This study is designed to evaluate the efficacy and safety of ixmyelocel-T, a patient-specific expanded multicellular therapy, for the treatment of patients with critical limb ischemia (CLI). The study is a randomized, vehicle controlled (placebo)study in CLI patients who have no option for revascularization procedures. All patients randomized will undergo a small volume bone marrow aspiration in a 15-minute outpatient or in-office procedure. All patients will receive injections of either ixmyelocel-T or vehicle-control into their pre-identified index leg. Patients will be followed for 18 months.