嵌有干细胞阵列的微纳米图案化钛表面杂化结构的仿生构建及对血管内膜体内原位再生影响的研究

Intact endothelium regeneration and endothelial function recovery have been regarded as one of the key methods to solve the problems in clinical application of cardiovascular implantable apparatus, such as thrombosis and intima hyperplasia, and improve their long-term lumen patency. However, there are still many challenges applying this principle in the artificial heart, mechanical circulatory support devices and artificial heart valve. Because of their characteristics, such as surface continuity and non-ingrowth, it’s needed to establish a suitable platform on the material surface for the integration of complex structure factors and the feasible construction strategy to imitate normal vascular tissue structure below endothelium to reveal the law of influence of complex structure factors on in situ endothelium regeneration. On the basis of the principles of tissue engineering and endothelialization, we will focus our research on the following work: Micro stripes array of copper doped TiO2 nanotubes with the feature of hierarchical micro/nano-structure will be used as such integration platform endued with catalytic activity for NO-releasing. Artificial ECM inserted by stem cell arrays will be biomimetic constructed on it and then modified by anti-CD34 serially.This biological hybrid structure will be applied to integrate biological matter in intima and blood. Beneath the artificial ECM, smooth muscle cells differentiated from the stem cells will be arrayed along the blood flow to form pericytes environment for endothelialization. Above the artificial ECM, endothelialization and anticoagulant function will be effectively regulated to accelerate endothelialization and at the same time to ensure that early antithrombogenicity can be maintained until intact endothelium regeneration. Influence of the artificial ECM mentioned above on in vivo endothelialization will be also studied in order to reveal the laws and establish the strategies and methods of endothelium regeneration and endothelial function recovery for achievement of restoration of intima with ordered structure in vivo on the surface.

“生物材料表面内皮完整再生及功能恢复”这一解决心血管系植入装置临床应用问题的关键原则，其应用仍存在诸多挑战。需要在材料表面建立一个结构整合平台、模仿构建正常血管内皮下层组织，用于揭示生物材料表面结构因素对内皮原位再生的影响规律。本研究借鉴组织工程和内皮化的基本技术原理，将微纳米多级结构的铜掺杂TiO2纳米管微条纹作为结构整合平台，赋予其一氧化氮催化释放活性；在其表面仿生构建CD34抗体修饰、嵌有干细胞阵列的胶原基人工ECM，赋予其与血液/血管内膜生物学要素的动态整合性：下层实现对干细胞行为的有效调制，以期获得沿血流取向分布的平滑肌为内皮化提供周细胞环境；上层实现对内皮化和抗凝血功能的有效调控，在加速钛基底材料表面内皮化的同时，确保前期良好的血液相容性。进一步揭示该表面对于体内内皮化的影响规律，建立心血管生物材料表面内皮再生及功能恢复的策略与方法；最终实现高度有序的内膜组织的体内修复/重建。

本项目借鉴组织工程和体内内皮化的基本技术原理，利用TiO2 纳米管微阵列作为心血管生物材料的多功能整合平台，成功构建了基于微纳双尺度结构的嵌有MSCs阵列的复合功能化的胶原基人工ECM。通过微纳双尺度结构有效调控MSCs的自组织分化；通过PDA修饰负载Cu的TiO2 纳米管，改善Cu催化NO释放的动力学行为，在实现对内皮化和抗凝血功能的有效调控的同时，显著消减了表面Cu暴露对MSCs的不利影响。通过揭示这一复合杂化结构与人工ECM上下两侧目标细胞的相互作用，实现了对上层ECs和下层MSCs的有效整合，成功获得了可促进体内内皮再生/修复的复合功能化人工ECM结构。通过对比构建过程形成的不同微纳米（杂化）结构的体内内膜修复效果，（杂化）结构表面，揭示了①微纳米（杂化）结构中嵌入的MSCs和②表面基于基质胶天然多组分复合功能优势构建的胶原基人工ECM是促进内皮再生及功能恢复的关键结构因素，并最终实现了高度有序的内膜组织的体内修复/重建，在大损伤和强刺激的植入条件下仍保证了很高的植入安全性和功能的有效性。从而为心血管生物材料表面改性提供了新的策略与重要技术方法。

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