Mechanical properties of healthy and tumor tissue

Many biological processes depend on cellular organization and the mechanical properties of multicellular aggregates. In general, the cells forming a tissue are in contact with an extracellular matrix, which, along with adhesion between cells, helps them to bind into tissues. Experiments on embryonic tissue [M. S. Steinberg, et al., J. Cell. Physiol., 173, (1997)] reveal viscoelastic behavior. During embryonic development, infections and healing processes, cells move and reorganize themselves intensively. Analogously, tumors are characterized by a continuous spatial reorganization which minimizes intracellular stresses. In this work we study the mechanical properties of cellular aggregates using computer simulations. The cells are represented by semi-rigid bodies with position and shape exhibiting thermal fluctuations. The corresponding Langevin equations are solved numerically. The interaction between cells involves an adhesion force, simulated by a harmonic potential, and a random force. We adjust the parameters that control the random force intensity and the interaction potential, to reproduce real biological tissue behavior. Then we introduce a tumor cell in the center of the tissue and compare the adhesion properties in healthy and tumor tissue.