend to include 60 patients, who will be randomized to undergo 30 intramuscular injections with either BM-MSC (30 injection sites with 5\*10\^6 MSCs each) or placebo in the lower leg of the ischemic extremity. Primary outcome i.e. therapy success, a composite outcome considering mortality, limb status, clinical status (Rutherford classification) and changes in pain score, will be assessed at six months.