骨种植体表面微纳米形貌和压力对间充质干细胞成骨分化的联合作用和机制研究

Titanium (Ti) based load bearing bone implants have been widely used in the orthopedic and dental clinics, yet further improvement is necessitated in terms of the long healing period for osseointegration establishment and the high failure rate. To that end, most of the current studies concentrate on the surface modification of Ti implants, such as the micro/nanotopographical modification. Mechanical stimuli are widely known to modulate the bone metabolism, and recently the evidences from clinics indicate that the mechanical stimuli also play a pivotal role in affecting the osseointegration of the load bearing bone implants. However, the combined effect of mechanical stimuli and implant surface micro/nanotopography on the functions of bone related cells and implant osseointegration as well as the underlying molecular mechanism are largely unclear. Based on our previous studies on the effect of micro/nanotopography on the functions of the mesenchymal stem cells (MSCs), this study is designed to uncover the combined effect of the mechanical stimuli and implant surface micro/nanotopography on the functions of MSCs especially osteogenic differentiation, which is the first study on this aspect to the best of our knowledge. First of all, we will establish the in vitro model of biomaterial-cell-pressure based on our preliminary work, and the related parameters will be optimized in terms of not impairing the normal attachment and growth of cells on the Ti substrates. On this in vitro model, a systemic study on the combined effect of mechanical stimuli and implant surface micro/nanotopography on the functions of MSCs especially osteogenic differentiation will be conducted. Then, we will try to uncover the underlying molecular mechenism for the combined effect via confirming the hypothesis that the signal axis of adhesion receptors-Rho GTPases-β-catenin/MAPK is involved. Finally, we will confirm whether it is such a condition in vivo via a simple in vivo model. The results of our present study are hoped to direct the optimization of the in vitro model for the load bearing implant assessment. By involving the mechanical stress, the in vitro model may give a better predication for the in vivo performance of the implants. Meanwhile, the results shall guide the surface topographical designing and optimization in terms of the mechanical stimuli, provide new means to accelerate the osseointegration process via proper mechanical stimuli, and guide the reasonably functional loading for a long-lasting stable implant performance. In addition, the results may also provide clues for achieving better hard tissue regeneration in terms of utilizing the mechanical stimuli.

载荷钛骨种植体广泛应用于临床，但仍需缩短治疗周期和降低失败率。目前研究主要集中在表面修饰如微纳米形貌修饰。临床证据表明力学刺激是种植体骨结合的一个重要且不可避免的影响因素，然而力学刺激与微纳米形貌共同作用时的效果、规律及分子机制尚不清楚。本项目在前期微纳米形貌影响间充质干细胞（MSCs）功能的研究基础上，率先考虑力学刺激与微纳米形貌对MSCs的共同作用和分子机制。首先建立生物材料-细胞-压力模型，对相关参数进行优化。然后基于该模型深入探索微纳米形貌和压力影响MSCs功能的规律及信号通路机制，并在体内动物模型上验证。本研究结果可指导优化载荷骨种植体的体外评价模型，将力学刺激纳入其中以更好地模拟载荷种植体在体内工作的实际情况。同时，研究结果为从力学刺激角度更全面地考虑种植体的表面形貌设计优化和促进其更快更好的骨结合，指导合理载荷保持其长期功能稳定，以及从力学刺激角度促进硬组织再生提供理论依据。

载荷钛骨种植体广泛应用于临床，但仍需缩短治疗周期和降低失败率。目前研究主要集中在表面修饰如微纳米形貌修饰。临床证据表明力学刺激是种植体骨结合的一个重要且不可避免的影响因素，然而力学刺激与微纳米形貌共同作用时的效果、规律及分子机制尚不清楚。本项目在前期微纳米形貌影响间充质干细胞(MSCs)功能的研究基础上，率先考虑力学刺激与微纳米形貌对MSCs的共同作用和分子机制。我们在前期微米坑/纳米管结构的基础上，还研发了梯度纳米管/纳米粒结构和梯度微米坑/纳米柱结构。我们发现0-120 kPa的静态正压力未导致钛表面MSCs的凋亡。0-120 kPa静态正压力条件下，随着压力值的增大，细胞伸展面积更大，细胞骨架更清晰。静态正压力显著促进胶原分泌和细胞外基质矿化，微纳米形貌表面的胶原分泌量和矿化度高于光滑表面。β-catenin和MAPK通路参与介导微纳米形貌和力学刺激对细胞功能的调控。体内实验表明，加力组的骨结合情况优于非加力组。本研究结果可指导优化载荷骨种植体的体外评价模型，将力学刺激纳入其 中以更好地模拟载荷种植体在体内工作的实际情况。同时，研究结果为从力学刺激角度更全面 地考虑种植体的表面形貌设计优化和促进其更快更好的骨结合，指导合理载荷保持其长期功能 稳定，以及从力学刺激角度促进硬组织再生提供理论依据。