MODELLING CELL POPULATION GROWTH

The growth of biological matter, e.g., tumor invasion, depends on various factors, mainly the tissue’s mechanical properties, implying elasticity, stiffness, or apparent viscosity. These properties are impacted by the characteristics of the tissue’s extracellular matrix and constituent cells, including, but not limited to, cell membrane stiffness, cell cytoskeleton mechanical properties, and the intensity and distribution of focal adhesions over the cell membrane. To compute and study the mechanical properties of tissues during growth and confluency, a theoretical and computational framework, called CellSim3D, was developed in our group based on a three-dimensional kinetic division model. In this work, CellSim3D is updated with a new set of cell mechanical parameters and force fields such as the asymmetric division rule, shape diversity, apoptosis process, and boundary conditions, e.g., periodic and Lees-Edwards boundary conditions. The package is upgraded to operate on multiple GPUs to further accelerate computations. This enables the inclusion of more complexity in the system. For instance, the simulation of macroscopic scale bicellular tissue growth with precise control over the mechanical properties of cells is now more feasible than before. The effects of cell-cell adhesion strength and intermembrane friction on growth kinetics and interface roughness dynamics of epithelial tissue were studied. It is reported that with fine alterations of the mechanical parameters such as the cell-cell adhesion strength, one could reliably reproduce different interface roughness scaling behaviors such as Kardar–Parisi–Zhang (KPZ)-like and Molecular Beam Epitaxy (MBE)-like scaling. In addition, it was observed that substrate heterogeneity and geometry have significant impacts on the morphology and interface roughness scaling of epithelial tissue. The results suggest that the interface roughness scaling of epithelial tissues cannot be classified by any well-known scaling universality class. Instead, it strongly depends on several other factors, such as the cell-cell adhesion strength. This explains the controversies observed in earlier experimental works over the interface roughness scaling of expanding epithelial tissue