The influence of age on adaptive bone formation and bone resorption
The influence of age on adaptive bone formation and bone resorption
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DOI：
10.1016/j.biomaterials.2014.07.051
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发表时间：
2014-11-01
期刊：
影响因子：
14
通讯作者：
Willie, Bettina M.
中科院分区：
文献类型：
--
作者：
Birkhold, Annette I.;Razi, Hajar;Willie, Bettina M.
骨是一种具有巨大适应能力的组织，能够平衡吸收和形成过程。众所周知，机械负荷会使这种平衡转向增加的形成，从而增强骨量和机械性能。目前尚不清楚的是，这种对机械负荷的适应性反应如何随着年龄的增长而变化。通过动态微断层扫描，我们发现在经受两周体内循环载荷的活小鼠胫骨内小梁骨的结构适应性变化会随着衰老而改变。对10周、26周和78周大的动物进行比较，发现适应能力有所下降。引人注目的是，适应是不对称的，因为负荷增加了形成，而不是减少了吸收。这种不对称进一步改变了（重新）模型的平衡，使之随着年龄的增长而净骨质流失。负荷导致矿化骨的表面积大大增加。有趣的是，在所有年龄组中，骨小梁的吸收厚度与负荷无关。这些数据表明，在青年时期，机械刺激诱导骨建模细胞的招募，而在老年时期，只有骨形成细胞受到影响。这些发现为引导小鼠和其他哺乳动物骨骼衰老的过程提供了机制上的见解。(C) 2014 Elsevier Ltd.版权所有。
Bone is a tissue with enormous adaptive capacity, balancing resorption and formation processes. It is known that mechanical loading shifts this balance towards an increased formation, leading to enhanced bone mass and mechanical performance. What is not known is how this adaptive response to mechanical loading changes with age. Using dynamic micro-tomography, we show that structural adaptive changes of trabecular bone within the tibia of living mice subjected to two weeks of in vivo cyclic loading are altered by aging. Comparisons of 10, 26 and 78 weeks old animals reveal that the adaptive capacity diminishes. Strikingly, adaptation was asymmetric in that loading increases formation more than it reduces resorption. This asymmetry further shifts the (re)modeling balance towards a net bone loss with age. Loading results in a major increase in the surface area of mineralizing bone. Interestingly, the resorption thickness is independent of loading in trabecular bone in all age groups. This data suggests that during youth, mechanical stimulation induces the recruitment of bone modeling cells whereas in old age, only bone forming cells are affected. These findings provide mechanistic insights into the processes that guide skeletal aging in mice as well as in other mammals. (C) 2014 Elsevier Ltd. All rights reserved.