Preeclampsia (PE) manifesting as hypertension and organ injury is mediated by vascular dysfunction. In biological fluids, extracellular vesicles (EVs) containing microRNA (miRNA), protein, and other cargo released from the placenta may serve as carriers to propagate injury, altering the functional phenotype of endothelial cells. PE has been consistently correlated with increased levels of placenta-derived EVs (pEVs) in maternal circulation. However, whether pEVs impaired endothelial cell function remains to be determined. In this study, researchers from the University of Alabama at Birmingham hypothesized that pEVs from pregnant women with severe PE (sPE) impair endothelial function through altered cell signaling.
The researchers obtained plasma samples from women with sPE (n = 14) and normotensive pregnant women (n = 15) for the isolation of EVs. The total number of EV and pEV contribution was determined by quantifying immunoreactive EV-cluster of designation 63 (CD63) and placental alkaline phosphatase (PLAP) as placenta-specific markers, respectively. Vascular endothelial functional assays were determined by cell migration, electric cell-substrate impedance sensing in human aortic endothelial cells (HAECs), and wire myography in isolated blood vessels, preincubated with EVs from normotensive and sPE women.
Plasma EV and pEV levels were increased in sPE when compared to normotensive without a significant size distribution difference in sPE (108.8 ± 30.2 nm) and normotensive-EVs (101.3 ± 20.3 nm). Impaired endothelial repair and proliferation, reduced endothelial barrier function, reduced endothelial-dependent vasorelaxation, and decreased nitrite level indicate that sPE-EVs induced vascular endothelial dysfunction. Moreover, sPE-EVs significantly downregulated endothelial nitric oxide synthase (eNOS and p-eNOS) when compared to normotensive-EV.
Confocal microscopic images revealed the colocalization of normotensive and sPE-EVs incubated with HAECs in 24 h
A, Imaging of PHK67 (green) dye stained the normotensive EVs that were immune labeled using TSG101 antibody (red). B, Imaging of PHK67 (green) dye stained the sPE-EVs that were immune labeled using TSG101 antibody (red). The PHK67 dye colocalized with TSG101 and yielded yellow signal and nuclei stained by DAPI in blue (bar, 20 μm). DAPI indicates diamidino-2-phenylindole; EVs, extracellular vesicles; HAECs, human aortic endothelial cells; PKH67, Paul Karl Horan dye 67; sPE, severe preeclampsia; TSG101, Tumor Susceptibility 101.