Three-dimensional biomimetic vascular model reveals a RhoA, Rac1, and N -cadherin balance in mural cell–endothelial cell-regulated barrier function

Abstract

The integrity of the endothelial barrier between circulating blood and tissue is important for blood vessel function and, ultimately, for organ homeostasis. Here, we developed a vessel-on-a-chip with perfused endothelialized channels lined with human bone marrow stromal cells, which adopt a mural cell-like phenotype that recapitulates barrier function of the vasculature. In this model, barrier function is compromised upon exposure to inflammatory factors such as LPS, thrombin, and TNFα, as has been observed in vivo. Interestingly, we observed a rapid physical withdrawal of mural cells from the endothelium that was accompanied by an inhibition of endogenous Rac1 activity and increase in RhoA activity in the mural cells themselves upon inflammation. Using a system to chemically induce activity in exogenously expressed Rac1 or RhoA within minutes of stimulation, we demonstrated RhoA activation induced loss of mural cell coverage on the endothelium and reduced endothelial barrier function, and this effect was abrogated when Rac1 was simultaneously activated. We further showed that N-cadherin expression in mural cells plays a key role in barrier function, as CRISPRmediated knockout of N-cadherin in the mural cells led to loss of barrier function, and overexpression of N-cadherin in CHO cells promoted barrier function. In summary, this bicellular model demonstrates the continuous and rapid modulation of adhesive interactions between endothelial and mural cells and its impact on vascular barrier function and highlights an in vitro platform to study the biology of perivascular-endothelial interactions.

Notch‐inducing hydrogels reveal a perivascular switch of mesenchymal stem cell fate

“…In addition to modulating their own microenvironment and providing ECM, MSCs have been shown to support endothelial cell functions during micro-capillary formation within natural ECM hydrogel materials [10][11][12][13]33,34]. However, the elucidation of specific niche signals and the control over the niche regulatory processes remain very difficult in natural materials.…”

“…During the formation of new blood capillaries, perivascular cells are recruited by endothelial cells and contribute to the stabilization and regulation of newly formed endothelial capillaries. Although the perivascular origin of MSCs remains controversial [9], MSCs can act as perivascular support cells [10][11][12][13]. This has led to the constantly debated hypothesis that during tissue regeneration, MSCs are mobilized from blood capillaries and that MSCs and perivascular cells are closely related cell types.…”

“…This has led to the constantly debated hypothesis that during tissue regeneration, MSCs are mobilized from blood capillaries and that MSCs and perivascular cells are closely related cell types. Although the perivascular origin of MSCs remains controversial [9], MSCs can act as perivascular support cells [10][11][12][13]. However, how MSCs adapt to the perivascular environment and which niche signals regulate their perivascular adaptation has not been addressed comprehensively.…”

Microfluidics‐Based Biomaterials and Biodevices

“…The integrity of endothelial barrier also plays an important role in the blood vessel function. Recently, a 3D biomimetic vascular model is designed to recapitulate perivascular‐mediated barrier function, offering a powerful complement to animal model . Although the microfluidics‐based artificial vessels show great potential for the treatment for vascular diseases, there remain many challenges for commercial artificial vascular grafts from the standpoint of clinical practice.…”

A Molecular Tension Sensor for N-Cadherin Reveals Distinct Forms of Mechanosensitive Adhesion Assembly in Adherens and Synaptic Junctions

“…These AJs exhibit a large degree of structural variability, ranging from several micron long puncta to 50 micron long ribbonlike structures that run the entire length of the cell depending on the exact cellular context [28,29]. Furthermore, N-cadherin is implicated in the regulation of VSMC migration, growth, and apoptosis as well as having a key role in the mechanosensitive physiological and pathological process, including the myogenic response, the maintenance of barrier function, and post-injury vasculature repair [28,[30][31][32][33]. Thus, a greater understanding of the mechanical loads experienced by N-cadherin in VSMCs is likely to inform several key aspects of cardiovascular physiology and pathophysiology.…”