具有原位催化一氧化氮释放的内皮功能仿生涂层用于心血管支架表面改性研究

Based on the recognition of the complications such as thrombus, inflammatory response, intimal hyperplasia and restenosis caused by stent intervention, a targeted strategy which can repair and cure the lesions of blood vessel was proposed. To achieve this goal, a nitric oxide (NO)-producing coating that has multiple functions such as anticoagulant, antiproliferative and anti-inflammatory properties and ability to promote re-endothelialization was presented as a vascular stent coating. The NO-producing coating was obtained by covalent conjugation of 3,3-diselenodipropionic acid (SeDPA) with glutathione peroxidase (GPx)-like catalytic activity to generate NO from S-nitrosothiols (RSNOs) via specific catalytic reaction in blood. The SeDPA was immobilized to an amine bearing plasma polymerized allylamine (PPAam) surface (SeDPA-PPAam). Here, the release rate of NO produced by the SeDPA-PPAam was adjusted and controlled by changing the amount of SeDPA on immobilized PPAam that can be accomplished through varying the density of primary amine groups of PPAam coatings. By means of evaluating the NO catalytic activity of SeDPA-PPAam, and the effects of NO produced by SeDPA-PPAam on hemocompatibility, growth behavior of endothelial cells (ECs), smooth muscle cells (SMCs) and inflammatory cells, reduction in restenosis and late stent thrombosis to understand the relationship between the NO release kinetics and physiological function, so as to provide the basic knowledge and serve as a guide for the design of the new type of the stent based on NO-functionalization.

针对血管支架在植入过程中存在的血栓、炎症反应、内膜增生和再狭窄等并发症，项目针对性的提出构建具有抗凝、抗炎、抑制内膜增生和内皮再生等多功能的支架涂层研究策略，实现病变血管修复和治愈。基于天然内皮层持续释放的一氧化氮（NO）同时兼有以上多重功能的特点，本项目选用富含胺基的等离子体聚烯丙胺（PPAam）涂层作为支架改性平台用于共价固定3,3’-二硒代二丙酸（SeDPA），实现血液环境下原位催化释放NO。项目通过调控PPAam涂层表面胺基密度控制SeDPA接枝量，从而实现对NO催化释放速率的仿生调控。通过评价NO-催化涂层支架的NO催化活性、血液相容性以及对平滑肌细胞、内皮细胞和炎性细胞的作用行为，建立NO催化释放动力学与其生理功能之间的相关性，进一步探索NO-催化涂层支架对再狭窄及晚期血栓的综合作用行为，为基于NO催化释放的内皮功能仿生涂层应用血管支架表面改性提供理论指导和奠定技术基础。

晚期血栓和再狭窄围是血管支架在临床上面临的两大并发症。提高支架生物相容性是降低支架内再狭窄和晚期血栓的有效手段之一。一氧化氮（NO）,主要是由内皮细胞（ECs）通过其分泌的一氧化氮合酶与精氨酸作用产生，而持续释放的NO不仅是维持心血管体内平衡和调节血管舒张的一个关键因素，而且NO还有具有许多重要的生物学功能如：抑制血小板激活、抑制平滑肌细胞（SMCs）增殖等功能。除此之外，NO在动脉粥样硬化预防和治疗方面也有着极为重要的作用。值得一提的是，NO在EPCs动员、分化中同样起着重要的作用。NO所具有的这些独特的生物学功能使其成为修饰血液接触类材料或器械（如血管支架）的理想分子。为了实现血管支架表面NO释放的功能，本研究借助于不依赖于基底材料性质的等离子体聚合这一通用表面改性技术，在支架表面预先沉积一层与基底材料具有牢固结合力且富含伯胺基官能团的PPAam涂层，再以PPAam表面的伯胺基为反应位点，结合碳二亚胺化学偶联技术，在其表面共价固定具有催化内源性供体亚硝基硫醇（RSNO）产生NO活性的联系化合物3,3’-二硒代二丙酸（SeDPA），以实现基于NO催化释放的内皮细胞功能仿生表面设计。研究结果表明，该SeDPA功能修饰的支架具有持续、稳定催化NO释放功能。通过持续释放NO，支架表面有效的抑制了血栓的形成，促进了内皮快速再说，显著的抑制了支架再狭窄。