Exosomes derived from human umbilical cord mesenchymal stem cells regulate lymphangiogenesis via the miR-302d-3p/VEGFR3/AKT axis to ameliorate inflammatory bowel disease

Background: Exosomes released from human umbilical cord mesenchymal stem cell (hucMSC-Ex) have been revealed to hold great potential for the development of new treatment approaches for various diseases, including inflammatory bowel disease (IBD). Lymphatic vessels are vital for IBD development and progression to colorectal cancer (CRC), as an occluded conduit for lymphatic fluid to return to the blood.Objective: The mechanism involved remains largely unexplored. Here, we investigate the therapeutic effect of hucMSC-Ex in a mouse model of IBD during the modulation of lymphangiogenesis.Methods: We established a dextran sulfate sodium (DSS)-induced IBD model in BALB/c mice and observed the influence of hucMSC-Ex on tissue repair, intestinal lymphatic function, changes in lymphangiogenesis, and infiltration of macrophages. We also evaluated the functional changes of human lymphatic endothelial cells (hLECs) in vitro to determine the mechanism by which hucMSC-Ex regulate lymphangiogenesis. Finally, we identified key molecules in hucMSC-Ex by sequencing, database comparison, and cell validation.Results: Results showed that hucMSC-Ex alleviates IBD in mice by improving intestinal lymphatic drainage, inhibiting lymphangiogenesis, and infiltration of macrophages. Mechanistically, the miRNA sequencing results showed that miR-302d-3p was highly expressed in hucMSC-Ex and played an important role in inhibiting lymphangiogenesis by targeting Fms-related receptor tyrosine kinase 4 (FLT4). At the same time, the phos-phorylation of AKT was inhibited and vascular endothelial growth factor receptor 3 (VEGFR3) was reduced.Conclusion: Collectively, our study suggests that hucMSC-Ex can regulate lymphangiogenesis via the miR-302d-3p/VEGFR3/AKT axis to ameliorate IBD. Our findings identify VEGFR3 as a potential therapeutic target in IBD, where tightly regulated lymphangiogenesis is crucial in its pathogenesis and progression.