The ADICROHN-3 study is a prospective, multicenter, open-label cohort study.

Its design is supported by the following elements:

• The results of the ADICROHN pilot study (EudraCT No. 2013-002602-31) and our 3-year study, which demonstrate an excellent safety profile with a promising efficacy signal.
• Data from the literature confirming that cryopreservation of FVS does not compromise the clonogenic and differentiation potential of mesenchymal progenitors, nor its regenerative effect.
• The ongoing ADICROHN-2 study (PHRC N 2019; EudraCT No. 2019-001948-21) confirming the feasibility of patient recruitment, mastery of the therapeutic approach, and the absence of adverse events related to the experimental treatment.
• The opportunity for a second FVS injection for patients initially treated but who did not respond to the treatment.
• The opportunity for a first FVS injection in patients in the placebo arm, thereby providing access to an innovative therapy available to patients included in this trial who are untreated and remain refractory to standard care.

To avoid compromising the results of the ongoing ADICROHN-2 study, enrolled patients will remain blinded to the treatment arm to which they belonged in the ADICROHN-2 study.

Inclusion Criteria:

• (1) Signing of a consent form.
• (2) Patients with Crohn's disease diagnosed at least 6 months prior, in accordance with clinical, endoscopic, histological, and/or radiological criteria.
• (3) Patients previously enrolled in or treated as part of the ADICROHN 2 study.
• (4) Non-active or mildly active luminal Crohn's disease, defined by a CDAI score ≤ 220.
• (5) Patients who failed to respond to the ADICROHN-2 protocol, defined by the persistence of anoperineal fistula(s) at the end of the ADICROHN-2 study and their persistence at the time of enrollment.
• (6) Patients who achieved success (combined remission) at the end of the ADICROHN-2 study but who have a recurrence of anoperineal fistula(s) at the time of enrollment.
• (7) Sufficient quantity of cryopreserved cells to allow for the innovative treatment, based on the number of fistulas to be treated.
• (8) Patients over 18 years of age.
• (9) Good general health based on medical history and clinical examination.
• (10) Women of childbearing age must have a negative pregnancy test (serum or urine; detection threshold: 25 mIU hCG/ml). Patients of both sexes must use a reliable method of contraception.
• (11) Enrollment in a social security program.

Exclusion Criteria:

• (1) Active, primarily luminal Crohn's disease requiring immediate treatment.
• (2) Patients who experienced intolerance to the advanced therapy medicinal product during the ADICROHN-2 study.
• (3) Presence of an abscess or collections > 2 cm at the time of enrollment, unless this issue is resolved during the fistula preparation period.
• (4) Rectal and/or anal stenosis and/or active proctitis resulting in a limitation of the surgical procedure.
• (5) Patients currently receiving corticosteroids or who have received them within the four weeks prior to the injection of the investigational product.
• (6) Malignant tumors or a history of malignant tumors within the past 5 years.
• (7) Congenital or acquired immunodeficiency.
• (8) Contraindications to local anesthetics and gadolinium (MRI contrast agent).
• (9) Contraindications to MRI: metallic foreign bodies (ferromagnetic material) and metallic implants (pacemakers, heart valves, vascular clips, surgical clips or staples, cochlear implants, any implanted electronic medical device or material [e.g., insulin pump], orthopedic medical prostheses.
• (10) Treatment with darvadstrocel administered < 6 months prior to enrollment)
• (11) Contraindications to general anesthesia.
• (12) BMI < 18 kg/m² to ensure an adequate amount of abdominal adipose tissue or other subcutaneous adipose tissue accessible via manual liposuction.
• (13) Coagulation disorders that contraindicate surgery.
• (14) Known hypersensitivity to human albumin.
• (15) Participation in another clinical trial (excluding observational studies).
• (16) Persons protected under Articles L1121-5, L1121-6, and L1121-8 of the Public Health Code (pregnant or breastfeeding women, persons deprived of liberty by judicial decision, persons in situations of social vulnerability, adults who are legally incapacitated or unable to give informed consent).