Long-Term Follow-Up of Crohn Disease Fistulas After Local Injections of Bone Marrow-Derived Mesenchymal Stem Cells.

Objective: To assess the long-term outcome of patients treated with serial intrafistular injections of autologous bone marrow-derived mesenchymal stem cells (MSCs) for refractory Crohn fistulas in terms of safety and efficacy.

Patients And Methods: Starting from January 10, 2007, through June 30, 2014, clinical evaluation, calculation of the Crohn disease activity index (CDAI), therapeutic management, and documentation of adverse events in 8 of the 10 patients (5 men; median age, 37 years) who had been injected locally with MSCs were prospectively recorded for 72 months. Cumulative probabilities of fistula recurrence and medical or surgical treatment were estimated using a Kaplan-Meier method, whereas differences among the pre- and post-MSC CDAI values were calculated with the Mann-Whitney U test.

Results: Following disease remission observed after 12 months from MSC treatment (P<.001), the mean CDAI score increased significantly during the subsequent 2 years (P=.007), and was then followed by a gradual decrease, with the patients achieving remission again (P=.02) at the end of the 5-year follow-up. The probability of fistula relapse-free survival was 88% at 1 year, 50% at 2 years, and 37% during the following 4 years, and the cumulative probabilities of surgery- and medical-free survival were 100% and 88% at 1 year, 75% and 25% at 2, 3, and 4 years, and 63% and 25% at 5 and 6 years, respectively. No adverse events were recorded.

Conclusion: Locally injected MSCs constitute a safe therapy that rescues refractory patients and regains responsiveness to drugs previously proved ineffective.