The intent of this clinical study is to evaluate the safety of the injection composed of autologous bone marrow derived endothelial cells (BM-ECs) and platelet-rich plasma extract (PRPE) for the treatment of critical limb ischemia.

Inclusion Criteria:

Limb ischemia patients(e.g. arteriosclerosis obliterans,diabetic critical limb ischemia, thromboangitis obliterans)

1. 18 Years to 80 Years (Adult, Senior);

2. Have ability to understand and comply with the study requirements, and provide the written informed consent prior to any procedures ;

3. Patient meets at least one of the following diagnostic criteria for the index limb:

   1. ABI<0.7mmHg
   2. TcpO2 <40 mm Hg
   3. Or, nonhealing ulcer due to local arterial compromise with no opportunity for revascularization;

4. Have no improvement after conservative treatment and are not suitable for surgical bypass surgery because no outflow tract of diseased vessel can be found by imaging;

5. Despite having good outflow artery, but the elderly and frail patients can also not tolerate revascularization or interventional surgery;

6. Unlikelihood of major amputation of the leg during the next 12 months;

7. Expected life span more than 2 years.

Exclusion Criteria:

1. Pregnant or lactating;
2. Diabetics with poorly controlled blood glucose levels (defined as HbA1c>7% and/or proliferative retinopathy);
3. Patients with decompensated cardiac, renal or liver disease;
4. Patients with confirmed malignant tumor;
5. Subjects are with serious heart, liver, kidney and lung failure or under poor general condition that are inability to undergo bone marrow harvesting and transplantation;
6. Known or suspected disease of the immune system or osteomyelitis;
7. Inability to sign informed consent form and to comply with the schedule of the study;
8. There has reason to suspect that the patient is forced to join the study;
9. Any other condition, in the opinion of the investigator, would render the patient unsuitable for the study.