新型软/硬仿生复合型软骨组织修复支架材料的制备与性能研究

There are technical difficulties in keeping consistency between natural-like tissue environment and mechanical strength during fabricating functional bionic scaffold materials. A novel soft/hard bionic composite scaffold, with both excellent biological properties and matched mechanical strength with cartilage tissue cicatrization, is prepared for cartilage tissue repairing engineering, and the microstructure, physicochemical properties and biological properties are also investigated. The porous hard scaffold of EMPLGA is composed of poly(lactide-co-glycolide) (PLGA) modified by ethylenediamine, and the soft hydrogel system contains gelatin and hyaluronic acid. EMPLGA is obtained by polymerized using ethylenediamine as modifier; and the influence of molding conditions on the microstructure and mechanical properites of the hard scaffold materials is investigated. The hydrogels are developed using bionic method and the componment of the hydrogels, cross-linking method and cross-linking conditions are optimized. The controlled gradual release system loaded bioactive factors is obtained and the gradual release behavior is investigated. The bionic composite scaffolds are prepared by adding hydrogels into the EMPLGA porous hard scaffold using capillarity method, furthermore, the in-vitro and in-vivo degradation behaviors of the composite scaffold are studied so that the degradation speed of the composite scaffold consists with the cicatrization speed of cartilage tissue. In addition, the in-vitro and in-vivo biological properties of the bionic composite scaffolds are investigated, and the effect of the composite scaffold composition, structure and the addion of active functional factor on cartilage tissue repairing is disclosed. This project will supply new perspective and important technical support for the designment of bionic scaffold materias and make a contribution to the revelation on life's mysteries.

在现有的功能仿生支架材料研究中，普遍存在着类天然组织环境与机械强度不能兼顾的技术瓶颈。基于此，本项目拟构建一种新型"软/硬"仿生复合软骨组织修复支架材料，其中多孔型"硬"支架由乙二胺改性聚丙乙交酯（EMPLGA）组成，"软"支架由明胶和透明质酸复合水凝胶体系组成。采用共聚法乙二胺改性聚丙乙交酯，并研究成型参数对"硬"支架微结构和力学性能的影响规律；采用仿生法制备复合水凝胶，并对其组分、交联方法和交联条件进行优化；构建生物活性因子分步控释体系，研究其分步释放行为；利用毛细作用将水凝胶复合到"硬"支架中，采用体外模拟（水解和酶解）和体内降解方法，阐明仿生复合支架体内外的降解机制；探索仿生复合支架在动物体内外的作用模式，揭示软骨修复材料组成、结构和活性功能物质的引入对软骨再生修复的效果。通过本项目的研究，可为新型功能仿生支架材料的设计提供新思路和重要技术支持，并有助于揭示生命体的奥秘。

采用直接接枝和开环聚合法合成了具有不同组成和分子量大小的马来酸酐改性共聚物MPLGA，酸酐接枝率在0.1-10%可调。进一步引入乙二胺改性，获得乙二胺改性聚丙乙交酯EMPLGA。采用滤沥法制备了具有不同孔径（200～500μm），高孔隙率（＞90%）和连通孔结构的硬支架。随着造孔剂颗粒增大，硬支架孔径增大，孔隙率升高，但力学性能下降。. 采用冷冻干燥法制备了Gel/HA软支架（100～400μm）。HA的加入能很好的改善支架材料的亲水性能，但水凝胶的抗压强度降低。采用乳化冷凝法，结合不同后处理方法，制备了表面光滑、表面皱褶和具有多孔结构等三种不同形貌的Gel/HA微球（10～500μm）。采用冷冻干燥法制备了基于明胶/透明质酸的微球/水凝胶复合体系，并携载淫羊藿苷等活性因子，通过控制微球的粒径和交联剂用量等，其释放80%所需时间可在3-5d内可控。. 采用毛细作用法制备了具有“软/硬”复合特征的Gel-HA/EMPLGA水凝胶型/多孔型软骨修复材料。“软/硬”复合软骨修复材料具有三维多孔连通结构，水凝胶粘附在硬支架多孔壁上，孔隙率达90%以上。随着交联剂含量和交联时间的增加，“软/硬”复合支架孔隙率和抗压强度增大，孔径变化不明显。. Gel-HA/EMPLGA“软/硬”仿生复合支架在PBS溶液体外降解，硬支架部分随着EMPLGA分子量增大、乙二胺接枝率的升高和D, L-丙交酯含量增大，其降解速率降低；Gel-HA软支架部分在降解初期无明显变化，随着交联度的增大和明胶含量的升高，其降解速率下降。体内降解呈现出与体外降解相同的变化，但降解速率比体外降解速率较慢，32周尚有少量支架残留。. 生物安全性试验评价表明该“软/硬”支架材料具有优异的生物相容性。以兔子股骨内髁创建软骨缺损模型，用该仿生复合支架修复缺损区域。20周后软骨缺损区纤维组织覆盖，炎症消失，软骨下支架可见血管侵入，支架材料部分降解，该支架材料具有良好的修复能力。活性因子的引入有利于软骨组织的修复。. 这种新型“软/硬”仿生复合型支架材料突破了类天然组织环境与机械强度不能兼顾的技术瓶颈，为解决软骨组织缺损提供了新的思路。