Cell-substrate separation: effect of applied force and temperature

Area of Science:

• Biophysics
• Cell Biology
• Materials Science

Background:

• Understanding cell-substrate interactions is crucial for tissue engineering and cell-based assays.
• Quantifying the mechanical properties of cell adhesion provides insights into cellular behavior and responses to physical stimuli.

Purpose of the Study:

• To measure the change in cell-substrate separation under controlled force using a novel combination of techniques.
• To determine the junctional resistivity and cell-substrate distance.
• To investigate the temperature dependence of cell adhesion forces and properties.

Main Methods:

• Combined Electric Cell-substrate Impedance Sensing (ECIS) with collagen-coated magnetic beads to apply controlled force (320 or 560 pN) to the dorsal surface of cells.
• Used integrin receptors on osteoblastlike ROS 17/2.8 cells for bead attachment.
• Analyzed impedance data to calculate cell-substrate separation and junctional resistivity at different temperatures (4, 22, and 37 degrees C).

Main Results:

• Applied forces increased cell-substrate separation by 10-25%.
• Measured cell-substrate distances decreased with increasing temperature (84 nm at 4°C, 45 nm at 22°C, 38 nm at 37°C).
• Calculated cell-substrate spring constants of approximately 28 pN/nm at 22°C and 63 pN/nm at 37°C.
• Estimated individual integrin-ligand adhesion bond spring constants between 10^-3 and 10^-1 pN/nm.
• Observed an increase in the number of adhesion bonds per cell with increasing temperature.

Conclusions:

• The applied forces induce significant changes in cell-substrate separation, demonstrating the mechanical responsiveness of cell adhesions.
• Cell-substrate adhesion strength and the number of adhesion bonds increase with temperature.
• The developed method provides a quantitative approach to study cell mechanics and adhesion properties.