超重环境对骨组织生物力学性能和形态结构的影响

目的 探讨超重环境对骨组织生物力学性能及骨组织形态结构的影响,为航天员和飞行员安全飞行训练及 最大耐受高重力值的确定提供理论支撑。 方法 采用本课题组自主设计的超重加载平台构建超重动物模型,加载 方式为腹背方向承受向心加速度,加速度分别为 5、10、20 g,离心 45 s,1 次/ d,5 d / 周,连续 4 周。 使用 Instron 5865 材料力学试验机对离体骨组织进行三点弯曲试验,通过测量力学参数的变化,分析超重环境对骨组织生物力学性 能的影响;通过双能 X 线骨密度仪扫描、Micro-CT 扫描、骨组织染色等技术,检测骨矿物质含量、骨密度及骨小梁等 形态学参数的变化,观察超重环境对骨组织形态结构的影响。 结果 超重加载可显著降低小鼠胫骨的断裂应力及 弹性模量。 超重环境导致骨组织中骨体积分数下降,骨小梁厚度以及骨小梁数量显著降低,骨小梁排列紊乱。 结 论 超重环境对骨组织生物力学性能及骨组织形态结构的影响与超重载荷的强度密切相关。 低(5 g)强度超重载 荷能够降低骨小梁厚度,但对其力学性能的影响很小。 中(10 g)、高(20 g)强度超重载荷能够显著触发骨流失以 及骨力学性能的下降。 随着超重载荷的增加,机体的生理调节无法阻止骨量和力学性能下降的趋势

Effects of Hyper-Gravity Environment on Biomechanical Properties and Histomorphology of Bone Tissues

Objective To investigate the influence of hyper-gravity environment on biomechanical properties and morphological structure of bone tissues, so as to provide theoretical support for safe flight training of astronauts and pilots and determination of the maximum tolerance value of hyper-gravity. Methods The hyper-gravity animal model was established by using the self-designed hyper-gravity loading platform. The loading mode was the ventral-dorsal direction which was subjected to centripetal acceleration of 5 g, 10 g, and 20 g, respectively (45 s, once a day, 5 d/ week, for 4 weeks). Instron 5865 material testing machine was used to perform three- point bending test on in vitro tibia, and the influence of hyper-gravity environment on mechanical properties of bone tissues was analyzed by measuring changes in mechanical parameters. Dual-energy X-ray absorptiometry, micro-CT scanning and bone tissue staining were utilized to test changes in bone mineral contents, bone mineral density, and to observe the influence of hyper-gravity environment on bone morphology. Results Hyper-gravity loading could reduce fracture stress and elastic modulus of the tibia in mice. The bone volume/ total volume (BV/ TV), trabecular thickness (Tb. Th) and trabecular number (Tb. N) were significantly decreased, and the trabecular arrangement was disordered under hyper-gravity environment. Conclusions The effect of hyper-gravity on biomechanical properties and morphological structure of bone tissues is related to the intensity of hyper- gravity. Low-strength ( 5 g) overload can reduce Tb. Th, but has little effect on its mechanical properties. Moderate ( 10 g) and high-strength ( 20 g) overload can significantly trigger bone loss and decrease bone mechanical properties. With the increase of hyper-gravity load, physiological regulation of the body can not prevent the decline of bone mass and mechanical properties.