Mouse Achilles tendons exhibit collagen disorganization but minimal collagen denaturation during cyclic loading to failure
Mouse Achilles tendons exhibit collagen disorganization but minimal collagen denaturation during cyclic loading to failure
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DOI：
10.1016/j.jbiomech.2023.111545
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发表时间：
2023-03-20
影响因子：
2.4
通讯作者：
Szczesny，Spencer E.
中科院分区：
文献类型：
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作者：
Pedaprolu，Krishna;Szczesny，Spencer E.
虽然过度使用是肌腱病的一个突出的危险因素，但疲劳引起的结构损伤导致肌腱退变仍不清楚。在某些肌腱中观察到胶原分子的变性和胶原纤维的解体，以响应疲劳载荷。然而，没有研究调查这些形式的组织损伤是否发生在跟腱中，跟腱通常表现为肌腱病。因此，本研究的目的是确定小鼠跟腱是否经历胶原变性和胶原纤维解体时，循环加载失败。与以前对其他储能肌腱的测试一致，我们发现小鼠跟腱的循环负荷产生胶原蛋白分解，但胶原蛋白变性最小。为了确定缺乏胶原蛋白变性是否是小鼠跟腱所独有的，我们单调地加载跟腱和其他小鼠肌腱至失效。我们发现，髌腱也是抵抗胶原变性，但屈趾长肌腱（FDL）和尾腱束没有。此外，跟腱和髌腱具有较低的拉伸强度和模量。虽然这可能是由于组织结构的差异造成的，但跟腱和髌骨肌腱在单调加载期间缺乏胶原蛋白变性很可能是由于其骨插入附近的失效，而FDL和尾肌腱中不存在这种情况。这些发现表明，小鼠跟腱对胶原蛋白原位变性具有抗性，并且跟腱变性可能不是由机械诱导的胶原蛋白分子损伤引起的。
While overuse is a prominent risk factor for tendinopathy, the fatigue-induced structural damage responsible for initiating tendon degeneration remains unclear. Denaturation of collagen molecules and collagen fiber disorganization have been observed within certain tendons in response to fatigue loading. However, no studies have investigated whether these forms of tissue damage occur in Achilles tendons, which commonly exhibit tendinopathy. Therefore, the objective of this study was to determine whether mouse Achilles tendons undergo collagen denaturation and collagen fiber disorganization when cyclically loaded to failure. Consistent with previous testing of other energy-storing tendons, we found that cyclic loading of mouse Achilles tendons produced collagen disorganization but minimal collagen denaturation. To determine whether the lack of collagen denaturation is unique to mouse Achilles tendons, we monotonically loaded the Achilles and other mouse tendons to failure. We found that the patellar tendon was also resistant to collagen denaturation, but the flexor digitorum longus (FDL) tendon and tail tendon fascicles were not. Furthermore, the Achilles and patellar tendons had a lower tensile strength and modulus. While this may be due to differences in tissue structure, it is likely that the lack of collagen denaturation during monotonic loading in both the Achilles and patellar tendons was due to failure near their bony insertions, which were absent in the FDL and tail tendons. These findings suggest that mouse Achilles tendons are resistant to collagen denaturation in situ and that Achilles tendon degeneration may not be initiated by mechanically-induced damage to collagen molecules.