Placental extracellular vesicles and pre-eclampsia

Pre-eclampsia is a hypertensive disease of pregnancy characterized by new-onset hypertension, with either proteinuria and/or organ dysfunction. Pre-eclampsia is a leading cause of maternal morbidity and mortality; however, the underlying cellular and molecular mechanisms are not well understood. There is consensus that the underlying mechanism(s) resulting in pre-eclampsia is centered around abnormal placentation, inadequate spiral-artery remodeling, and deficiency in trophoblast invasion, resulting in impaired maternal blood flow to the placenta and a release of signals and/or inflammatory mediators into maternal circulation triggering the systemic manifestations of pre-eclampsia. ER stress, resulting in impaired autophagy and placental release of aggregated proteins, may also confer systemic stress to maternal organs in pre-eclampsia. Extracellular vesicles (EVs), lipid-bilayer enclosed structures containing macromolecules including proteins, miRNA, and other important nucleotides, have been suggested to play an important role in this maternal-fetal communication. Circulating EVs are present in greater quantity in the plasma of pre-eclampsia subjects compared to normal pregnancy, and the placental derived EVs have been shown to have altered protein and RNA cargo. In this review, we will focus on EVs and their role in pre-eclampsia, specifically their role in immune responses, inflammation, altered angiogenesis, and endothelial dysfunction.