Scaling the Microrheology of Living Cells

Scaling the Microrheology of Living Cells

1 OCTOBER 2001 | Ben Fabry, Geoffrey N. Maksym, James P. Butler, Michael Glogauer, Daniel Navajas, Jeffrey J. Fredberg
The paper presents a scaling law that governs the elastic and frictional properties of various living cell types over a wide range of time scales and under different biological conditions. The authors identify these cells as soft glassy materials existing close to a glass transition, suggesting that cytoskeletal proteins may regulate cell mechanical properties by modulating the effective noise temperature of the matrix. This effective noise temperature is an easily quantified measure of the cytoskeleton's ability to deform, flow, and reorganize. The study uses magnetic beads coated with RGD peptides to bind to integrin receptors on the surface of human airway smooth muscle cells, and measures the torque and displacement of the beads under oscillatory magnetic fields. The results show that the elastic and loss moduli of the cells follow power-law dependencies on frequency, with a loss tangent that is frequency-insensitive and of order 0.1, characteristic of soft glassy materials. The authors propose that the parameter \( x \) in the structural damping law represents the effective noise temperature, which can be regulated by cytoskeletal proteins. This suggests that the cytoskeleton's mechanical functions may be essential for cell processes such as contraction, spreading, and division.The paper presents a scaling law that governs the elastic and frictional properties of various living cell types over a wide range of time scales and under different biological conditions. The authors identify these cells as soft glassy materials existing close to a glass transition, suggesting that cytoskeletal proteins may regulate cell mechanical properties by modulating the effective noise temperature of the matrix. This effective noise temperature is an easily quantified measure of the cytoskeleton's ability to deform, flow, and reorganize. The study uses magnetic beads coated with RGD peptides to bind to integrin receptors on the surface of human airway smooth muscle cells, and measures the torque and displacement of the beads under oscillatory magnetic fields. The results show that the elastic and loss moduli of the cells follow power-law dependencies on frequency, with a loss tangent that is frequency-insensitive and of order 0.1, characteristic of soft glassy materials. The authors propose that the parameter \( x \) in the structural damping law represents the effective noise temperature, which can be regulated by cytoskeletal proteins. This suggests that the cytoskeleton's mechanical functions may be essential for cell processes such as contraction, spreading, and division.
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[slides and audio] Scaling the microrheology of living cells.