Model-based traction force microscopy reveals differential tension in cellular actin bundles

Area of Science:

• Cell biology
• Biophysics
• Mechanobiology

Background:

• Adherent cells interact with their physical environment through forces at the cell-substrate interface.
• Traction force microscopy (TFM) is a technique used to measure these cellular forces by analyzing substrate deformations.
• Traditional TFM methods often require regularization, which can introduce uncertainties in force calculations.

Purpose of the Study:

• To develop a more robust and accurate method for measuring cellular forces.
• To improve the inverse problem-solving in traction force microscopy.
• To investigate the mechanical tension differences within cellular stress fibers.

Main Methods:

• A novel traction force microscopy technique was developed, integrating additional image data of cytoskeleton and adhesion structures.
• A biophysical model was employed to enhance the inverse procedure, eliminating the need for regularization.
• The method was applied to U2OS cells to measure stress fiber tension.

Main Results:

• The new TFM method provides a more robust calculation of cell-substrate forces.
• Ventral stress fibers in U2OS cells were found to be under significantly higher mechanical tension.
• Compared to dorsal stress fibers and transverse arcs, ventral stress fibers exhibit distinct mechanical properties.

Conclusions:

• The developed TFM technique offers improved accuracy and robustness in measuring cellular forces.
• Significant differences in mechanical tension exist among various stress fiber types within cells.
• This advancement in TFM can provide deeper insights into cell mechanics and mechanotransduction.