Predictive Factors of Autologous Bone Marrow-Derived Mesenchymal Stem Cell Therapy's Success in the Treatment of Perianal Fistulas in Patients With Crohn's Disease.

Introduction Crohn's disease (CD)-associated perianal fistulas are a challenging and debilitating complication, often resistant to standard medical and surgical treatments. Mesenchymal stem cell (MSC) therapy, particularly using adipose- or bone marrow-derived MSCs (AMSCs/BM-MSCs), offers a promising regenerative approach, yet data on autologous BM-MSCs remain limited. Objective This pilot study aimed to evaluate the safety and efficacy of autologous BM-MSCs in treating perianal fistulas in CD patients, and to identify potential predictive factors influencing treatment outcomes. Methods A single-center, prospective, single-blind randomized study was conducted over six months at Mohammed VI University Hospital in Marrakech, Morocco. Twenty CD patients with complex perianal fistulas unresponsive to conventional therapy were enrolled, of whom eight completed the 24-week follow-up. Patients were randomized into two groups: local BM-MSC administration only (CroMaPCs) and combined local plus intravenous administration (CroMaPCs+). Outcomes were assessed clinically and radiologically at Weeks 2, 6, and 24. Results At 24 weeks, complete fistula healing was observed in three patients (37.5%), with higher response and healing rates in the CroMaPCs+ group (50%) compared to the CroMaPCs group (25%). No treatment-related adverse events were reported. Factors such as age, immunosuppressive therapy, and combined BM-MSC intravenous administration may have influenced outcomes, although the small sample size limits definitive conclusions. Conclusion Autologous BM-MSC therapy appears safe and potentially effective in managing refractory perianal fistulas in CD. Combined local and systemic administration may enhance healing. Larger, controlled trials are needed to validate these findings and refine patient selection and treatment protocols.