Endoscopic submucosal injection of adipose-derived mesenchymal stem cells ameliorates TNBS-induced colitis in rats and prevents stenosis

Background: Mesenchymal stem cells have potential applications in inflammatory bowel disease due to their immunomodulatory properties. Our aim was to evaluate the feasibility, safety and efficacy of endoscopic administration of adipose-derived mesenchymal stem cells (ASCs) in a colitis model in rats. Methods: Colitis was induced in rats by rectal trinitrobenzenesulfonic acid (TNBS). After 24 h ASCs (107 cells) or saline vehicle were endoscopically injected into the distal colon. Rats were followed for 11 days. Daily weight, endoscopic score at days 1 and 11, macroscopic appearance at necropsy, colon length and mRNA expression of Foxp3 and IL-10 in mesenteric lymph nodes (MLN) were analyzed. Results: Endoscopic injection was successful in all the animals. No significant adverse events or mortality due to the procedure occurred. Weight evolution was significantly better in the ASC group, recovering initial weight by day 11 (-0.8% +/- 10.1%, mean +/- SD), whereas the vehicle group remained in weight loss (-6.7% +/- 9.2%, p = 0.024). The endoscopic score improved in the ASC group by 47.1% +/- 5.3% vs. 21.8% +/- 6.6% in the vehicle group (p < 0.01). Stenosis was less frequent in the ASC group (4.8% vs. 41.2%, p < 0.01). Colon length significantly recovered in the ASC group versus the vehicle group (222.6 +/- 17.3 mm vs. 193.6 +/- 17.9 mm, p < 0.001). The endoscopic score significantly correlated with weight change, macroscopic necropsy score and colon length. Foxp3 and IL-10 mRNA levels in MLN recovered with ASC treatment. Conclusions: ASC submucosal endoscopic injection is feasible, safe and ameliorates TNBS-induced colitis in rats, especially stenosis.