Background: Gestational diabetes mellitus is associated with long-term maternal metabolic and cardiovascular disease (including vascular dysfunction). However, the mechanisms driving these long-term effects are not well understood. Placental extracellular vesicles (EVs) are lipid-based carriers of bioactive cargo secreted from the placenta, and play a role in maternal adaptation to pregnancy and vascular homeostasis. Here we aim to investigate whether high glucose conditions might contribute to maternal vascular dysfunction, by altering the abundance, content, and vascular actions of placental-derived EVs.
Methods: Healthy term placental tissue explants (n=5) were cultured under high glucose (25mM; simulating hyperglycaemia) or control conditions (5mM glucose). Secreted placental EVs were isolated from explantculture media by ultracentrifugation. EV protein cargo was extracted and proteomics performed using Liquid Chromatography-Mass Spectrometry. Human umbilical vein endothelial cells (HUVECs, n=6) were treated with control or high glucose placental EVs, and effect on endothelial function/activation pathways assessed by qPCR, ELISA, and leukocyte adhesion assays. Functional response of human omental arteries was assessed following incubation with control or high-glucose placental EVs, using wire myography (n=5).
Results: 5,167 proteins were identified in placental EVs; 57 proteins were uniquely present following high glucose exposure. The most abundantly expressed proteins were associated with integrins, ubiquitination, angiogenesis, cellular repair, growth and survival. HUVEC treatment with both control and high glucose placental EVs significantly upregulated mRNA expression of markers of endothelial dysfunction (VCAM, ICAM), inflammation (CCL2, CCL7, CX3CL1), oxidative stress (NOS3), and anti-angiogenic factor FLT1 (protein secretion also increased); inflammatory CXCL8 was downregulated. Both control and high glucose placental EVs increased leukocyte adhesion to endothelial cells. Treatment with high glucose placental EVs reduced omental artery constriction; opposing our hypothesis that they would promote vasoconstriction.
Conclusion: These data hold significant potential to inform how hyperglycaemia can change bioactive cargo of placental EVs and their actions on the systemic vasculature.