RhoA mediates flow-induced endothelial sprouting in a 3-D tissue analogue of angiogenesis

Abstract

Endothelial cells (ECs) integrate signals from the local microenvironment to guide their behaviour. RhoA is involved in vascular endothelial growth factor (VEGF) - driven angiogenesis, but its role in mechanotransduction during sprouting has not been established. Using dominant negative cell transfections in a microfluidic device that recapitulates angiogenic sprouting, we show that endothelial cells respond to interstitial flow in a RhoA-dependent manner while invading into a 3-D extracellular matrix. Furthermore, RhoA regulates flow-induced, but not VEGF gradient-5 induced tip cell filopodial extensions. Thus, RhoA pathways mediate mechanically-activated but not VEGF- induced endothelial morphogenesis.

Three-Dimensional Microfluidic Collagen Hydrogels for Investigating Flow-Mediated Tumor-Endothelial Signaling and Vascular Organization

“…34 Many of these models have provided insight into the field of cancer research by identifying novel mechanisms of flow-guided endothelial alignment, sprouting, and vessel formation. 65,81,82 However, to the best of our knowledge, there are no existing in vitro culture models that are specifically designed to investigate the effect of flow shear stress on tumor-endothelial signaling or vascular organization within the context of the tumor microenvironment.…”

The same but different: signaling pathways in control of endothelial cell migration

“…VEGF potently induced EC migration, but only in ECs that were not exposed to fluid shear stress. Furthermore, this response to shear stress was mediated via RhoA [58]. Therefore, in a pro-angiogenic setting, shear stress might limit the pro-angiogenic and pro-migratory effect of 90 Cell adhesion and migration (a) Under vascular endothelial growth factor (VEGF) stimulation, the Rac1 GEF Vav2 is activated by Src-mediated phosphorylation, which leads to Rac1 activation and corresponding microtubule (MT) rearrangement and actin polymerization to form lamellipodia.…”

Microfluidic approaches to the study of angiogenesis and the microcirculation

“…First, the hybrid microchannels produce the necessary contact between the microvessel wall and the intervessel matrix to mediate sprouting angiogenesis and anastomosis of vessel sprouts (Figure B). Second, the favorable optical properties of PDMS enable monitoring of the dynamics of sprout extension and branching with high‐resolution confocal time‐lapse microscopy . Third, the semiporous hydrogel also facilitates interstitial flow driven by a pressure gradient across the hydrogel (Figure B) where fluid originates from one vessel, is filtered across its vessel wall, percolates through the hydrogel, and is absorbed across the wall of another vessel .…”