Biocompatibility of biomaterial designed for the closure of congenital heart defects covalently coated by chitosan/heparin:an in vitro evaluation

Objective To assess the effect of bioactive coating on biocompatibility of Nitiols designed for the closure of congenital heart defects in vitro.Methods We investigated the biocompatibility of Nitinols in 2005—2006,at the Department of Cardiology,the First Affiliated Hospital of Nanjing Medical University.The chitosan(Chi)/heparin(Hep)was covalently immobilized onto the surface of Nitinol slices.The hemocompatibility of biomaterials was evaluated by using the hemolysis test;anticoagulant activity was studied in vitro in a dynamic model with whole blood.Surface characterizations such as protein adsorption and platelet adhesion were performed by using scanning electron microscopy.Cytotoxicity of human umbilical vein endothelial cells(HUVECs)was evaluated with light microscopy,and with fluorescence microscope after double-staining of Ki67 and fibronectin.Results (1)The hemolysis test:White blood count(WBC),red blood count(RBC)and platelet count(PC)were all in normal range and there were no evident difference in each group.The hemolysis rates of biomaterials were all less than 5%.Chitosan(Chi)/heparin(Hep)did significantly prolong the APTT,PT,and TT compared with others;in addition,differential density of Hep coated showed no significant difference.The immobilization of chitosan(Chi)/heparin(Hep)caused that the protein adsorption,platelet adhesion,and thrombus formation were all reduced by the immobilization of Hep.(2)Cyte-compatibility test:After 72 h of incubation,there showed no abnormal morphology.HUVECs were able to grow next to all kinds of slices.By fluorescence microscope adhering cells were typically best to the Fn coating,followed by the basic coating,and then the uncoating.Ki67 expression was mainly HUVEC proliferation decreased in the order:basic coating=uncoatingheparin coating.Conclusion Anti-thrombogenicity in vitro of biomaterials designed for the closure of congenital heart defects can be improved by immobilizing Chi/Hep conjugating onto the surface,but proliferation of HUVEC could be inhibited by Chi/Hep coating.