Using autologous bone marrow mononuclear cells (BM-MNC) to treat patients with chronic limb ischemia has been proved safe and effective. However, processing bone marrow by Ficoll density gradient centrifugation is not only time consuming but also expensive. Manually processing of bone marrow also results in large variation in therapeutic cell quantity and quality which directly leads deviation of safety and efficacy of the cell therapy. This study is aiming to compare an automated bone marrow processing system with a conventional manual method in term of safety and efficacy.

Using autologous bone marrow mononuclear cells (BM-MNC) to treat patients with chronic limb ischemia has been proved safe and effective. However, processing bone marrow by Ficoll density gradient centrifugation is not only time consuming but also expensive. Manually processing of bone marrow also results in large variation in therapeutic cell quantity and quality which directly lead deviation of safety and efficacy of the cell therapy. This study is aiming to compare an automated bone marrow processing system with a conventional manual method in term of safety and efficacy.

ResQ system developed by Thermogenesis in USA provides an automatic cell processing system for bone marrow. The system takes less than 30 minutes to concentrate the therapeutic mononuclear cells including stem cells in a closed system without adding any additive such as separation reagent (Ficoll). The system also be able to be operated at point of care.

The study is designed to prove no inferior of safety and efficacy of bone marrow cells processed by ResQ to those of cells using conventional manual method. The conventional manual method is involved Ficoll density gradient centrifugation and cell washing stems in an open system. Each of test arms (ResQ vs manual method) consists of 25 patients. The primary outcome is safety which is measured by cell treatment-related adverse events. The secondary endpoints include resting ankle-brachial pressure index (ABI)and toe brachial pressure index (TBI) , transcutaneous oxygen pressure (TcPO2), claudication distance, rest pain scale evaluation, collateral vessel scale, etc.

Inclusion Criteria:

1. fontaine's stage 2-4 or resting ABI <0.7
2. age between 20 and 80 years old
3. sign informed consent, voluntary subjects
4. diagnosis of lower extremity arterial occlusive disease, or diabetic lower limb ischemia, or Buerger's disease

Exclusion Criteria:

1. poorly controlled diabetes (HBA1c> 7.0%) and proliferative retinopathy (III-IV stage)
2. malignancy history in the past five years or serum level of tumor markers elevated more than doubled
3. severe heart, liver, kidney, respiratory failure or poor general condition can not tolerate BM-MNC transplantation
4. serious infections (such as cellulitis, osteomyelitis, etc.)or gangrene that a major amputation cannot be avoided
5. aortic or iliac or common femoral artery occlusion
6. pregnant female, or reproductive age female who wants to give birth throughout the course of the study
7. life expectancy less than a year