Electrically measuring viscoelastic parameters of adherent cell layers under controlled magnetic forces

Area of Science:

• Biophysics
• Cell Mechanics
• Electrical Cell-Substrate Impedance Sensing (ECIS)

Background:

• Osteosarcoma cells exhibit a coin-like topology with a domed apex.
• Mechanical stress can influence cellular morphology and intercellular interactions.

Purpose of the Study:

• To investigate the time- and frequency-dependence of impedance in osteosarcoma cells under mechanical stress.
• To characterize the viscoelastic properties of cells and cell-substrate adhesion.

Main Methods:

• Electrical Cell-Substrate Impedance Sensing (ECIS) was employed to measure impedance changes.
• Osteosarcoma cells were subjected to controlled vertical stress using magnetic beads.
• A viscoelastic model with viscous and elastic elements was used to analyze the data.

Main Results:

• Applied stress caused rapid decreases in resistance (<2s) and slower changes (60-150s time constant).
• The time constant was temperature-dependent, being longer at lower temperatures (22°C vs. 37°C).
• Viscoelastic parameters showed temperature dependence: cell body viscosity and spring constants decreased with increasing temperature, while cell-substrate adhesion modulus increased.

Conclusions:

• Mechanical stress significantly impacts osteosarcoma cell height, separation, and adhesion bonds.
• ECIS can effectively measure these stress-induced changes and provide insights into cell viscoelasticity.
• The study provides quantitative viscoelastic parameters for cell bodies and cell-substrate adhesion systems at physiological temperatures.