Inclusion Criteria:

• Signed informed consent.
• Patients of either gender ≥ 18 years and ≤ 75 years of age.
• Patients with Crohn's Disease (CD) diagnosed at least 6 months prior to Screening visit in accordance with accepted clinical, endoscopic, histological and/or radiological criteria.
• Presence of complex perianal fistula(s) with a maximum of 2 internal openings and a maximum of 3 external openings.
• Clinically controlled, non active or mildly active CD, during the last six months prior to Screening visit.
• Patients whose perianal fistulas were previously treated and have shown an inadequate response or a loss of response while they were receiving either an immunosuppressive agent or TNF-α antagonist or vedolizumab or ustekinumab, or having documented intolerance.
• Women of childbearing potential (WCBP) must have negative serum pregnancy test at screening (sensitive to 25 IU human chorionic gonadotropin [hCG]). Both WCBP or male patients participating in this study, with a WCBP as partner, must agree to use an adequate method of contraception during the entire duration of the study.

Exclusion Criteria:

• Concomitant rectovaginal or rectovesical fistula(s).
• Patient naïve to prior specific medical treatment for complex perianal fistula(s) including IS or anti-TNFs.
• Presence of a perianal collection > 2 cm in at least two dimensions on the central reading MRI at Screening visit that was not adequately drained as confirmed by the surgeon.
• Severe rectal and/or anal stenosis and/or severe proctitis (defined as the presence of large [> 0.5 cm diameter] ulcers in the rectum) that make impossible to follow the surgery procedure manual.
• Patient with diverting stomas.
• Active, uncontrolled infection requiring parenteral antibiotics.
• Patient with ongoing systemic or rectal steroids for CD in the last 2 weeks prior to the Preparation visit.
• Patients with major alteration on any of the following laboratory tests or increased risk for the surgical procedure:
  • Serum creatinine levels > 1.5 times the ULN;
  • Total bilirubin > 1.5 ULN;
  • AST/ALT > 3 times ULN;
  • Hemoglobin < 10.0 g/dL;
  • Platelets < 75.0 x10^9/L;
  • Albuminemia < 3.0 g/dL.
• Suspected or documented infectious enterocolitis within two weeks prior to Screening visit.
• Any prior invasive malignancy diagnosed within the last 5 years prior to Screening visit. Patients with basal-cell carcinoma of the skin completely resected outside the perineal region can be included.
• Current or recent (within 6 months prior to the Screening visit) history of severe, progressive, and/or uncontrolled hepatic, haematological, gastrointestinal (other than CD), renal, endocrine, pulmonary, cardiac, neurological or psychiatric disease that may result in patients increased risk from study participation and/or lack of compliance with study procedures.
• Patients with primary sclerosing cholangitis.
• Patients with known chronically active hepatopathy of any origin, including cirrhosis and patients with persistent positive HBV surface antigen (HBsAg) and quantitative HBV polymerase chain reaction (PCR), or positive serology for HCV and quantitative HCV PCR within 6 months prior to Screening.
• Congenital or acquired immunodeficiencies, including patients known to be HIV carriers.
• Known allergies or hypersensitivity to penicillin or aminoglycosides; DMEM (Dulbecco Modified Eagle's Medium); bovin serum; local anaesthetics or gadolinium (MRI contrast).
• Contraindication to MRI scan (e.g., due to the presence of pacemakers, hip replacements or severe claustrophobia).
• Severe trauma within 6 months prior to Screening visit.
• Pregnant or breastfeeding women.
• Patients who do not wish to or cannot comply with study procedures.
• Patients currently receiving, or having received any investigational drug within 3 months prior to Screening visit.
• Patients previously treated with Cx601 or other allogeneic stem-cell therapy cannot be enrolled into this clinical study.
• Any major surgery of the GI tract (including one or more segments of the colon or terminal ileum) within 6 months prior the screening or any minor surgery of the GI tract within 3 months prior to screening.
• Patients who had local perianal surgery other than drainage for the fistula within 6 months prior to the Screening visit, or those who may need surgery in the perianal region for reasons other than fistulas at the time of inclusion in the study.
• Contraindication to the anaesthetic procedure.