Inclusion Criteria:

• Subjects will have one or more clinical indications diagnostic of CLI such as: distal extremity pain at rest that requires the subject to use analgesics for >2 weeks; or peripheral ischemic ulcer(s); or areas of gangrene.
• The subject will have a TcPO2 of </= 40 mmHg.
• Subjects will have one or both of the following hemodynamic indicators of severe peripheral arterial occlusive disease: (a) Ankle systolic pressure of </= 70 mmHg; (b)Toe systolic pressure </= 50 mmHg.
• The subject is a poor candidate for standard revascularization treatment options for peripheral arterial disease, based on inadequate bypass conduit, unfavorable anatomy, or poor operative risk.
• Subject has signed an informed consent form either directly or through a legally authorized representative
• If female, the subject must be (a) at least one year post-menopausal, or (b) surgically sterile, or (c) if the subject is of child-bearing potential, she must have been practicing contraception for at least 12 weeks prior to entering the study.
• If subject is of reproductive potential, he or she must be using an accepted and effective (barrier) form of birth control during the study.
• Subjects will be on a statin and an anti-platelet agent as part of their standard of care and must be stable on these regimens for at least 4 weeks prior to treatment.

Exclusion Criteria:

• Subjects, who in the opinion of the investigator, have a vascular disease prognosis that indicates they would require a major amputation (at or above the ankle) within 4 weeks of start of treatment.
• Subjects with a diagnosis of Buerger's disease (Thromboangitis Obliterans).
• Subjects with hemodynamically significant aorto-iliac occlusive disease.
• Subjects who have had a revascularization procedure within 12 weeks prior to treatment initiation that remains patent. Revascularization procedures that are evidenced to have failed for >2 weeks prior to treatment initiation are acceptable.
• Subjects who require a change in their hypertension medication as part of their standard of care within 4 weeks prior to treatment.
• Evidence or history of malignant neoplasm (clinical, laboratory or imaging), except for basal cell carcinoma of the skin.
• Subjects who have proliferative diabetic retinopathy or severe, non-proliferative retinopathy
• Subjects with end stage renal disease (ESRD) defined as significant renal dysfunction evidenced by a creatinine of > 2.5, or receiving chronic hemodialysis therapy.
• A subject who has hepatic cirrhosis, viral hepatitis, or is HIV positive.
• Subjects with a clinically significant liver enzyme abnormality (i.e., AST or ALT more than two times the upper limit of normal and/or bilirubin more than 50% the upper limit of normal).
• Subjects requiring the use of hyperbaric oxygen treatment for wound healing during the screening and 6 month follow-up period.