Substrate stiffness and VE-cadherin mechano-transduction coordinate to regulate endothelial monolayer integrity

Abstract

The vascular endothelium is subject to diverse mechanical cues that regulate vascular endothelial barrier function. In addition to rigidity sensing through integrin adhesions, mechanical perturbations such as changes in fluid shear stress can also activate force transduction signals at intercellular junctions. This study investigated how extracellular matrix rigidity and intercellular force transduction, activated by vascular endothelial cadherin, coordinate to regulate the integrity of endothelial monolayers. Studies used complementary mechanical measurements of endothelial monolayers grown on patterned substrates of variable stiffness. Specifically perturbing VE-cadherin receptors activated intercellular force transduction signals that increased integrin-dependent cell contractility and disrupted cell-cell and cell-matrix adhesions. Further investigations of the impact of substrate rigidity on force transduction signaling, demonstrated how cells integrate extracellular mechanics cues and intercellular force transduction signals, to regulate endothelial integrity and global tissue mechanics. VE-cadherin specific signaling increased focal adhesion remodeling and cell contractility, while sustaining the overall mechanical equilibrium at the mesoscale. Conversely, increased substrate rigidity exacerbates the disruptive effects of intercellular force transduction, by increasing heterogeneity in monolayer stress distributions. The results provide new insights into how substrate stiffness and intercellular force transduction coordinate to regulate endothelial monolayer integrity.

Determining mechanical features of modulated epithelial monolayers using subnuclear particle tracking

“…There is evidence to suggest that epithelial monolayers are more responsive to substrate stiffness than sparsely seeded cells (Ng et al, 2012). Generally, the trend of increased force generation with increased substrate stiffness is consistent with traction force microscopy data (Andresen Eguiluz et al, 2017;Krishnan et al, 2011). From exponential fitting of our data, we found that cells would generate 90% of the force generated on glass (glass set to 50 GPa, essentially infinite stiffness) on a substrate with an elastic modulus of about 60 kPa.…”

Balance of mechanical forces drives endothelial gap formation and may facilitate cancer and immune-cell extravasation

“…That, in turn, may be affected by extravasating cells that may obstruct blood flow. Similarly, matrix stiffness was shown to affect endothelial monolayer integrity [42,43]. Some complications in validating our results in vivo involve the lack of available in vitro cultures that are required to provide high throughput, microscopy resolution and level of experimental control that is lacking in vivo, making direct comparison of computational models to in vivo experiments unfeasible.…”

Endothelial Cell Mechanotransduction in the Dynamic Vascular Environment

“…TFM and MSM (monolayer stress microscopy) revealed that increasing matrix rigidity raised the average EC monolayer stress as well as enhanced fluctuations in monolayer stress, thus increasing susceptibility to gap formation. [53] Accordingly, Stroka and Aranda-Espinoza found that the fraction of neutrophils transmigrating across tumor necrosis factor-α (TNF-α)-stimulated HUVEC monolayers increased with increasing stiffness (0.42 to 280 kPa) of PA gels. This increased transmigration produced large holes in the monolayer on more rigid substrates and was not the result of changes in ICAM-1 expression, which remained constant with changing rigidity.…”