Anti-Inflammatory Role of Mesenchymal Stromal Cell-Derived Extracellular Vesicles in Primary Sclerosing Cholangitis

Abstract

Primary Sclerosing Cholangitis (PSC) is a chronic cholestatic liver disease characterised by progressive bile duct inflammation, fibrotic remodelling, and eventual liver failure. Its aetiology remains incompletely defined but is thought to arise from a convergence of abnormal immune responses, genetic predisposition, and microbial influences. Clinically, PSC is strongly associated with inflammatory bowel disease and carries a markedly increased risk of cholangiocarcinoma. The disease often develops insidiously and may remain asymptomatic for years, delaying diagnosis until advanced stages. Therapeutic options remain inadequate: ursodeoxycholic acid (UDCA) can improve biochemical parameters but fails to halt disease progression, and liver transplantation although curative, is complicated by frequent recurrence in the graft. As a result, long-term outcomes remain poor, underscoring the urgent need for new strategies that can directly modify PSC disease activity.

Against this background, Mesenchymal Stromal Cell-Derived Extracellular Vesicles (MSC-EVs) have emerged as promising candidates for cell-free therapy, offering stability, nanoscale size, and the capacity to deliver bioactive molecules with immunomodulatory and regenerative functions. Their potential as anti-inflammatory agents is recognised, yet their mechanisms of action on hepatic endothelium remain poorly defined. The central aim of this thesis was therefore to investigate the anti-inflammatory effects of umbilical cord derived MSC-EVs (Orbsen Therapeutics) on Hepatic Sinusoidal Endothelial Cells (HSECs) and to delineate the molecular pathways involved. Complete characterisation confirmed a well-defined vesicle population that expressed canonical markers and lacked detectable cellular contaminants.Functionally, MSC-EVs attenuated TNF-α-induced HSEC activation, lowering adhesion molecule expression (ICAM-1, VCAM-1) and limiting immune cell adhesion and transmigration under shear flow. At the mechanistic level, they suppressed NF-κB activation, reduced IL-6 and CXCL10 secretion, preserved mitochondrial ATP production, and mitigated oxidative stress. At the molecular level, miR-146a-5p was identified as a key MSC-EVs cargo that repressed inflammatory signalling pathways in HSECs. Collectively, these findings establish MSC-EVs as multifunctional modulators of endothelial inflammation, integrating effects on adhesion, intracellular signalling, and metabolism. By targeting the endothelial gateway to immune recruitment, MSC-EVs provide a mechanistic foundation for the development of novel disease-modifying therapies in PSC.