Reversible shear stress-mediated mechanoregulation of endothelial cell function in thixotropic hydrogels via L-type Ca channel and focal adhesion molecules for accelerated vascularization.

Developing functional vascular networks in engineered tissues is crucial for regenerative medicine. Recently, thixotropic hydrogel has emerged as a promising approach due to their 3D-printability and force-responsive dynamics. However, their gel-sol transitions under physiological loading and subsequent mechanoregulation mechanism on vascularization remains inadequately explored. Here, the reversible shear stress induced in thixotropic hydrogels under bionic cyclic stretching (5 % strain, and 0.5, 1 or 1.5 Hz) has been demonstrated to significantly accelerate endothelial cell adhesion, migration, and angiogenesis. These dynamic mechanical responses are precisely quantified and monitored through computational simulations and specially designed experimental apparatus. Mechanistic investigations reveals that the mechanically regulated cell behavior is mediated by cell adhesion molecules and calcium signaling pathways, which can be inhibited using Talin bloker (e.g., neomycin) and L-type voltage-gated calcium channel antagonists (e.g., verapamil), respectively. Furthermore, subcutaneous implantation of thixotropic hydrogels in rats results in denser and more rapid vascularization compared to non-thixotropic hydrogels. The reversible shear stress-regulated vascularization strategy is anticipated to offer a novel and efficient approach for constructing functional blood vessels in regenerative medicine.