【作者】 林全愧；

【导师】 沈家骢； 计剑；

【作者基本信息】 浙江大学 ， 材料学， 2010， 博士

【摘要】 血栓和再狭窄是心血管疾病术后面临的两大主要问题。其主要原因是心血管植入材料表面的内皮化不完全或内皮化延迟而导致的凝血或平滑肌增生。植入体材料表面的原位快速内皮化是解决术后血栓和再狭窄的根本途径。本论文针对心血管植入材料表面原位快速内皮化问题,采用层层静电自组装技术,设计了两种不同类型的天然聚电解质多层膜涂层对植入材料进行表面修饰,以期实现材料表面的高内皮细胞选择性粘附和快速内皮化。1.细胞惰性多层膜及其功能化构建内皮细胞选择性粘附界面研究—研究首先利用多层膜的生物大分子固定作用,采用具有抗凝血性的天然聚多糖肝素作为聚阴离子,细胞相容性良好但致凝血性的天然聚多糖壳聚糖作为聚阳离子,在医用聚酯材料PET表面进行层层静电自组装。依据肝素的可扩散性及聚多糖聚电解质多层膜高亲水性特点,构建得到了协同抗凝血及阻抗非特异性细胞粘附的肝素/壳聚糖多层膜涂层。石英晶体微天平(QCM-D)及椭偏仪测试表明了肝素和壳聚糖交替组装到基材表面。对QCM-D和椭偏仪所获得的数据进行分析可以得出,所获得的肝素/壳聚糖多层膜为溶胀的类水凝胶性质的薄膜涂层。QCM-D和紫外光谱结果表明该多层膜涂层在生理缓冲溶液PBS中具有较良好的稳定性。体外血液相容性评价和人血管内皮细胞/平滑肌细胞培养结果表明,该多层膜涂层具有良好的抗凝血和阻抗非特异性细胞粘附的特点。化学交联前后的肝素/壳聚糖多层膜的QCM-D分析和细胞培养结果表明,肝素/壳聚糖多层膜的类水凝胶状溶胀的特点是导致该涂层具有阻抗非特异性细胞粘附性质的主要原因。研究随后通过静电组装在阻抗非特异性细胞粘附的肝素/壳聚糖多层膜表面分别进行血管内皮细胞特异性的REDV短肽和抗CD34抗体分子的固定。体外血管内皮细胞和平滑肌细胞的培养结果表明:REDV短肽功能化和抗CD34抗体功能化的肝素/壳聚糖多层膜都能够获得特异选择性的内皮细胞粘附功能。通过在阻抗非特异性细胞粘附的肝素/壳聚糖多层膜表面修饰内皮细胞特异性的粘附分子可以实现内皮细胞的特异选择性粘附功能。2.细胞活性多层膜及其功能化促进快速内皮化的研究—研究利用抗凝血性的肝素作为聚阴离子,细胞相容性良好但致凝血性的天然细胞外基质组分胶原蛋白作为聚阳离子,在316L医用不锈钢表面进行层层静电自组装。依据肝素的可扩散性和天然生物大分子本身的生物学性质特点,构建得到了协同抗凝血及高内皮细胞相容性的肝素/胶原多层膜涂层。激光共聚焦显微镜和扫描电镜结果表明肝素/胶原多层膜能够实现对不锈钢支架进行表面修饰,获得良好的多层膜涂层支架。体外血液相容性评价和内皮细胞培养结果表明,该多层膜涂层具有良好的抗凝血和高内皮细胞相容性的特点。研究随后通过戊二醛对肝素/胶原多层膜进行化学交联并在其表面固定血管内皮细胞特异性的抗CD34抗体。QCM-D,椭偏仪及酶联免疫吸附测定结果表明了抗CD34抗体在肝素/胶原多层膜表面的成功固定。椭偏仪和QCM-D的结果还表明了化学交联及抗体固定后的多层膜具有比原多层膜更好的静态及流动态的稳定性。体外血管内皮细胞/平滑肌细胞培养结果表明,肝素/胶原多层膜不仅促进内皮细胞的粘附增殖,同样也促进平滑肌细胞的粘附增殖。即单纯的胶原/肝素多层膜不能实现对内皮细胞的选择性诱导。而抗CD34抗体功能化的肝素/胶原多层膜则能获得特异性的内皮细胞快速粘附和快速内皮化。体外内皮细胞活力及NO分泌测定结果表明抗CD34抗体修饰的肝素/胶原多层膜表面的内皮细胞具有很高的细胞活性并且能够很好地保持内皮细胞功能。荧光显微镜照片显示了该抗体功能化多层膜能够对不锈钢支架进行表面修饰。动物体内实验结果表明,抗CD34抗体功能化肝素/胶原多层膜修饰的支架能明显加速血管内皮细胞在支架表面的富集,从而实现快速内皮化。与裸支架及单纯肝素/胶原多层膜修饰支架相比,抗CD34抗体功能化肝素/胶原多层膜修饰的支架能显著减少新生内膜的形成。这种内皮细胞选择性诱导的多层膜涂层支架可能成为通过快速内皮化解决支架术后再狭窄和远期血栓的有效途径。更多还原

【Abstract】 Surface induced thrombosis and restenosis constitute major clinical failures of cardiovascular stent implantation. Previous researches have demonstrated that the occurrences of thrombosis and restenosis are ultimately due to the endothelium injury or delayed/uncompleted endothelialization on the stent. The in situ rapid endothelialization of the implants may be the ultimate solution to the thrombosis and restenosis. Two kinds of natural polyelectrolyte multilayer coatings were designed and coated onto biomedical devices in this dissertation, to realize the high selective attachment of the endothelial cells (EC) and rapid endothelialization on the biomedical material surfaces.1. The study of cell-resistant polysaccharide multilayer and its functionalization for EC selective attachment.—Two natural polysaccharides, antithrombogenic heparin and cytocompatible while thrombogenic chitosan, were chosen as the polyanion and polycation, respectively, to construct polyelectrolyte multilayer on the poly(ethylene terephalate) (PET) surface. Considering that the diffusion property of heparin in the multilayer and the swollen hydrogel-like property of the polysaccharide multilayers, we hypothesis that the multilayer which is fabricated of heparin and chitosan may have the synergic properties of excellent hemocompatibility and non-specifically cell-resistant. Quartz crystal microbalance with dissipation (QCM-D) and spectroscopic ellipsometry results indicate the successful alternate deposition of heparin and chitosan onto the substrate. The analysis of the data from the QCM-D and ellipsometry reveal that the heparin/chitosan multilayer preserves swollen and hydrogel-like property. The QCM-D and Ultraviolet spectroscopy (UV) measurements show that the heparin/chitosan multilayers are stable under PBS incubation and flushing conditions. The in vitro hemocompatibility tests and human vascular EC/smooth muscle cell (SMC) culture results reveal that a surface coating with synergic properties of excellent antithrombogenicity and non-specifically cell-resistant was obtained via layer-by-layer deposition of the heparin and chitosan. Furthermore, the QCM-D analysis and the cell culture results of the heparin/chitosan multilayer before and after chemical crosslinking demonstrate that the swollen and hydrogel-like property of the native heparin/chitosan multilayer is the essential reason to the cell-resistant of this coating.The vascular EC specific adhesive peptide sequence REDV and the vascular EC targeting antibody anti-CD34 were immobilized onto the cell-resistant heparin/chitosan multilayer subsequently. The in vitro human vascular EC/SMC culture results reveal that the functionalization of the REDV and anti-CD34 antibody onto the cell-resistant heparin/chitosan multilayer can achieve specifically selective attachment of vascular EC.2. The study of cell-compatible natural polyelectrolyte multilayer and its functionalization for rapid endothelialization.—Two natural polyelectrolytes, antithrombogenic heparin and cytocompatible while thrombogenic collagen, which is one of the extracellular matrix proteins, were chosen as the polyanion and polycation, respectively, to construct polyelectrolyte multilayer on the 316L stainless steel disk surface. The results of QCM-D, ellipsometry, UV and atomic force microscopy (AFM) results indicate the successful fabrication of heparin/chitosan multilayer. The QCM-D and ellipsometry measurements show that the heparin/collagen multilayers are stable both under PBS incubation and flushing conditions. The in vitro hemocompatibility tests and human vascular EC culture results reveal that an antithromboresistant and EC compatible surface coating was obtained via layer-by-layer deposition of the heparin and collagen. The heparin/collagen multilayer was also performed onto the stainless steel stent surface. The fluorescent photographs show that a smooth and homogenous stent surface coating was obtained via heparin/collagen multilayer modification. The results of scanning electronic microscopy (SEM) and confocal laser scanning microscopy (CLSM) show that good EC affinity of the heparin/collagen multilayer modified stent is also obtained. These results indicate that antithrombogenic and EC favorable surface coating was obtained via layer-by-layer deposition of heparin and collagen onto stent.The vascular EC targeting antibody anti-CD34 was subsequent immobilized onto the cytocompatible heparin/collagen multilayer after glutaraldehyde crosslinking. The ellipsometry and QCM-D results demonstrate that the antibody functionalized multilayer coatings is stable both in static incubation and flushing conditions. The in vitro hemocompatibility tests and EC/SMC culture results indicate that both heparin/collagen multilayers with or without the anti-CD34 antibody functionalization not only preserve good hemocompatibility, but also promote cell attachment and growth notably. The heparin/collagen multilayer coatings show no selectivity in promotion of EC and SMC, whereas the attachment and growth of the vascular EC can be specifically enhanced on the anti-CD34 antibody functionalized heparin/collagen multilayer. The metabolic activity assessment and the NO secretion measurements further indicate that the EC adherent to the anti-CD34 antibody functionalized multilayer surface have better viability and possess the specific function of the natural vascular EC. In vivo experiments indicate that the anti-CD34 antibody can enrich and accelerate the attachment of the vascular cells onto the stent and rapid endothelialization is realized. Compared with bare stents and heparin/collagen multilayer modified stents, the neointimal hyperplasia on the anti-CD34 antibody functionalized multilayer modified stents is significantly inhibited. The success of the anti-CD34 antibody functionalized heparin/collagen multilayer coating in rapid endothelialization and anti-restenosis might indicate that the immobilization of EC specific ligands onto a cytocompatible matrix can be a good approach for in situ endothelialization and a possible solution to in stent restenosis.更多还原