Abstract

Fluid Shear Stress Regulates the Landscape of microRNAs in Endothelial Cell-Derived Exosomes and Modulates the Function of Endothelial Cells

Kihwan Kwon, Professor, Ewha Womans University College of Medicine

Endothelial cells (ECs) are constantly exposed to fluid shear stress (FSS) by blood flow that modulates endothelial function and vascular pathophysiology. Exosomes are potent mediators of intercellular communication, and their contents reflect cellular stress. We explored the differential regulation of miRNA profiles of EC-exosomes by atheroprone and atheroprotective flow and conducted a network analysis to identify the main biological processes modulated by exosomal miRNAs.

Exosomes were collected from culture media of human umbilical vein endothelial cells exposed to laminar shear stress (LSS; 20 dyne/cm2) and low-oscillatory shear stress (OSS; ±5 dyne/cm2). The differential expression of exosomal miRNA profiles was analyzed by miRNA sequencing and validated by qRT-PCR. A total of 26 miRNAs were selected for Gene Ontology (GO) analysis and the main biological processes regulated by EC-exosomes were involved in endothelial activation such as angiogenesis, cell migration, and vascular inflammation. OSS-exosomes promoted tube formation, cell migration, monocyte adhesion, and apoptosis. Shear stress-induced EC-exosomes had the same effects on endothelial mechanotransduction signaling as direct stimulation by FSS. In vivo studies using partial carotid artery ligation models showed that treatment with LSS-exosomes reduced the expression of pro-inflammatory genes, whereas treatment with OSS-exosomes had the opposite effect. In miRNA-target network and protein expression analyses, OSS-exosomes upregulated the expression of proteins that promoted angiogenesis, cell migration, and inflammatory responses, whereas they downregulated the expression of proteins that prevent apoptosis and inflammatory responses. In conclusions, understanding the landscape of EC-exosomal miRNAs regulated by differential FSS establishes their biological functions on a system level such as angiogenesis, cell migration, and vascular inflammation.