具有微导管结构的微纤增强聚谷氨酸基可注射水凝胶及其软骨缺损修复研究

The injectable hydrogel with connected porous structure provides an ideal way to repair cartilage defect in clinical practice, which can ensure a supply of sufficient space for cell growth and extracellular matrix (ECM) secretion, contribute to nutrient exchange, so as to support and promote cartilage regeneration. In this project, the soluble gelatin microsphere is used as a porogen of macropore. The gelatin microfiber which can be dissolved in a phased manner is served as both porogen of microtube and microfiber reinforcement of the hydrogel. The microfiber reinforced poly(L-glutamic acid) based injectable hydrogel with microtube structure will be fabricated through inter-macromolecular Schiff base /Diels-Alder chemical crosslinking. The hydrogel mimics the composition and structure of natural ECM. In situ incorporation of macropore and microtube structure is expected to solve the problem of small pore size and lack of internal pore connectivity for traditional injectable hydrogels, thus creating a microenvironment favoring cartilage regeneration. The hydrogel with the combination of the dual network and microfiber composite reinforcement is expected to effectively solve the problem of insufficient mechanical strength of the injectable pore-forming hydrogel. The structure and properties of the hydrogels will be studied, and a rabbit articular cartilage defect model will be established to evaluate the effect of injectable hydrogel on repair the cartilage defects. The project will provide a scientific basis for the design and study of efficient, safe, simple injectable hydrogel system used in the regeneration of cartilage defect.

具有内部连通多孔结构的可注射水凝胶可为细胞生长和细胞外基质（ECM）分泌提供空间，并有利于营养物质供给，从而支持和促进软骨再生，为临床软骨缺损修复提供一条有发展潜力的新途径。本项目在以可溶性明胶微球为大孔致孔剂基础上，提出以分阶段溶出的明胶微纤为微导管致孔剂和微纤增强体，通过高分子间席夫碱/Diels-Alder化学交联，构建具有微导管结构的微纤增强聚谷氨酸基可注射水凝胶。该水凝胶模拟天然ECM的组成和结构。通过原位定制内部连通微导管和大孔结构，解决传统可注射水凝胶孔隙尺寸偏小、内部孔贯通性不足的难题，创造利于软骨再生的微环境。结合双网络与微纤复合增强机制，可有效改善原位致孔水凝胶机械强度不足的问题。对该可注射水凝胶的结构和性能进行深入研究，并建立兔关节软骨缺损模型，评价该可注射水凝胶对软骨缺损修复效果。该项目为设计和研究有效、安全、简便的软骨缺损修复用可注射水凝胶提供科学依据。

可注射性水凝胶通过微创方式植入，可填充任意形状的缺损，为软骨缺损修复与再生提供了一条有发展潜力的新途径。具有内部连通多孔结构的可注射水凝胶可为细胞生长和细胞外基质分泌提供空间，从而支持和促进软骨再生。本项目通过原位定制内部连通大孔结构，解决传统可注射水凝胶孔隙尺寸偏小、内部孔贯通性不足的难题，创造利于软骨再生的微环境。本项目开展工作如下：1）以可溶性明胶微球为大孔致孔剂，进一步引入纳米纤维素晶须或明胶微纤为增强剂，构建晶须增强原位致孔聚L-谷氨酸/海藻酸钠/聚乙二醇（PLGA/ALG/PEG）双网络可注射水凝胶和明胶微纤复合原位致孔葡聚糖/羧甲基壳聚糖（Dex/CMCS）可注射水凝胶。2）通过模板挤出法制备具有温敏性的明胶微纤，并以此为致孔剂，以壳/核结构的聚乳酸/明胶短纤维为增强剂，构建具有微孔道结构的纤维复合羧甲基醛基化聚乙二醇/壳聚糖（APA/CMCS）可注射水凝胶。3）基于“碎胶重组”策略，通过机械破碎获得的微凝胶间双重动态作用（席夫碱反应和静电作用）实现重组，构建可注射大孔壳聚糖/聚乙二醇-硅钨酸（CS/PEG-SiW）双网络水凝胶。对上述可注射水凝胶的结构和性能进行深入研究，揭示其凝胶化过程、原位致孔机理、双网络与微纤复合增强机制。上述水凝胶具有相互连通的大孔结构，同时保持良好的机械强度。水凝胶具有良好的生物相容性，可为细胞的存活与增殖、细胞外基质分泌和成软骨分化提供了良好的环境，可有效促进大鼠膝关节软骨缺陷的修复。该项目为设计和研究有效、安全、简便的软骨缺损修复用可注射水凝胶提供科学依据。另外，通过席夫碱交联和非共价nHA-BP螯合制备纳米羟基磷灰石/聚（L-谷氨酸）-葡聚糖（nHA/PLGA-Dex）双交联可注射水凝胶，该水凝胶具有良好的组织粘附性、自愈合和成骨活性，成功用于大鼠颅骨缺损修复，为临床应用提供科学依据。