静脉注射导电纳米凝胶诱导低氧微环境促进心肌功能重建的研究

Myocardial tissues injured during myocardial infarction (MI), which would lead to heart failure, are one of the leading causes of death. Surgical treatments of MI, including injectable myocardium tissue engineering, will cause new damages to the infracted myocardium. With the rapid development of nanotechnology, the functional nanoparticles with rational structures and properties can be taken by intravenous injection, providing a new strategy to treat MI. In this proposal, a conductive nanogel system constructed by self-assembly forming phenylboronic acid ester bond is designed to target the two main clinical symptoms of MI which are of the lack of electrophysiological signal transduction in infarcted zone and difficult vascularization of neo-myocardium. After intravenous injection, the nanogel will be aggregated in MI zone due to the Enhanced Permeability and Retention (EPR) effects, thus promoting the electrophysiological signaling of damaged myocardium. Meanwhile, the laccase encapsulated in the nanogel can consume oxygen to catalyze the oxidation of ferulic acid, and induce a hypoxia microenvironment to up-regulate the expression of hypoxia-inducible factor and promote the vascularization process. This project aims to build a conductive nanogel system to achieve the treatment of MI through intravenous injection, expecting to drastically relieve the pain of patients during clinical treatments and reduce complex surgical procedures. This design concept of conductive nanogel system broadens the application scope of traditional nanogels which are merely used as drug-loading vectors; the success of our proposal would provide a new way to facilitate the treatment of MI efficiently.

心肌梗死引起的心肌损伤，进而发展导致心力衰竭是全球最首要的致死原因之一。目前心肌梗死的手术治疗，包括可注射型心肌组织工程的方式都会给薄弱、受损的心肌带来新的危害。随着纳米技术的快速发展，合理设计的功能型纳米粒子给静脉注射治疗心肌梗死提供了新思路。本项目针对心梗区电生理信号传导缺失和新生心肌血管化困难的两大临床症状，通过自组装形成苯硼酸酯键构建导电纳米凝胶体系；其经静脉注射后能通过EPR效应富集于心梗区，促进受损心肌的电生理信号传导；同时负载的漆酶会消耗氧气催化氧化纳米凝胶体系中阿魏酸基团，诱导心梗区产生低氧微环境，上调缺氧诱导因子的表达，促进心梗区血管化。本项目考虑减轻临床治疗心梗患者的痛苦和复杂的手术程序，构建设计导电纳米凝胶体系，探索静脉注射治疗心梗的新策略。该导电纳米凝胶的设计理念突破了传统纳米凝胶仅仅作为药物载体的观点，本项目的成功实现有望给心梗治疗提供方便高效的新途径。

心肌梗死（MI）是全球最首要的致死原因之一，心梗发生后，受损心肌内发生微环境变化（缺血缺氧、炎症反应、氧化应激，电信号异常）使心肌细胞坏死,纤维瘢痕形成，造成心室重构和心功能下降。因此对MI的治疗一直面临很大挑战。本课题针对MI微环境的改变及静脉注射纳米粒子难以靶向心梗区域的问题，发展了多功能可注射凝胶和心肌补片，取得了如下成果：（1）构建了负载干细胞的可注射水凝胶体系。设计制备了导电可注射水凝胶，负载质粒DNA-eNOs（内皮型一氧化氮合酶）纳米复合物和脂肪间充质干细胞（ADSCs）用于心肌梗死的治疗，通过导电水凝胶、ADSCs以及eNOs的上调表达三者的联合作用来修复受损的心肌组织。发展了负载功能化间充质干细胞聚集体（FMA）的可注射透明质酸基水凝胶，将负载功能化间充质干细胞聚集体的水凝胶注射到梗死区，有效地减少心梗区域的纤维化进一步扩大，并抑制心室不良重构。（2）设计制备了ROS响应型载中药丹参酮药可注射凝胶体系，丹参酮明显减少大鼠心梗面积，提高心室壁厚度。（3）黏附性导电贴片与可注射水凝胶联合应用治疗心肌梗死。制备了多巴胺接枝的明胶（GelDA），再将多巴胺改性聚吡咯得到（DA-PPy）与GelDA混合，通过FeCl3引发体系形成具有粘附性导电性的水凝胶（GelDA/DA-Py）。将该黏附水凝胶补片贴附到心梗区外部，而氧化透明质酸（HA-CHO）与酰肼化透明质酸(HHA)凝胶直接注射到心脏内部。这种联合治疗与单一方法治疗相比显著促进了梗死区域的血管再生。（4）发展了负载人工凋亡细胞（AACs）和血管内皮生长因子（VEGF）的可注射水凝胶体系，通过AACs对免疫的调控降低炎症反应和促进原位血管再生提高了对MI的治疗效果。（5）构建了中草药交联的携带rBMSCs@聚两性离子微凝胶的生物大分子水凝胶。中药葛根素（PUE）反应交联可注射水凝胶缓解梗塞区域的氧化应激，装载在聚两性离子微凝胶的MSCs保持高的存活率和干性。由于该凝胶体系对梗死区微环境的调节和干细胞旁分泌作用，纤维化减少，心室壁厚度增加，新生血管形成能力提高，显著恢复了心脏功能和心室结构。本项目成果为心肌梗死治疗提供了新的策略。