Structural optimization analysis of endothelial cell remodeling to fluid flow

A finite element analysis using structural optimization method was performed to simulate the remodeling of bovine aortic endothelial cells (BAECs). BAECs showed marked elongation and aligned in the flow direction after exposing to shear stress of 2 Pa for 24 hours. An atomic force microscope (AFM) was used to measure cell surface geometries, showing that the peak cell height decreased significantly from 2.8 ± 1.0 μm (mean ± SD) to 1.4 ± 0.5 μm with fluid flow. The fluorescence images showed that control cells exhibited dense peripheral bands of F-actin filaments, while sheared cells exhibited centrally located F-actin stress fibers parallel to the flow direction. A finite element model was generated on the basis of the cell surface geometries, in which elastic modulus of each element was changed in accordance with an objective stress together with update of cell shape. The results showed that the cell height decreased with fluid flow and the higher elastic modulus appeared in the upstream region of the nucleus in the final step, which may correspond with cytoskeletal structure. The present analysis should be effective for clarifying the remodeling of endothelial cells.