Main ASO Study: This study will compare safety and efficacy of intramuscular transplantation of autologous CD34+ cells (CLBS12) plus standard of care (SOC) pharmacotherapy (cell treatment arm) versus SOC pharmacotherapy alone (e.g., antiplatelets, anticoagulants, and vasodilators including prostanoids) (control arm) in subjects with CLI categorized as Rutherford score 4 or 5 due to ASO aged 20 to 80 years and with no endovascular or surgical revascularization options. Subjects assigned to the cell treatment arm will continue SOC pharmacotherapy and will also receive subcutaneous injections of GRAN® 5 ug/kg/day for 5 days and undergo apheresis on the last day of GRAN® administration. Then each subject in the cell treatment arm will receive intramuscular injections of autologous CD34+ cells. Subjects assigned to the control arm will continue to receive SOC pharmacotherapy alone with the possibility of receiving cell treatment via the rescue option.