The long-term effects of extracellular vesicles from normotensive and preeclamptic placentae on the cardiovascular system

Abstract

Introduction: During pregnancy, the placenta releases significant numbers of extracellular vesicles (EVs) into the maternal circulation, which are increasingly recognised as essential mediators of cellto- cell communication. Normotensive placental EVs have been reported to contribute to maternal cardiovascular adaptations during pregnancy. The hypothesis was that they could also prevent or correct cardiovascular dysfunction later in life. Conversely, EVs derived from preeclamptic placentae cause vasoconstriction and endothelial cell activation, an antecedent of both preeclampsia (PE) and cardiovascular disease (CVD). Thus, it was proposed that preeclamptic placental EVs serve as a mechanistic link between PE and premature CVD in women. Methods: Spontaneously hypertensive rats (SHRs) were used as an animal model to assess whether 1) normotensive placental EVs mitigate long-term CVD/renal disease and 2) preeclamptic placental EVs exacerbate the severity of long-term CVD/renal disease. Mechanisms underlying placental EV uptake were studied using inhibitors of phagocytosis or endocytosis, trypsin treatment, and integrin-blocking peptides. Endothelial cell activation was evaluated through monocyte adhesion assays post-EV exposure, with and without integrinblocking peptide treatment. Results: Administration of normotensive placental EVs to SHRs mitigated progressive hypertension and cardiovascular function decline over time, and enhanced endothelium-dependent relaxation in resistance arteries. Conversely, preeclamptic placental EVs exacerbated hypertension and induced a pro-vasoconstrictive, anti-vasodilatory phenotype in resistance arteries. Normotensive placental EVs also protected against renal small vessel thickening and attenuated renal fibrosis, whereas preeclamptic placental EVs contributed to renal small vessel thickening in SHRs. Furthermore, placental large- and small-EVs exhibited interactions with various recipient cells in vitro, with liver cells showing the highest interaction, followed by endothelial and kidney cells. Dose-, time-, and energy-dependent interactions were observed between placental EVs and recipient cells, with outer membrane proteins, particularly integrins, significantly involved in EV uptake. Conclusions: The findings presented in this thesis provide crucial insights into the cellular mechanisms underlying EV uptake and, for the first time, unveil the long-lasting effects induced by placental EVs in vivo. The study highlights the potential therapeutic role of normotensive placental EVs in protecting against CVD/ renal disease and emphasises the contribution of preeclamptic placental EVs as a mechanistic link driving the long-term cardiovascular consequences of PE.