The dynamics of collagen uncrimping and lateral contraction in tendon and the effect of ionic concentration
The dynamics of collagen uncrimping and lateral contraction in tendon and the effect of ionic concentration
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DOI：
10.1016/j.jbiomech.2013.06.029
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发表时间：
2013-09-03
影响因子：
2.4
通讯作者：
Soslowsky, Louis J.
中科院分区：
文献类型：
--
作者：
Buckley, Mark R.;Sarver, Joseph J.;Soslowsky, Louis J.
在拉伸载荷下，肌腱经历了一些独特的结构变化，这些变化决定了其力学响应。例如，已知拉伸肌腱可诱导波浪形胶原原纤维的渐进式“解卷曲”和由组织流出的液体介导的广泛侧缩。然而，尚不清楚这些过程是否相互依赖。此外，胶原解卷曲的速率依赖性及其对肌腱粘弹性力学性能的贡献尚不清楚。因此，本研究的目的是(a)开发一种方法，允许同时测量动态载荷下肌腱的卷曲、应力、轴向应变和侧向收缩；(b)通过测试不同肿胀状态下的肌腱，确定胶原解卷曲与侧缩的相互依赖性；(c)评估胶原蛋白解卷曲过程如何依赖于加载速率。将不同离子环境下的小鼠尺侧腕屈肌腱动态拉伸至设定的应变水平，利用平面偏光镜对其进行成像。对所得图像的分析允许直接测量卷曲频率和间接测量肌腱厚度。我们的研究结果表明，胶原解卷曲和侧缩可以独立发生，而间质液直接影响肌腱力学。此外，拉伸应力、横向收缩和胶原解卷曲程度均与速率相关，表明胶原解卷曲在肌腱的动态力学响应中起作用。本研究首次描述了肌腱中胶原蛋白解卷曲的时间依赖性，并建立了健康肌腱的结构-功能关系，可用于更好地理解和评估疾病或损伤后肌腱力学的变化。(C) 2013 Elsevier Ltd.版权所有。
Under tensile loading, tendon undergoes a number of unique structural changes that govern its mechanical response. For example, stretching a tendon is known to induce both the progressive "uncrimping" of wavy collagen fibrils and extensive lateral contraction mediated by fluid flow out of the tissue. However, it is not known whether these processes are interdependent. Moreover, the rate-dependence of collagen uncrimping and its contribution to tendon's viscoelastic mechanical properties are unknown. Therefore, the objective of this study was to (a) develop a methodology allowing for simultaneous measurement of crimp, stress, axial strain and lateral contraction in tendon under dynamic loading; (b) determine the interdependence of collagen uncrimping and lateral contraction by testing tendons in different swelling conditions; and (c) assess how the process of collagen uncrimping depends on loading rate. Murine flexor carpi ulnaris (FCU) tendons in varying ionic environments were dynamically stretched to a set strain level and imaged through a plane polariscope with the polarizer and analyzer at a fixed angle. Analysis of the resulting images allowed for direct measurement of the crimp frequency and indirect measurement of the tendon thickness. Our findings demonstrate that collagen uncrimping and lateral contraction can occur independently and interstitial fluid impacts tendon mechanics directly. Furthermore, tensile stress, transverse contraction and degree of collagen uncrimping were all rate-dependent, suggesting that collagen uncrimping plays a role in tendon's dynamic mechanical response. This study is the first to characterize the time-dependence of collagen uncrimping in tendon, and establishes structure-function relationships for healthy tendons that can be used to better understand and assess changes in tendon mechanics after disease or injury. (C) 2013 Elsevier Ltd. All rights reserved.