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Regional rheological differences in locomoting neutrophils
M Yanai1, J P Butler, T Suzuki
1Dept. of Geriatric and Respiratory Medicine, Tohoku University School of Medicine, 1-1 Seiryo-machi, Sendai 980-8574, Japan. dept@geriat.med.tohoku.ac.jp
American Journal of Physiology. Cell Physiology
|May 28, 2004
Summary
Intracellular rheology reveals leading neutrophil regions are more fluidlike than trailing regions. This suggests intracellular pressure may drive cell locomotion, differing from cell membrane studies.
Area of Science:
- Cellular mechanics
- Biophysics
- Immunology
Background:
- Intracellular rheology offers insights into leukocyte locomotion and migration.
- Understanding regional differences in neutrophil mechanics is crucial for deciphering cell movement.
Purpose of the Study:
- To characterize regional rheological differences in human neutrophils during spontaneous locomotion.
- To compare viscoelasticity and structural damping models for describing intracellular rheology.
Main Methods:
- Optical trapping of intracellular granules in human neutrophils.
- Measurement of granule displacement following a step change in trap position.
- Analysis using viscoelasticity and structural damping models.
Main Results:
- Structural damping provided a better fit to intracellular rheology data than simple viscoelasticity.
- Leading neutrophil regions exhibited significantly lower stiffness and viscosity (more fluidlike behavior) compared to body and trailing regions.
- Cytoskeletal disruption with cytochalasin D or nocodazole reduced elasticity and viscosity in body/trailing regions, with cytochalasin D inhibiting locomotion.
Conclusions:
- Structural damping effectively describes intracellular rheology.
- The fluidlike nature of the leading edge supports the hypothesis that intracellular pressure generates motive force for neutrophil locomotion.
- Findings suggest distinct roles for the cell cortex and focal adhesion complexes compared to cell membrane-based studies.