Extracellular vesicle‐derived microRNA‐18b ameliorates preeclampsia by enhancing trophoblast proliferation and migration via Notch2/TIM3/mTORC1 axis

Preeclampsia (PE), a common disorder of pregnancy, is characterized by insufficient trophoblast migration and inadequate vascular remodelling, such that promotion of trophoblast proliferation might ameliorate PE. In the current study, we sought to study the underlying mechanism of extracellular vesicle (EV)‐derived microRNA‐18 (miR‐18b) in PE. Human umbilical cord mesenchymal stem cells (HUCMSCs) isolated from placental tissues were verified through osteogenic, adipogenic and chondrogenic differentiation assays. Bioinformatics analyses and dual‐luciferase reporter gene assay were adopted to confirm the targeting relationship between miR‐18b and Notch2. The functional roles of EV‐derived miR‐18b and Notch2 in trophoblasts were determined using loss‐ and gain‐of‐function experiments, and trophoblast proliferation and migration were assayed using CCK‐8 and Transwell tests. In vivo experiments were conducted to determine the effect of EV‐derived miR‐18b, Notch2 and TIM3/mTORC1 in a rat model of PE, with monitoring of blood pressure and urine proteinuria. TUNEL staining was conducted to observe the cell apoptosis of placental tissues of PE rats. We found down‐regulated miR‐18b expression, and elevated Notch2, TIM3 and mTORC1 levels in the placental tissues of PE patients compared with normal placenta. miR‐18b was delivered to trophoblasts and targeted Notch2 and negatively its expression, whereas Notch2 positively mediated the expression of TIM3/mTORC1. EV‐derived miR‐18b or Notch2 down‐regulation enhanced trophoblast proliferation and migration in vitro and decreased blood pressure and 24 hours urinary protein in PE rats by deactivating the TIM3/mTORC1 axis in vivo. In summary, EV‐derived miR‐18b promoted trophoblast proliferation and migration via down‐regulation of Notch2‐dependent TIM3/mTORC1.