(33) The Transcription Factor HIF2α Regulates the Secretion of Extracellular Vesicles by Human Extravillous Trophoblasts, Influencing Endometrial Remodeling

Xiangning Song¹, Jacob R. Beal¹, Indrani C. Bagchi², and Milan K. Bagchi¹
1. Departments of Molecular and Integrative Physiology, University of Illinois Urbana-Champaign, Urbana, IL
2. Departments of Comparative Biosciences, University of Illinois Urbana-Champaign, Urbana, IL

Abstract Text:

During early pregnancy in humans, extravillous trophoblast (EVT) cells develop from trophoblast stem cells through a lineage-specific differentiation process. These cells invade the endometrium to facilitate proper placental development. Previous research in our laboratory has shown that extracellular vesicles (EVs) secreted by human endometrial stromal cells enhance the differentiation of EVT cells. However, the mechanisms by which EVT cells communicate to influence maternal tissue remain unclear. In this study, we utilized an in vitro system where multipotent human trophoblast stem cells differentiate into EVT cells in response to specific signaling inducers. We discovered that EVT cells secrete EVs into the conditioned media. After purifying these EVs and conducting mass spectrometry analysis, we found that they contained various protein cargos, which may play roles in cell-cell communication. One prominent EV cargo was matrix metalloproteinase-2 (MMP2), known for its role in extracellular matrix remodeling. Notably, we observed that hypoxia stimulates both EVT differentiation and EV secretion. Using a lentivirus-mediated loss-of-function approach, we found that the hypoxia-inducible factor HIF2α is crucial for regulating EVT differentiation and EV secretion. Furthermore, the absence of HIF2α expression in EVT cells resulted in impaired invasive properties, as shown by a transwell invasion analysis. Interestingly, EVs derived from EVT cells slowed down the migration and remodeling of endometrial stromal cells, presumably to facilitate EVT invasion through the stromal tissue during placentation. In contrast, EVT-EVs lacking MMP2 did not exhibit this effect. Overall, our findings support the idea that EVs secreted by both endometrial and trophoblast cells are essential for the bidirectional communication between maternal and fetal tissues, which is vital for proper placental formation. Additionally, hypoxia and HIF2α play key regulatory roles in orchestrating this process.

This work was supported by the Eunice Kennedy Shriver NICHD/NIH R01 HD090066 and R21 HD109726 (to ICB and MKB). XS is a Toxicology Scholar partly supported by the NIEHS training grant T32 ES007326. JRB is supported by NICHD training grant HD108075.