Abstract
Crohn's disease (CD) is a chronic inflammatory disease of the gastrointestinal intestinal tract and has characteristic hypertrophic adipose changes observed in the mesentery. To better understand the role of the mesentery in the pathophysiology of Crohn's disease (CD), we evaluated the immunomodulatory potential of mesenchymal stem cells (MSCs) and their secreted extracellular vesicles (EVs) derived from Crohn's patients. MSCs and EVs were isolated from the mesentery and subcutaneous tissues of CD patients and healthy individuals subcutaneous tissues, and were analysed for differentiation, cytokine expression, self-renewal and proliferation. The varying capacity of these tissue-derived MSCs and EVs to attenuate T-cell activation was measured in in vitro and an in vivo murine model. RNA sequencing of inflamed Crohn's disease mesentery tissue revealed an enrichment of T-cell activation compared to non-inflamed subcutaneous tissue. MSCs and MSC-derived EVs isolated from Crohn's mesentery lose their ability to attenuate DSS-induced colitis compared to subcutaneous tissue-derived cell or EV therapy. We found that treatment with subcutaneous isolated MSCs and their EV product compared to Crohn's mesentery MSCs or EVs, the inhibition of T-cell proliferation and IFN-γ, IL-17a production increased, suggesting a non-inflamed microenvironment allows for T-cell inhibition by MSCs/EVs. Our results demonstrate that Crohn's patient-derived diseased mesentery tissue MSCs lose their immunosuppressive capacity in the treatment of colitis by distinct regulation of pathogenic T-cell responses and/or T-cell infiltration into the colon.