Step-wise CAG@PLys@PDA-Cu^(2+)modification on micropatterned nanofibers for programmed endothelial healing

Native-like endothelium regeneration is a prerequisite for material-guided small-diameter vascular regeneration.In this study,a novel strategy is proposed to achieve phase-adjusted endothelial healing by step-wise modification of parallel-microgroove-patterned(i.e.,micropatterned)nanofibers with polydopamine-copper ion(PDA-Cu^(2+))complexes,polylysine(PLys)molecules,and Cys-Ala-Gly(CAG)peptides(CAG@PLys@PDA-Cu^(2+)).Using electrospun poly(L-lactide-co-caprolactone)random nanofibers as the demonstrating biomaterial,step-wise modification of CAG@PLys@PDA-Cu^(2+)significantly enhanced substrate wettability and protein adsorption,exhibited an excellent antithrombotic surface and outstanding phase-adjusted capacity of endothelium regeneration involving cell adhesion,endothelial monolayer formation,and the regenerated endothelium maturation.Upon in vivo implantation for segmental replacement of rabbit carotid arteries,CAG@PLys@PDA-Cu^(2+)modified grafts(2 mm inner diameter)with micropatterns on inner surface effectively accelerated native-like endothelium regeneration within 1 week,with less platelet aggregates and inflammatory response compared to those on non-modified grafts.Prolonged observations at 6-and 12-weeks post-implantation demonstrated a positive vascular remodeling with almost fully covered endothelium and mature smooth muscle layer in the modified vascular grafts,accompanied with well-organized extracellular matrix.By contrast,non-modified vascular grafts induced a disorganized tissue formation with a high risk of thrombogenesis.In summary,step-wise modification of CAG@PLys@PDA-Cu^(2+)on micropatterned nanofibers can significantly promote endothelial healing without inflicting thrombosis,thus confirming a novel strategy for developing functional vascular grafts or other blood-contacting materials/devices.