Interface Instabilities and Fingering in Growing Biofilms and Tumors

Nikodem Poplawski, Department of Physics, Indiana University

We simulate the growth and study the interface morphology of a two-dimensional, single-species bacterial biofilm and a single-phenotype tumor growing in medium representing healthy tissue. We use the cell-oriented Glazier-Graner-Hogeweg (GGH) model, which treat cells as spatially-extended, deformable and adhesive bodies, and implement it with the CompuCell3D modeling environment. We show that the biofilm/tumor growth rate per unit nutrient consumed determines whether the growing biofilm/tumor develops a smooth or fingered interface. Such fingering instabilities of tumors may lead to metastases in medical contexts. We also show that the sensitivity of biofilm/tumor morphology to cell-medium surface tension, which is difficult to do using other modeling approaches, increases with nutrient consumption: high surface tension produces dendritic structures and low surface tension produces seaweed-like structures, as in directional solidification.