Naoya Sakamoto

Responses of Living Cells to Hydrodynamic Stimuli Due to Fluid Flow

Cells, the basic units of our body, are constantly exposed to fluid-dynamic stimuli. Typical examples are the epithelial cells of tubular organs, including blood and lymphatic vessels and renal tubes, which are in direct contact with flowing fluid. In addition, other cell types such as smooth muscle cells, fibroblasts, articular chondrocytes, and bone cells are subjected to interstitial fluid flow, which is the movement of fluid through the extracellular matrix of tissues elicited by differences in hydrostatic pressure and deformation of tissues. Fluid-dynamic stimuli can modulate cell alignment, proliferation, differentiation, migration, and cytokine secretion. These morphological and functional responses of cells play important roles not only in the maintenance of physiological functions of tissues but also in the development and progression of disease. Many attempts have been made to understand the effect of fluid-dynamic stimuli on cells. This chapter summarizes cellular responses induced by such stimuli, mainly focusing on the effect of shear stress on vascular cells, which have been extensively investigated in vitro over the last three decades. In addition, the possible mechanisms by which cells sense shear stress are also introduced briefly.