The effect of cortical elasticity and active tension on cell adhesion mechanics

We consider a cell as a filled, elastic shell with an active surface tension and non-specific adhesion. We perform numerical simulations of this model in order to study the mechanics of cell-cell separation. By variation of parameters, we are able to recover well-known limits of JKR, DMT, adhesive vesicles with surface tension (BWdG) and thin elastic shells. We further locate biological cells on this parameter space by comparing to existing experiments on S180 cells. Using this model, we show that mechanical parameters can be obtained that are consistent with both Dual Pipette Aspiration (DPA) and Micropipette Aspiration (MA), a problem not successfully tackled so far. We estimate a cortex elastic modulus of E c ≈ 15 kPa, an effective cortex thickness of t c ≈ 0.3 µm and an active tension of γ ≈ 0.4 nN/µm. With these parameters, a JKR-like scaling of the separation force is recovered. Finally, the change of contact radius with applied force in a pull-off experiment was investigated. For small forces, a scaling similar to both BWdG and DMT is found. Manuscript submitted to Biophysical Journal.