The aims of our study are to evaluate the feasibility and safety of endoscopic injection of adipose tissue-derived mesenchymal stem cells in human subjects with moderate active ulcerative colitis, assessing the absence of adverse events associated to the investigational drug, and to evaluate the efficacy of the treatment to induce remission of moderate active ulcerative colitis, by improvements in disease activity index, quality of life index, and endoscopic index.

Mesenchymal stem cells (MSC) may be a therapeutic option in diseases associated with severe inflammation or auto-immune diseases, due to their immunomodulatory and anti-inflammatory properties. A number of clinical trials are being conducted worldwide testing th efficacy of MSC, mainly isolated from bone marrow, for different conditions, such as Graft Versus host Disease, refractory Crohn's Disease, ischemic stroke, acute myocardial infarction, type I Diabetes Mellitus, or Chronic Obstructive Pulmonary Disease. Usually, the route of administration of the cells in these studies is intravenous. Local injection of MSC for fistulizing Crohn's Disease has proven efficacious. Endoscopy is a routinary technique for the evaluation of gastrointestinal and colonic conditions. The purpose of our study is to evaluate safety and efficacy of the intracolonic injection by using a colonoscope of allogeneic adipose tissue-derived MSC in patients with moderate active ulcerative colitis.

Inclusion Criteria:

• Patients of either sex aged 18 years and older
• Signed informed consent
• Patients with ulcerative colitis diagnosed at least 6 months earlier in accordance with usual criteria
• Left-sided colitis with moderate activity defined by a modified Truelove-Witts score between 11 and 21, and with no response to 4 weeks of treatment with oral and/or topical 5-aminosalicylates
• Negative pregnancy test for women of childbearing potential (from menarche to menopause) using consistently and correctly highly effective (i.e. less than 1% failure rate per year) methods of birth control

Exclusion Criteria:

• Mental disability that impedes adequate understanding of the study and of the associated procedures
• Extensive colitis
• Patients with an impaired general state which requires, according to the investigator judgment, immediate treatment with corticosteroids and/or anti-Tumor Necrosis Factor (TNF) and/or surgery
• Patients that fulfill criteria of corticodependency and in ongoing treatment with corticosteroids
• Patients with previous colectomies
• Known history of alcohol or other addictive substances abuse
• History of malignant disease - Patients having participated in clinical trials with any investigational drug within 6 months prior to enrolment in this study
• Patients with known allergies to penicillin, gentamicin, aminoglycosides, human serum albumin (HSA), Dulbecco's modified Eagle medium (DMEM), or materials of bovine origin
• Pregnant or breastfeeding women
• Presence of severe concomitant diseases
• Patients with suspicion of Crohn?s enterocolitis, indeterminate colitis, ischaemic colitis, radiation colitis, diverticular disease associated colitis, or microscopic colitis