Longitudinal shear stress response in human endothelial cells to atheroprone and atheroprotective conditions

Abstract

The two main blood flow patterns, namely, pulsatile shear (PS) prevalent in straight segments of arteries and oscillatory shear (OS) observed at branch points, are associated with atheroprotective (healthy) and atheroprone (unhealthy) vascular phenotypes, respectively. The effects of blood flow-induced shear stress on endothelial cells (ECs) and vascular health have generally been studied using human umbilical vein endothelial cells (HUVECs). While there are a few studies comparing the differential roles of PS and OS across different types of ECs at a single time point, there is a paucity of studies comparing the temporal responses between different EC types. In the current study, we measured OS and PS transcriptomic responses in human aortic endothelial cells (HAECs) over 24 h and compared these temporal responses of HAECs with our previous findings on HUVECs. The measurements were made at 1, 4, and 24 h in order to capture the responses at early, mid, and late time points after shearing. The results indicate that the responses of HAECs and HUVECs are qualitatively similar for endothelial function-relevant genes and several important pathways with a few exceptions, thus demonstrating that HUVECs can be used as a model to investigate the effects of shear on arterial ECs, with consideration of the differences. Our findings show that HAECs exhibit an earlier response or faster kinetics as compared to HUVECs. The comparative analysis of HAECs and HUVECs presented here offers insights into the mechanisms of common and disparate shear stress responses across these two major endothelial cell types.

Single-Cell RNA Sequencing Reveals Endothelial Cell Transcriptome Heterogeneity Under Homeostatic Laminar Flow

“…This is consistent with other studies that analyzed freshly isolated aortic EC. 34 , 35 Most of our top significant changes in EC gene expression under flow are shared with published data, 18 – 22 suggesting that EC flow responses are similar when flow parameters are similar, and that species differences or use of primary EC from a particular source (ie, arterial versus venous) in culture do not affect the outcomes. Gene ontology analysis of transcriptome expression heterogeneity changes with flow revealed that protein translation and oxidative metabolism pathways are associated with elevated variance while protein processing is associated with reduced variance, and cell-cell interactions are found in both categories, suggesting complexity in these categories in response to flow.…”

Dysfunctional Vascular Endothelium as a Driver of Atherosclerosis: Emerging Insights Into Pathogenesis and Treatment

“…Many of these preclinical findings hold promise for the development of atherosclerosis treatments through pharmacological modulation of the endothelium (e.g., mitigating atherogenic responses or promoting atheroprotective functions in ECs). However, further investigation is required in vitro to determine the generalizability of endothelial responses between vascular cell models (e.g., shared and distinct behaviors of different EC lines under varying flow conditions) ( Maurya et al, 2021 ), as well as in vivo to identify translatability in preclinical models and long-term safety and efficacy in individuals with CVD.…”

Vascular Endothelial Galectins in Leukocyte Trafficking

“…Critically, in vitro culture of ECs still remains problematic. The distinct expressional changes between human EC types in response to different shear stress patterns emphasizes the importance of choosing the right models, with consideration for cell type and contextual interactions, to study endothelialspecific responses in vitro (32). Whilst many research groups have attempted to mimic physiological flow conditions using expensive and/or specialist equipment, the problem still remains that the complex physiological EC environment cannot be mimicked ex vivo.…”

“…Perturbations in shear stress can disturb EC mechanosensitive protein signaling, contributing to the pathophysiological angiogenesis in tumor vasculature where low shear stress is experienced, and driving inflammation in atherosclerosis-prone vascular niches and flow-obstructing pathologies where shear stress is disturbed (30,31). Deep sequencing of the transcriptome of human umbilical vein EC (HUVEC) and human aortic EC (HAEC) in response to patterns of shear stress has identified changes in expression of galectins not only in response to specific flow patterns, but also across EC type (32). Collectively, these findings suggest that expression of individual galectins is highly dependent on the tissue microenvironment and that a more in-depth comparison of the patterns of galectin expression across different vascular beds could be insightful for understanding galectin regulation and function in this context.…”