负载双因子的纳米水凝胶/PET复合材料促进人工韧带-骨整合的效应及机制研究

The anterior cruciate ligament reconstruction is one of the research focuses of sports medicine. A number of clinical studies have shown the efficacy and safety of artificial ligaments is satisfied in the short-middle term, but there are risks such as graft loosening and rupture in the long term, which is attributed to the poor graft-bone healing resulted from the low bioactivity of artificial ligaments. The preliminary study of hydroxyapatite (HAp) coating on the poly (ethylene terephthalate) (PET) surface could effectively induce the osteoblast differentiation, but the graft-bone healing in vivo is not stable due to the low binding force and uniformity of the coating. This study is supposed to use silk fibrin as organic substrate and HAp as inorganic component. Silk fibrin/HAp hydrogel combined with heparin microsphere loaded with VEGF and BMP-2 was used to modify the PET surface via photochemical crosslinking method. In vitro tests on cell compatibility, in vivo animal experiments, biomechanical tests are used to evaluate the effect of the modified material and multi-factor timing management on vascularization and osteoinduction comprehensively, investigating its mechanism on promoting osseointegration, thus providing experimental and theoretical basis for the further development of highly active artificial ligament material meeting the clinical requirements.

前交叉韧带损伤重建术的移植物选择是运动医学研究的热点和难点。临床研究表明聚对苯二甲酸乙二醇酯(PET)人工韧带的中短期疗效及安全性较为满意，但仍存在远期移植物松动断裂等风险。其主要原因是PET材料细胞相容性及骨诱导性能较差而造成的移植物—骨整合不佳。我们的前期研究表明，在PET人工韧带材料表面行羟基磷灰石（HAp）涂层可一定程度诱导自体骨长入，但涂层不均及与材料间结合不牢等问题限制了其应用，且其体内促进移植物—骨整合效应有限。本项目拟以天然高分子丝蛋白为有机基体，HAp为无机组份，并通过肝素微球分别负载VEGF和BMP-2制备双因子丝蛋白/HAp复合水凝胶，并经光化学交联法将水凝胶与PET材料复合，构建一体化的人工韧带—骨复合材料。从细胞学、组织学、生物力学等多层面进行综合评估，验证其双因子时序递送及促移植物—骨整合效能并探讨其内在机制，为研制符合临床需求的人工韧带材料提供实验和理论依据。

前交叉韧带（Anterior cruciate ligament，ACL）损伤会导致膝关节不稳，进而发生退变，ACL重建是治疗ACL损伤的重要手段。人工韧带是ACL重建的重要移植物，但人工韧带生物相容性且成骨诱导性差，可能导致移植物-骨整合不良，严重影响ACL重建的远期预后。针对人工韧带的不足，项目负责人根据申请书内容和实际情况开发了免疫成骨活性人工韧带和人工韧带-人工骨一体化移植物。免疫成骨活性人工韧带通过化学接枝和物理吸附的方法将硫酸软骨素（CS）和骨形成蛋白-2（BMP-2）负载在人工韧带上。CS能够调节免疫微环境，促进巨噬细胞向M2修复型极化，同时能够增强BMP-2的成骨能力，有效改善人工韧带的不足。而人工韧带-人工骨一体化移植物则采用膜引导的软硬界面设计策略，将具有成骨诱导性的人工骨与人工韧带有机结合，在保留人工韧带高强度力学性能的同时，提高移植物成骨诱导能力。两种新型人工韧带移植物均有效改善了既往人工韧带生物相容性和成骨诱导性差的不足，具备较高的临床转化前景。此外，项目负责人还对肌腱再生植入物进行了一定探索，对超细纤维/纳米纤维芯鞘纱线编织支架和脐带来源植入物促进髌腱再生的效果及机制进行了研究。