Mechanics of single cells: rheology, time dependence, and fluctuations.
The results of mechanical measurements on single cultured epithelial cells using both magnetic twisting cytometry (MTC) and laser tracking microrheology (LTM) are described. Our unique approach uses laser deflection for high-performance tracking of cell-adhered magnetic beads either in response to an oscillatory magnetic torque (MTC) or due to random Brownian or ATP-dependent forces (LTM). This approach is well suited for accurately determining the rheology of single cells, the study of temporal and cell-to-cell variations in the MTC signal amplitude, and assessing the statistical character of the tracers' random motion in detail. The temporal variation of the MTC rocking amplitude is surprisingly large and manifests as a frequency-independent multiplicative factor having a 1/f spectrum in living cells, which disappears upon ATP depletion. In the epithelial cells we study, random bead position fluctuations are Gaussian to the limits of detection both in the Brownian and ATP-dependent cases, unlike earlier studies on other cell types.
Massiera
Gladys
G
Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
Van Citters
Kathleen M
KM
Biancaniello
Paul L
PL
Crocker
John C
JC
D000255:Adenosine Triphosphate / Q000737:chemistry / Q000378:metabolism; D000818:Animals; D001703:Biophysics / Q000379:methods*; D002448:Cell Adhesion; D003585:Cell Biology; D045744:Cell Line, Tumor; D002522:Chlorocebus aethiops; D004847:Epithelial Cells / Q000378:metabolism; D007834:Lasers; D008280:Magnetics; D051379:Mice; D041681:NIH 3T3 Cells; D016011:Normal Distribution; D009991:Oscillometry; D010587:Phagocytosis; D012212:Rheology / Q000379:methods*; D015398:Signal Transduction; D013997:Time Factors
D000255:Adenosine Triphosphate
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