Primary endpoint not met, remaining long-term follow-up not needed.

This trial will evaluate the safety and efficacy of concentrated bone marrow aspirate (cBMA) to prevent or delay major amputation and/or death in subjects with critical limb ischemia (CLI) due to severe peripheral arterial disease (PAD).

This is a prospective, randomized, double-blind, placebo controlled, multicenter trial intended for subjects with critical limb ischemia (CLI) that are unsuitable for revascularization. The investigational treatment utilizes autologous concentrated bone marrow aspirate (cBMA) at the point of care. The bone marrow aspirate is obtained from the subject's hip, concentrated with a bone marrow concentration device, and delivered intramuscularly to the affected limb. Subjects meeting the inclusion/exclusion criteria will be randomized to receive either the investigational treatment (cBMA) or a placebo control (sham treatment).

Inclusion Criteria:

• Unilateral or bilateral lower extremity ischemia due to advanced peripheral arterial disease
• Unsuitable for revascularization
• Minor tissue loss (Rutherford Category 5) or ischemic rest pain (Rutherford Category 4) with ABI ≤ 0.6, or TBI ≤ 0.4, or TcPO2 ≤ 50 mm Hg
• Competent to give consent
• No current malignancy or history of previous malignancy within the last five years, with the exception of adequately treated non-melanoma skin cancer (evidence of standard preventative cancer screenings required)

Exclusion Criteria:

• Major tissue loss (Rutherford Category 6)
• Diabetics on oral or insulin therapy with uncontrolled or untreated proliferative retinopathy (evidence of retinal exam required)
• Poorly controlled diabetes mellitus with HbA1C > 10% (evidence of HbA1C test required)
• Uncompensated congestive heart failure (New York Heart Association Class IV) and/or other conditions that preclude general anesthesia
• Myocardial infarction or stroke within last 90 days
• Elevated liver function tests (AST or ALT more than twice normal upper limit)
• Renal disease (creatinine > 2.5 mg/dl) or chronic hemodialysis
• White blood cell count < 3,000/µL or > 15,000/µL, platelet count < 100,000/µL, or hematocrit < 32%
• Topical growth hormone therapy within last 90 days, or injected growth hormone therapy within last 180 days
• Disease of central nervous system and/or other conditions that impair cognitive function
• Two or more episodes of pulmonary embolus with a documented DVT in index leg or history of DVT in index leg without evidence of clot resolution
• Current infection of index leg
• Pregnant women (negative urine pregnancy test required)
• Lower extremity venous disease with pitting edema in index leg
• Recent history (in the 6 months prior to screening) of bone marrow disease or treatment with any medication or procedure which adversely affects the bone marrow and would prohibit transplantation
• Current osteomyelitis in index leg
• Existing HIV diagnosis
• Organ transplant recipients
• Known terminal disease process with life expectancy less than one year
• Severe concomitant disease(s) or any additional condition(s) which the investigator feels constitute(s) criteria for exclusion of a particular subject
• Major amputation required within 30 days
• Inclusion in any other clinical study that may affect the outcome of this study
• Uncorrected stenosis(es) of greater than 50% in the common and/or external iliac artery and/or common femoral artery of the index leg.