Bilayer vascular grafts with on-demand NO and H2S release capabilities

Nitric oxide (NO) and hydrogen sulfide (H2S) gasotransmitters exhibit potential therapeutic effects in the car-diovascular system. Herein, biomimicking multilayer structures of biological blood vessels, bilayer small-diameter vascular grafts (SDVGs) with on-demand NO and H2S release capabilities, were designed and fabri-cated. The keratin-based H2S donor (KTC) with good biocompatibility and high stability was first synthesized and then electrospun with poly (L-lactide-co-caprolactone) (PLCL) to be used as the outer layer of grafts. The elec-trospun poly (& epsilon;-caprolactone) (PCL) mats were aminolyzed and further chelated with copper (II) ions to construct glutathione peroxidase (GPx)-like structural surfaces for the catalytic generation of NO, which acted as the inner layer of grafts. The on-demand release of NO and H2S selectively and synergistically promoted the proliferation and migration of human umbilical vein endothelial cells (HUVECs) while inhibiting the proliferation and migration of human umbilical artery smooth muscle cells (HUASMCs). Dual releases of NO and H2S gaso-transmitters could enhance their respective production, resulting in enhanced promotion of HUVECs and inhi-bition of HUASMCs owing to their combined actions. In addition, the bilayer grafts were conducive to forming endothelial cell layers under flow shear stress. In rat abdominal aorta replacement models, the grafts remained patency for 6 months. These grafts were capable of facilitating rapid endothelialization and alleviating neo-intimal hyperplasia without obvious injury, inflammation, or thrombosis. More importantly, the grafts were expected to avoid calcification with the degradation of the grafts. Taken together, these bilayer grafts will be greatly promising candidates for SDVGs with rapid endothelialization and anti-calcification properties.