3D生物打印PEG水凝胶新型复合支架调控心脏瓣膜再生机制研究

There are two key problems need to be resolved for the ideal heart valve prosthesis construction. First, improving the mechanical property of scaffold. Second, accelerating the superficial endothelialization and inner recellularization of scaffold. On this basis of our early study, EPCs aptamer-PEG-decellularized valve scaffold has been constructed. In this project, this scaffold will be modified to mimic the process of repair and regeneration of the native valve. Novel hybrid scaffold was constructed using printing 3D structures of PEG gels covalently crosslinked with decellularized valve and EPCs aptamer, combining with BMSCs and TGF-β2 encapsulated collagen solution, with .which we expect to achieve objects as follows: 1) the mechanical property of novel hybrid scaffold is improved; 2) EPCs could be recruited from blood by aptamers covalently bonded to the PEG gel layer, and accelerating the superficial endothelialization of scaffold, while BMSCs in collagen solution would differentiate into interstitial cells accelerating the inner recellularization of scaffold; 3) we are supposed to clarify the mechanism of stem cells recruit, adhesion, layer-separated growth of cells in scaffold, mechanical property and regulation of the regeneration of heart valve.

目前理想心脏瓣膜替代物研究领域的热点和难点是：1）改善组织工程支架力学性能；2）促进种子细胞在支架中分层生长，即支架表面内皮化和内部再细胞化。本课题组在前期研究制备的内皮祖细胞(EPCs)适配子（aptamer）+聚乙二醇（PEG）+去细胞瓣叶支架基础上进一步改性，模拟正常瓣膜修复和再生过程，采用3D生物打印技术制备具有网格状孔隙结构的PEG水凝胶，再将包裹骨髓间充质干细胞（BMSCs）/转化生长因子-β2（TGF-β2）的胶原液填充于其孔隙中，借助PEG活性基团分别共价键合去细胞瓣叶和aptamer，构建新型复合支架。一方面调整成胶和打印条件，改善支架力学性能；另一方面，aptamer招募循环血EPCs黏附于支架表面实现内皮化，而胶原液中TGF-β2诱导BMSCs向间质细胞分化实现支架内部再细胞化。在此基础上探讨干细胞招募、黏附—支架细胞分层生长—力学性能—心脏瓣膜再生之间的内在调控机制

目前理想心脏瓣膜替代物研究领域的热点和难点是：1）改善组织工程支架力学性能；2）促进种子细胞在支架中分层生长，即支架表面内皮化和内部再细胞化。本课题组在前期研究基础上进一步改性，模拟正常瓣膜修复和再生过程，采用3D生物打印技术将聚乙二醇-海藻酸钠水凝胶交联去细胞瓣膜，并借助聚乙二醇活性基团分别共价键合去细胞瓣叶和适配子，构建新型复合支架。聚乙二醇-海藻酸钠水凝胶交联去细胞瓣膜构建的复合组织工程瓣膜支架具有良好的生物学和生物力学性能，比目前临床上使用的戊二醛交联的瓣膜生物学性能更好，具有成为下一代瓣膜替代物的潜力。适配子可促进内皮祖细胞在去细胞瓣支架上的特异性黏附和增殖，并且适配子固定的去细胞瓣支架能从流体环境中捕获内皮祖细胞。因此，适配子可促进去细胞瓣支架再内皮化。在此基础上初步探讨了干细胞招募、黏附—支架细胞分层生长—力学性能—心脏瓣膜再生之间的内在调控机制。