Regensburg 2013 – scientific programme

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BP: Fachverband Biologische Physik

BP 32: Cell Adhesion and Mechanics

BP 32.11: Talk

Friday, March 15, 2013, 12:15–12:30, H43

Cell plasticity is tightly linked to elastic stresses in the cytoskeleton — •Richard Gerum, Navid Bonakdar, Michael Kuhn, Achim Schilling, Anna Lippert, Marina Spörrer, Astrid Mainka, and Ben Fabry — Biophysics, University of Erlangen-Nuremberg, Erlangen, Germany

Cells show pronounced non-linear visco-elastic and visco-plastic properties under large deformations and forces. We used a high-force magnetic tweezer setup to deliver unidirectional forces of up to 30nN to fibronectin-coated magnetic beads bound to cell surface adhesion receptors. To probe cells with bidirectional forces, the cell culture plate was placed on a rotational/translational stage such that the magnetic bead remained at a constant distance to the magnetic tweezer tip after a 180° rotation. Bead displacements were measured during application of force steps (creep response) and after the force was removed (recovery response). With increasing force magnitude, the recovery became increasingly incomplete, indicating the emergence of plastic behavior. This plasticity was a constant fraction (~20%) of the total bead displacement, regardless of duration and magnitude of force application. The plastic behavior is attributable to a buildup of excess slack in the cytoskeletal fibers. The creep and the recovery response were fully characterized by a simple power-law vs. time, indicating that plastic energy dissipation during cell deformations is tightly linked to elastic stress dissipation.