组织引导性生物材料激活干细胞调控心脏瓣膜再生机制研究

Tissue regeneration is the focus of biomedical research in 21 century. Guided tissue regenerative biomaterials are playing a key role in tissue regeneration and repair. Early study has confirmed that PEG-decellularized valve material has outstanding biomechanical properties, and it would be essential in regulating heart valve regeneration to enhance the property of guiding tissue regeneration and thus obtain cellular constituent and ECM structure that similar to natural valves. In this project, PEG-decellularized valve material will be modified with PEG gels, combining with stem cells and SELEX technology, with which we expect to achieve objects as follows. 1) Guided tissue regenerative materials capable of inducing heart valves regeneration are fabricated by modifying PEG-decelluarized valve materials with double layer PEG gels encapsulating VEGF and BMDCs/TGF-β2. 2) BMDCs could be recruited from blood by aptamers covalently bonded to the PEG gel layers, and then differentiate into endothelial cells by VEGF released from gels; while BMDCs in BMDCs/TGF-β2 PEG gel layer would differentiate into interstitial cells. In this way, the materials could be recellularized and thus provide the foundation of manufacturing a novel substitute of heart valve.3) On this basis we are supposed to clarify the mechanism that how guided regenerative biomaterials recruit and induce BMDCs differentiation and regulate the regeneration of heart valves.

组织再生是21世纪生物医学领域研究的热点，组织引导性生物材料是诱导组织再生和修复的重要载体。课题组前期研究已制备具有独立自主知识产权及良好生物力学性能的PEG-去细胞瓣生物材料。如何进一步赋予其引导组织再生活性，获得类似天然瓣膜的细胞成分和基质结构，是调控心脏瓣膜再生的关键。本项目以PEG-去细胞瓣生物材料为基础，结合SELEX、水凝胶及干细胞技术，旨在实现：1）制备双层PEG水凝胶，分别封装VEGF和BMDCs/TGF-β2，键合PEG-去细胞瓣，获得诱导心脏瓣膜再生的组织引导性生物材料；2）VEGF水凝胶层共价键合适配子，特异性招募诱导循环血BMDCs向内皮细胞分化，同时BMDCs/TGF-β2水凝胶层促进BMDCs向瓣膜间质细胞分化，实现生物材料分层定向再细胞化；3）阐明组织引导性生物材料-BMDCs招募、粘附、分化-心脏瓣膜再生的调控机制，为新型心脏瓣膜替代物研制提供理论依据。

组织再生是21世纪生物医学领域研究的热点，组织引导性生物材料是诱导组织再生和修复的重要载体。本项目利用连续蛋白溶解方法制备了低免疫原性去细胞瓣，SELEX技术筛选出可特异性结合骨髓间充质干细胞（BMSCs）的核酸适配子，通过优化官能团和反应条件获得了最佳基质金属蛋白酶（MMP）敏感型聚乙二醇（PEG）水凝胶，制备了负载基质细胞衍生因子（SDF）-1酶敏感型PEG水凝胶-去细胞瓣与特异性结合CD133适配子-去细胞瓣两种支架，构建了体内诱导心脏瓣膜再生的组织引导性生物材料。负载SDF-1酶敏感型水凝胶-去细胞瓣复合支架能促进BMSCs黏附、增殖和分化，实现支架材料间质细胞化和细胞外基质重塑；特异性结合CD133适配子-去细胞瓣能特异性招募内皮祖细胞，实现支架材料内皮化。初步揭示了负载SDF-1酶敏感型水凝胶-去细胞瓣招募BMSCs，促进后者在材料表面黏附并分化为瓣膜间质细胞，且抑制外周血单个核细胞黏附，促进M2型巨噬细胞浸润，有助调控去细胞瓣再细胞化与细胞外基质重塑。本项目以良好力学性能的PEG-去细胞瓣材料为基础，综合运用SELEX、水凝胶及干细胞技术，制备了具有独立自主知识产权的组织引导性生物材料，特异性招募循环血干细胞，获得类似天然瓣膜的细胞成分和细胞外基质，为新型心脏瓣膜替代物研制提供了理论依据。

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