Small extracellular vesicles from pregnant women with maternal supraphysiological hypercholesterolemia impair endothelial cell function in vitro

Maternal physiological hypercholesterolemia MPH, maternal total cholesterol (TC) levels at term of pregnancy ≤280 mg/dL) occurs to assure fetal development. Maternal supraphysiological hypercholesterolemia (MSPH, TC levels >280 mg/dL) is a pathological condition associated with maternal, placental, and fetal endothelial dysfunction and early neonatal atherosclerosis development. Small extracellular vesicles (sEVs) are delivered to the extracellular space by different cells, where they modulate cell functions by transporting active signaling molecules, including proteins and miRNA. Aim: To determine whether sEVs from MSPH women could alter the function of endothelial cells (angiogenesis, endothelial activation and nitric oxide synthesis capacity). Methods: This study included 24 Chilean women (12 MPH and 12 MSPH). sEVs were isolated from maternal plasma and characterized by sEV markers (CD9, Alix and HSP70), nanoparticle tracking analysis, transmission electron microscopy, and protein and cholesterol content. The endothelial cell line HMEC-1 was used to determine the uptake of labeled sEVs and the effects of sEVs on cell viability, endothelial tube formation, endothelial cell activation, and endothelial nitric oxide expression and function. Results: In MSPH women, the plasma concentration of sEVs was increased compared to that in MPH women. MSPH-sEVs were highly taken up by HMEC-1 cells and reduced angiogenic capacity and the expression and activity of eNOS without changing cell viability or endothelial activation compared to MPH-sEVs. Conclusion: sEVs from MSPH women impair angiogenesis and nitric oxide synthesis in endothelial cells, which could contribute to MSPH-associated endothelial dysfunction.