Contribution of collagen fiber undulation to regional biomechanical properties along porcine thoracic aorta.
Contribution of collagen fiber undulation to regional biomechanical properties along porcine thoracic aorta.
复制标题
DOI：
10.1115/1.4029637
复制
发表时间：
2015-05
期刊：
影响因子：
--
通讯作者：
Shahrokh Zeinali-Davarani;Yunjie Wang;Ming-Jay Chow;Raphaël Turcotte;Yanhang Zhang
中科院分区：
文献类型：
--
作者：
Shahrokh Zeinali-Davarani;Yunjie Wang;Ming-Jay Chow;Raphaël Turcotte;Yanhang Zhang
作为主要的细胞外基质成分，弹性蛋白和胶原蛋白在调节主动脉壁的力学特性，从而调节正常的心血管功能方面起着至关重要的作用。主动脉的机械特性，已知随年龄和多种疾病以及与心脏的接近程度而变化，已归因于壁成分的含量和结构的变化。本研究的重点是层特异性胶原蛋白波动在猪胸降主动脉机械性能变化中的作用。平面双轴拉伸试验进行表征超弹性各向异性力学行为的组织从四个位置沿胸主动脉解剖。多光子显微镜用于成像相关的区域微观结构。基于指数和招募的本构模型被用来解释观察到的力学行为，同时考虑到主动脉壁是两层具有独立性质的复合材料。与胸主动脉近端区域相比，在远端区域观察到硬度升高，这与模型中估计的内侧和外膜胶原募集更尖锐和更早一致。多光子图像进一步支持了我们的预测，即远端区域的高刚度与胶原纤维的波动较小有关。基于招募的模型进一步表明，无论位置如何，介质中的胶原蛋白从拉伸开始就被招募，而外膜胶原蛋白则延迟开始参与。进行参数敏感性分析，根据估计模型参数的置信度来区分模型。
As major extracellular matrix components, elastin, and collagen play crucial roles in regulating the mechanical properties of the aortic wall and, thus, the normal cardiovascular function. The mechanical properties of aorta, known to vary with age and multitude of diseases as well as the proximity to the heart, have been attributed to the variations in the content and architecture of wall constituents. This study is focused on the role of layer-specific collagen undulation in the variation of mechanical properties along the porcine descending thoracic aorta. Planar biaxial tensile tests are performed to characterize the hyperelastic anisotropic mechanical behavior of tissues dissected from four locations along the thoracic aorta. Multiphoton microscopy is used to image the associated regional microstructure. Exponential-based and recruitment-based constitutive models are used to account for the observed mechanical behavior while considering the aortic wall as a composite of two layers with independent properties. An elevated stiffness is observed in distal regions compared to proximal regions of thoracic aorta, consistent with sharper and earlier collagen recruitment estimated for medial and adventitial layers in the models. Multiphoton images further support our prediction that higher stiffness in distal regions is associated with less undulation in collagen fibers. Recruitment-based models further reveal that regardless of the location, collagen in the media is recruited from the onset of stretching, whereas adventitial collagen starts to engage with a delay. A parameter sensitivity analysis is performed to discriminate between the models in terms of the confidence in the estimated model parameters.