Regulation of the Th17/Treg balance by human umbilical cord mesenchymal stem cell-derived exosomes protects against acute experimental colitis

Increasing evidence suggests that mesenchymal stem cells (MSCs) have immunosuppressive properties mediated by MSC-derived small extracellular vesicles (sEV). Exosomes are small extracellular vesicles that contain components that regulate immune cell function. We investigated the immunomodulatory effects of MSC-derived Exosome (MSC-Exo) on the severity of colitis using the dextran sulfate sodium (DSS)-induced colitis model. Exosomes were administrated intraperitoneally. Daily changes in body weight, stool consistency, and bleeding were assessed to determine the impact of MSC-Exos on colitis. Several measurements were taken, including the colon weight, length, and histological analysis of the colon tissues. The percentage of regulatory T cells and IL-10, TGF-β, IL-17, TNF-α, and IFN-γ levels were calculated in the mesenteric lymph node (MLN) and spleen. The results showed MSC-Exos improved clinical manifestations of colitis. Colon macroscopic and histological observations also showed improvement in tissue destruction. The results illustrated that MSC-Exos might attenuate colitis by regulating Treg/Th17 balance, increasing anti-inflammatory, and decreasing pro-inflammatory cytokines expression. As a result, MSC-Exos could be used as an immunomodulatory approach to treating bowel inflammation.