Please select the eligibility criteria that correspond to the clinical trial below.
Title: A Clinical and Histological Analysis of Mesenchymal Stem Cells in Amputation
Brief Summary: Patients undergoing semi-elective lower extremity major amputation from complications associated with atherosclerotic limb ischemia will received intra-muscular injections of allogeneic Mesenchymal Stromal Cells in the leg above and below the point of amputation to prevent ischemic wound complications after surgery and decrease the incidence of revision and further amputation. Cohort Groups 1-4 will serve as controls.


Options:
A: Inclusion Criteria:

1. Be ≥ 40 and ≤90 years of age.
2. Patients requiring lower extremity major amputation, as determined by an independent vascular specialist.
3. If ulceration or gangrene present, it is distal to malleoli (to allow adequate length of ATM area of approximately 3cm x 10cm x 3 cm)
4. Amputation can safely be performed up to 30 days after screening, as determined by an independent vascular or orthopedic surgeon.
5. Females of childbearing potential must be willing to use one form of birth control for the duration of the study. Female participants must undergo a blood or urine pregnancy test at screening.

Exclusion Criteria:

1. Patients who are pregnant, planning to become pregnant in the next 12 months, or lactating.
2. CHF hospitalization within the last 1 month prior to enrollment.\*
3. Acute coronary syndrome in the last 1 month prior to enrollment.\*
4. HIV positive, or active, untreated HCV as determined by review of medical records.
5. History of cancer within the last 5 years, except basal cell skin carcinoma
6. Inability to provide written informed consent due to cognitive or language barriers (interpreter permitted).
7. Concurrent enrollment in another clinical investigative trial that may alter the outcomes of enrollment in this trial.
8. Any condition requiring immunosuppressant medications (e.g., for treatment of organ transplants, psoriasis, Crohn's disease, alopecia areata).
9. Presence of any clinical condition that in the opinion of the PI or the sponsor makes the patient not suitable to participate in the trial.

   * As defined by the standard definitions of CHF and ACS by the American Heart Association.
B: Inclusion Criteria:

* 21-80 years of age
* moderate or high-risk Critical Limb Ischemia (Rutherford Clinical Severity Score 4 or 5)
* unsuitable for conventional revascularization

Exclusion Criteria:

* advanced CLI (Rutherford Clinical Severity Score 6) characterized by extensive tissue loss or gangrene
* advance AV block or NYHA Class III or Class IV heart failure
* myocardial infarction within 3 months of treatment
* successful coronary or lower extremity revascularization within 3 months of study enrollment
* arterial insufficiency in the lower extremity is the result of a non-atherosclerotic disorder with the exception of thromboangitis obliterans (Buerger's Disease)
* co-morbidity associated with life expectancy of less than 1 year
C: Inclusion Criteria:

1. Patients with atherosclerotic peripheral artery disease with classic claudication (exercise-induced pain, cramps, fatigue, or other equivalent discomfort involving large muscle groups of the leg(s) that is consistently relieved by rest) or atypical leg pain (exertional leg pain that does not begin at rest or does not resolve consistently with rest) as defined by the San Diego Claudication Questionnaire.
2. Age ≥40 years
3. Resting ankle-brachial index \<0.90 or a resting toe-brachial index of \<0.70 at baseline testing
4. Presence of significant stenosis or occlusion of infrainguinal arteries including the superficial femoral artery, popliteal artery and/or infrapopliteal arteries as determined by: Duplex ultrasound imaging (occlusion or focal doubling of peak systolic velocity of one or more affected segments) OR lower extremity computed Tomography Angiography (CTA) OR lower extremity magnetic resonance angiography (MRA) OR lower extremity catheter-based contrast arteriography. Each of these noninvasive and invasive anatomic assessments will identify patients with at least a 50% stenosis in the affected segment.

Exclusion Criteria:

1. Presence of any musculoskeletal disease, cardiac or pulmonary disease, or neurological disease that limits the patient's ability to walk to fulfill protocol requirements (claudication must be the consistent primary exercise limitation)
2. Inability to complete treadmill testing per protocol requirements.
3. Ability to walk for more than 12 minutes on the treadmill during treadmill testing.
4. Patients who identify both legs as equivocally symptomatic or alternate between symptomatic legs on the baseline treadmill tests.
5. Patients with critical limb ischemia (ischemic rest pain or ischemia-related non healing wounds or tissue loss (Rutherford categories 4-6).
6. Recent (\<3 months) infrainguinal revascularization (surgery or endovascular revascularization) or revascularization planned during study period
7. Patients with a patent infrainguinal bypass graft in the index limb, with or without evidence of a hemodynamically significant stenosis or other defect (kinking, pseudoaneurysm, or fistula). Patients with an occluded infrainguinal bypass graft or a patent aortobifemoral or femoral-femoral bypass graft are NOT excluded.
8. Patients with \>2+ lower extremity pitting edema
9. Patients with myelodysplastic syndrome (MDS)
10. Patients who are pregnant or lactating, planning to become pregnant in the next 12 months, or are unwilling to use acceptable forms of birth control during study participation.
11. Congestive Heart Failure hospitalization within the last 1 month prior to enrollment
12. Acute coronary syndrome in the last 1 month prior to enrollment
13. Human Immunodeficiency Virus positive, active Hepatitis B Virus or Hepatitis C Virus Disease
14. History of cancer within the last 5 years, except basal cell skin carcinoma
15. Any bleeding diathesis defined as an International Normalized Ratio ≥ 2.0 (off anticoagulation therapy) or history of platelet count less than 100,000 or hemophilia
16. Contraindication to magnetic resonance imaging (MRI) (including knee/tibial/fibular replacement hardware in the index leg) or known allergy to MRI contrast media
17. Chronic kidney disease \[effective Glomerular Filtration Rate \<30 by modification of diet in renal disease (MDRD) or Mayo or Cockcroft-Gault formula\]
18. Uncontrolled diabetes \[Hemoglobin A1C (HbA1C)\>8.5\]
19. Planned change to (initiate or terminate) active involvement in a supervised exercise program (e.g., with a trainer, exercise protocol, and goals, such as in a peripheral arterial disease, cardiac or pulmonary rehabilitation program) during study participation
20. Plans to change medical therapy during the duration of the study, (i.e. patients who use cilostazol should remain on a stable dose for four weeks prior to enrollment and should not change doses for the 6 months of the study duration.) As always, cilostazol can be discontinued if new heart failure or intolerance occurs during study participation.
21. Any condition requiring immunosuppressant medications (e.g., for treatment of organ transplants, psoriasis, Crohn's disease, alopecia areata).
22. History of inflammatory or progressively fibrotic conditions (e.g. rheumatoid arthritis, systemic lupus erythematosis, vasculitic disorders, idiopathic pulmonary fibrosis, retroperitoneal fibrosis).
23. Patients with any untreated stenosis \> 70% of the distal aorta, common iliac, or external iliac arteries by CT, Angiography or MRI imaging will be excluded from enrollment (patients with previously successfully revascularized inflow stenoses may enroll in PACE). Subjects who were screen failures for a flow-limiting proximal lesion may be rescreened 3 months after successful angioplasty/stenting.
24. Inability to provide written informed consent due to cognitive or language barriers (interpreter permitted)
25. Concurrent enrollment in another clinical interventional investigative trial.
26. Presence of any clinical condition that in the opinion of the principal Investigator or the sponsor makes the patient not suitable to participate in the trial
D: Inclusion Criteria:

* Diabetic patients under treatment (type I or II)
* Critical limb ischemia (rest pain and/or non-healing ischemic ulcers lasting more than 4 weeks, and/or Ankle-Brachial Index \< 0,8)
* Not suitable to be revascularized (surgical and interventional consensus)

Exclusion Criteria:

* Neoplastic disease and/or hematologic disease during the last 2 years
* Diabetic retinopathy
* Ischemic ulcer greater than 10 cm2
* Major amputation at target limb
* Life expectancy \> 2 years

Answer: A