A high failure rate of titanium implants in diabetic patients has been indicated in clinical evidences. Excessive oxidative stress at the bone-implant interface plays an important role in the impaired osteointegration under diabetic conditions. While the underlying mechanisms remain unknown and the targeted treatments are urgently needed. Ophiopogonin D (OP-D), isolated from Chinese herbal Radix Ophiopogon japonicus, is generally reported to be a potent antioxidant agent. In the present study, we hypothesized that OP-D exerted promotive effects on osteointegration against oxidative stress, and investigated the underlying mechanisms associated with alteration of Wnt/β-catenin signaling pathway. Rabbit osteoblasts incubated on titanium alloy implant were co-cultured with normal serum (NS), diabetic serum (DS), DS + OP-D, DS + NAC (a potent ROS inhibitor) and DS + OP-D + Dkk1 (a Wnt inhibitor) for examinations of osteoblast behaviors. For in vivo study, titanium alloy implants were implanted into the femoral condyle defects on diabetic rabbits. Results demonstrated that diabetes-induced oxidative stress resulted in osteoblast dysfunctions and apoptotic injury at the bone-implant interface, concomitant with the inactivation of Wnt/β-catenin signaling. Importantly, OP-D administration attenuated oxidative stress, directly reactivating Wnt/β-catenin signaling. Osteoblast dysfunctions were thus reversed as evidenced by improved osteoblast adhesion, proliferation and differentiation, and ameliorated apoptotic injury, exerting similar effects to NAC treatment. In addition, the positive effects afforded by OP-D were confirmed by improved osteointegration and oetogenesis within the titanium alloy implants in vivo by Micro-CT and histological analyses. Furthermore, the pro-osteogenic effects of OP-D were almost completely abolished by the Wnt inhibitor Dkk1. These results demonstrated, for the first time, OP-D administration alleviated the damaged osteointegration of titanium alloy implants under diabetic conditions by means of inhibiting oxidative stress via a Wnt/β-catenin-dependent mechanism. The OP-D administration would become a reliable treatment strategy for implant failure therapy in diabetics due to the optimal anti-oxidative and pro-osteogenic properties.

临床证据表明，糖尿病患者中钛植入物的高失败率。在糖尿病条件下，骨-植入物界面的过度氧化应激在受损的骨整合中起重要作用。虽然基本机制仍然未知，并且迫切需要靶向治疗。麦冬D（OP-D），选自中药麦冬，据报道是有效的抗氧化剂。在本研究中，我们假设OP-D对骨整合抵抗氧化应激具有促进作用，并研究了与Wnt /β-catenin信号通路改变有关的潜在机制。将在钛合金植入物上孵育的兔成骨细胞与正常血清（NS），糖尿病血清（DS），DS + OP-D，DS + NAC（有效的ROS抑制剂）和DS + OP-D + Dkk1（Wnt抑制剂）检查成骨细胞的行为。对于体内研究表明，将钛合金植入物植入糖尿病兔的股骨dy缺损中。结果表明，糖尿病引起的氧化应激导致成骨细胞功能障碍和骨-植入界面的凋亡性损伤，并伴随Wnt /β-catenin信号的失活。重要的是，OP-D给药可减轻氧化应激，直接激活Wnt /β-catenin信号传导。因此，成骨细胞功能障碍得以逆转，这表现为成骨细胞粘附性，增殖和分化的改善以及凋亡的减轻，与NAC治疗具有相似的作用。此外，OP-D提供的积极作用已通过体内钛合金植入物内部的骨整合和成骨作用的改善得到证实。通过Micro-CT和组织学分析。此外，Wnt抑制剂Dkk1几乎完全消除了OP-D的促成骨作用。这些结果首次证明，OP-D给药通过经由Wnt /β-catenin依赖性机制抑制氧化应激，减轻了糖尿病条件下钛合金植入物受损的骨整合。由于具有最佳的抗氧化和促成骨特性，OP-D给药将成为糖尿病患者植入失败治疗的可靠治疗策略。