分区载药生物可吸收支架的制备及其血管正性重构作用机制的研究

Bioresorbable scaffold (BRS) is an important innovation in the field of vascular interventional therapy, which has been confirmed effective and safe by plenty of clinical studies. Despite all its advantages, a few of problems still remain to be solved, such as subacute stent thrombosis, intimal hyperplasia, unclear mechanism of vascular positive remodeling and so on. In view of these problems, this project intends to fabricate poly L-lactic acid BRS (PLLA BRS) via three-dimensional printing technology on the basis of our previous research, while loading everolimus into struts, and then chemically coating with polyethylene glycol, zwitterion and CD144 antibody in sequence to achieve partitioned drug coating and time sequence release, thus develop a multiple biofunctional BRS with the properties of anti-thrombosis, re-endothelialization enhancement and intimal hyperplasia inhibitation. We will evaluate the biological behavior of BRS (degradation and bio-absorption, re-endothelialization, thrombosis and intimal hyperplasia) and study the morphological and functional repair of target vessel (plaque regression, late lumen gain and vasomotion) through in vivo test, endovascular imaging and histological examination. Besides, gene and protein expression will be analyzed by whole transcriptome sequencing (lncRNA / mRNA) and iTRAQ quantitative protein technique for the further discussion of the possible molecular mechanism of how BRS cause vascular positive remodeling. Consequently, the successful implementation of this project could promote the further conversion of experimental BRS into clinical application.

生物可吸收支架（BRS）是血管介入治疗领域理念与技术的重要创新，已有大量临床研究证实其安全性和有效性，但仍存在亚急性血栓形成、远期内膜增生以及对血管正性重构作用机制不清等问题。针对这些问题，本项目拟结合前期研究基础，应用三维打印技术制备左旋聚乳酸BRS、并在支架体部载入依维莫司，然后在支架表面依次修饰聚乙二醇、两性离子和CD144抗体，实现分区载药、时序控释，从而研制一种具有抗血栓、促内皮化及抑制内膜增生等多重生物学功能的BRS。通过动物体内实验、腔内影像学与组织学检测，研究BRS在体生物学演变与转归（降解吸收、内皮化、血栓形成及内膜增生等）和靶血管形态与功能修复（斑块消退、管腔重获及血管舒缩等）；并采用转录组测序和iTRAQ定量蛋白质技术分析靶血管基因（lncRNA/mRNA）和蛋白质表达，初步探讨该BRS血管正性重构作用的分子机制。本课题的顺利实施可促进实验BRS向临床应用进一步转化。

目前支架植入术已成为治疗血管狭窄性疾病的主要方法之一，但术后较高的支架内再狭窄率严重影响远期效果。尽管药物涂层支架的使用将ISR 发生率降至10%以下，但仍未从根本上解决永久性金属支架自身诸多问题，例如长期物理刺激导致慢性炎症反应，涂层药物导致内皮化延迟、内皮功能紊乱以及晚期支架血栓形成等。为解除永久性支架对血管的“笼蔽效应”（Cage Effect），生物可吸收支架（Bioresorbable Scaffold, BRS）应运而生，并被誉为血管介入治疗领域的第四次革命。本项目针对当前临床使用的BRS易引发亚急性血栓形成、远期内膜增生以及对血管重构作用机制不清等问题，（1）在前期工作基础之上，结合三维打印、化学修饰、分区载药等技术，构建出一种具有多重生物学功能的新型药物涂层BRS（DE-BRS），机械物理、生物力学性能优于传统BRS，实现药物时序控释；（2）通过动物体内外实验，采用影像学、组织学以及分子生物学检测手段，证实该BRS具有良好的抗血栓、促内皮化以及抑制内膜增生等生物学功能;（3）BRS体内生物相容性良好，可长期维持血管通畅、促进血管正性重构；（4）BRS体内降解、吸收过程有待于动物体内实验后期观察与解析。本项目的研究成果将加深临床医学、生物材料学、机械制造等多门学科的有机结合，进一步推动医用生物功能材料的发展。该DE-BRS的研发及相关作用机制阐述对于提高心脏及外周血管疾病介入治疗水平，大幅降低该类疾病的致死、致残率都具有较好科研意义和实用价值。

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