Stiffening Matrix Induces Age‐Mediated Microvascular Phenotype Through Increased Cell Contractility and Destabilization of Adherens Junctions

Abstract

Aging is a major risk factor in microvascular dysfunction and disease development, but the underlying mechanism remains largely unknown. As a result, age‐mediated changes in the mechanical properties of tissue collagen have gained interest as drivers of endothelial cell (EC) dysfunction. 3D culture models that mimic age‐mediated changes in the microvasculature can facilitate mechanistic understanding. A fibrillar hydrogel capable of changing its stiffness after forming microvascular networks is established. This hydrogel model is used to form vascular networks from induced pluripotent stem cells under soft conditions that mimic young tissue mechanics. Then matrix stiffness is gradually increased, thus exposing the vascular networks to the aging‐mimicry process in vitro. It is found that upon dynamic matrix stiffening, EC contractility is increased, resulting in the activation of focal adhesion kinase and subsequent dissociation of β ‐catenin from VE‐Cadherin mediated adherens junctions, leading to the abruption of the vascular networks. Inhibiting cell contractility impedes the dissociation of β ‐catenin, thereby preventing the deconstruction of adherens junctions, thus partially rescuing the age‐mediated vascular phenotype. The findings provide the first direct evidence of matrix's dynamic mechano‐changes in compromising microvasculature with aging and highlight the importance of hydrogel systems to study tissue‐level changes with aging in basic and translational studies.

Enzymatically Crosslinked Collagen as a Versatile Matrix for In Vitro and In Vivo Co‐Engineering of Blood and Lymphatic Vasculature

“…[22] Finally, light-mediated crosslinking of collagen-methacrylate and collagen-norbornene has shown promising results in generating hydrogels of varying stiffness in a light-dose dependent manner. [23,24] The requirement of photoinitiators and possible phototoxicity at low wavelengths are limiting factors. [23][24][25] In this study, we report a novel and highly versatile modification of the collagen backbone lysine groups by conjugation of a PEG-based terminal azide group.…”

“…[23,24] The requirement of photoinitiators and possible phototoxicity at low wavelengths are limiting factors. [23][24][25] In this study, we report a novel and highly versatile modification of the collagen backbone lysine groups by conjugation of a PEG-based terminal azide group. Azide groups were further modified with specific enzyme recognition peptides bearing a complementary alkyne group using copper-catalyzed azide-alkyne click (CuAAC) chemistry.…”

“…[ 22 ] Finally, light‐mediated crosslinking of collagen‐methacrylate and collagen‐norbornene has shown promising results in generating hydrogels of varying stiffness in a light‐dose dependent manner. [ 23,24 ] The requirement of photoinitiators and possible phototoxicity at low wavelengths are limiting factors. [ 23–25 ]…”

“…[ 23,24 ] The requirement of photoinitiators and possible phototoxicity at low wavelengths are limiting factors. [ 23–25 ]…”

BEYOND THE ENDOTHELIUM: THE ROLE OF MURAL CELLS IN VASCULAR BIOLOGY: In vitro systems to study endothelial/pericyte cell interactions

“…However, constructing physiologically relevant in vitro systems that successfully incorporate both cell types and the complexity of their interactions continues to be a challenge. In vitro culture systems provide numerous advantages, such as tunability of the cellular microenvironment through engineered materials to mimic the extracellular matrix (ECM) and isolate the role of specific matrix properties on vascular function ( 15 , 16 , 17 ). Additionally, using hydrogels to create three-dimensional (3D) models allows for the visualization of vascular network formation and angiogenesis while recapitulating the 3D spatial arrangement observed in vivo compared to 2D models.…”