Pappu, Vijay. Three-dimensional computational modeling and simulation of cell rolling and deformation on an adhesive surface in shear flow. Retrieved from https://doi.org/doi:10.7282/T3VM4CJ9
DescriptionThree-dimensional computational modeling and simulations are presented on the rolling motion of a deformable cell on an adhesive surface in shear flow. The problem is motivated primarily by the adhesive rolling motion of white blood cells or leukocytes in response to inflammation in the body. The methodology is based on an immersed boundary method to predict cell deformation, and a Monte Carlo simulation to model the random formation and breakage of the adhesion bonds formed between a ligand-bearing cell and a receptor-coated surface. The multiscale and multiphysics modeling developed in this study allows us to resolve the complex coupling between the hydrodynamics, the deformation dynamics of the cell, and the biophysics of the adhesion bonds. In the thesis, we address the sequence of events that are encountered in the multistep process of cell rolling, namely, the initial arrest of the cell, followed by its deformation and spreading on the substrate, and the subsequent quasi-steady rolling motion. We provide phase diagrams for cell adhesion/escape, and showed that the hydrodynamic lift, that exists on a deformable cell in the wall-bounded motion, plays a major role in the process. The experimentally observed 'stop-and-go' motion of the cells is predicted in our simulations. After providing results on the general adhesive rolling motion, we focus specifically on the rolling dynamics of the leukocytes, and study the effect of cell deformability, shear rate and cell concentration on the instantaneous and time-averaged rolling characteristics. We also study the biophysical characteristics of the adhesion bonds during the rolling process. Finally, we consider the effect of the adherent leukocytes on the surrounding flow in terms of the changes in tracer dispersion and the vascular flow resistance. Comparison with experimental measurements (in vitro and in vivo) is presented throughout the thesis.