Cellular Membrane Mechanics Cell and tissue cultures are influenced by exposure to mechanical loading. For example, it is known that cells cultured as monolayers on flexible membranes under strain align themselves in the direction of the applied force, exposure to steady laminar shear stress can induce morphological changes within a cell, and applied fluid shear stress can reversibly regulate gene expression. Although mechanical loading has been identified a factor affecting cell structure and metabolism, hydrodynamic forces are generally characterized at the macroscopic scale. Force distribution at the microscopic cellular scale has not been characterized, in part because it is very difficult to measure stress and strain at the sub micron scale. Force distribution on the cellular membrane in various flow conditions is being characterized in our lab using computational models based on the immersed boundary method and the boundary integral method. The ability to determine the mechanical loading on a cell allows us to relate controlled laboratory experiments where the response of a cell line has been characterized to physiological flow conditions in the body and flow environments within large scale production bioreactors.