抗纤维化与促“H”型血管核壳结构生物支架修复临界骨缺损

Critical bone defect repaired with anti-fibrosis and“H”-type core-shell bionic scaffold

背景:在骨组织愈合过程中,促进新生骨的血管化是加速骨组织修复的常用策略,然而骨缺损修复过程中过快的纤维化进程常常被忽略。目的:设计并制备一种具有调节新生骨痂内纤维化及血管化进程的核壳结构仿生支架,表征其物理学特征,验证其体内外抗纤维化与促成骨性能。方法:制备具有调节新生骨痂内纤维化及血管化进程的核壳结构仿生支架,外层壳结构由聚己内酯静电纺丝纳米纤维负载成纤维细胞活化蛋白抑制剂组成,内层核结构由甲基丙烯酸酐明胶水凝胶负载去铁胺组成,表征静电纺丝和水凝胶的物理学特征,利用活死染色与CCK-8实验验证材料的生物相容性。通过成纤维细胞体外实验分析支架壳结构的抗纤维化作用,通过MC3T3-E1细胞体外实验分析支架壳结构中成纤维细胞活化蛋白抑制剂的促成骨作用,通过人脐静脉内皮细胞分析支架核结构中去铁胺的促血管形成作用。通过大鼠临界骨缺损实验评估核壳结构仿生支架的骨修复作用。结果与结论:①核壳结构仿生支架具有良好的生物相容性,静电纺丝技术制备的聚己内酯电纺纤维具有疏水性,在物理层面上有效阻隔外源性纤维组织长入,电纺纤维膜在2周内可有效释放抗纤维化药物成纤维细胞活化蛋白抑制剂,释放的抗纤维化药物可以抑制骨缺损周围成纤维细胞的生长、黏附,有效降低成纤维相关蛋白的表达,同时可促进MC3T3-E1细胞成骨蛋白的表达,加快其矿化速度;支架核结构中的去铁胺可促进人脐静脉内皮细胞的迁移、成管能力,并促进其强烈表达“H”血管特征性蛋白。②在SD大鼠的股骨制造临界骨缺损模型中,相较于聚己内酯膜,核壳结构仿生支架实现了骨缺损的有效修复。③结果表明,核壳结构仿生支架在预防骨痂过度纤维化的同时促进新生骨痂内“H”血管形成,能有效避免骨不连的发生,加速临界骨缺损修复进程。

BACKGROUND:During bone tissue healing,promoting the vascularization of new bone is a common strategy to accelerate the repair of bone tissue.However,the rapid fibrosis process during bone defect repair is often ignored.OBJECTIVE:To design and prepare a core-shell structure bionic scaffold to regulate the process of fibrosis and vascularization in new callus,characterize physical characteristics of the scaffold,and verify the anti-fibrosis and osteogenic properties in vitro and in vivo.METHODS:A core-shell structure bionic scaffold to regulate the process of fibrosis and vascularization in new callus was designed and prepared.The outer shell structure of the scaffold was composed of polycaprolactone electrospun nanofibers loaded with fibroblast activating protein inhibitor;and the inner core structure was composed of gelatin methacrylate hydrogel loaded with deferoxamine.The physical characteristics of electrospun and hydrogel were characterized,and the biocompatibility of the material was verified by live-dead staining and CCK-8 assay.The antifibrotic effect of core-shell structure was analyzed by fibroblast in vitro assay.The osteogenic effect of fibroblast activating protein inhibitor in core-shell structure was analyzed by MC3T3-E1 cells in vitro assay.The vasogenic effect of deferoxamine in core-shell structure was analyzed by human umbilical vein endothelial cells.The effect of bionic core-shell scaffold on bone repair was evaluated by critical bone defect test in rats.RESULTS AND CONCLUSION:(1)The core-shell structure bionic scaffold had good biocompatibility.Hydrophobic polycaprolactone electrospun fibers prepared by electrospinning technology could effectively block the ingrowth of exogenous fibrous tissue on the physical level.The electrospun fiber membrane could effectively release the anti-fibrosis drug fibroblast activating protein inhibitor within 2 weeks,and the released anti-fibrosis drug could inhibit the growth and adhesion of fibroblasts around bone defects,effectively reduced the expression of fibroblast-related proteins,promoted the expression of osteoblast protein in MC3T3-E1 cells,and accelerated its mineralization rate.The deferoxamine in the core-shell structure could promote the migration and vascular formation ability of human umbilical vein endothelial cells,and promoted their strong expression of“H”vascular characteristic protein.(2)In critical bone defect model of SD rats established in the femur,compared with polycaprolactone membrane,the core-shell structure bionic scaffold could effectively repair bone defects.(3)These findings indicate that the core-shell structure bionic scaffold can prevent excessive fibrosis of callus and promote the formation of“H”vessels in the new callus,which can effectively avoid the occurrence of nonunion and accelerate the repair process of critical bone defect.