Constitutive material modeling of cell: a micromechanics approach

Area of Science:

• Cellular mechanics
• Biophysics
• Materials science

Background:

• Experimental and theoretical studies show variations in cell mechanical properties.
• Understanding these variations requires correlating mechanical properties with cellular structure.
• Cytoplasmic inhomogeneity due to stress fibers and actin cortex influences cell mechanics.

Purpose of the Study:

• To develop a mathematical framework correlating cell mechanical properties with cellular structure.
• To account for cytoplasmic inhomogeneity caused by stress fibers and actin cortex.
• To explain discrepancies in mechanical properties derived from different experimental techniques.

Main Methods:

• Developed a constitutive model using the Mori-Tanaka method of homogenization.
• Treated the cell as a fiber-reinforced composite medium.
• Validated the model using finite element analysis with atomic force microscopy (AFM) and magnetic twisting cytometry (MTC) data.

Main Results:

• The model shows good correlation with reported experimental results.
• Increased stress fiber volume fraction enhances cell stiffness.
• Stress fibers alter the force-displacement behavior in AFM and MTC experiments.
• Identified stress fibers as a likely cause for differences in mechanical properties derived from AFM and MTC.

Conclusions:

• The developed mathematical framework successfully correlates cell mechanical behavior with cell composition.
• Stress fibers significantly influence cell stiffness and mechanical response.
• This work provides a crucial link between cellular structure and mechanical properties in cell mechanics.
• The findings aid in understanding and predicting cell mechanical behavior based on internal structure.