HIF2α-Regulated Pathways Control Human Extravillous Trophoblast Functions by Modulating Cell-to-Cell Communication Through Extracellular Vesicles.

Successful pregnancy in humans requires extravillous trophoblast (EVT) cells to invade the endometrium, remodel maternal tissue, and establish a functional placenta. How trophoblasts communicate with the endometrium to coordinate this remodeling remains poorly understood. We previously demonstrated that human endometrial stromal cells communicate through secreted extracellular vesicles (EVs) at the maternal-fetal interface, but whether trophoblasts engage in reciprocal EV-mediated communication remained unknown. Here, using an in vitro trophoblast stem cell differentiation model, we show that EVT cells secrete EVs carrying protein cargo that regulates endometrial stromal cell remodeling, revealing a previously unrecognized arm of maternal-fetal communication. Hypoxia, a defining feature of early placentation, enhanced EV secretion, EVT differentiation, and trophoblast invasion, and these responses required hypoxia-inducible factor 2α (HIF2α). Loss of HIF2α impaired EVT differentiation and significantly reduced EV production. Functionally, EVT-derived EVs altered endometrial stromal cell remodeling, in part through HIF2α-regulated cargo proteins including matrix metalloproteinase 2 (MMP2). MMP2 depletion reduced both EVT invasion and EV-mediated stromal remodeling, identifying MMP2 as an important mediator of trophoblast-maternal communication. Strikingly, MMP2 deficiency also redirected trophoblast cell fate toward the syncytiotrophoblast (ST) lineage, accompanied by morphological and molecular genetic hallmarks of syncytialization, revealing an unexpected role for a matrix-remodeling enzyme in trophoblast lineage specification. Together, these findings establish a hypoxia-regulated trophoblast EV signaling pathway that links oxygen sensing to trophoblast differentiation, invasion, and maternal tissue remodeling, and reveal an unexpected connection between extracellular matrix remodeling and trophoblast cell-fate decisions during early placental development.