Endothelium-Mimicking Bilayer Vascular Grafts with Dual-Releasing of NO/H₂S for Anti-Inflammation and Anticalcification

Vascular complications caused by diabetes impair the activities of endothelial nitric oxide synthase (eNOS) and cystathionine γ-lyase (CSE), resulting in decreased physiological levels of nitric oxide (NO) and hydrogen sulfide (H 2 S). The low bioavailability of NO and H 2 S hinders the endothelialization of vascular grafts. In this study, endothelium-mimicking bilayer vascular grafts were designed with spatiotemporally controlled dual releases of NO and H 2 S for in situ endothelialization and angiogenesis. Keratin-based H 2 S donor was synthesized and electrospun with poly( l -lactide- co -ε-caprolactone) (PLCL) as the outer layer of the graft to release H 2 S. Hyaluronic acid, one of the major glycosaminoglycans in endothelial glycocalyx, was complexed with Cu ions as the inner layer to mimic glutathione peroxidase (GPx) and maintain long-term physiological NO flux. The synergistic effects of NO and H 2 S of bilayer grafts selectively promoted the regeneration and migration of human umbilical vascular endothelial cells (HUVECs), while inhibiting the overproliferation of human umbilical artery smooth muscle cells (HUASMCs). Bilayer grafts could effectively prevent vascular calcification, reduce inflammation, and alleviate endothelial dysfunction. The in vivo study in a rat abdominal aorta replacement model for 1 month showed that the graft had a good patency rate and had potential for vascular remodeling in situ.