Dynamic Matrix Stiffening Reprograms Endothelial Angiogenic Remodeling via α2‐Integrin Mechanotransduction

Progressive stiffening of the extracellular matrix (ECM) is a hallmark of vascular aging and fibrosis. Stiffening the ECM disrupts endothelial adherens junctions and barrier function, but whether endothelial cells impact pericellular ECM, which in turn affects endothelial cell fate, remains unclear. Here, we use a phototunable collagen–hyaluronic acid hydrogel to impose in situ stiffening around endothelial colony‐forming cells (ECFCs). In compliant matrices, ECFCs realigned collagen fibers, generated pericellular stiffening, and deposited nascent protein in spatial register with reorganized collagen. Dynamic stiffening disrupted this local feedback, with collagen alignment and pericellular stiffening suppressed despite unchanged collagen density, while nascent protein deposition increased but became uncoupled from constructive remodeling. Transcriptomic profiling revealed a shift from angiogenic, matrix‐constructive programs toward stress‐adaptive states. We identify α2‐integrin as a key regulator of endothelial biosynthesis and collagen organization under dynamic stiffening. Inhibition of α2‐integrin abolished stiffness‐induced nascent protein deposition and weakened endothelial adhesion to collagen. Together, these findings establish α2‐integrin–dependent mechanotransduction as a checkpoint linking dynamic ECM stiffening to suppression of endothelial pericellular remodeling, with implications for impaired vascular regeneration in aging and fibrosis.