Analysis of damage phenomena in cells and informatics of vascular microstructure for medical applications

为了辅助心血管系统的医学诊断和治疗，通过对血管细胞和组织的行为进行数学建模和描述，可以使用数值分析来预测无法从测量中直观推测的现象。本研究从细胞和组织的三维结构出发，进行了实验和理论研究，以再现或预测与主动脉内皮细胞和组织损伤相关的力学行为。肌动蛋白细胞骨架的重构被认为是由损伤引起的。利用激光共聚焦扫描显微镜测量和有限元分析，成功地重建和预测了培养的猪主动脉内皮细胞在准静态或循环拉伸下的三维变形和肌动蛋白应力纤维的形成。Neo-Hookean模型在0.3微米(n=…)的平均误差内再现了细胞的变形形状6)除了顶部体积太小而无法准确检测外，说明细胞的变形可以用一个合适的弹性模型来近似。细胞底部的细胞内应力纤维取向遵循应变极限假设，应变极限为5%。不能仅使用应变极限来预测应力纤维在根尖区域的取向。还测量了暴露于冲击波的培养内皮细胞的增殖率。在5次冲击波作用后，细胞密度在2-4小时内显著高于对照组。猪主动脉组织也暴露在-80℃的最低温度下，观察其应力-应变关系和组织结构，并进行数学建模和数值模拟。尽管行为受损，但主动脉组织并没有硬化，而是变软了。据推测，这种变化是由胶原蛋白成分的机械和结构变化引起的。较少

To assist medical diagnosis and treatment of the cardiovascular system, numerical analyses can be used to predict phenomena which cannot be intuitively speculated from measurements, by mathematically modeling and describing the behaviors of vascular cells and tissues. In this study, both experimental and theoretical studies were carried out taking account of the three-dimensional structure of cells and tissues to reproduce or predict the mechanical behaviors related to damages of aortic endothelial cells and tissues.Remodeling of actin cytoskeletons is thought to be caused by damage. Confocal scanning laser microscopic measurement and finite element analysis were successfully performed for reconstruction and prediction of three-dimensional deformation of cultured porcine aortic endothelial cells and formation of actin stress fibers under quasi-static or cyclic stretching of the substrate. A neo-Hookean model reproduced the deformed shape of cells within a mean error of 0.3 microns (n = … More 6) except for the top region which has too small volume to detect accurately, indicating that the cellular deformation can be approximated by an adequate elastic model. Intracellular stress fibers at the cell bottom oriented following the strain limit hypothesis with 5% strain limit. The orientation of stress fibers in the apical region was not predicted using the strain limit only.Proliferation rate was measured for cultured endothelial cells which were exposed to shock waves. After 5 pulses of shock waves, the cell density increased significantly in 2-4 hours compared to the control.Porcine aortic tissues were also exposed to freezing with the minimum temperature of -80 degrees C. Their stress-strain relationships and histological structures were examined, and a mathematical modeling and numerical simulations were carried out. The aortic tissue was not hardened and rather softened in spite of the damaged behavior. It is speculated that such change was caused by mechanical and structural changes in collagenous components. Less