基于电导活性/强度可控的新型心肌组织工程用智能水凝胶的研制及其评价

"Soft"and "wet"hydrogel with simulated cardiac extracellular matrix is an ideal scaffold for cardiac tissue engineering. However, the poor mechanical strength and low electrical conductivity limits their applications in cardiac tissue engineering. First, this project intends to design and prepare the double network (DN) hydrogel with controllable mechanical strength. The hydrogel will has appropriate stiffness similar with nature myocardial tissue and flexibility to adapt the contraction-stretch of heart. Moreover, it also has the self-healing capabilities for the tiny cracks of hydrogel. Second, the conductive polymer (e.g. polyaniline) will be grafted on the chitosan molecule via radical polymerization. Electroconductive DN hydrogels (EDN) with controllable mechanical strength will be prepared using the chitosan-g-conductive polymer as the raw materials. Then, some bioactive molecules will be introduced into the EDN hydrogel to build the controlled release system for cardiac tissue engineering. On this basis, the EDN hydrogel's modulation raw and molecular mechanisms on physiological behavior of cardiomyocytes will be investigated in vitro. The matching character between mechanical properties of EDN hydrogel and behavior of heart's contraction-stretch will be studied in vivo. The effect of conductive properties of EDN hydrogel for the integration of EDN hydrogel and host myocardium also will be studied in vivo. The project is expected to fundamentally solve the poor mechanical properties and low electrical conductivity of hydrogel for cardiac tissue engineering. In addition, this project also can provide the new ideas and technology to develop novel smart hydrogel for cardiac tissue engineering.

具有模拟心肌细胞外基质的"软""湿"水凝胶是一类理想的心肌组织工程用支架材料，但其力学性能和导电性能较差的本质属性限制了其在心肌组织工程中的应用。本项目拟首先从天然心肌的力学特性入手，设计并制备刚性/柔性链结构和纳米粒子增强型力学强度可控的双网络（DN）水凝胶，该水凝胶不仅具有与天然心肌相似的刚度和适应心脏有节律收缩-舒张的柔度，且具有凝胶内部微小裂痕自愈能力。其次，将聚苯胺等导电高分子通过氧化聚合接枝到壳聚糖分子链上，并以此为基材构筑心肌适应性电导活性/强度可控双网络（EDN）水凝胶及活性分子程序性释放体系。在此基础上，体外研究EDN水凝胶对心肌细胞生物学行为的作用规律及分子机制，体内探索其力学性能与心脏收缩-舒张的匹配性、导电特性与宿主心肌整合的内在关系。本项目有望从根本上解决心肌组织工程用水凝胶力学性能和导电性能差的缺点，为研制新型的心肌组织工程用水凝胶提供新的思路和技术途径。

以支架材料和种子细胞为基础的心肌组织工程是目前被认为最具前景的心梗治疗新方法。其中，支架材料起非常关键的作用。传统的具有良好生物相容性的支架材料能够支持细胞的粘附和生长，但其力学性能和导电性能较差的本质属性限制了其在心肌组织工程中的应用。本项目旨在研制适合心肌组织工程应用的导电支架材料，经过四年的研究，取得以下研究进展：1、采用“一步法”设计并研制了系列具有良好导电特性和力学强度的水凝胶或多孔支架材料，明确了其组成/结构和力学/导电性能之间的内在关系。此外，为了调控心梗恶劣的氧自由基微环境，研制了多种兼具导电和抗氧化性能的支架材料,建立了心肌组织工程用导电支架制造技术平台；2、以棕色脂肪干细胞（BADSCs）为模型细胞，明确了支架材料力学性能和导电特性对BADSCs存活、增殖及向心肌细胞分化的规律及相关分子机制；3、通过可注射性导电支架材料单独或携带干细胞体内心梗区域注射研究，明确了导电支架材料对心梗微环境的调控作用及对受损心肌的修复效果。这些研究结果表明所研制导电支架材料不仅具有良好的生物相容性，支持BADSCs细胞的粘附，同时能够提高其向心肌细胞分化的能力，提高对受损心肌的修复效果。这些研究成果共发表SCI检索学术论文21篇，申请中国发明专利5项，其中1项获得授权，培养研究生7名,1人获得国家优秀青年科学基金资助。该项目的实施，为开发适合心脏电生理特征和力学特性的支架材料奠定了一定的实验基础。