Collagen fibrils from both positional and energy-storing tendons exhibit increased amounts of denatured collagen when stretched beyond the yield point.
Collagen fibrils from both positional and energy-storing tendons exhibit increased amounts of denatured collagen when stretched beyond the yield point.
复制标题
当拉伸超过屈服点时，来自位置肌腱和储能肌腱的胶原原纤维表现出变性胶原蛋白的数量增加。
DOI：
10.1016/j.actbio.2022.11.018
复制
发表时间：
2023
影响因子：
9.7
通讯作者：
Weiss,JeffreyA
中科院分区：
文献类型：
--
作者：
Lin,AllenH;Slater,ChristopherA;Martinez,Callie-Jo;Eppell,StevenJ;Yu,SMichael;Weiss,JeffreyA
胶原蛋白分子是肌腱的基本结构单元，在机械过载时会变性。我们最近证明，在肌腱拉伸过程中，胶原蛋白变性发生在位置肌腱和储能肌腱的应力应变曲线的屈服点。我们有兴趣研究这种负载如何在整个胶原蛋白层次结构中转移，并试图确定当胶原纤维被拉伸时胶原蛋白变性的开始。原纤维位于胶原蛋白层次结构中胶原蛋白分子之上的一层，可以更直接地探测应变对胶原蛋白分子的影响。我们从位置肌腱和储能肌腱类型中分离出胶原纤维，并使用微机电系统装置将它们拉伸至不同程度的应变。我们用荧光标记的胶原蛋白杂交肽对原纤维进行染色，这些肽特异性地结合变性胶原蛋白，并检查拉伸超过应力-应变曲线屈服点的样品是否表现出变性胶原蛋白数量增加。我们发现两种肌腱类型的胶原原纤维中的胶原变性发生在屈服点。在产后位置原纤维中发现的变性胶原蛋白数量比在能量储存原纤维中的多。尽管与位置肌腱相比，储能肌腱的原纤维具有更大的屈服应变和屈服应力，但仍然如此。有趣的是，两种肌腱类型的胶原原纤维的峰值模量是相同的。这些结果可能是由于与位置肌腱相比，储能肌腱中的交联密度更大而得到解释。从这项研究中获得的见解可以通过针对原纤维水平的胶原蛋白分子损伤来帮助管理肌腱和其他肌肉骨骼损伤。意义声明当肌腱拉伸或撕裂时，可能会导致胶原蛋白变性（损伤）。根据其生物力学功能，肌腱被认为具有不同交联剖面的位置或能量存储。通过拉伸胶原纤维而不是两种肌腱类型的束，我们可以更直接地检查拉伸拉伸对肌腱中胶原蛋白分子的影响。我们发现，无论肌腱类型如何，当原纤维拉伸超过应力应变曲线的屈服点时，原纤维中的胶原蛋白都会发生变性。这可以深入了解负荷在肌腱损伤和衰竭期间如何影响不同的肌腱亚结构，这将有助于临床医生和研究人员了解损伤机制，并可能将胶原蛋白分子损伤作为治疗策略，从而改善损伤后的临床结果。
Collagen molecules are the base structural unit of tendons, which become denatured during mechanical overload. We recently demonstrated that during tendon stretch, collagen denaturation occurs at the yield point of the stress-strain curve in both positional and energy-storing tendons. We were interested in investigating how this load is transferred throughout the collagen hierarchy, and sought to determine the onset of collagen denaturation when collagen fibrils are stretched. Fibrils are one level above the collagen molecule in the collagen hierarchy, allowing more direct probing of the effect of strain on collagen molecules. We isolated collagen fibrils from both positional and energy-storing tendon types and stretched them using a microelectromechanical system device to various levels of strain. We stained the fibrils with fluorescently labeled collagen hybridizing peptides that specifically bind to denatured collagen, and examined whether samples stretched beyond the yield point of the stress-strain curve exhibited increased amounts of denatured collagen. We found that collagen denaturation in collagen fibrils from both tendon types occurs at the yield point. Greater amounts of denatured collagen were found in post-yield positional fibrils than in energy-storing fibrils. This is despite a greater yield strain and yield stress in fibrils from energy-storing tendons compared to positional tendons. Interestingly, the peak modulus of collagen fibrils from both tendon types was the same. These results are likely explained by the greater crosslink density found in energy-storing tendons compared to positional tendons. The insights gained from this study could help management of tendon and other musculoskeletal injuries by targeting collagen molecular damage at the fibril level.Statement of significanceWhen tendons are stretched or torn, this can lead to collagen denaturation (damage). Depending on their biomechanical function, tendons are considered positional or energy-storing with different crosslink profiles. By stretching collagen fibrils instead of fascicles from both tendon types, we can more directly examine the effect of tensile stretch on the collagen molecule in tendons. We found that regardless of tendon type, collagen denaturation in fibrils occurs when they are stretched beyond the yield point of the stress-strain curve. This provides insight into how load affects different tendon sub-structures during tendon injuries and failure, which will help clinicians and researchers understand mechanisms of injuries and potentially target collagen molecular damage as a treatment strategy, leading to improved clinical outcomes following injury.