Selected Contribution: Time course and heterogeneity of contractile responses in cultured human airway smooth muscle cells (original) (raw)
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Mechanical properties of cultured human airway smooth muscle cells from 0.05 to 0.4 Hz
Journal of applied physiology (Bethesda, Md. : 1985), 2000
We investigated the rheological properties of living human airway smooth muscle cells in culture and monitored the changes in rheological properties induced by exogenous stimuli. We oscillated small magnetic microbeads bound specifically to integrin receptors and computed the storage modulus (G') and loss modulus (G") from the applied torque and the resulting rotational motion of the beads as determined from their remanent magnetic field. Under baseline conditions, G' increased weakly with frequency, whereas G" was independent of the frequency. The cell was predominantly elastic, with the ratio of G" to G' (defined as eta) being approximately 0. 35 at all frequencies. G' and G" increased together after contractile activation and decreased together after deactivation, whereas eta remained unaltered in each case. Thus elastic and dissipative stresses were coupled during changes in contractile activation. G' and G" decreased with disruption ...
AJP: Cell Physiology, 2004
We probed elastic and loss moduli in the adherent human airway smooth muscle cell through a variety of receptor systems, each serving as a different molecular window on cytoskeletal dynamics. Coated magnetic microbeads were attached to the cell surface via coating-receptor binding. A panel of bead coatings was investigated: a peptide containing the sequence RGD, vitronectin, urokinase, activating antibody against 1 β integrin, non-activating antibody against 1 β integrin, blocking antibody against 1 β integrin, antibody against 3 β integrin, and acetylatedlow density lipoprotein. An oscillatory mechanical torque was applied to the bead and resulting lateral displacements were measured at baseline, after actin disruption by cytochalasin D, or after contractile activation by histamine. As expected, mechanical moduli depended strongly upon bead type and bead-coating, differing at the extremes by as much as two orders of magnitude. In every case, however, elastic and loss moduli increased with frequency, f, as a weak power law, f x-1 . Moreover, with few exceptions data could be scaled such that suitably normalized elastic and frictional responses depended solely on the power law exponent x. Taken together, these data suggest that power law behavior represents a generic feature of underlying protein-protein dynamics.
Biophysical Journal, 2005
Complex rheology of airway smooth muscle cells and its dynamic response during contractile stimulation involves many molecular processes, foremost of which are actomyosin cross-bridge cycling and actin polymerization. With an atomic force microscope, we tracked the spatial and temporal variations of the viscoelastic properties of cultured airway smooth muscle cells. Elasticity mapping identified stiff structural elements of the cytoskeletal network. Using a precisely positioned microscale probe, picoNewton forces and nanometer level indentation modulations were applied to cell surfaces at frequencies ranging from 0.5 to 100 Hz. The resulting elastic storage modulus (G9) and dissipative modulus (G$) increased dramatically, with hysteresivity (h ¼ G$/ G9) showing a definitive decrease after stimulation with the contractile agonist 5-hydroxytryptamine. Frequency-dependent assays showed weak power-law structural damping behavior and universal scaling in support of the soft-glassy material description of cellular biophysics. Additionally, a high-frequency component of the loss modulus (attributed to cellular Newtonian viscosity) increased fourfold during the contractile process. The complex shear modulus showed a strong sensitivity to the degree of actin polymerization. Inhibitors of myosin light chain kinase activity had little effect on the stiffening response to contractile stimulation. Thus, our measurements appear to be particularly well suited for characterization of dynamic actin rheology during airway smooth muscle contraction.
Measurement of cell microrheology by magnetic twisting cytometry with frequency domain demodulation
Journal of applied physiology (Bethesda, Md. : 1985), 2001
Magnetic twisting cytometry (MTC) (Wang N, Butler JP, and Ingber DE, Science 260: 1124-1127, 1993) is a useful technique for probing cell micromechanics. The technique is based on twisting ligand-coated magnetic microbeads bound to membrane receptors and measuring the resulting bead rotation with a magnetometer. Owing to the low signal-to-noise ratio, however, the magnetic signal must be modulated, which is accomplished by spinning the sample at approximately 10 Hz. Present demodulation approaches limit the MTC range to frequencies <0.5 Hz. We propose a novel demodulation algorithm to expand the frequency range of MTC measurements to higher frequencies. The algorithm is based on coherent demodulation in the frequency domain, and its frequency range is limited only by the dynamic response of the magnetometer. Using the new algorithm, we measured the complex modulus of elasticity (G*) of cultured human bronchial epithelial cells (BEAS-2B) from 0.03 to 16 Hz. Cells were cultured in ...
Biorheology, 2003
This study aims at quantifying the cellular mechanical properties based on a partitioning of the cytoskeleton in a cortical and a cytosolic compartments. The mechanical response of epithelial cells obtained by magnetocytometry - a micromanipulation technique which uses twisted ferromagnetic beads specifically linked to integrin receptors - was purposely analysed using a series of two Voigt bodies. Results showed that the cortical cytoskeleton has a faster response ( approximately 1 s) than the cytosolic compartment ( approximately 30 s). Moreover, the two cytoskeletal compartments have specific mechanical properties, i.e., the cortical (resp. cytosolic) cytoskeleton has a rigidity in the range: 49-85 Pa (resp.: 74-159 Pa) and a viscosity in the range 5-14 Pa.s (resp.: 593-1534 Pa.s), depending on the level of applied stress. Depolymerising actin-filaments strongly modified these values and especially those of the cytosolic compartment. The structural relevance of this two-compartmen...
AJP: Cell Physiology, 2004
airway smooth muscle cells cultured actin cytoskeletal remodeling and stiffening in Localized mechanical stress induces time-dependent You might find this additional information useful... 42 articles, 31 of which you can access free at: This article cites http://ajpcell.physiology.org/cgi/content/full/287/2/C440#BIBL 7 other HighWire hosted articles, the first 5 are: This article has been cited by [PDF] [Full Text] [Abstract] , July 1, 2005; 289 (1): C49-C57. Am J Physiol Cell Physiol A. M. Brainard, A. J. Miller, J. R. Martens and S. K. England actin-channel-caveolin complex in the regulation of myometrial smooth muscle K+ current Maxi-K channels localize to caveolae in human myometrium: a role for an [PDF] [Full Text] [Abstract] , August 1, 2005; 99 (2): 634-641. remodeling Airway smooth muscle tone modulates mechanically induced cytoskeletal stiffening and [PDF] [Full Text] [Abstract] , December 1, 2005; 289 (6): C1388-C1395. Rat airway smooth muscle cell during actin modulation: rheology and glassy dynamics [PDF] [Full Text] [Abstract] , March 15, 2006; 90 (6): 2199-2205. Biophys. J. M. F. Coughlin, M. Puig-de-Morales, P. Bursac, M. Mellema, E. Millet and J. J. Fredberg Filamin-A and Rheological Properties of Cultured Melanoma Cells [PDF] [Full Text] [Abstract] , June 1, 2006; 290 (6): L1227-L1237. mechanical force and the cytoskeleton Viscoelastic and dynamic nonlinear properties of airway smooth muscle tissue: roles of including high-resolution figures, can be found at: Updated information and services http://ajpcell.physiology.org/cgi/content/full/287/2/C440 can be found at: AJP -Cell Physiology about Additional material and information http://www.the-aps.org/publications/ajpcell
Airway mechanics and methods used to visualize smooth muscle dynamics in vitro
Pulmonary Pharmacology & Therapeutics, 2009
Contraction of airway smooth muscle (ASM) is regulated by the physiological, structural and mechanical environment in the lung. We review two in vitro techniques, lung slices and airway segment preparations, that enable in situ ASM contraction and airway narrowing to be visualized. Lung slices and airway segment approaches bridge a gap between cell culture and isolated ASM, and whole animal studies. Imaging techniques enable key upstream events involved in airway narrowing, such as ASM cell signalling and structural and mechanical events impinging on ASM, to be investigated.
Biophysical Journal, 2001
By using magnetic bead microrheology we study the effect of inflammatory agents and toxins on the viscoelastic moduli of endothelial cell plasma membranes in real time. Viscoelastic response curves were acquired by applying short force pulses of ϳ500 pN to fibronectin-coated magnetic beads attached to the surface membrane of endothelial cells. Upon addition of thrombin, a rapid stiffening of the membrane was observed within 5 s, followed by recovery of the initial deformability within 2 min. By using specific inhibitors, two known pathways by which thrombin induces actin reorganization in endothelial cells, namely activation of Ca 2ϩ -calmodulin-dependent myosin light chain kinase and stimulation of Rho/Rhokinase, were excluded as possible causes of the stiffening effect. Interestingly, the cytotoxic necrotizing factor of Escherichia coli, a toxin which, in addition to Rho, activates the GTPases Rac and CDC42Hs, also induced a dramatic stiffening effect, suggesting that the stiffening may be mediated through a Rac-or Cdc42Hs-dependent pathway. This work demonstrates that magnetic bead microrheometry is not only a powerful tool to determine the absolute viscoelastic moduli of the composite cell plasma membrane, but also a valuable tool to study in real time the effect of drugs or toxins on the viscoelastic parameters of the plasma membrane.
Clinical hemorheology and microcirculation, 2005
Using Magnetic Twisting Cytometry (MTC) technique, we attempted to characterize in vitro the rigidity of the lining tissue covering the lung alveolar wall from its apical face. We purposely used a cellular model constituted by a monolayer of human alveolar epithelial cell (A549) over which microbeads, fixed to InterCellular Adhesion Molecule (ICAM-1), exert a controlled mechanical stress. ICAM-1 expression was induced by Tumor Necrosis Factor-alpha (TNF-alpha). Rigidity measurements, performed in the course of cytochalasin D depolymerization, reveal the force transmitter role of the transmembrane receptor ICAM-1 and demonstrate that ICAM-1 and F-actin linkages confers mechanical rigidity to the apical face of the epithelial cell monolayer resembling that provided by integrins. These results confirm the ability of MTC in identifying transmembrane mechanoreceptors in relation with F-actin. Molecular linkages between ICAM-1 and F-actin were observed by spatial visualisations of the str...