Bilayer vascular grafts incorporated with S-nitrosated keratin nanoparticles and resveratrol to enhance long-term nitric oxide release and endothelialization.

Intimal hyperplasia, thrombosis formation, and vascular calcification are the leading causes of failure in small-diameter vascular grafts. In the study, bilayer vascular grafts with separately released nitric oxide (NO) and resveratrol (RESV) were fabricated. S-nitrosated keratin nanoparticles (KNPs) were synthesized and subsequently electrospun with poly(ε-caprolactone) (PCL) to prolong the NO release for up to 25 d in the presence of ascorbic acid and trypsin, serving as the inner layer of grafts. Additionally, RESV was incorporated into poly(L-lactide-co-ε-caprolactone) (PLCL) fibers to alleviate oxidative stress and inflammation, acting as the outer layer of the grafts. The PCL/KNPs//PLCL/RESV bilayer grafts were capable of promoting endothelial cell proliferation while inhibiting the excessive proliferation of smooth muscle cells. Notably, bilayer grafts could regulate macrophage polarization toward the M2 phenotype. In rat abdominal aorta replacement models, the grafts retained patency for 3 months. These grafts could accelerate endothelialization without apparent intimal hyperplasia, thrombosis, inflammation, and calcification. These bilayer grafts are promising for small-diameter tissue-engineered vascular grafts. STATEMENT OF SIGNIFICANCE: • S-nitrosated keratin nanoparticles (KNPs) were synthesized and subsequently electrospun to prolong the NO release for 25 d • Resveratrol (RESV) was incorporated into PLCL fibers to alleviate oxidative stress and inflammation. • Bilayer grafts promoted EC proliferation while inhibiting SMC proliferation. • Bilayer grafts accelerated endothelialization without intimal hyperplasia, thrombosis, and calcification in vivo.