Cell mechanics by atomic force, traction force, and ion conductance microscopy

Seminar | February 13 | 12-1 p.m. | 106 Stanley Hall | Note change in date

 Tilman Schaeffer, University of Tubingen (Germany)

 Bioengineering (BioE)

I will present the development and application of novel scanning probe instrumentation and methods in the field of cell mechanics.

Using force clamp force mapping (FCFM), an atomic force microscopy (AFM) imaging mode that combines force-distance curves with an added force clamp phase, we observed that the creep behavior of living cells conforms to a power-law material model. When comparing normal and cancerous human breast cancer cells in an epithelial monolayer, we found that normal cells respond to adjacent cells by increasing their stiffness and reducing their fluidity but cancerous cells do not.

We developed a combination of AFM with traction force microscopy (TFM) for simultaneous measurement of viscoelastic material properties and traction forces of single living cells. This combination allowed us to show a direct correlation between passive material properties (stiffness, fluidity) and active contractile prestress of adherent fibroblast and epithelial cells. We demonstrate that stiffness, fluidity, and contractile prestress are modulated by the activity of the actomyosin machinery.

By applying high-speed, non-contact scanning ion conductance microscopy (SICM), we resolved morphodynamics in spread human platelets and observed wave-like movements of the lamellipodium and dynamic protrusions on the platelet body. Using a SICM method that we developed for generating maps of elastic modulus across the surface of living cells, we have studied the effect of thrombin, a potent platelet activator, on the mechanical properties of living platelets.

 CA, monamw@berkeley.edu, 5106663362