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

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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