The Anti-Inflammatory Effects of Adipose Tissue Mesenchymal Stem Cell Exosomes in a Mouse Model of Inflammatory Bowel Disease.

Inflammatory bowel disease (IBD) is a group of chronic, relapsing inflammatory disorders that affect the gastrointestinal tract, with the primary subtypes being ulcerative colitis (UC) and Crohn's disease (CD). We aimed to evaluate the therapeutic potential of extracellular vesicles released by adipose-tissue-derived mesenchymal stem cells, which we, in this manuscript, call "exosomes" (ASC-EXOs), in a mouse model of IBD. We specifically aimed to determine the effectiveness of different treatment protocols and compare the effects with that of anti-IL-12 p40 monoclonal antibody. The addition of dextran sulfate sodium (DSS) to drinking water induced multiple signs of IBD, including weight loss, soft stool, and bloody feces. ASC-EXOs given by either intraperitoneal (IP) or intravenous (IV) routes resulted in moderate improvement in these signs of IBD. IV ASC-EXOs resulted in significantly reduced body weight loss, improved histopathological scoring, and suppressed the disease activity index (DAI) compared to the IBD control group. Also, a reduction in PCR for pro-inflammatory cytokines was observed. IV ASC treatment resulted in dose-related reduction in IBD signs, including weight loss. An increasing number of injections with ASC-EXOs reduced histopathological scores as well as DAI. Co-administration of ASC-EXOs with anti-IL-12 p40 significantly decreased DAI scores in the ASC-EXO + anti-IL-12 p40 group. In conclusion, ASC-EXOs have potential as a therapeutic agent for IBD, but the route of administration, number of injections, and dosage need to be considered to optimize the effects of ASC-EXO treatment. This study also highlights the potential benefits of combination therapies of ASC-EXOs and anti-IL-12. Our findings pave the way for further studies to unravel the underlying therapeutic mechanisms of ASC-EXOs in IBD treatment.