【作者】 张峰；

【导师】 杨志禄；

【作者基本信息】 西南交通大学 ， 机械工程（专业学位）， 2018， 硕士

【摘要】 血管支架介入治疗因具有创伤小、效果显著等优势,已成为心血管疾病治疗的重要手段之一。然而,临床使用的裸金属支架（BMS）由于自身生物相容性不足等原因,支架植入3-6个月后的再狭窄率高达20-30%。药物洗脱支架（DES）通过释放药物有效的抑制了平滑肌的增殖,将支架再狭窄率降低到10%左右。然而,释放的药物在抑制平滑肌细胞增殖的同时也抑制了内皮细胞的生长,大大延迟了内皮化进程,增加了晚期血栓的风险。目前,临床应用的支架依然面临着再狭窄和晚期血栓两大并发症。健康、完整的内皮层是维持血管微环境稳态、凝血平衡及平滑肌细胞正常生长的关键。而内皮细胞功能的发挥强烈依赖于其持续释放的信号分子一氧化氮（NO）。这是由于NO具有许多重要的生理功能,如:通过上调血小板和平滑肌细胞环磷酸鸟苷（cGMP）合成起到抗凝血和抑制平滑肌细胞增殖的功能,促进受损内皮组织修复等。而这些功能正是理想的血管支架所梦寐以求的。因此,通过表面修饰手段赋予血管支架具有类似天然血管内皮细胞持续、稳定释放NO的功能有望解决血管支架的临床并发症。铜离子,因其具有高效催化血液中NO供体-亚硝基硫醇释放NO的活性,被用于血液接触类材料表面功能修饰,实现内皮细胞功能仿生。然而,金属支架材料表面缺少反应性官能团,使得铜离子在其表面固定成为难点和挑战。多巴胺（DA）,因其具有氧化自聚合、与广谱材料粘附及与过渡金属离子螯合的多重特殊属性,被广泛的用于生物材料表面改性。基于此,本论文立足于创新表面改性技术,发展出一种具有内源性NO供体催化释放功能的金属-儿茶酚表面化学改性方法,实现金属316L不锈钢支架表面内皮细胞功能仿生。利用多巴胺自聚合成膜及螯合金属离子的能力,通过“一步浸涂法”在316L不锈钢支架表面沉积含有Cu^II-DA配位复合物的NO-催化涂层。通过改变涂层制备所用DA和Cu^II的化学计量比调节Cu^II-DA涂层中铜离子的含量,从而实现支架表面NO催化释放速率的精准调控。此外,该涂层能够维持长期、持续、稳定的NO催化释放活性;应用于支架表面改性,该涂层不仅具有优异的粘附能力,且在支架的撑开过程中表现出优异的顺应性,无涂层破损、剥离和脱落问题。系统的血液和细胞相容性评价表明,Cu^II-DA通过催化NO释放,显著的抑制了血小板的粘附/激活、且选择性的促进内皮细胞生长而抑制平滑肌细胞的粘附、增殖和迁移。同时,我们发现,NO对内皮细胞生长行为有着严格的剂量要求,当NO催化释放速率超过6×10^-10 mol×cm^-2×min^-1左右,内皮细胞增殖能力开始下降。半体内血液循环结果表明,该涂层改性的支架材料具有优异的抗血栓能力。体内支架植入结果证明,经Cu^II-DA涂层改性的血管支架能够快速促进内皮再生,有效抑制了内膜的增生和支架再狭窄。更多还原

【Abstract】 Vascular stent for interventional therapy has become an important mean of cardiovascular disease treatment because of its advantages such as small trauma and significant effect.However,due to the lack of biocompatibility,the restenosis rate of bare metal stent（BMS）was 20-30%after the stent implantation for 3-6 months.Drug eluting stents（DES）effectively inhibited the proliferation of smooth muscle cells（SMCs）by releasing drugs.Therefore,the restenosis rate of the stent was reduced to about 10%.In addition to inhibiting the smooth muscle,the drugs released from the stent had a bad effect including inhibiting the growth of endothelial cells,greatly delaying the process of endothelialization and increasing the risk of late thrombus.The clinical application of stent is still facing two major complications of restenosis and late thrombosis at present.A healthy and intact endothelium is the key to maintain the homeostasis of blood vessel microenvironment,coagulation balance and normal growth of SMCs.The function of endothelial cells is strongly dependent on the sustained release of signaling molecules nitric oxide（NO）.This is due to the fact that NO has many important physiological functions,such as upregulating platelet and smooth muscle cell cyclic guanosine monophosphate（cGMP）synthesis to achieve anticoagulant and inhibiting the proliferation of smooth muscle cells,and promoting the repair of damaged endothelial tissue.And these functions are exactly necessary for the ideal vascular stents.Therefore,the function of the vascular stents with the continuous and stable release of NO by means of surface modification is expected to solve the clinical complications of vascular stent.Therefore,the vascular stent function of sustained and stable release of NO similar to natural vascular endothelial cells which is given by surface modification is expected to solve the clinical complications of vascular stent.Copper ion which has the activity of highly efficient catalyzing the release of NO from the NO donor-nitroso alcohol in the blood is used to modify the surface function of the blood contact materials to realize the biomimetic function of endothelial cells.However,the lack of reactive functional groups on the surface of metal scaffolds makes it difficult and challenging to immobilized copper ions on the surface.Dopamine（DA）has been widely used in the surface modification of biomaterials because of its self-polymerization,adhesion to broad-spectrum materials and chelating with transition metal ions.Based on this,this paper is established in the innovative surface modification technology.A metal catechol surface chemical modification method with endogenous NO donor catalytic release function has been developed to realize the biomimetic function of endothelial cell function on the surface of metal 316L stainless steel scaffold.The NO-generating coating containing Cu^II-DA coordination compound was deposited on the surface of 316L stainless steel scaffold by"one step dip coating"by using the ability of dopamine self polymerization and chelating metal ions.The precise regulation of NO catalytic release rate on the surface of the scaffold is achieved by changing the stoichiometric ratio of DA and Cu^II to adjust the content of copper ions in the Cu^II-DA coating.In addition,the coating can maintain long-term,sustained,and stable NO release activity.Applied to the surface modification of the stent,the coating not only has an excellent adhesion ability,but also exhibits excellent compliance during the stenting process without coating damage,peeling,and shedding.The systemic blood and cell compatibility evaluations indicated that Cu^II-DA inhibited platelet adhesion/activation by selectively catalyzing NO release as well as selectively promoted endothelial cell growth and inhibits smooth muscle cell adhesion,proliferation,and migration.At the same time,we found that NO has a strict dose requirement for the growth behavior of endothelial cells.When the rate of NO release exceeded 6×10^-1010 mol cm^-2 min^-1,the proliferation of endothelial cells began to decline.The blood circulation resulted in the half-body show that the coating modified scaffold material had excellent antithrombotic ability.The results of in vivo stenting demonstrated that the vascular stent modified by the Cu^II-DA coating could rapidly promote endothelial regeneration and effectively inhibit the proliferation of intima and stent restenosis.更多还原