Hypoxia, the result of disrupted vasculature, can be categorized in the main limiting factors for fracture healing. A lack of oxygen can cause cell apoptosis, tissue necrosis, and late tissue healing. Remedying hypoxia by supplying additional oxygen will majorly accelerate bone healing. In this study, biphasic calcium phosphate (BCP) scaffolds were fabricated by robocasting, an additive manufacturing technique. Then, calcium peroxide (CPO) particles, as an oxygen-releasing agent, were coated on the BCP scaffolds. Segmental radial defects with the size of 15 mm were created in rabbits. Uncoated and CPO-coated BCP scaffolds were implanted in the defects. The empty (control) group received no implantation. Repairing of the bone was investigated via X-ray, histological analysis, and biomechanical tests at 3 and 6 months postoperatively, with immunohistochemical examinations at 6 months after operation. According to the radiological observations, formation of new bone was augmented at the interface between the implant and host bone and internal pores of CPO-coated BCP scaffolds compared to uncoated scaffolds. Histomorphometry analysis represented that the amount of newly formed bone in the CPO-coated scaffold was nearly two times higher than the uncoated one. Immunofluorescence staining revealed that osteogenic markers, osteonectin and octeocalcin, were overexpressed in the defects treated with the coated scaffolds at 6 months of postsurgery, demonstrating higher osteogenic differentiation and bone mineralization compared to the uncoated scaffold group. Furthermore, the coated scaffolds had superior biomechanical properties as in the case of 3 months after surgery, the maximal flexural force of the coated scaffolds reached to 134 N, while it was 92 N for uncoated scaffolds. The results could assure a boosted ability of bone repair for CPO-coated BCP scaffolds implanted in the segmental defect of rabbit radius because of oxygen-releasing coating, and this system of oxygen-generating coating/scaffold might be a potential for accelerated repairing of bone defects.

中文翻译：

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用于加速骨骼再生的释氧支架

缺氧是脉管系统破裂的结果，可以归类为骨折愈合的主要限制因素。缺氧会导致细胞凋亡，组织坏死和晚期组织愈合。通过提供额外的氧气来纠正缺氧，将大大促进骨骼的愈合。在这项研究中，双相磷酸钙（BCP）支架是通过自动浇铸（一种增材制造技术）制造的。然后，将过氧化钙（CPO）颗粒作为氧气释放剂涂覆在BCP支架上。在兔中产生了15 mm的节段性径向缺损。将未涂覆和CPO涂覆的BCP支架植入缺损处。空的（对照组）没有接受植入。术后3个月和6个月通过X射线，组织学分析和生物力学测试研究了骨的修复，术后6个月进行免疫组织化学检查。根据放射学观察，与未涂覆的支架相比，在植入物和宿主骨之间的界面和CPO涂覆的BCP支架的内部孔之间增加了新骨的形成。组织形态计量学分析表明，在CPO涂层支架中新形成的骨骼数量几乎是未涂层骨骼的两倍。免疫荧光染色显示，在术后6个月，用涂层支架治疗的缺损中成骨标记物，骨连接素和八钙都过表达，与未涂层支架组相比，骨形成分化和骨矿化程度更高。此外，涂层支架在手术后3个月的情况下具有优异的生物力学性能，涂层支架的最大弯曲力达到134 N，而未涂层支架的最大弯曲力为92N。该结果可确保由于释放氧气涂层而增强了植入在兔the骨节段缺损中的CPO涂层BCP支架的骨修复能力，并且这种产生氧气的涂层/支架系统可能具有加速骨骼修复的潜力。缺陷。