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.