Cardiovascular diseases have been the leading cause of death in modern society.Using vascular stents to treat these coronary and peripheral artery diseases has been one of the most effective and rapidly adopted medical interventions.During the twenty-five years’development of vascular stents,revolutionary cardiovascular stents like drug eluting stents and endothelial progenitor cells capture stents have emerged.In this review,the evolution of vascular stents is summarized,aiming to provide a glimpse into the future of vascular stents.Advanced designs,focusing on the investigations of new substrates,new platforms,new drugs and new biomolecules are currently under evaluation with promising clinical studies.The concept of"time sequence functional stent"has been raised in this paper.It presents anti-proliferative properties in the first phase after implantation and subsequently support endothelialization.It also shows long-term inertness without release of toxic ions or toxic degradation products.The success of this concept is briefly presented with a clinical study in this model stents.
Absorbable metals have been widely tested in various in vitro settings using cells to evaluate their possible suitability as an implant material.However,there exists a gap between in vivo and in vitro test results for absorbable materials.A lot of traditional in vitro assessments for permanent materials are no longer applicable to absorbable metallic implants.A key step is to identify and test the relevant microenvironment and parameters in test systems,which should be adapted according to the specific application.New test methods are necessary to reduce the difference between in vivo and in vitro test results and provide more accurate information to better understand absorbable metallic implants.In this investigative review,we strive to summarize the latest test methods for characterizing absorbable magnesium-based stent for bioabsorption/biodegradation behavior in the mimicking vascular environments.Also,this article comprehensively discusses the direction of test standardization for absorbable stents to paint a more accurate picture of the in vivo condition around implants to determine the most important parameters and their dynamic interactions.
Biodegradable magnesium（Mg）-based vascular stents have been designed as temporary scaffolds to treat angiostenotic lesions for the maintenance of normal blood flow.Numerous studies have presented in vitro and in vivo tests for the evaluation of the safety and feasibility of Mg-based vascular stents and the related materials. Therein the cytocompatibility is a basic and important parameter in the evaluation system. In this review, we summarize the applications and limitations of in vitro evaluation methods including basic characterization methods and direct and indirect cytotoxicity tests. We discuss the influencing factors on cytotoxicity, such as surface roughness, preconditioning of sample surface, cell type for the biocompatibility evaluation in direct contact as well as conditions for the formation of extracts/degradation products for indirect assays. Besides, we highlight the recent in vivo animal tests and clinical trials about Mgbased stents along with some associated results. The aim of this review is to provide a meaningful reference in the further developments and related evaluation methods of Mg-based stents.
Ping LiNingling ZhouHua QiuManfred F MaitzJuan WangNan Huang
Surface properties are considered to be important factors in addressing proper functionalities.In this paper,a multifunctional mussel-inspired coating was prepared via the direct copolymerization of epigallocatechin gallate(EGCG)and arginine.The coating formation was confirmed by X-ray photoelectron spectroscopy and Fourier transform infrared spectra.The EGCG/arginine coating contained diverse functional groups like amines,phenols and carboxyls,whose densities were also tunable.Such mussel-inspired coating could also be applied as an ad-layer for its secondary reactivity,demonstrated by quartz crystal microbalance technique.Moreover,the tunable surface density of phenols showed potential ability in modulating endothelial cell and smooth muscle cell viability.The coatings rich in phenols presented excellent free radical scavenging property.Current results strongly indicated the potential of EGCG/arginine coatings to be applied as an ad-layer for vascular materials.
Rifang LuoLinlin TangLingxia XieJin WangNan HuangYunbing Wang
The adsorption of fibrinogen can be used as a quick indicator of surface haemocompatibility because of its prominent role in coagulation and platelet adhesion. In this work the molecular interaction between fibrinogen and a modified titanium oxide surface/platelet has been studied by quartz crystal microbalanee with dissipation （QCM-D） in situ. In order to further characterize the conformation of adsorbed fibrinogen, αC and γ-chain antibody were used to check the orientation and denaturation of fibrinogen on solid surface. QCM-D investiga- tions revealed the fibrinogen have the trend to adsorb on hydropllilic surface in a side-on orientation by positively charged αC domains, which would reduce the exposure of platelet bonding site on γ chain and enable less platelet adhesion and be activated. These obser- vations suggest that certain conformations of adsorbed fibrinogen are less platelet adhesive than others, which opens a possibility for creating a non-platelet adhesive substrates.
An-sha ZhaoZhao WangXiao-hua ZhuManfred F. MaitzNan Huang
