Efficacy of Mesenchymal Stromal Cells for Fistula Treatment of Crohn's Disease: A Systematic Review and Meta-Analysis

The introduction of mesenchymal stromal cells (MSCs) has changed the management of Crohn's fistula, while it remains controversial. The aim of this study was to provide an overview of efficacy and optimum state of MSCs treatment on Crohn's fistula. Studies reporting MSCs treatment on Crohn's fistula were searched and included. A fixed-effects model was used to assess the efficacy of MSCs, and outcomes of healing and recurrence were used to evaluate the best states of MSCs intervention. Fourteen articles were enrolled (n = 477). Pooled analysis showed MSCs had a significant efficacy compared to other treatments [risk difference: 0.21 (0.09, 0.32), P = 0.000]. Notably, after MSCs treatment, the group of Crohn's disease activity index (CDAI) baseline > 150 group had a higher healing rate (HR) and a clinical response (a change in CDAI of > 50 points) (79.17 +/- 8.78 vs. 47.54 +/- 15.90, P = 0.011) compared to CDAI baseline of < 150. The duration time of CD and fistulas had a negative correlation with HR accompanied by MSC therapy (r = -0.900, -0.925). Then, a moderate dose MSCs (2-4 x 10(7) cells/ml) had a higher HR (80.07%) and lower recurrence rate (RR 13.98%) compared to other dosages. Moreover, adipose-derived MSCs therapy had an advantage over bone marrow-derived MSCs in terms of low RR (7.4 +/- 4.28 vs. 13.39 +/- 0.89). The evidence supported the effect of MSCs at a more appropriate time of Crohn's fistula. And CDAI baseline (the points > 150) has been a candidate for evaluating effectiveness of MSCs application on Crohn's fistula.