Regensburg 2010 – scientific programme

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BP: Fachverband Biologische Physik

BP 32: Posters: Physics of Cells

BP 32.44: Poster

Thursday, March 25, 2010, 17:15–20:00, Poster B1

Nonlinear Cell Mechanics Is Plastic Mechanics — Lars Wolff, •Andrea Kramer, and Klaus Kroy — Institut f. Theoretische Physik, Universität Leipzig

Recent investigations of the dynamical linear and nonlinear mechanical properties of single living cells have identified (at least) three major universal patterns of cell rheology: (i) power-law rheology, (ii) viscoelastic stiffening, and (iii) inelastic softening or "fluidization". We present a polymer-physics based minimal model that robustly reproduces all of these features and suggests their close mutual interdependence. In particular, the supposedly antagonistic effects of viscoelastic stiffening and fluidization are predicted to actually reinforce each other and the structural damping. The highly redundant nonlinear dynamical shear response of living cells is traced back to inanimate material properties shared by much simpler in vitro models of the cytoskeleton, notably by pure F-actin solutions, which has so far been experimentally validated only for (i) & (ii). According to the model, the core mechanism responsible for the mechanics of living cells and tissues is comprised by a small set of equations coupling semiflexible polymer dynamics as described by the glassy wormlike chain model with "bond"-kinetics in the highly degenerate free energy landscape of an "Arrhenius gel". The good quantitative agreement of model predictions for viscoelastic and inelastic protocols with experimental data from both in vitro model systems and living cells suggests intriguing new directions for future experiments aiming to relate microscopic structural parameters with the mechanical response.