The presence of polymer coating on a coronary stent is a major mediator of coronary inflammation reaction thereby affects re-endothelialization. Poly(styrene-block-isobutylene-block-styrene) (SIBS) is one of the most attractive alternatives to serve as stent coating, but has shown less than optimal biocompatibility. Increasing the sulfonic acid content in the polymer can result in increased strength and hydrophilicity. The present study was undertaken to determine the mechanism of action and in vivo efficacy of sulfonated SIBS (S-SIBS) designed specifically as a stent polymer with reduced inflammatory potential and greater endothelialization preservation potential. The blood compatibility of S-SIBS in vitro and its ability to support the attachment of human umbilical vein endothelial cells (HUVECs) were first assessed to get some insight into its potential use in vivo. Baer metal stent (BMS), S-SIBS-coated stent without drug (BMS Plus S-SIBS), standard drug-eluting stent (DES) and S-SIBS-coated drug-eluting stent (DES Plus S-SIBS) were then implanted in the coronary arteries of a porcine model. Neointimal hyperplasia was evaluated at 28 and 180 days, and re-endothelialization was evaluated at 7 and 28 days post stents implantation. The results showed that DES Plus S-SIBS exhibited similar ability to reduce neointimal hyperplasia but preserved endothelialization compared with standard DES. These results suggest potentially promising performance of S-SIBS-coated stent in human clinical applications of coronary stenting.
[Show abstract][Hide abstract] ABSTRACT: As a biostable elastomer, the hydrophobicity of styrenic block copolymer (SBC) intensely limits its biomedical applications. In order to overcome such shortcoming, the SBC films were grafted with hyaluronic acid (HA) using a coupling agent. The surface chemistry of the modified films was examined by ATR-FTIR and XPS techniques, and the surface morphology was visually described by AFM. The biological performances of the HA-modified films were evaluated by a series of experiments, such as protein adsorption, platelet adhesion, and in vitro cytocompatibility. It was found that the HA-modified samples showed a low adhesiveness to fibroblast at the initial stage; however, it stimulated the growth of fibroblast. The L929 fibroblast growth presented a strong dependence on the molecular weight (MW) of HA. The samples modified with 17kDa HA exhibited the worst wettability and platelet adhesion, while providing the best results of supporting fibroblast proliferation.
[Show abstract][Hide abstract] ABSTRACT: Angioplasty with stents is the most important method for the treatment of coronary artery disease (CAD). However, the drug-eluting stents (DES) which have been widely used nowadays have the increased risks of inflammatory reactions and late stent thrombosis (LST) due to the persistence of polymer coatings. To improve the bio-safety, a novel polymer-free composite drug-eluting coating composed of magnetic mesoporous silica nanoparticles (MMSNs) and carbon nanotubes (CNTs) is constructed using the electrophoretic deposition (EPD) method in this study. A crack-free two-layered coating with impressive "network" nanotopologies is successfully obtained by regulating the composition and structures. This nanostructured coating exhibits excellent mechanical flexibility and blood compatibility in vitro, and the drug-loading and release performance is satisfactory as well. The in vivo study shows that this composite coating has obvious advantages of rapid endothelialization due to its unique 3D nanostructured topologies in comparison with the commercial polymer-coated DES. This study is aimed to provide new ideas and reliable data to design novel functional coatings which could accelerate the re-endothelialization process and avoid inflammatory reactions, thus improving the in vivo bio-safety of DES.
[Show abstract][Hide abstract] ABSTRACT: Cardiovascular implants find wide clinical applications, making a great contribution to the treatment of cardiovascular diseases. Such devices, endovascular stents, artificial vascular grafts, prosthetic heart valves to name a few typical examples, have been the mainstay of cardiovascular surgery. However, failure cases of the implants still exist, which urge us to understand what has happened at the blood-contacting interface and how the tissues have responded during the post-implantation period. Aiming to eliminate these pathological events, various approaches of surface modification of the cardiovascular devices have been used in order to improve hemocompatibility and cytocompatibility. In this review, the blood-biomaterial interfacial events and the evolution of the surface modification strategies are discussed, together with the recent developments on the surface modification of cardiovascular materials like biomimetic extracellular matrix and accelerated endothelialization. These novel surface modification strategies open a new chapter on designing ideal blood-friendly implantable materials. (C) 2013 Published by Elsevier B.V.
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