骨质疏松兔松质骨微观结构和微观成分的时间序贯性变化

Temporal Changes of Microarchitecture and Micro-components of Trabecular Bone in Osteoporotic Rabbit Model

目的:研究去势手术建立骨质疏松兔模型中松质骨微观结构和微观成分的时间序贯性变化。方法:40只新西兰白兔随机分为假手术组(sham组,n=20)和骨质疏松组(OP组,n=20)。OP组兔子给予去势手术处理,sham组给予假手术处理。分别于术后的0周、4周、6周、8周,利用DXA测量腰椎骨密度(每组每个时间点选择5只动物)。之后处死动物,采集腰椎标本。利用Micro-CT、FTIR、腰椎轴向压缩试验得到松质骨的微观结构、微观成分(骨矿盐晶体和胶原)和宏观力学参数。利用t检验比较同一时间点两组之间的相关参数。结果:OP组BMD逐渐下降,松质骨微观结构逐渐疏松,微观组成属性逐渐改变,宏观力学强度均逐渐下降。FTIR在4周时即检测到OP组腰椎骨矿盐和胶原基质比(P=0.046)、骨矿盐结晶度(P=0.018)、胶原交联比(P=0.006)发生显著性改变,早于BMD和微观结构的变化。OP组腰椎宏观生物力学强度在第8周时达到最低点(P=0.001)。结论:去势手术后,腰椎松质骨骨矿盐晶体和胶原属性最早发生变化,松质骨微观成分和微观结构的改变是导致椎体强度明显改变的原因。FTIR技术可以较早的检测到骨质疏松发生过程中骨组织微观成分的改变。

Objective： To assess the temporal changes of microarchitecture and micro-components of trabecular bone in osteoporotic rabbit model induced by ovariectomy （OVX）. Methods： 40 rabbits were allocated randomly into 2 groups, Osteoporotic（OP） group（n=20） and sham group（n=20）. OP group received bilateral OVX operation, while sham group only received sham operation. DXA analyses of vertebral body were done at pre-OVX, 4 weeks, 6 weeks and 8 weeks after operation. Then the rabbits were euthanized to get vertebral bodies. Micro-CT was used to get the microarehitectural parameters of vertebral trabecular bone. FT1R tests were used to measure mineral crystal and collagen properties of trabecular bone. Compressive test was performed on L5 vertebrae. Differences in BMD, microarchitectural parameters, micro-components, and macromechanical parameters between two groups at the same time point were compared with independent-samples t test. Results： BMD was deceased, microarchitecture became more damaged, micro-components changed and macromechanical properties became weaker with time going on. FTIR could test the significant differences of mineral crystal （P=0.018） and collagen （P=0.006） properties between OP and sham group 4 weeks after operation, which was earlier than BMD and microarchitecture. Strength of vertebral bodies became weakest at the end of experiment （P=0.001）. Conclusions： The osteoporotic rabbit models were successfully established 8 weeks after OVX operation. The significant changes of mineral crystal and collagen properties could be detectable earliest. The degradations of bone strength were attributed to the changes of microarchitecture and micro-components. FTIR method could detect the changes of mineral crystal and collagen at an early time.