Regulation of macrophage polarization and promotion of endothelialization by NO generating and PEG-YIGSR modified vascular graft

As an effective clinic treatment for cardiovascular disease, vascular transplantation gains much acceptance recently. However, due to the acute thrombosis and intimal hyperplasia, long-term failure of synthetic grafts after implanted in small diameter blood vessel decelerates its commercial use. The continued acute inflammation and delayed endothelialization have been considered as fundamental reasons. To enhance the adhesion and organization of endothelial cells (ECs) and improve the vascular remodeling process, we have constructed a vascular graft based on electrospun polycaprolactone (PCL) matrix, on which organoselenium-immobilized polyethyleneimine (SePEI) for in situ nitric oxide (NO) generation and hyaluronic acid (HA) grafted with poly (ethylene glycol) (PEG) modified Tyr-Ile-Gly-Ser-Arg (YIGSR) for antifouling and EC adhesion were deposited through electrostatic layer-by-layer assembly. The in vitro results showed that SePEI deposited on the grafts could catalyze stable generation of NO. After in situ implantation in rats for 4 and 8 weeks, the graft promoted the transformation of macrophages into an anti-inflammatory phenotype (M2), which helped endothelium remodeling. YIGSR on the outmost layer facilitated more rapid and organized EC adhesion compared to PCL and non-modified grafts. PEG polymer chain on the outmost layer mitigated nonspecific adsorption of undesirable blood components. In our study, we first demonstrated the regulation of macrophage polarization by an NO-generating vascular graft. The results indicated that the approach of anti-inflammatory macrophage polarization and enhanced endothelialization through NO generation and PEG-modified YIGSR in our study may provide a new perspective for the clinic application of cell-free small-diameter vascular grafts.