微纳米形貌表面改性改善糖尿病致钛合金植入物失稳的作用及机制研究

Titanium (Ti) and Ti-based materials have been the most widely used medical biomaterials as bone substitutes for orthopedic applications with favorable clinical results. But the implant stability is not satisfied with the diabetic patients, whose incidence of implant destabilization reaches up to 10%-20%. Our previous study suggested that oxidative stress at the “titanium-bone” interface is an important reason for implant destabilization. However, the underlying mechanisms have not been systemically illustrated, neither have there been specifically effective managements. Our preparing experimental results and previous literature reviews demonstrated that: reactive oxygen species (ROS) firstly inhibited osteoblast adhesion at the “titanium-bone” interface under diabetic condition. Micro/nano-textured topography surface modification was capable of activating focal adhesion kinase (FAK), which mediated cellular adhesion and triggered downstream osteoblastic signaling BMP-2/Smad. On the basis of the above researches, the present study would investigate the promotive effect of micro/nano-textured titanium alloy surface on titanium implant destabilization induced by ROS overproduction under diabetic condition and the underlying molecular mechanisms. To achieve this goal, the in vivo and in vitro “titanium-bone” interface model would be established to investigate the supporting influence of micro/nano-textured titanium surface on FAK-mediated osteoblast adhesion. In addition, the promotion of FAK-BMP-2/Smad signaling pathway involved and the eventual implant osteointegration would also be explored. From the present study, an in depth understanding of the promotive effect of micro/nano-textured topography surface on titanium implant stability and the underlying mechanisms may provide theoretical supports in decreasing the implant failure and improving efficacy of clinical therapy.

医用钛合金作为使用最广泛的骨植入材料有着良好的临床治疗效果，然而糖尿病患者钛植入物失败率高达10%-20%。本课题组前期研究发现“钛—骨”界面氧化应激是导致钛植入物失稳的重要原因，然而尚未对其机制进行系统性阐明，也缺乏针对性改善措施。我们的预实验结果结合文献回顾表明：糖尿病条件下，活性氧簇（ROS）会首先抑制界面成骨细胞的粘附功能；钛合金微纳米形貌表面改性能够激活调控粘附的粘着斑激酶（FAK）；而FAK对下游成骨通路BMP-2/Smad起重要的调控作用。本课题拟在此基础上，深入探究微纳米形貌改性改善糖尿病环境中ROS过量累积致钛植入物失稳的作用及分子机制。通过建立体内、外糖尿病条件下“钛—骨”界面模型，研究微纳米形貌改性改善FAK介导的细胞粘附的效果，及其对FAK-BMP-2/Smad通路表达和最终骨整合的促进作用，为临床治疗和预防糖尿病患者钛植入物失稳提供理论依据。

项目背景：流行病学研究表明，糖尿病患者钛金属植入物失稳率较正常人群显著增加，“钛金属—骨质”界面上活性氧簇（reactive oxygen species，ROS）爆发导致成骨细胞的生物功能受损是重要原因。然而具体分子生物学机制尚不明确，切目前缺乏有效的改善措施。金属材料表面微形貌改性及生物涂层修饰是两种可行的改性手段。.研究内容：本研究使用3D打印技术制造孔隙均匀的钛金属支架，建立体外、体内 “钛-骨”界面模型。使用酸蚀和阳极氧化技术构建钛金属表面微纳米形貌改性，使用冻干法进行丝素蛋白涂层修饰，通过体外进行成骨细胞黏附、增殖、分化、凋亡功能，分子生物学检测，氧化应激及抗氧化水平检测，体内进行显微CT分析、组织学染色，评价两种改性方式对糖尿病环境中钛金属骨整合效果的改善作用并分析分子机制。.重要结果及关键数据：糖尿病环境中两种改性方式均能改善成骨细胞各项生物功能，其中微纳米形貌改性显著改善细胞黏附功能，黏附相关的FAK磷酸化增强，FAK介导的BMP-2/Smad通路显著激活，从而改善了细胞成骨分化功能。丝素蛋白显著降低ROS水平，ROS密切调控的NF-κB通路表达下调，细胞生物功能改善，凋亡损伤减轻。动物实验中显微CT和组织学结果显示：与单纯支架相比，两种改性支架内部可见更多的连续新生骨分布，同时钛金属与新生骨整合效果更好。.科学意义：本研究深入揭示了糖尿病介导的高ROS导致钛金属内植物失稳的内在原因，并针对性的提出了微形貌改性和生物材料修饰这两种物理和生物学改性方式。特别提出了FAK-BMP-2/Smad通路和NF-κB通路一正一反的调控作用。两种改性方式将为解决糖尿病致钛金属植入物失稳的研究提供重要的思路和实验依据，同时相关产品的研发将造福广大糖尿病及相关代谢性疾病患者，具有重大的科学意义。