Luetkemeyer Callan M, Neu Corey P, Calve Sarah
bioRxiv. 2023 Feb 3:2023.01.31.526318. doi: 10.1101/2023.01.31.526318.
Soft tissue injuries (such as ligament, tendon, and meniscus tears) are the result of extracellular matrix damage from excessive tissue stretching. Deformation thresholds for soft tissues, however, remain largely unknown due to a lack of methods that can measure and compare the spatially heterogeneous damage and deformation that occurs in these materials. Here, we propose a method for defining : multimodal strain limits for biological tissues analogous to yield criteria that exist for crystalline materials. Specifically, we developed a method for defining injury criteria for mechanically-driven fibrillar collagen denaturation in soft tissues, using regional multimodal deformation and damage data. We established this new method using the murine medial collateral ligament (MCL) as our model tissue. Our findings revealed that multiple modes of deformation contribute to collagen denaturation in the murine MCL, contrary to the common assumption that collagen damage is driven by strain in the fiber direction alone. Remarkably, our results indicated that hydrostatic strain, or volumetric expansion, may be the best predictor of mechanically-driven collagen denaturation in ligament tissue, suggesting crosslink-mediated stress transfer plays a role in molecular damage accumulation. This work demonstrates that collagen denaturation can be driven by multiple modes of deformation and provides a method for defining deformation thresholds, or injury criteria, from spatially heterogeneous data.
软组织损伤（如韧带、肌腱和半月板撕裂）是组织过度拉伸导致细胞外基质损伤的结果。然而，由于缺乏能够测量和比较这些材料中发生的空间异质性损伤和变形的方法，软组织的变形阈值在很大程度上仍然未知。在此，我们提出一种为生物组织定义多模态应变极限的方法，类似于晶体材料中存在的屈服准则。具体而言，我们开发了一种利用区域多模态变形和损伤数据来定义软组织中机械驱动的纤维状胶原蛋白变性损伤标准的方法。我们以小鼠内侧副韧带（MCL）作为模型组织建立了这种新方法。我们的研究结果表明，多种变形模式会导致小鼠MCL中的胶原蛋白变性，这与通常认为胶原蛋白损伤仅由纤维方向的应变驱动的假设相反。值得注意的是，我们的结果表明静水应变或体积膨胀可能是韧带组织中机械驱动的胶原蛋白变性的最佳预测指标，这表明交联介导的应力传递在分子损伤积累中起作用。这项工作表明胶原蛋白变性可由多种变形模式驱动，并提供了一种从空间异质性数据定义变形阈值或损伤标准的方法。
