Decreased miR-92a-3p expression potentially mediates the pro-angiogenic effects of oxidative stress-activated endothelial cell-derived exosomes by targeting tissue factor

Abstract

Angiogenesis is an essential pathological feature of vulnerable atherosclerotic plaque. Exosome-derived microRNAs (miRNAs or miRs) have been proven to be important regulators of angiogenesis. However, the role of exosomes, which are secreted by endothelial cells (ECs) under conditions of oxidative stress, in angiogenesis remain unclear. The present study aimed to investigate the effects and mechanism of oxidative stress-activated endothelial-derived exosomes in angiogenesis. Exosomes were isolated from H2O2-stimulated human umbilical vein ECs (HUVECs; termed Exo-H2O2) by differential centrifugation and characterized by transmission electron microscopy, nanoparticle tracking analysis and western blot analysis. Exo-H2O2enhanced HUVEC proliferation, migration and tube formation, as determined by EdU incorporation assay, scratch wound migration assay and tube formation assay, respectively. miR-92a-3p was identified as the predominantly downregulated miRNA in the Exo-H2O2-treated HUVECs by small RNA sequencing, and the expression of primary miR-92a (pri-miR-92a-1) was also decreased, as shown by RT-qPCR. Similarly, the inhibition of miR-92a-3p promoted angiogenesis in vitro and in vivo. miR-92a-3p overexpression blocked the pro-angiogenic effects of Exo-H2O2on target ECs. Tissue factor (TF), a molecule involved in angiogenesis, was increased in HUVECs in which miR-92a-3p expression was downregulated, as shown by mRNA sequencing. TF was also predicted as a target of miR-92a-3p by using the RNAhybrid program. The overexpression or suppression of miR-92a-3p modified TF expression at both the mRNA and protein level, as measured by RT-qPCR and western blot analysis, respectively. Luciferase reporter assays suggested that miR-92a-3p inhibited TF expression by binding to the 3' untranslated region of TF. On the whole, the findings of the present study demonstrate that exosomes released from oxidative stress-activated ECs stimulate angiogenesis by inhibiting miR-92a-3p expression in recipient ECs, and TF may be involved in the regulatory effects of miR-92a-3p on angiogenesis.