Stress relaxation microscopy: imaging local stress in cells

Area of Science:

• Cellular biomechanics
• Structural biology
• Cellular biology

Background:

• Cellular response to mechanical stimuli influences cell type and function.
• Understanding spatial force distribution is key to cell activity.
• Existing experimental methods for cell mechanics have limitations.

Purpose of the Study:

• To develop a simple scanning probe-based methodology for analyzing cell mechanics.
• To overcome limitations of existing experimental techniques in capturing cell complexity.
• To generate maps of cellular mechanical properties.

Main Methods:

• Utilized a scanning probe-based methodology.
• Applied stress relaxation analysis (force decay at constant deformation).
• Extracted relaxational responses at cellular sublocalizations to generate maps.

Main Results:

• Developed a method to map cell mechanics using stress relaxation.
• Identified a generalized viscoelastic model describing cell surface force decay.
• Detected two distinct relaxation times (0.1s and 1s) attributed to membrane and cytoskeleton dynamics.

Conclusions:

• Cell relaxation curves are accurately modeled by a generalized viscoelastic model.
• Relaxation time mapping can detect non-uniformities in cell membrane and cytoskeleton.
• This technique shows promise for cell type and disease identification.