Perianal fistulas are in the forefront (42 to 72, 4%) of morbid complication of Crohn's disease, affecting nearly one- third of patients and complicating abscesses in 35-48% of cases. The current treatment is based on the combination of drainage (proctologic and surgical), and biologics techniques, but the failure rate varies from 30 to 80%. Actually, innovative cell therapy procedures are validated by Cell-Easy with the use of allogenic mesenchymal stem cells for the immunomodulatory, anti-inflammatory, angiogenic and trophic properties (CellReady®) and represent a promising option in the treatment of perianal fistulas associated with Crohn's disease. This phase I/II study is designed to evaluate the treatment of complex perianal fistulas associated with Crohn's disease, after failure of conventional treatment by injection of allogeneic cultured adipose-derived stromal cell (AdMSC) into the fistula.

The injection of adipose stromal cells is currently evaluated in clinical studies for repair-damaged tissues in various diseases (limb ischemia, osteoarthritis, systemic slerosis...). Immunoregulatory and anti-inflammatory properties of AdMSC's are responsible for accelerating healing and represents an innovative approach to treat perianal fistulas associated with Crohn's disease.

This phase I/II study is designed to evaluate the treatment of complex perianal fistulas associated with Crohn's disease, after failure of conventional treatment by injection of AdMSC (CellReady®) into the fistula.

Different doses of AdMSC will be tested for a dose escalation (5.10*7 and 10.10*7 cells) and injected in the in the wall of the fistula.

Inclusion Criteria:

• Patients over 18 years old,
• Patients who signed the informed consent,
• Patient affiliated to a social security system,
• Controlled luminal Crohn's disease characterized by an Harvey-Bradshaw score less or equal than 8 and diagnosed on clinical, endoscopic, histological and/or radiological criteria for more than 3 months,
• Colonoscopy less than a year old without ulcer in the rectum,
• Presence of complex chronic perianal fistula with a maximum of two internal ports and three external ports,
• Patient treated with a combined treatment (drainage on setons + anti-TNFα) and who failed conventional treatment after 6 months and whose intraluminal disease (intestinal damage) is controlled

Exclusion Criteria:

• Refusal of the patient to participate in the study,
• Positive QuantiFERON test,
• Patient with transplanted organ,
• History of cancer in the last five years or lympho-proliferative disease,
• Persistent bacterial or viral infection,
• Patient with a contraindication to MRI,
• Known allergy to Gadolinium,
• Known allergy to Albumine,
• End-stage organ failure,
• Pregnant or breastfeeding women,
• Women of childbearing age without effective contraception throughout the duration of the study,
• Patient under judicial protection, under guardianship or curatorship.
• Patient previously treated with ALOFISEL®