Dave, ManeeshManeeshDaveDev, AtulAtulDevSomoza, Rodrigo ARodrigo ASomozaZhao, NanNanZhaoViswanath, SatishSatishViswanathMina, Pooja RaniPooja RaniMinaChirra, PrathyushPrathyushChirraObmann, Verena CarolaVerena CarolaObmannMahabeleshwar, Ganapati HGanapati HMahabeleshwarMenghini, PaolaPaolaMenghiniJohnson, Blythe DurbinBlythe DurbinJohnsonNolta, JanJanNoltaSoto, ChristopherChristopherSotoOsme, AbdullahAbdullahOsmeKhuat, Lam TLam TKhuatMurphy, WilliamWilliamMurphyCaplan, Arnold IArnold ICaplanCominelli, FabioFabioCominelli2024-10-252024-10-252023-05-24https://boris-portal.unibe.ch/handle/20.500.12422/172120OBJECTIVE Mesenchymal stem cells (MSCs) are novel therapeutics for treatment of Crohn's disease. However, their mechanism of action is unclear, especially in disease-relevant chronic models of inflammation. Thus, we used SAMP-1/YitFc, a chronic and spontaneous murine model of small intestinal inflammation, to study the therapeutic effect and mechanism of human bone marrow-derived MSCs (hMSC). DESIGN hMSC immunosuppressive potential was evaluated through in vitro mixed lymphocyte reaction, ELISA, macrophage co-culture, and RT-qPCR. Therapeutic efficacy and mechanism in SAMP were studied by stereomicroscopy, histopathology, MRI radiomics, flow cytometry, RT-qPCR, small animal imaging, and single-cell RNA sequencing (Sc-RNAseq). RESULTS hMSC dose-dependently inhibited naïve T lymphocyte proliferation in MLR via PGE 2 secretion and reprogrammed macrophages to an anti-inflammatory phenotype. hMSC promoted mucosal healing and immunologic response early after administration in SAMP model of chronic small intestinal inflammation when live hMSCs are present (until day 9) and resulted in complete response characterized by mucosal, histological, immunologic, and radiological healing by day 28 when no live hMSCs are present. hMSC mediate their effect via modulation of T cells and macrophages in the mesentery and mesenteric lymph nodes (mLN). Sc-RNAseq confirmed the anti-inflammatory phenotype of macrophages and identified macrophage efferocytosis of apoptotic hMSCs as a mechanism of action that explains their long-term efficacy. CONCLUSION hMSCs result in healing and tissue regeneration in a chronic model of small intestinal inflammation. Despite being short-lived, exert long-term effects via macrophage reprogramming to an anti-inflammatory phenotype. DATA TRANSPARENCY STATEMENT Single-cell RNA transcriptome datasets are deposited in an online open access repository 'Figshare' (DOI: https://doi.org/10.6084/m9.figshare.21453936.v1 ).en600 - Technology::610 - Medicine & healthworking_paper10.48350/1899633729275310.1101/2023.05.22.541829