Mesenchymal Stem Cells (MSCs) for Perianal Fistula

Inclusion Criteria: * Men and Women 18-75 years of age with a diagnosis of unhealing perianal fistulas in the setting of Crohn's disease and must be on maximal standard of care therapy (e.g., antibiotics, 5-ASA, and immunomodulator, anti-TNF, anti-integrin, and anti-interleukin therapies) for at least six months duration. * Presence of perianal fistula with maximum of two internal fistula tracts and a maximum of three external openings based on clinical assessment and MRI. Fistula must have been draining for at least 6 weeks prior to the screening visit. * Medically refractory perianal fistulizing Crohn's disease (i.e., standard of care such as antibiotics, immunosuppressives) * Have no contraindications to MR evaluations: e.g., pacemaker or magnetically active metal fragments, claustrophobia * Ability to comply with protocol * Competent and able to provide written informed consent * Concurrent Crohn's-related therapies with stable doses corticosteroids, 5- ASA drugs, immunomodulators, anti-TNF therapy, anti-integrin and anti-interleukin therapies are permitted. * A female participant and of childbearing potential must have a negative serum or urine pregnancy test at time of screening, and must not plan to become pregnant during the study. Exclusion Criteria: * Inability to give informed consent. * Clinically significant medical conditions within the six months before administration of MSCs: e.g. myocardial infarction, active angina, congestive heart failure or other conditions that would, in the opinion of the investigators, compromise the safety of the patient. * Specific exclusions: Hepatitis B or C, HIV, Abnormal AST or ALT at screening * History of cancer including melanoma (with the exception of localized skin cancers) in the past five years * Received treatment with an investigational drug or device within 60 days of randomization or have not completed 5 half-life washout (whichever is later) for drugs or biologics. If the half-life of the product is not known, then subjects cannot be randomized within 6 months of investigation drug treatment. * Participated in a cell therapy-based trial within 6 months before randomization * Participated in Crohn's/ulcerative colitis or any fistulizing Crohn's study within 6 months before randomization * Pregnant or breast feeding or trying to become pregnant. * Presence of a rectovaginal or perineal body fistula * Change in Crohn's immunosuppressive regimen prior to enrollment. Subjects should be on stable, maximal medical therapy for 4 months prior to enrollment. * Uncontrolled intestinal Crohn's disease which will require escalation for medical therapy or surgery within 3 months of enrollment * Severe anal canal disease that is stenotic and requires dilation or severe proctitis making difficult to the surgery * A female or male participant unwilling to agree to use acceptable contraception methods during participation in study. Acceptable contraception methods include: Implants, injectables, combined oral contraceptives, an intrauterine device, a bilateral tubal ligation, a vasectomy, a vasectomized partner for female participant, double-barrier methods, and physical barrier if male participant is not vasectomized * Associated perianal abscess(es). * Laboratory exclusions: Serum creatinine levels \>1.5 times the upper limit of normal (ULN). Total bilirubin \>1.5 × ULN. Aspartate aminotransferase (AST) or alanine aminotransferase (ALT) \>5.0 × ULN. Hemoglobin \<10.0 g/dL for females or \<11.0 g/dL for males. Platelets \<75.0 × 109/L. * Any contraindications to MRI or surgical or anesthetic procedure(s) * Any major GI surgery or major perianal local surgery within 6 months of randomization