Phase I-II, Multicenter, Randomized, Controlled, Proof of Concept Clinical Trial to determine feasibility, safety and efficacy of the use of Allogenic adipose-derived adult mesenchymal stem cells expanded on fibrinhyaluronic biological matrix in the treatment of venous ulcer of the lower limbs.

Inclusion Criteria:

1. Signing of the informed consent (IC) after reading the patient information sheet.
2. Over 18 years of both sexes.
3. Active or recurrent venous ulcer in the lower extremity with an area between 5-10 cm2
4. Grade III injury on the Widmer scale.
5. Independence and/or availability to go to the referral center on an outpatient basis.
6. Distal pulses in palpable lower limbs (tibial and foot). ABI between 0.8 - 1.3

Exclusion Criteria:

1. Any pathology for which the investigator considers that compression bandaging is contraindicated and/or previous acute deep vein thrombosis (DVT), within the first 10 days from the onset of symptoms.
2. Grade III obesity with a body mass index (BMI) >40; or underweight patients (BMI <18.5).
3. Active neoplasia and/or being treated with cytostatics.
4. Patients undergoing radiotherapy treatment in areas close to the lesion.
5. Clinical signs of colonization or local infection of the lesion.
6. Patients with more than one lesion compatible with UV in the same lower limb.
7. Erysipelas.
8. Infectious cellulite.
9. Osteomyelitis.
10. Lymphangitis.
11. Chronic lymphedema.
12. Therapy with corticosteroids or immunosuppressants.
13. Venous ulcer grade I or II on the Widmer scale.
14. Lesions close to possible or diagnosed cancerous lesions.
15. Non-localized wounds in the lower extremities.
16. Ongoing infection and/or sepsis.
17. Critical ischemia in the lower limbs or other venous diseases of unknown origin.
18. Immunocompromised patients.
19. Dependent patients with severe mobility limitations.
20. Dialysis patients.