A complex system approach to tumor morphology changes

Abstract

We have developed an agent-based computational model to unravel the complex mechanism of interaction between immune cells and cancer cells. Instead of the usual mono-formalism approach where entities are either all discrete or all continuous, we have taken a complex systems approach where the model is a hybrid of continuous fields and discrete agents. In the model, nutrients, growth factors and chemokines are continuous fields on a regular lattice whereas cancer cells and immune cells are discrete off-lattice autonomous mobile agents. Off-lattice modeling of cells allows the simulation of experimentally observed superdiffusive behavior of mammalian cells and cell mobility is not restricted by a lattice and a limited set of possible directions. In addition to that, unlike cellular automata model on square lattice which describes cell-cell and cell-ECM adhesion through heuristic stochastic terms, an off-lattice model addresses the adhesion forces in a more realistic mechanical aspect. Our model explains the interactions between cancer cells and immune cells that lead to different morphological growth patterns of tumors in the presence and absence of immune cells. Simulation results from the model demonstrate tumor morphologies that are similar to those observed in the experiments.