Heterogeneity of deformation of aortic wall at the microscopic level: Contribution of heterogeneous distribution of collagen fibers in the wall
Heterogeneity of deformation of aortic wall at the microscopic level: Contribution of heterogeneous distribution of collagen fibers in the wall
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DOI：
10.3233/bme-130771
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发表时间：
2013-01-01
影响因子：
1
通讯作者：
Matsumoto, Takeo
中科院分区：
文献类型：
--
作者：
Sugita, Shukei;Matsumoto, Takeo
越来越多的证据表明，胶原纤维在主动脉壁内分布不均。为了研究胶原微结构对局部主动脉壁变形的影响，在双折射成像显微镜下，将猪胸主动脉垂直于径向切成100 μ m厚的薄片，用实验室自制的拉力仪进行双轴拉伸。根据每个50 × 50 μ m(2)面积的细胞核荧光图像计算应变张量分量。测定阻滞Ret和慢轴方位角θ分别作为胶原密度和纤维方向的指标。主动脉壁变形高度不均匀：在主动脉切片中应变的标准偏差明显大于均匀硅胶片的3-5倍。最大主应变方向与θ呈显著负相关（R = -0.077），最小主应变方向与θ呈显著正相关。（r = 0.345）。这表明主动脉在胶原蛋白密度高的区域和胶原纤维排列的方向上不容易扩张。微观异质性可能引起平滑肌细胞的异质性反应，并对主动脉壁的机械稳态有重要影响。
There is growing evidence of heterogeneous distribution of collagen fibers in the aortic wall. To investigate the effects of collagen microstructure on local aortic wall deformation, porcine thoracic aortas were sliced into 100 mu m-thick sections perpendicular to their radial direction and stretched biaxially with a laboratory-made tensile tester under a microscope equipped with a birefringence imaging system. Strain tensor components were calculated from fluorescent images of the cell nuclei for each 50 x 50 mu m(2) area. Retardance Ret and slow axis azimuth theta were measured as indices of collagen density and fiber direction, respectively. Aortic wall deformation was highly heterogeneous: standard deviations of strains were significantly larger, by 3-5 times, in aortic slices than in homogeneous silicone sheets. A significant negative correlation was found between maximum principal strain and theta (R = -0.077), and a positive correlation between minimum principal strain direction and. (R = 0.345). These indicate that the aorta is less distensible in areas with higher collagen density and in the direction of collagen fiber alignment. Microscopic heterogeneity may induce heterogeneous responses of smooth muscle cells and have crucial effects on mechanical homeostasis in the aortic wall.