Efficacy and safety of stem cell therapy for fistula management: An overview of existing systematic reviews

Background: Fistulas, abnormal connections between two anatomical structures, significantly impact the quality of life and can result from a variety of causes, including congenital defects, inflammatory conditions, and surgical complications. Stem cell therapy has emerged as a promising alternative due to its potential for regenerative and immunomodulatory effects. This overview of systematic reviews aimed to assess the safety and efficacy of stem cell therapy in managing fistulas, drawing on the evidence available. Methods: This umbrella review was conducted following the Joanna Briggs Institute (JBI) methodology to assess the efficacy and safety of stem cell therapy for treating various types of fistulas. A comprehensive search was performed across multiple electronic databases including PubMed, Embase, Cochrane Register, and Web of Science up to May 5th, 2024. Systematic reviews focusing on stem cell therapy for fistulas were included, with data extracted on study design, stem cell types, administration methods, and outcomes. The quality of the reviews was assessed using the AMSTAR 2 tool, and meta-analyses were conducted using R software version 4.3. Results: Nineteen systematic reviews were included in our umbrella review. The stem cell therapy demonstrated by significant improvements in clinical remission rates, with a relative risk (RR) of 1.299 (95% CI: 1.192 to 1.420). Stem cell therapy enhanced fistula closure rates, both short-term (RR=1.481; 95% CI: 1.036 to 2.116) and long-term (RR=1.422; 95% CI: 1.091 to 1.854). The safety analysis revealed no significant increase in the risk of adverse events with stem cell therapy, showing a pooled RR of 0.972 (95% CI: 0.739 to 1.278) for general adverse events and 1.136 (95% CI: 0.821 to 1.572) for serious adverse events, both of which indicate a safety profile comparable to control treatments. Re-epithelialization rates also improved (RR=1.44; 95% CI: 1.322 to 1.572). Conclusion: Stem cell therapy shows promise as an effective and safe treatment for fistulas, particularly in inducing remission and promoting closure of complex fistulas. The findings advocate for further high-quality research to confirm these benefits and potentially incorporate stem cell therapy into standard clinical practice for fistula management. Future studies should focus on long-term outcomes and refining stem cell treatment protocols to optimize therapeutic efficacy.