Safety and Tolerability Of Allogeneic Mesenchymal Stromal Cells in Pediatric Inflammatory Bowel Disease

Inclusion Criteria: * For the young adult cohort, patients must be ages 17 ≤22 years * For the pediatric cohort, patients must be ages 12 ≤16 years * Patients must have moderate-severely active CD or UC (defined in section 2.3), and documented active disease on flexible sigmoidoscopy, colonoscopy or MR enterography within the preceding 2 months. * Patients who have failed or are intolerant of biologic therapy. Specifically, the patient will have recurrence or persistence of active disease despite current or past treatment with a biologic. At the time of enrollment, study subjects may be currently receiving 5-aminosalicylates, corticosteroids (≤ 20 mg daily or up to 0.5 mg/kg/day if weight \<40 kg), methotrexate, 6MP/azathioprine, or a biologic (either as monotherapy or in combination). During the treatment phase, if the treating physician thinks that a medication dose should be lowered to avoid side effects, this should be recorded. * Patient or parent/guardian capable of providing informed consent. Exclusion Criteria: * • Patients \< 12 years of age or \>22 years of age * Pregnant or breastfeeding. Serum pregnancy test must be negative at screening for female subjects of childbearing potential. Urine pregnancy test must remain negative at each of 4 infusion visits. * Patients with toxic mega-colon or intestinal perforation * Evidence of autoimmune chronic active hepatitis or sclerosing cholangitis. * Patients with fever \> 39° C or clinically significant active infection within 1 week (i.e. chronic infections including Hepatitis B/C or HIV or acute infections, including urinary tract infection and respiratory tract infection) * Received an agent not approved by the FDA for marketed use in any indication or any small molecule inhibitors (i.e. naltrexone) within 60 days of enrollment. * Subjects who are taking greater than 20 mg (or if body weight \<40 kg, 0.5 mg/kg) of prednisone daily. * Clinically significant abnormal biochemical and hematological parameters, including: * Neutrophil count \< 1000 cells/mm3 * Hemoglobin \< 8 g/dl * Platelet count ≤ 130 cells/mm3 * Creatinine ≥ 1.2 x the upper limit of normal * Alanine aminotransferase (ALT) and/or aspartate aminotransferase (AST) ≥ 2x the upper limit of normal * Conjugated bilirubin greater than 1.2. mg/dL * Has active infection with enteric pathogens as evidenced by positive microbiological culture of stool or C.difficile toxin PCR. * Had bowel surgery other than perianal procedures (fistulotomy, seton placement, abscess drainage) within 3 months of enrollment. * Has uveitis * Has known pulmonary disease, excluding mild intermittent asthma