A phase IB/IIA study of ex vivo expanded allogeneic bone marrow-derived mesenchymal stem cells for the treatment of rectovaginal fistulizing Crohn's disease.

BACKGROUND: Crohn-related rectovaginal fistulas are notoriously difficult to treat. Studies of mesenchymal stem cells for the treatment of perianal Crohn fistulizing disease have largely excluded rectovaginal fistulas. The aim of this study was to determine the safety and efficacy of mesenchymal stem cells for refractory rectovaginal fistulizing Crohn disease. METHODS: A phase IB/IIA randomized control trial was performed in a 3:1, single-blinded study. Patients included were adult women with an anovaginal/rectovaginal fistula in the setting of Crohn disease. Seventy-five million mesenchymal stem cells were administered with a 22G needle after curettage and primary closure of the fistula tract at day 0 and month 3. Adverse and serious adverse events were recorded at post-procedure day 1, week 2, week 6, month 3, month 6, and month 12, along with clinical healing, magnetic resonance imaging, and patient-reported outcomes. RESULTS: A total of 19 patients were enrolled and treated-15 treatment and 4 control. There were no adverse or serious adverse events related to mesenchymal stem cell therapy. At 6 months, 50% of the treatment group and 0% of the control had complete clinical and radiographic healing; 91.7% of the treatment group had improvement at 6 months with only one patient having a lack of response, whereas only 50% of the control group had improvement at 6 months. CONCLUSION: Bone marrow-derived mesenchymal stem cells offer a safe alternative treatment approach for rectovaginal fistulas in the setting of Crohn disease. Complete healing was achieved in half of the patients.

A Phase I Study of Ex Vivo Expanded Allogeneic Bone Marrow-Derived Mesenchymal Stem Cells for the Treatment of Pediatric Perianal Fistulizing Crohn's Disease.

BACKGROUND: Perianal fistulizing Crohn's disease is notoriously difficult to treat. Recent studies of mesenchymal stem cells have demonstrated safety and efficacy of this novel treatment approach. However, no studies to date have included pediatric patients. We sought to determine safety and efficacy of mesenchymal stem cells for pediatric perianal fistulizing Crohn's disease. METHODS: This was a phase I clinical trial to evaluate safety and feasibility of mesenchymal stem cells in pediatric perianal Crohn's patients 13 to 17 years of age. At the time of an exam under anesthesia, following curettage of the fistula tract and closure of the internal opening with absorbable suture, 75 million mesenchymal stem cells were administered with a 22-gauge needle. This was repeated at 3 months if complete clinical and radiographic healing were not achieved. Adverse and serious adverse events at were measured at postprocedure day 1, week 2, week 6, month 3, month 6, and month 12. Clinical healing, radiographic healing per magnetic resonance imaging, and patient-reported outcomes were measured at the same time points. RESULTS: Seven pediatric patients were enrolled and treated (6 male; median age of 16.7 years). There were no adverse or serious adverse events related to the investigational product or injection procedure. At 6 months, 83% had complete clinical and radiographic healing. The perianal Crohn's Disease Activity Index, Wexner incontinence score, and Van Assche score had all decreased at 6 months. CONCLUSIONS: Bone marrow-derived mesenchymal stem cells offer a safe, and likely effective, treatment approach for pediatric perianal fistulizing Crohn's disease.