Analyzing the interplay between single cell rheology and force generation through large deformation finite element...

Area of Science:

• Biophysics
• Cell Mechanics
• Computational Biology

Background:

• Understanding cell mechanical properties is crucial for cell behavior.
• Cell spreading dynamics influence cell shape, force generation, and focal adhesion formation.
• Previous studies have measured cell mechanical properties using parallel plate setups.

Purpose of the Study:

• To extract mechanical properties of single cells during spreading using finite element modeling.
• To investigate the relationship between cell spreading, shape evolution, and traction force generation.
• To explain the localization of force-sensitive focal contacts at cell edges.

Main Methods:

• Finite element modeling (FEM) of cell spreading between two parallel microplates.
• Axisymmetric computations at finite strains to model cell shape evolution and traction forces.
• Modeling the cell as two distinct components: a hyperelastic cortex and a Newtonian fluid or hyperelastic interior.

Main Results:

• The elastic modulus of the cell cortex was estimated at approximately 1,000 Pa.
• The cell interior exhibited a viscosity of 1,000 Pa.s (biphasic model) or an elastic modulus of 100 Pa (hyperelastic model).
• Stresses were observed to concentrate at the edge of the cell-substrate contact area.

Conclusions:

• FEM analysis successfully extracted cell mechanical properties consistent with experimental data.
• Cell spreading and mechanical straining are linked to the force applied by the cell on its substrate.
• The findings provide a simple explanation for the concentration of focal contacts at cell edges.