Oral Presentation ESA-SRB-ANZBMS 2024 in conjunction with ENSA

Hypoxia alters the proteome of small human placental extracellular vesicles and their effect on endothelial dysfunction (#13)

Bianca Fato 1 2 3 , Natasha de Alwis 1 2 3 , Ishara Atukorala 1 2 , Anjali Garg 1 2 3 , Lydia Baird 1 2 3 , Tu'uhevaha Kaitu'u-Lino 1 2 , Natalie Hannan 1 2 3
  1. University of Melbourne, Parkville, VICTORIA, Australia
  2. Department of Obstetrics and Gynaecology , University of Melbourne, Parkville, Victoria, Australia
  3. Therapeutics Discovery and Vascular Function Group, Heidelberg, Victoria, Australia

Extracellular vesicles (EVs) have important roles in placental development and vascular homeostasis in pregnancy. Hypoxia (low oxygen that features with placental dysfunction) is proposed to alter the secretion and biochemical composition of placental EVs. Here, we investigated the effect of hypoxia on the proteome of small placental EVs and their effect on endothelial function.

 

Placental tissue was collected at term caesarean section (n=5). Placental explants were cultured (48 hours) under hypoxic (1% O2) or control conditions (8% O2). EVs were isolated from explant media by differential centrifugation. EV size and concentration was determined by nanoparticle tracking analysis. Proteins isolated from EVs were assessed by Liquid Chromatography-Mass Spectrometry (matched vesicle concentrations). Human umbilical vein endothelial cells (HUVECs, n=6) were cultured with control or hypoxic placental EVs (6 hours), to investigate endothelial function. Markers of endothelial dysfunction were analysed (qPCR, ELISA), in addition to endothelial tube formation and leukocyte adhesion assays. Wire myography explored the vascular response of human omental arteries following incubation with control or hypoxic placental EVs (n=5) to vasoconstrictor, endothelin-1, and vasodilator, bradykinin.

 

6,421 proteins were identified in small placental EVs; 43 proteins were uniquely expressed in hypoxic placental EVs. The most abundant were associated with inflammation, angiogenesis, cellular repair, and survival. HUVECs cultured with placental EVs from control and hypoxic conditions demonstrated an upregulation in mRNA expression of endothelial dysfunction markers (VCAM, ICAM), pro-inflammatory (CCL2, CCL7, CX3CL1), oxidative stress (NOS3) and anti-angiogenic factors (sFLT1; secretion was also increased); and downregulated inflammatory cytokine, CXCL8. Interestingly, all placental EVs increased leukocyte adhesion. However, they did not alter omental artery vasoreactivity.

 

The proteome of small EVs was altered in placenta cultured under hypoxia. Small placental EVs drive endothelial dysfunction, endothelial-leukocyte adhesion, and increase antiangiogenic factors. These data demonstrate that placental hypoxia alters bioactive compounds in EVs and their actions on vasculature.