Mesenchymal Stem Cell Injection in Crohn's Disease Strictures: a phase I-II clinical study.

Background and aim Mesenchymal stem cells (MSCs) have anti-inflammatory and anti-fibrotic properties and could be a potential therapy for Crohn's Disease (CD) strictures. In this phase I-II pilot trial, we assessed safety and efficacy of local MSC injection to treat CD strictures. Methods CD patients with a short (less than 5 cm in length) non-passable stricture accessible by ileocolonoscopy were included. Allogenic bone-marrow derived MSCs were injected in the 4 quadrants of the stricture. Adverse events and clinical scores were evaluated at each followup visit while endoscopy and magnetic resonance enterography were performed at baseline, week (W)12 and W48. The main judgement criterion for efficacy was the complete (defined by the ability to pass the ileocolonoscope) or partial (defined by a diameter increase) resolution of the stricture at W12. Second efficacy criteria included assessment of the stricture at W48 and evolution of clinical scores at W12 and W48. Results We performed 11 MSC injections in 10 CD patients (3 primary and 7 anastomotic strictures; 1 stricture injected twice). MSC injections were well tolerated but 4 hospitalizations for occlusion were reported. At W12, 5 patients presented a complete or partial resolution of the stricture (2 complete and 3 partial). Seven patients were re-evaluated at W48 (1 dilated, 1 operated, and 1 lost to follow-up) and 4 patients had a complete resolution. The evolution of clinical scores between W0, W12 and W48 was not statistically significant. Conclusion MSCs injection in CD stricture was well tolerated and may offer a benefit.