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Combriat T, Olsen PA, Låstad SB, Malthe-Sørenssen A, Krauss S, Dysthe DK. Acoustic Wave-Induced Stroboscopic Optical Mechanotyping of Adherent Cells. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2307929. [PMID: 38417124 DOI: 10.1002/advs.202307929] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Revised: 02/02/2024] [Indexed: 03/01/2024]
Abstract
In this study, a novel, high content technique using a cylindrical acoustic transducer, stroboscopic fast imaging, and homodyne detection to recover the mechanical properties (dynamic shear modulus) of living adherent cells at low ultrasonic frequencies is presented. By analyzing the micro-oscillations of cells, whole populations are simultaneously mechanotyped with sub-cellular resolution. The technique can be combined with standard fluorescence imaging allowing to further cross-correlate biological and mechanical information. The potential of the technique is demonstrated by mechanotyping co-cultures of different cell types with significantly different mechanical properties.
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Affiliation(s)
- Thomas Combriat
- Njord Centre, Department of Physics, University of Oslo, P.O. Box 1048 Blindern, Oslo, 0316, Norway
- Hybrid Technology Hub, University of Oslo, Institute of Basic Medical Sciences P.O. Box 1110 Blindern, Oslo, 0317, Norway
- Center for Computing in Science Education, University of Oslo, P.O. Box 1048 Blindern, Oslo, 0316, Norway
| | - Petter Angell Olsen
- Hybrid Technology Hub, University of Oslo, Institute of Basic Medical Sciences P.O. Box 1110 Blindern, Oslo, 0317, Norway
- Department of Immunology and Transfusion Medicine, Oslo University Hospital, P.O. Box 4950, Nydalen, Oslo, 0424, Norway
| | - Silja Borring Låstad
- Njord Centre, Department of Physics, University of Oslo, P.O. Box 1048 Blindern, Oslo, 0316, Norway
| | - Anders Malthe-Sørenssen
- Njord Centre, Department of Physics, University of Oslo, P.O. Box 1048 Blindern, Oslo, 0316, Norway
- Center for Computing in Science Education, University of Oslo, P.O. Box 1048 Blindern, Oslo, 0316, Norway
| | - Stefan Krauss
- Hybrid Technology Hub, University of Oslo, Institute of Basic Medical Sciences P.O. Box 1110 Blindern, Oslo, 0317, Norway
- Department of Immunology and Transfusion Medicine, Oslo University Hospital, P.O. Box 4950, Nydalen, Oslo, 0424, Norway
| | - Dag Kristian Dysthe
- Njord Centre, Department of Physics, University of Oslo, P.O. Box 1048 Blindern, Oslo, 0316, Norway
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2
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Silvani G, Romanov V, Martinac B. Sounding a New Era in Biomechanics with Acoustic Force Spectroscopy. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1436:109-118. [PMID: 36571699 DOI: 10.1007/5584_2022_757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The acoustic force spectroscopy (AFS) tool was recently introduced as a novel tool for probing mechanical properties of biomolecules, expanding the application of sound waves to high-throughput quantification of the mechanical properties of single cells. By using controlled acoustic forces in the piconewton to nanonewton range, tens to hundreds of cells functionalized by attached microspheres can simultaneously be stretched and tracked in real-time with sub millisecond time response. Since its first application, several studies have demonstrated the potential and versatility of the AFS for high-throughput measurements of force-induced molecular mechanisms, revealing insight into cellular biomechanics and mechanobiology at the molecular level. In this chapter, we describe the operation of the AFS starting with the underlying physical principles, followed by a run-down of experimental considerations, and finally leading to applications in molecular and cellular biology.
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Affiliation(s)
- Giulia Silvani
- School of Material Science and Engineering, University of New South Wales, Sydney, NSW, Australia
| | - Valentin Romanov
- Victor Chang Cardiac Research Institute, Lowy Packer Building, Darlinghurst, NSW, Australia
| | - Boris Martinac
- Victor Chang Cardiac Research Institute, Lowy Packer Building, Darlinghurst, NSW, Australia.
- St Vincent's Clinical School, University of New South Wales, Sydney, NSW, Australia.
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3
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Caveolin-1 dolines form a distinct and rapid caveolae-independent mechanoadaptation system. Nat Cell Biol 2023; 25:120-133. [PMID: 36543981 PMCID: PMC9859760 DOI: 10.1038/s41556-022-01034-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 10/21/2022] [Indexed: 12/24/2022]
Abstract
In response to different types and intensities of mechanical force, cells modulate their physical properties and adapt their plasma membrane (PM). Caveolae are PM nano-invaginations that contribute to mechanoadaptation, buffering tension changes. However, whether core caveolar proteins contribute to PM tension accommodation independently from the caveolar assembly is unknown. Here we provide experimental and computational evidence supporting that caveolin-1 confers deformability and mechanoprotection independently from caveolae, through modulation of PM curvature. Freeze-fracture electron microscopy reveals that caveolin-1 stabilizes non-caveolar invaginations-dolines-capable of responding to low-medium mechanical forces, impacting downstream mechanotransduction and conferring mechanoprotection to cells devoid of caveolae. Upon cavin-1/PTRF binding, doline size is restricted and membrane buffering is limited to relatively high forces, capable of flattening caveolae. Thus, caveolae and dolines constitute two distinct albeit complementary components of a buffering system that allows cells to adapt efficiently to a broad range of mechanical stimuli.
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4
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Lee S, Bashir KMI, Jung DH, Basu SK, Seo G, Cho MG, Wierschem A. Measuring the linear viscoelastic regime of MCF-7 cells with a monolayer rheometer in the presence of microtubule-active anti-cancer drugs at high concentrations. Interface Focus 2022; 12:20220036. [PMID: 36330318 PMCID: PMC9560786 DOI: 10.1098/rsfs.2022.0036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Accepted: 09/06/2022] [Indexed: 10/16/2023] Open
Abstract
The rheological properties of cells have vital functional implications. Depending, for instance, on the life cycle, cells show large cell-to-cell variations making it cumbersome to quantify average viscoelastic properties of cells by single-cell techniques. Microfluidic devices, typically working in the nonlinear viscoelastic range, allow fast analysis of single-cell deformation. Averaging over a large number of cells can also be achieved by studying them in a monolayer between rheometer discs. This technique allows applying well-established rheological standard procedures to cell rheology. It offers further advantages like studying cells in the linear viscoelastic range while quantifying cell vitality. Here, we study the applicability of the technique to rather adverse conditions, like for microtubule-active anti-cancer drugs and for a cell line with large size variation. We found a strong impact of the gap width and of normal forces on the moduli and obtained high vitality levels during the rheological study. To enable studying the impact of microtubule-active drugs on vital cells at concentrations several orders of magnitude beyond the half maximal effective concentration for cytotoxicity, we arrested the cell cycle with hydroxyurea. Irrespective of the high concentrations, we observed no clear impact of the microtubule-active drugs.
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Affiliation(s)
- Suhyang Lee
- German Engineering Research and Development Center, LSTME-Busan Branch, Gangseo-Gu, Busan 46742, Republic of Korea
- Institute of Fluid Mechanics, Friedrich-Alexander-Universität Erlangen-Nürnberg, Cauerstr. 4, Erlangen 91058, Germany
| | | | - Dong Hee Jung
- German Engineering Research and Development Center, LSTME-Busan Branch, Gangseo-Gu, Busan 46742, Republic of Korea
- Division of Energy and Bioengineering, Dongseo University, Sasang-gu, Busan 47011, Republic of Korea
| | - Santanu Kumar Basu
- Institute of Fluid Mechanics, Friedrich-Alexander-Universität Erlangen-Nürnberg, Cauerstr. 4, Erlangen 91058, Germany
| | - Gayeon Seo
- Division of Energy and Bioengineering, Dongseo University, Sasang-gu, Busan 47011, Republic of Korea
| | - Man-Gi Cho
- German Engineering Research and Development Center, LSTME-Busan Branch, Gangseo-Gu, Busan 46742, Republic of Korea
- Division of Energy and Bioengineering, Dongseo University, Sasang-gu, Busan 47011, Republic of Korea
| | - Andreas Wierschem
- German Engineering Research and Development Center, LSTME-Busan Branch, Gangseo-Gu, Busan 46742, Republic of Korea
- Institute of Fluid Mechanics, Friedrich-Alexander-Universität Erlangen-Nürnberg, Cauerstr. 4, Erlangen 91058, Germany
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Efremov YM, Zurina IM, Presniakova VS, Kosheleva NV, Butnaru DV, Svistunov AA, Rochev YA, Timashev PS. Mechanical properties of cell sheets and spheroids: the link between single cells and complex tissues. Biophys Rev 2021; 13:541-561. [PMID: 34471438 PMCID: PMC8355304 DOI: 10.1007/s12551-021-00821-w] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Accepted: 07/05/2021] [Indexed: 12/13/2022] Open
Abstract
Cell aggregates, including sheets and spheroids, represent a simple yet powerful model system to study both biochemical and biophysical intercellular interactions. However, it is becoming evident that, although the mechanical properties and behavior of multicellular structures share some similarities with individual cells, yet distinct differences are observed in some principal aspects. The description of mechanical phenomena at the level of multicellular model systems is a necessary step for understanding tissue mechanics and its fundamental principles in health and disease. Both cell sheets and spheroids are used in tissue engineering, and the modulation of mechanical properties of cell constructs is a promising tool for regenerative medicine. Here, we review the data on mechanical characterization of cell sheets and spheroids, focusing both on advances in the measurement techniques and current understanding of the subject. The reviewed material suggest that interplay between the ECM, intercellular junctions, and cellular contractility determines the behavior and mechanical properties of the cell aggregates.
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Affiliation(s)
- Yuri M. Efremov
- Institute for Regenerative Medicine, Sechenov First Moscow State Medical University (Sechenov University), 119991 8-2 Trubetskaya St, Moscow, Russia
- World-Class Research Center “Digital Biodesign and Personalized Healthcare”, Sechenov University, Moscow, 119991 Russia
| | - Irina M. Zurina
- Institute for Regenerative Medicine, Sechenov First Moscow State Medical University (Sechenov University), 119991 8-2 Trubetskaya St, Moscow, Russia
- FSBSI Institute of General Pathology and Pathophysiology, 125315, 8 Baltiyskaya St, Moscow, Russia
| | - Viktoria S. Presniakova
- Institute for Regenerative Medicine, Sechenov First Moscow State Medical University (Sechenov University), 119991 8-2 Trubetskaya St, Moscow, Russia
| | - Nastasia V. Kosheleva
- Institute for Regenerative Medicine, Sechenov First Moscow State Medical University (Sechenov University), 119991 8-2 Trubetskaya St, Moscow, Russia
- World-Class Research Center “Digital Biodesign and Personalized Healthcare”, Sechenov University, Moscow, 119991 Russia
- FSBSI Institute of General Pathology and Pathophysiology, 125315, 8 Baltiyskaya St, Moscow, Russia
| | - Denis V. Butnaru
- Institute for Urology and Reproductive Health, Sechenov University, Moscow, Russia
| | - Andrey A. Svistunov
- Sechenov First Moscow State Medical University (Sechenov University), 119991, 8-2 Trubetskaya St, Moscow, Russia
| | - Yury A. Rochev
- Institute for Regenerative Medicine, Sechenov First Moscow State Medical University (Sechenov University), 119991 8-2 Trubetskaya St, Moscow, Russia
- Centre for Research in Medical Devices (CÚRAM), National University of Ireland Galway, Galway, H91 W2TY, Ireland
| | - Peter S. Timashev
- Institute for Regenerative Medicine, Sechenov First Moscow State Medical University (Sechenov University), 119991 8-2 Trubetskaya St, Moscow, Russia
- World-Class Research Center “Digital Biodesign and Personalized Healthcare”, Sechenov University, Moscow, 119991 Russia
- Department of Polymers and Composites, N.N. Semenov Institute of Chemical Physics, 119991 4 Kosygin St, Moscow, Russia
- Chemistry Department, Lomonosov Moscow State University, Leninskiye Gory 1–3, Moscow, 119991 Russia
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Aermes C, Hayn A, Fischer T, Mierke CT. Cell mechanical properties of human breast carcinoma cells depend on temperature. Sci Rep 2021; 11:10771. [PMID: 34031462 PMCID: PMC8144563 DOI: 10.1038/s41598-021-90173-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 04/30/2021] [Indexed: 12/21/2022] Open
Abstract
The knowledge of cell mechanics is required to understand cellular processes and functions, such as the movement of cells, and the development of tissue engineering in cancer therapy. Cell mechanical properties depend on a variety of factors, such as cellular environments, and may also rely on external factors, such as the ambient temperature. The impact of temperature on cell mechanics is not clearly understood. To explore the effect of temperature on cell mechanics, we employed magnetic tweezers to apply a force of 1 nN to 4.5 µm superparamagnetic beads. The beads were coated with fibronectin and coupled to human epithelial breast cancer cells, in particular MCF-7 and MDA-MB-231 cells. Cells were measured in a temperature range between 25 and 45 °C. The creep response of both cell types followed a weak power law. At all temperatures, the MDA-MB-231 cells were pronouncedly softer compared to the MCF-7 cells, whereas their fluidity was increased. However, with increasing temperature, the cells became significantly softer and more fluid. Since mechanical properties are manifested in the cell's cytoskeletal structure and the paramagnetic beads are coupled through cell surface receptors linked to cytoskeletal structures, such as actin and myosin filaments as well as microtubules, the cells were probed with pharmacological drugs impacting the actin filament polymerization, such as Latrunculin A, the myosin filaments, such as Blebbistatin, and the microtubules, such as Demecolcine, during the magnetic tweezer measurements in the specific temperature range. Irrespective of pharmacological interventions, the creep response of cells followed a weak power law at all temperatures. Inhibition of the actin polymerization resulted in increased softness in both cell types and decreased fluidity exclusively in MDA-MB-231 cells. Blebbistatin had an effect on the compliance of MDA-MB-231 cells at lower temperatures, which was minor on the compliance MCF-7 cells. Microtubule inhibition affected the fluidity of MCF-7 cells but did not have a significant effect on the compliance of MCF-7 and MDA-MB-231 cells. In summary, with increasing temperature, the cells became significant softer with specific differences between the investigated drugs and cell lines.
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Affiliation(s)
- Christian Aermes
- Biological Physics Division, Faculty of Physics and Earth Science, Peter Debye Institute of Soft Matter Physics, University of Leipzig, Linnéstr. 5, 04103, Leipzig, Germany
| | - Alexander Hayn
- Biological Physics Division, Faculty of Physics and Earth Science, Peter Debye Institute of Soft Matter Physics, University of Leipzig, Linnéstr. 5, 04103, Leipzig, Germany
| | - Tony Fischer
- Biological Physics Division, Faculty of Physics and Earth Science, Peter Debye Institute of Soft Matter Physics, University of Leipzig, Linnéstr. 5, 04103, Leipzig, Germany
| | - Claudia Tanja Mierke
- Biological Physics Division, Faculty of Physics and Earth Science, Peter Debye Institute of Soft Matter Physics, University of Leipzig, Linnéstr. 5, 04103, Leipzig, Germany.
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7
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Reina-Torres E, Boussommier-Calleja A, Sherwood JM, Overby DR. Aqueous Humor Outflow Requires Active Cellular Metabolism in Mice. Invest Ophthalmol Vis Sci 2021; 61:45. [PMID: 32845955 PMCID: PMC7452856 DOI: 10.1167/iovs.61.10.45] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Purpose Conventional wisdom posits that aqueous humor leaves the eye by passive bulk flow without involving energy-dependent processes. However, recent studies have shown that active processes, such as cell contractility, contribute to outflow regulation. Here, we examine whether inhibiting cellular metabolism affects outflow facility in mice. Methods We measured outflow facility in paired enucleated eyes from C57BL/6J mice using iPerfusion. We had three Experimental Sets: ES1, perfused at 35°C versus 22°C; ES2, perfused with metabolic inhibitors versus vehicle at 35°C; and ES3, perfused at 35°C versus 22°C in the presence of metabolic inhibitors. Inhibitors targeted glycolysis and oxidative phosphorylation (2-deoxy-D-glucose, 3PO and sodium azide). We also measured adenosine triphosphate (ATP) levels in separate murine anterior segments treated like ES1 and ES2. Results Reducing temperature decreased facility by 63% [38%, 78%] (mean [95% confidence interval (CI)], n = 10 pairs; P = 0.002) in ES1 after correcting for changes in viscosity. Metabolic inhibitors reduced facility by 21% [9%, 31%] (n = 9, P = 0.006) in ES2. In the presence of inhibitors, temperature reduction decreased facility by 44% [29%, 56%] (n = 8, P < 0.001) in ES3. Metabolic inhibitors reduced anterior segment adenosine triphosphate (ATP) levels by 90% [83%, 97%] (n = 5, P<<0.001), but reducing temperature did not affect ATP. Conclusions Inhibiting cellular metabolism decreases outflow facility within minutes. This implies that outflow is not entirely passive, but depends partly on energy-dependent cellular processes, at least in mice. This study also suggests that there is a yet unidentified mechanism, which is strongly temperature-dependent but metabolism-independent, that is necessary for nearly half of normal outflow function in mice.
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Affiliation(s)
- Ester Reina-Torres
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | | | - Joseph M Sherwood
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Darryl R Overby
- Department of Bioengineering, Imperial College London, London, United Kingdom
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8
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Boot RC, Koenderink GH, Boukany PE. Spheroid mechanics and implications for cell invasion. ADVANCES IN PHYSICS: X 2021. [DOI: 10.1080/23746149.2021.1978316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Affiliation(s)
- Ruben C. Boot
- Department of Chemical Engineering, Delft University of Technology, Delft, The Netherlands
| | - Gijsje H. Koenderink
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft, The Netherlands
| | - Pouyan E. Boukany
- Department of Chemical Engineering, Delft University of Technology, Delft, The Netherlands
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9
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Romanov V, Silvani G, Zhu H, Cox CD, Martinac B. An Acoustic Platform for Single-Cell, High-Throughput Measurements of the Viscoelastic Properties of Cells. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2021; 17:e2005759. [PMID: 33326190 DOI: 10.1002/smll.202005759] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 12/01/2020] [Indexed: 06/12/2023]
Abstract
Cellular processes including adhesion, migration, and differentiation are governed by the distinct mechanical properties of each cell. Importantly, the mechanical properties of individual cells can vary depending on local physical and biochemical cues in a time-dependent manner resulting in significant inter-cell heterogeneity. While several different methods have been developed to interrogate the mechanical properties of single cells, throughput to capture this heterogeneity remains an issue. Here, single-cell, high-throughput characterization of adherent cells is demonstrated using acoustic force spectroscopy (AFS). AFS works by simultaneously, acoustically driving tens to hundreds of silica beads attached to cells away from the cell surface, allowing the user to measure the stiffness of adherent cells under multiple experimental conditions. It is shown that cells undergo marked changes in viscoelasticity as a function of temperature, by altering the temperature within the AFS microfluidic circuit between 21 and 37 °C. In addition, quantitative differences in cells exposed to different pharmacological treatments specifically targeting the membrane-cytoskeleton interface are shown. Further, the high-throughput format of the AFS is utilized to rapidly probe, in excess of 1000 cells, three different cell lines expressing different levels of a mechanosensitive protein, Piezo1, demonstrating the ability to differentiate between cells based on protein expression levels.
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Affiliation(s)
- Valentin Romanov
- Department of Molecular Cardiology and Biophysics, Victor Chang Cardiac Research Institute, Darlinghurst, Sydney, NSW, 2010, Australia
| | - Giulia Silvani
- Department of Molecular Cardiology and Biophysics, Victor Chang Cardiac Research Institute, Darlinghurst, Sydney, NSW, 2010, Australia
| | - Huiyu Zhu
- Faculty of Science, University of Technology Sydney, Ultimo, Sydney, NSW, 2007, Australia
| | - Charles D Cox
- Department of Molecular Cardiology and Biophysics, Victor Chang Cardiac Research Institute, Darlinghurst, Sydney, NSW, 2010, Australia
- St Vincent's Clinical School, University of New South Wales, Sydney, NSW, 2010, Australia
| | - Boris Martinac
- Department of Molecular Cardiology and Biophysics, Victor Chang Cardiac Research Institute, Darlinghurst, Sydney, NSW, 2010, Australia
- St Vincent's Clinical School, University of New South Wales, Sydney, NSW, 2010, Australia
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10
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Gensbittel V, Kräter M, Harlepp S, Busnelli I, Guck J, Goetz JG. Mechanical Adaptability of Tumor Cells in Metastasis. Dev Cell 2020; 56:164-179. [PMID: 33238151 DOI: 10.1016/j.devcel.2020.10.011] [Citation(s) in RCA: 87] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 09/18/2020] [Accepted: 10/16/2020] [Indexed: 12/12/2022]
Abstract
The most dangerous aspect of cancer lies in metastatic progression. Tumor cells will successfully form life-threatening metastases when they undergo sequential steps along a journey from the primary tumor to distant organs. From a biomechanics standpoint, growth, invasion, intravasation, circulation, arrest/adhesion, and extravasation of tumor cells demand particular cell-mechanical properties in order to survive and complete the metastatic cascade. With metastatic cells usually being softer than their non-malignant counterparts, high deformability for both the cell and its nucleus is thought to offer a significant advantage for metastatic potential. However, it is still unclear whether there is a finely tuned but fixed mechanical state that accommodates all mechanical features required for survival throughout the cascade or whether tumor cells need to dynamically refine their properties and intracellular components at each new step encountered. Here, we review the various mechanical requirements successful cancer cells might need to fulfill along their journey and speculate on the possibility that they dynamically adapt their properties accordingly. The mechanical signature of a successful cancer cell might actually be its ability to adapt to the successive microenvironmental constraints along the different steps of the journey.
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Affiliation(s)
- Valentin Gensbittel
- INSERM UMR_S1109, Tumor Biomechanics, Strasbourg, France; Université de Strasbourg, Strasbourg, France; Fédération de Médecine Translationnelle de Strasbourg (FMTS), Strasbourg, France
| | - Martin Kräter
- Max Planck Institute for the Science of Light & Max-Planck-Zentrum für Physik und Medizin, Erlangen, Germany
| | - Sébastien Harlepp
- INSERM UMR_S1109, Tumor Biomechanics, Strasbourg, France; Université de Strasbourg, Strasbourg, France; Fédération de Médecine Translationnelle de Strasbourg (FMTS), Strasbourg, France
| | - Ignacio Busnelli
- INSERM UMR_S1109, Tumor Biomechanics, Strasbourg, France; Université de Strasbourg, Strasbourg, France; Fédération de Médecine Translationnelle de Strasbourg (FMTS), Strasbourg, France
| | - Jochen Guck
- Max Planck Institute for the Science of Light & Max-Planck-Zentrum für Physik und Medizin, Erlangen, Germany.
| | - Jacky G Goetz
- INSERM UMR_S1109, Tumor Biomechanics, Strasbourg, France; Université de Strasbourg, Strasbourg, France; Fédération de Médecine Translationnelle de Strasbourg (FMTS), Strasbourg, France.
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11
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Viscoelasticity and Volume of Cortical Neurons under Glutamate Excitotoxicity and Osmotic Challenges. Biophys J 2020; 119:1712-1723. [PMID: 33086042 DOI: 10.1016/j.bpj.2020.09.022] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 08/28/2020] [Accepted: 09/21/2020] [Indexed: 01/15/2023] Open
Abstract
Neural activity depends on the maintenance of ionic and osmotic homeostasis. Under these conditions, the cell volume must be regulated to maintain optimal neural function. A disturbance in the neuronal volume regulation often occurs in pathological conditions such as glutamate excitotoxicity. The cell volume, mechanical properties, and actin cytoskeleton structure are tightly connected to achieve the cell homeostasis. Here, we studied the effects of glutamate-induced excitotoxicity, external osmotic pressure, and inhibition of actin polymerization on the viscoelastic properties and volume of neurons. Atomic force microscopy was used to map the viscoelastic properties of neurons in time-series experiments to observe the dynamical changes and a possible recovery. The data obtained on cultured rat cortical neurons were compared with the data obtained on rat fibroblasts. The neurons were found to be more responsive to the osmotic challenges but less sensitive to the inhibition of actin polymerization than fibroblasts. The alterations of the viscoelastic properties caused by glutamate excitotoxicity were similar to those induced by the hypoosmotic stress, but, in contrast to the latter, they did not recover after the glutamate removal. These data were consistent with the dynamic volume changes estimated using ratiometric fluorescent dyes. The recovery after the glutamate-induced excitotoxicity was slow or absent because of a steady increase in intracellular calcium and sodium concentrations. The viscoelastic parameters and their changes were related to such parameters as the actin cortex stiffness, tension, and cytoplasmic viscosity.
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12
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Mok S, Al Habyan S, Ledoux C, Lee W, MacDonald KN, McCaffrey L, Moraes C. Mapping cellular-scale internal mechanics in 3D tissues with thermally responsive hydrogel probes. Nat Commun 2020; 11:4757. [PMID: 32958771 PMCID: PMC7505969 DOI: 10.1038/s41467-020-18469-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Accepted: 08/25/2020] [Indexed: 02/07/2023] Open
Abstract
Local tissue mechanics play a critical role in cell function, but measuring these properties at cellular length scales in living 3D tissues can present considerable challenges. Here we present thermoresponsive, smart material microgels that can be dispersed or injected into tissues and optically assayed to measure residual tissue elasticity after creep over several weeks. We first develop and characterize the sensors, and demonstrate that internal mechanical profiles of live multicellular spheroids can be mapped at high resolutions to reveal broad ranges of rigidity within the tissues, which vary with subtle differences in spheroid aggregation method. We then show that small sites of unexpectedly high rigidity develop in invasive breast cancer spheroids, and in an in vivo mouse model of breast cancer progression. These focal sites of increased intratumoral rigidity suggest new possibilities for how early mechanical cues that drive cancer cells towards invasion might arise within the evolving tumor microenvironment.
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Affiliation(s)
- Stephanie Mok
- Department of Chemical Engineering, McGill University, 3610 University Street, Montreal, QC, H3A 0C5, Canada
| | - Sara Al Habyan
- Rosalind and Morris Goodman Cancer Research Centre, McGill University, 160 Pine Ave W, Montreal, QC, H3A 1A3, Canada
| | - Charles Ledoux
- Department of Chemical Engineering, McGill University, 3610 University Street, Montreal, QC, H3A 0C5, Canada
| | - Wontae Lee
- Department of Chemical Engineering, McGill University, 3610 University Street, Montreal, QC, H3A 0C5, Canada
| | - Katherine N MacDonald
- Department of Chemical Engineering, McGill University, 3610 University Street, Montreal, QC, H3A 0C5, Canada
| | - Luke McCaffrey
- Rosalind and Morris Goodman Cancer Research Centre, McGill University, 160 Pine Ave W, Montreal, QC, H3A 1A3, Canada
| | - Christopher Moraes
- Department of Chemical Engineering, McGill University, 3610 University Street, Montreal, QC, H3A 0C5, Canada.
- Rosalind and Morris Goodman Cancer Research Centre, McGill University, 160 Pine Ave W, Montreal, QC, H3A 1A3, Canada.
- Department of Biomedical Engineering, McGill University, 3775 University Street, Montreal, QC, H3A 2B4, Canada.
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13
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Berntsen P, Ericsson T, Swenson J, Sjögren L. Complex modulus and compliance for airway smooth muscle cells. Phys Rev E 2020; 101:032410. [PMID: 32289912 DOI: 10.1103/physreve.101.032410] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 01/24/2020] [Indexed: 11/07/2022]
Abstract
A cell can be described as a complex viscoelastic material with structural relaxations that is modulated by thermal and chemically nonequilibrium processes. Tissue morphology and function rely upon cells' physical responses to mechanical force. We measured the frequency-dependent mechanical relaxation response of adherent human airway smooth muscle cells under adenosine triphosphate (ATP) depletion and normal ATP conditions. The frequency dependence of the complex compliance J^{*} and modulus G^{*} was measured over the frequencies 10^{-1}<f<10^{3} Hz at selected temperatures between 4<T<54^{∘}C. Our results show characteristic relaxation features which can be interpreted by the mode-coupling theory (MCT) of viscoelastic liquids. We analyze the shape of the spectra in terms of a so-called A_{4} scenario with logarithmic scaling laws. Characteristic timescales τ_{β} and τ_{α} appear with corresponding energy barriers E_{β}≈(10-20)k_{B}T and E_{α}≈(20-30)k_{B}T. We demonstrate that cells are close to a glass transition. We find that the cell becomes softer around physiological temperatures, where its surface structure is more liquid-like with a plateau modulus around 0.1-0.8 kPa compared with the more solid-like interior cytoskeletal structures with a plateau modulus 1-15 kPa. Corresponding values for the viscosity are 10^{2}-10^{3} Pa s for the surface structures closer to the membrane and 10^{4}-10^{6} Pa s for the core cytoskeletal structures.
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Affiliation(s)
- Peter Berntsen
- Australian Research Council (ARC) Centre of Excellence in Advanced Molecular Imaging, Department of Chemistry and Physics, La Trobe Institute for Molecular Sciences, La Trobe University, Melbourne, Victoria 3086, Australia
| | - Thomas Ericsson
- Department of Mathematical Sciences, Chalmers University of Technology, and the University of Gothenburg, 41296 Göteborg, Sweden
| | - Jan Swenson
- Department of Physics, Chalmers University of Technology, 41296 Göteborg, Sweden
| | - Lennart Sjögren
- Department of Physics, University of Gothenburg, 41296 Göteborg, Sweden
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High-speed force spectroscopy: microsecond force measurements using ultrashort cantilevers. Biophys Rev 2019; 11:689-699. [PMID: 31588961 PMCID: PMC6815269 DOI: 10.1007/s12551-019-00585-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Accepted: 08/27/2019] [Indexed: 10/25/2022] Open
Abstract
Complete understanding of the role of mechanical forces in biological processes requires knowledge of the mechanical properties of individual proteins and living cells. Moreover, the dynamic response of biological systems at the nano- and microscales span over several orders of magnitude in time, from sub-microseconds to several minutes. Thus, access to force measurements over a wide range of length and time scales is required. High-speed atomic force microscopy (HS-AFM) using ultrashort cantilevers has emerged as a tool to study the dynamics of biomolecules and cells at video rates. The adaptation of HS-AFM to perform high-speed force spectroscopy (HS-FS) allows probing protein unfolding and receptor/ligand unbinding up to the velocity of molecular dynamics (MD) simulations with sub-microsecond time resolution. Moreover, application of HS-FS on living cells allows probing the viscoelastic response at short time scales providing deep understanding of cytoskeleton dynamics. In this mini-review, we assess the principles and recent developments and applications of HS-FS using ultrashort cantilevers to probe molecular and cellular mechanics.
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15
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Bohec P, Tailleur J, van Wijland F, Richert A, Gallet F. Distribution of active forces in the cell cortex. SOFT MATTER 2019; 15:6952-6966. [PMID: 31432058 DOI: 10.1039/c9sm00441f] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
In this work, we study in detail the distribution of stochastic forces generated by the molecular motors activity, in the actin cortex of pre-muscular cells. By combining active and passive rheology experiments, performed on the same micro-bead bound to the actin network through membrane adhesive receptors, we measure the auto-correlation function Cff(τ) of the average force pulling on the bead. As for any out-of-equilibrium system, the force distribution differs from the thermodynamical equilibrium one, especially at long time scale τ⪆ 1 s where the bead motion becomes partially directed. Thus the fluctuation-dissipation theorem does not apply and one can measure the distance from equilibrium through its violation. We investigate the influence of different parameters on the force distribution, focusing particularly on the role of ligand density: a detailed study shows how the amplitude of active forces increases when the bead is more tightly attached to the cortex. We introduce and study a model, which takes into account the number of bonds between the bead and the cytoskeleton, as well as the viscoelastic properties of the medium. This model faithfully accounts for the experimental observations. Also, it is shown that the amplitude of active forces increases with temperature. Finally, our data confirm that ATP depletion in the cell, or partial inhibition of the actomyosin activity, leads to a decrease of the amplitude of the force distribution. Altogether, we propose a consistent and quantitative description for the motion of a micrometric probe interacting with the actin network, and for the amplitude of the stochastic forces generated by molecular motors in the cortex surrounding this probe.
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Affiliation(s)
- P Bohec
- Matière et Systèmes Complexes, UMR 7057 associée au CNRS et à l'Université Paris-Diderot, 10 rue Alice Domon et Léonie Duquet, F-75013 Paris, France.
| | - J Tailleur
- Matière et Systèmes Complexes, UMR 7057 associée au CNRS et à l'Université Paris-Diderot, 10 rue Alice Domon et Léonie Duquet, F-75013 Paris, France.
| | - F van Wijland
- Matière et Systèmes Complexes, UMR 7057 associée au CNRS et à l'Université Paris-Diderot, 10 rue Alice Domon et Léonie Duquet, F-75013 Paris, France.
| | - A Richert
- Matière et Systèmes Complexes, UMR 7057 associée au CNRS et à l'Université Paris-Diderot, 10 rue Alice Domon et Léonie Duquet, F-75013 Paris, France.
| | - F Gallet
- Matière et Systèmes Complexes, UMR 7057 associée au CNRS et à l'Université Paris-Diderot, 10 rue Alice Domon et Léonie Duquet, F-75013 Paris, France.
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Sunnerberg JP, Moore P, Spedden E, Kaplan DL, Staii C. Variations of Elastic Modulus and Cell Volume with Temperature for Cortical Neurons. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:10965-10976. [PMID: 31380651 PMCID: PMC7306228 DOI: 10.1021/acs.langmuir.9b01651] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Neurons change their growth dynamics and mechanical properties in response to external stimuli such as stiffness of the local microenvironment, ambient temperature, and biochemical or geometrical guidance cues. Here we use combined atomic force microscopy (AFM) and fluorescence microscopy experiments to investigate the relationship between external temperature, soma volume, and elastic modulus for cortical neurons. We measure how changes in ambient temperature affect the volume and the mechanical properties of neuronal cells at both the bulk (elastic modulus) and local (elasticity maps) levels. The experimental data demonstrate that both the volume and the elastic modulus of the neuron soma vary with changes in temperature. Our results show a decrease by a factor of 2 in the soma elastic modulus as the ambient temperature increases from room (25 °C) to physiological (37 °C) temperature, while the volume of the soma increases by a factor of 1.3 during the same temperature sweep. Using high-resolution AFM force mapping, we measure the temperature-induced variations within different regions of the elasticity maps (low and high values of elastic modulus) and correlate these variations with the dynamics of cytoskeleton components and molecular motors. We quantify the change in soma volume with temperature and propose a simple theoretical model that relates this change with variations in soma elastic modulus. These results have significant implications for understanding neuronal development and functions, as ambient temperature, cytoskeletal dynamics, and cellular volume may change with variations in physiological conditions, for example, during tissue compression and infections in vivo as well as during cell manipulation and tissue regeneration ex vivo.
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Eshrati M, Amadei F, Staffer S, Stremmel W, Tanaka M. Shear-Enhanced Dynamic Adhesion of Lactobacillus rhamnosus GG on Intestinal Epithelia: Correlative Effect of Protein Expression and Interface Mechanics. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:529-537. [PMID: 30567428 DOI: 10.1021/acs.langmuir.8b02931] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The oral uptake of probiotic microorganisms as food additives is one widely used strategy to sustain and improve the homeostasis of intestinal microbiota that protect the intestinal epithelia from attack by pathogenic bacteria. Once delivered to the ileum and colon, probiotics must adhere and form colonies on mucus that coats the surface of intestinal epithelial cells. Although an increasing amount of knowledge about the genetic and molecular level mechanisms of probiotics-mucus interactions has been accumulated, little is known about the physicochemical aspects of probiotics-mucus interactions under physiological shear in intestines. In this study, we established well-defined models of intestinal epithelial cell monolayers based on two major constituents of gut epithelia, enterocytes and goblet cells. First, the formation of a polarized cell monolayer sealed by tight junctions was monitored by transepithelial electrical resistance over time. The establishment of tight junctions and secretion of mucus proteins (mucin) was confirmed by immunofluorescence staining. In the next step, we measured the elasticity of cell monolayer surfaces by indentation using particle-assisted atomic force microscopy. The effective elastic modulus of goblet cell-like cells was 30 times smaller compared to that of enterocyte-like cells, which can be attributed to the secretion of a 3 μm thick mucin layer. As probiotics, we used Lactobacillus rhamnosus GG (LGG), which is one of the most widely used strains as food additives. To investigate the dynamic adhesion of LGG to the intestine model surface, we transferred the epithelial cell monolayer into a microfluidic chamber. A distinct difference in dynamic adhesion between two cell types was observed, which could be attributed to the difference in the mucin expression amount. Remarkably, we found that the dynamic LGG adhesion is enhanced by the increase in shear stress, showing a maximum binding efficiency at 0.3 Pa. Finally, we examined the persistence of LGG adhesion by a stepwise increase in the shear stress exerted on adherent LGG, demonstrating that LGG could withstand high shear stress even beyond that of physiological stress. The obtained results present a large potential to quantitatively understand the influence of engineered foods and probiotics on the homeostasis of microbiota on the surface of intestinal epithelia.
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Affiliation(s)
- Maryam Eshrati
- Physical Chemistry of Biosystems, Institute of Physical Chemistry , Heidelberg University , D69120 Heidelberg , Germany
| | - Federico Amadei
- Physical Chemistry of Biosystems, Institute of Physical Chemistry , Heidelberg University , D69120 Heidelberg , Germany
| | - Simone Staffer
- Internal Medicine IV , University Hospital Heidelberg , D69120 Heidelberg , Germany
| | - Wolfgang Stremmel
- Internal Medicine IV , University Hospital Heidelberg , D69120 Heidelberg , Germany
- Medical Center Baden-Baden , D76530 Baden-Baden , Germany
| | - Motomu Tanaka
- Physical Chemistry of Biosystems, Institute of Physical Chemistry , Heidelberg University , D69120 Heidelberg , Germany
- Center for Integrative Medicine and Physics, Institute for Advanced Study , Kyoto University , 606-8501 Kyoto , Japan
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18
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Bidirectional mechanobiology between cells and their local extracellular matrix probed by atomic force microscopy. Semin Cell Dev Biol 2018; 73:71-81. [DOI: 10.1016/j.semcdb.2017.07.020] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Revised: 07/13/2017] [Accepted: 07/17/2017] [Indexed: 01/08/2023]
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19
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Wang C, Li L, Liu Z. Experimental research on the relationship between the stiffness and the expressions of fibronectin proteins and adaptor proteins of rat trabecular meshwork cells. BMC Ophthalmol 2017; 17:268. [PMID: 29284449 PMCID: PMC5747132 DOI: 10.1186/s12886-017-0662-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Accepted: 12/12/2017] [Indexed: 12/28/2022] Open
Abstract
Background Trabecular meshwork (TM) plays an important role in maintaining normal intraocular pressure (IOP). Studies have shown that glaucomatous TM tissues are stiffer than those of normal tissue. The high expression of fibronectin protein (FN) and adaptor protein (LNK) may be related to high resistance to aqueous humor outflow as well as high IOP. Our concern is what factors lead to the variation of the stiffness of trabecular tissue/cells. Methods Atomic force microscope (AFM) and Western blot (WB) analysis were applied to test TM cells of rats cultured with different concentrations of dexamethasone (DEX) and mifepristone (MIF). Rat TM cells were randomly divided into 7 groups, marked as D1, D2, D3 and M1, M2 M3 for different concentrations of DEX and MIF, respectively, and C for blank control. Results The elastic modulus of the treated cells were 2.67 ± 0.914 KPa, 2.92 ± 0.986 KPa, 4.52 ± 1.22 KPa for D1, D2, D3, 2.06 ± 0.745 KPa, 1.23 ± 0.462 KPa, 0.467 ± 0.275 KPa for M1, M2, M3, and 2.43 ± 0.713 KPa for C group, respectively. Expressions of FN and LNK increase (decrease) with the increase of the concentrations of DEX (MIF). Discussion We focus on the relationship between the stiffness and the expressions of FN and LNK of rat TM cells. We analyzed the correlation between cell stiffness and FN, LNK expression, discussed the relationship between cell stiffness and aqueous humor outflow resistance. Conclusions The changes of TM cell stiffness and the expressions of FN and LNK are positively correlated.
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Affiliation(s)
- Chuan Wang
- Department of Biomechanics and Rehabilitation Engineering, School of Biomedical Engineering, Capital Medical University, No.10 Xitoutiao, You An Men, Beijing, 100069, People's Republic of China.,Beijing Key Laboratory of Fundamental Research on Biomechanics in Clinical Application, Capital Medical University, Beijing, 100069, China.,YanJing Medical College, Capital Medical University, Beijing, 100069, China
| | - Lin Li
- Department of Biomedical Informatics, School of Biomedical Engineering, Capital Medical University, No.10 Xitoutiao, You An Men, Beijing, 100069, People's Republic of China.
| | - Zhicheng Liu
- Department of Biomechanics and Rehabilitation Engineering, School of Biomedical Engineering, Capital Medical University, No.10 Xitoutiao, You An Men, Beijing, 100069, People's Republic of China. .,Beijing Key Laboratory of Fundamental Research on Biomechanics in Clinical Application, Capital Medical University, Beijing, 100069, China.
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20
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Auger N, Rhéaume MA, Bilodeau-Bertrand M, Tang T, Kosatsky T. Climate and the eye: Case-crossover analysis of retinal detachment after exposure to ambient heat. ENVIRONMENTAL RESEARCH 2017; 157:103-109. [PMID: 28549308 DOI: 10.1016/j.envres.2017.05.017] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Revised: 05/12/2017] [Accepted: 05/13/2017] [Indexed: 06/07/2023]
Abstract
BACKGROUND Retinal detachment is an important cause of visual loss, but the association with outdoor heat exposure has not been studied. Our objective was to determine the relationship between acute exposure to high outdoor temperature and risk of retinal detachment. MATERIALS AND METHODS We analysed 14,302 individuals with inpatient procedures for retinal detachment from April through September between 2006 and 2013 in the province of Quebec, Canada. Using a time-stratified case-crossover study design, we examined the association of retinal detachment with outdoor summer temperature the preceding week. We estimated odds ratios (OR) and 95% confidence intervals (CI) for mean weekly temperature according to subtypes of retinal detachment (traction, serous, rhegmatogenous, breaks), and assessed associations by age and sex. RESULTS Exposure to elevated temperature the preceding week was associated with a higher likelihood of traction detachment, but not other forms of retinal detachment. Associations were stronger at <75 years of age in both men and women. Relative to 15°C, a mean weekly temperature of 25°C was associated with an OR for traction detachment of 2.71 (95% CI 1.56-4.71) before 55 years, 2.73 (95% CI 1.61-4.64) at 55-64 years, and 1.98 (95% CI 1.30-3.02) at 64-75 years. DISCUSSION Elevated outdoor temperatures may be associated with an increased risk of traction retinal detachment. In light of climate change, a better understanding of the impact of heat waves on the eye and other sensory organs is needed.
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Affiliation(s)
- Nathalie Auger
- University of Montreal Hospital Research Centre, 900 Saint-Denis, Montreal, Quebec, Canada H2X 0A9; Institut national de santé publique du Québec, 190 Crémazie E Blvd, Montreal, Quebec, Canada H2P 1E2.
| | - Marc-André Rhéaume
- University of Montreal Hospital Research Centre, 900 Saint-Denis, Montreal, Quebec, Canada H2X 0A9; Department of Ophthalmology, University of Montreal, 2900 Édouard-Montpetit, Montreal, Quebec, Canada H3T 1J4
| | - Marianne Bilodeau-Bertrand
- University of Montreal Hospital Research Centre, 900 Saint-Denis, Montreal, Quebec, Canada H2X 0A9; Institut national de santé publique du Québec, 190 Crémazie E Blvd, Montreal, Quebec, Canada H2P 1E2
| | - Tina Tang
- Faculty of Medicine, McGill University, 3655, Promenade Sir-William-Osler, Montreal, Quebec, Canada H3G 1Y6
| | - Tom Kosatsky
- National Collaborating Centre for Environmental Health, British Columbia Centre for Disease Control, 601 West Broadway, Vancouver, British Columbia, Canada V5Z 4C2
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21
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Li M, Dang D, Liu L, Xi N, Wang Y. Atomic Force Microscopy in Characterizing Cell Mechanics for Biomedical Applications: A Review. IEEE Trans Nanobioscience 2017; 16:523-540. [PMID: 28613180 DOI: 10.1109/tnb.2017.2714462] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Cell mechanics is a novel label-free biomarker for indicating cell states and pathological changes. The advent of atomic force microscopy (AFM) provides a powerful tool for quantifying the mechanical properties of single living cells in aqueous conditions. The wide use of AFM in characterizing cell mechanics in the past two decades has yielded remarkable novel insights in understanding the development and progression of certain diseases, such as cancer, showing the huge potential of cell mechanics for practical applications in the field of biomedicine. In this paper, we reviewed the utilization of AFM to characterize cell mechanics. First, the principle and method of AFM single-cell mechanical analysis was presented, along with the mechanical responses of cells to representative external stimuli measured by AFM. Next, the unique changes of cell mechanics in two types of physiological processes (stem cell differentiation, cancer metastasis) revealed by AFM were summarized. After that, the molecular mechanisms guiding cell mechanics were analyzed. Finally the challenges and future directions were discussed.
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22
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Lanzicher T, Martinelli V, Long CS, Del Favero G, Puzzi L, Borelli M, Mestroni L, Taylor MRG, Sbaizero O. AFM single-cell force spectroscopy links altered nuclear and cytoskeletal mechanics to defective cell adhesion in cardiac myocytes with a nuclear lamin mutation. Nucleus 2016; 6:394-407. [PMID: 26309016 DOI: 10.1080/19491034.2015.1084453] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
Previous investigations suggested that lamin A/C gene (LMNA) mutations, which cause a variety of human diseases including muscular dystrophies and cardiomyopathies, alter the nuclear mechanical properties. We hypothesized that biomechanical changes may extend beyond the nucleus.
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Affiliation(s)
- Thomas Lanzicher
- a Department of Engineering and Architecture ; University of Trieste ; Trieste Italy
| | - Valentina Martinelli
- a Department of Engineering and Architecture ; University of Trieste ; Trieste Italy.,b International Center for Genetic Engineering and Biotechnology ; Trieste Italy
| | - Carlin S Long
- c Cardiovascular Institute & Adult Medical Genetics; University of Colorado Denver Anschutz Medical Campus ; CO USA
| | - Giorgia Del Favero
- d Department of Food Chemistry and Toxicology ; University of Vienna ; Waehringer Str. 38A-1090 Vienna Austria
| | - Luca Puzzi
- a Department of Engineering and Architecture ; University of Trieste ; Trieste Italy
| | - Massimo Borelli
- e Department of Life Sciences ; University of Trieste ; Trieste Italy
| | - Luisa Mestroni
- c Cardiovascular Institute & Adult Medical Genetics; University of Colorado Denver Anschutz Medical Campus ; CO USA
| | - Matthew R G Taylor
- c Cardiovascular Institute & Adult Medical Genetics; University of Colorado Denver Anschutz Medical Campus ; CO USA
| | - Orfeo Sbaizero
- a Department of Engineering and Architecture ; University of Trieste ; Trieste Italy.,c Cardiovascular Institute & Adult Medical Genetics; University of Colorado Denver Anschutz Medical Campus ; CO USA
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Sessions JW, Hanks BW, Lindstrom DL, Hope S, Jensen BD. Transient Low-Temperature Effects on Propidium Iodide Uptake in Lance Array Nanoinjected HeLa Cells. J Nanotechnol Eng Med 2016. [DOI: 10.1115/1.4033323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Understanding environmental factors relative to transfection protocols is key for improving genetic engineering outcomes. In the following work, the effects of temperature on a nonviral transfection procedure previously described as lance array nanoinjection are examined in context of molecular delivery of propidium iodide (PI), a cell membrane impermeable nucleic acid dye, to HeLa 229 cells. For treatment samples, variables include varying the temperature of the injection solution (3C and 23C) and the magnitude of the pulsed voltage used during lance insertion into the cells (+5 V and +7 V). Results indicate that PI is delivered at levels significantly higher for samples injected at 3C as opposed to 23C at four different postinjection intervals (t = 0, 3, 6, 9 mins; p-value ≤ 0.005), reaching a maximum value of 8.3 times the positive control for 3 C/7 V pulsed samples. Suggested in this work is that between 3 and 6 mins postinjection, a large number of induced pores from the injection event close. While residual levels of PI still continue to enter the treatment samples after 6 mins, it occurs at decreased levels, suggesting from a physiological perspective that many lance array nanoinjection (LAN) induced pores have closed, some are still present.
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Affiliation(s)
- John W. Sessions
- Department of Mechanical Engineering, Brigham Young University, Provo, UT 84602 e-mail:
| | - Brad W. Hanks
- Department of Mechanical Engineering, Brigham Young University, Provo, UT 84602 e-mail:
| | - Dallin L. Lindstrom
- Department of Exercise Science, Brigham Young University, Provo, UT 84602 e-mail:
| | - Sandra Hope
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT 84602 e-mail:
| | - Brian D. Jensen
- Department of Mechanical Engineering, Brigham Young University, Provo, UT 84602 e-mail:
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Oyama K, Arai T, Isaka A, Sekiguchi T, Itoh H, Seto Y, Miyazaki M, Itabashi T, Ohki T, Suzuki M, Ishiwata S. Directional bleb formation in spherical cells under temperature gradient. Biophys J 2016. [PMID: 26200871 DOI: 10.1016/j.bpj.2015.06.016] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Living cells sense absolute temperature and temporal changes in temperature using biological thermosensors such as ion channels. Here, we reveal, to our knowledge, a novel mechanism of sensing spatial temperature gradients within single cells. Spherical mitotic cells form directional membrane extensions (polar blebs) under sharp temperature gradients (≥∼0.065°C μm(-1); 1.3°C temperature difference within a cell), which are created by local heating with a focused 1455-nm laser beam under an optical microscope. On the other hand, multiple nondirectional blebs are formed under gradual temperature gradients or uniform heating. During heating, the distribution of actomyosin complexes becomes inhomogeneous due to a break in the symmetry of its contractile force, highlighting the role of the actomyosin complex as a sensor of local temperature gradients.
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Affiliation(s)
- Kotaro Oyama
- Department of Physics, School of Advanced Science and Engineering, Waseda University, Tokyo, Japan.
| | - Tomomi Arai
- Department of Physics, School of Advanced Science and Engineering, Waseda University, Tokyo, Japan
| | - Akira Isaka
- Department of Physics, School of Advanced Science and Engineering, Waseda University, Tokyo, Japan
| | - Taku Sekiguchi
- Department of Physics, School of Advanced Science and Engineering, Waseda University, Tokyo, Japan
| | - Hideki Itoh
- Department of Physics, School of Advanced Science and Engineering, Waseda University, Tokyo, Japan; Institute of Medical Biology, Agency for Science, Technology and Research (A(∗)STAR), Singapore, Singapore
| | - Yusuke Seto
- Department of Physics, School of Advanced Science and Engineering, Waseda University, Tokyo, Japan
| | - Makito Miyazaki
- Department of Physics, School of Advanced Science and Engineering, Waseda University, Tokyo, Japan
| | - Takeshi Itabashi
- Department of Physics, School of Advanced Science and Engineering, Waseda University, Tokyo, Japan
| | - Takashi Ohki
- Department of Physics, School of Advanced Science and Engineering, Waseda University, Tokyo, Japan
| | - Madoka Suzuki
- WASEDA Bioscience Research Institute in Singapore (WABIOS), Singapore, Singapore; Organization for University Research Initiatives, Waseda University, Tokyo, Japan.
| | - Shin'ichi Ishiwata
- Department of Physics, School of Advanced Science and Engineering, Waseda University, Tokyo, Japan; WASEDA Bioscience Research Institute in Singapore (WABIOS), Singapore, Singapore; Organization for University Research Initiatives, Waseda University, Tokyo, Japan.
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Simon M, Dokukin M, Kalaparthi V, Spedden E, Sokolov I, Staii C. Load Rate and Temperature Dependent Mechanical Properties of the Cortical Neuron and Its Pericellular Layer Measured by Atomic Force Microscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:1111-1119. [PMID: 26727545 DOI: 10.1021/acs.langmuir.5b04317] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
When studying the mechanical properties of cells by an indentation technique, it is important to take into account the nontrivial pericellular interface (or pericellular "brush") which includes a pericellular coating and corrugation of the pericellular membrane (microvilli and microridges). Here we use atomic force microscopy (AFM) to study the mechanics of cortical neurons taking into account the presence of the above pericellular brush surrounding cell soma. We perform a systematic study of the mechanical properties of both the brush layer and the underlying neuron soma and demonstrate that the brush layer is likely responsible for the low elastic modulus (<1 kPa) typically reported for cortical neurons. When the contribution of the pericellular brush is excluded, the average elastic modulus of the cortical neuron soma is found to be 3-4 times larger than previously reported values measured under similar physiological conditions. We also demonstrate that the underlying soma behaves as a nonviscous elastic material over the indentation rates studied (1-10 μm/s). As a result, it seems that the brush layer is responsible for the previously reported viscoelastic response measured for the neuronal cell body as a whole, within these indentation rates. Due to of the similarities between the macroscopic brain mechanics and the effective modulus of the pericellular brush, we speculate that the pericellular brush layer might play an important role in defining the macroscopic mechanical properties of the brain.
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Affiliation(s)
- Marc Simon
- Department of Physics and Astronomy, ‡Center for Nanoscopic Physics, §Department of Mechanical Engineering, and ∥Department of Biomedical Engineering, Tufts University , Medford, Massachusetts 02155, United States
| | - Maxim Dokukin
- Department of Physics and Astronomy, ‡Center for Nanoscopic Physics, §Department of Mechanical Engineering, and ∥Department of Biomedical Engineering, Tufts University , Medford, Massachusetts 02155, United States
| | - Vivekanand Kalaparthi
- Department of Physics and Astronomy, ‡Center for Nanoscopic Physics, §Department of Mechanical Engineering, and ∥Department of Biomedical Engineering, Tufts University , Medford, Massachusetts 02155, United States
| | - Elise Spedden
- Department of Physics and Astronomy, ‡Center for Nanoscopic Physics, §Department of Mechanical Engineering, and ∥Department of Biomedical Engineering, Tufts University , Medford, Massachusetts 02155, United States
| | - Igor Sokolov
- Department of Physics and Astronomy, ‡Center for Nanoscopic Physics, §Department of Mechanical Engineering, and ∥Department of Biomedical Engineering, Tufts University , Medford, Massachusetts 02155, United States
| | - Cristian Staii
- Department of Physics and Astronomy, ‡Center for Nanoscopic Physics, §Department of Mechanical Engineering, and ∥Department of Biomedical Engineering, Tufts University , Medford, Massachusetts 02155, United States
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Schlosser F, Rehfeldt F, Schmidt CF. Force fluctuations in three-dimensional suspended fibroblasts. Philos Trans R Soc Lond B Biol Sci 2015; 370:20140028. [PMID: 25533089 PMCID: PMC4275901 DOI: 10.1098/rstb.2014.0028] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Cells are sensitive to mechanical cues from their environment and at the same time generate and transmit forces to their surroundings. To test quantitatively forces generated by cells not attached to a substrate, we used a dual optical trap to suspend 3T3 fibroblasts between two fibronectin-coated beads. In this simple geometry, we measured both the cells' elastic properties and the force fluctuations they generate with high bandwidth. Cell stiffness decreased substantially with both myosin inhibition by blebbistatin and serum-starvation, but not with microtubule depolymerization by nocodazole. We show that cortical forces generated by non-muscle myosin II deform the cell from its rounded shape in the frequency regime from 0.1 to 10 Hz. The amplitudes of these forces were strongly reduced by blebbistatin and serum starvation, but were unaffected by depolymerization of microtubules. Force fluctuations show a spectrum that is characteristic for an elastic network activated by random sustained stresses with abrupt transitions.
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Affiliation(s)
- Florian Schlosser
- Third Institute of Physics-Biophysics, Georg August University, 37077 Göttingen, Germany
| | - Florian Rehfeldt
- Third Institute of Physics-Biophysics, Georg August University, 37077 Göttingen, Germany
| | - Christoph F Schmidt
- Third Institute of Physics-Biophysics, Georg August University, 37077 Göttingen, Germany
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27
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Li M, Liu L, Xi N, Wang Y, Xiao X, Zhang W. Effects of temperature and cellular interactions on the mechanics and morphology of human cancer cells investigated by atomic force microscopy. SCIENCE CHINA-LIFE SCIENCES 2015; 58:889-901. [PMID: 26354505 DOI: 10.1007/s11427-015-4914-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2014] [Accepted: 05/06/2015] [Indexed: 12/19/2022]
Abstract
Cell mechanics plays an important role in cellular physiological activities. Recent studies have shown that cellular mechanical properties are novel biomarkers for indicating the cell states. In this article, temperature-controllable atomic force microscopy (AFM) was applied to quantitatively investigate the effects of temperature and cellular interactions on the mechanics and morphology of human cancer cells. First, AFM indenting experiments were performed on six types of human cells to investigate the changes of cellular Young's modulus at different temperatures and the results showed that the mechanical responses to the changes of temperature were variable for different types of cancer cells. Second, AFM imaging experiments were performed to observe the morphological changes in living cells at different temperatures and the results showed the significant changes of cell morphology caused by the alterations of temperature. Finally, by co-culturing human cancer cells with human immune cells, the mechanical and morphological changes in cancer cells were investigated. The results showed that the co-culture of cancer cells and immune cells could cause the distinct mechanical changes in cancer cells, but no significant morphological differences were observed. The experimental results improved our understanding of the effects of temperature and cellular interactions on the mechanics and morphology of cancer cells.
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Affiliation(s)
- Mi Li
- State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang, 110016, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - LianQing Liu
- State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang, 110016, China.
| | - Ning Xi
- State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang, 110016, China. .,Department of Electrical and Computer Engineering, Michigan State University, East Lansing, MI, 48824, USA.
| | - YueChao Wang
- State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang, 110016, China
| | - XiuBin Xiao
- Department of Lymphoma, Affiliated Hospital of Military Medical Academy of Sciences, Beijing, 100071, China
| | - WeiJing Zhang
- Department of Lymphoma, Affiliated Hospital of Military Medical Academy of Sciences, Beijing, 100071, China
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28
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Hecht FM, Rheinlaender J, Schierbaum N, Goldmann WH, Fabry B, Schäffer TE. Imaging viscoelastic properties of live cells by AFM: power-law rheology on the nanoscale. SOFT MATTER 2015; 11:4584-4591. [PMID: 25891371 DOI: 10.1039/c4sm02718c] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
We developed force clamp force mapping (FCFM), an atomic force microscopy (AFM) technique for measuring the viscoelastic creep behavior of live cells with sub-micrometer spatial resolution. FCFM combines force-distance curves with an added force clamp phase during tip-sample contact. From the creep behavior measured during the force clamp phase, quantitative viscoelastic sample properties are extracted. We validate FCFM on soft polyacrylamide gels. We find that the creep behavior of living cells conforms to a power-law material model. By recording short (50-60 ms) force clamp measurements in rapid succession, we generate, for the first time, two-dimensional maps of power-law exponent and modulus scaling parameter. Although these maps reveal large spatial variations of both parameters across the cell surface, we obtain robust mean values from the several hundreds of measurements performed on each cell. Measurements on mouse embryonic fibroblasts show that the mean power-law exponents and the mean modulus scaling parameters differ greatly among individual cells, but both parameters are highly correlated: stiffer cells consistently show a smaller power-law exponent. This correlation allows us to distinguish between wild-type cells and cells that lack vinculin, a dominant protein of the focal adhesion complex, even though the mean values of viscoelastic properties between wildtype and knockout cells did not differ significantly. Therefore, FCFM spatially resolves viscoelastic sample properties and can uncover subtle mechanical signatures of proteins in living cells.
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Affiliation(s)
- Fabian M Hecht
- Institute of Applied Physics, University of Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany.
| | - Johannes Rheinlaender
- Institute of Applied Physics, University of Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany.
| | - Nicolas Schierbaum
- Institute of Applied Physics, University of Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany.
| | - Wolfgang H Goldmann
- Department of Physics, University of Erlangen-Nuremberg, Henkestraße 91, 91052 Erlangen, Germany
| | - Ben Fabry
- Department of Physics, University of Erlangen-Nuremberg, Henkestraße 91, 91052 Erlangen, Germany
| | - Tilman E Schäffer
- Institute of Applied Physics, University of Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany.
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29
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Hayashi K, Iwata M. Stiffness of cancer cells measured with an AFM indentation method. J Mech Behav Biomed Mater 2015; 49:105-11. [PMID: 26004036 DOI: 10.1016/j.jmbbm.2015.04.030] [Citation(s) in RCA: 106] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Revised: 04/28/2015] [Accepted: 04/30/2015] [Indexed: 12/13/2022]
Abstract
The stiffness of cancer cells and its changes during metastasis are very important for understanding the pathophysiology of cancer cells and the mechanisms of metastasis of cancer. As the first step of the studies on the mechanics of cancer cells during metastasis, we determined the elasticity and stiffness of cancer cells with an indentation method using an atomic force microscope (AFM), and compared with those of normal cells. In most of the past AFM studies, Young׳s elastic moduli of cells have been calculated from force-indentation data using Hertzian model. As this model is based on several important assumptions including infinitesimal strain and Hooke׳s linear stress-strain law, in the exact sense it cannot be applied to cells that deform very largely and nonlinearly. To overcome this problem, we previously proposed an equation F=a[exp(bδ)-1] to describe relations between force (F) and indentation (δ), where a and b are parameters relating with cellular stiffness. In the present study, we applied this method to cancer cells instead of Young׳s elastic modulus. The conclusions obtained are: 1) AFM indentation test data of cancer cells can be very well described by the above equation, 2) cancer cells are softer than normal cells, and 3) there are no significant locational differences in the stiffness of cancer cells between the central and the peripheral regions. These methods and results are useful for studying the mechanics of cancer cells and the mechanisms of metastasis.
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Affiliation(s)
- Kozaburo Hayashi
- Department of Biomedical Engineering, School of Engineering, Okayama University of Science, 1-1 Ridai-cho, Kita-ku, Okayama 700-0001, Japan; Department of Biomedical Engineering, College of Engineering, National Cheng Kung University, Tainan, Taiwan; Division of Bioengineering, Department of Mechanical Science and Bioengineering, Graduate School of Engineering Science, Osaka University, Toyonaka, Japan.
| | - Mayumi Iwata
- Department of Biomedical Engineering, School of Engineering, Okayama University of Science, 1-1 Ridai-cho, Kita-ku, Okayama 700-0001, Japan.
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30
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Distinct impact of targeted actin cytoskeleton reorganization on mechanical properties of normal and malignant cells. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1853:3117-25. [PMID: 25970206 DOI: 10.1016/j.bbamcr.2015.05.008] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Revised: 04/23/2015] [Accepted: 05/05/2015] [Indexed: 01/19/2023]
Abstract
The actin cytoskeleton is substantially modified in cancer cells because of changes in actin-binding protein abundance and functional activity. As a consequence, cancer cells have distinctive motility and mechanical properties, which are important for many processes, including invasion and metastasis. Here, we studied the effects of actin cytoskeleton alterations induced by specific nucleation inhibitors (SMIFH2, CK-666), cytochalasin D, Y-27632 and detachment from the surface by trypsinization on the mechanical properties of normal Vero and prostate cancer cell line DU145. The Young's modulus of Vero cells was 1300±900 Pa, while the prostate cancer cell line DU145 exhibited significantly lower Young's moduli (600±400 Pa). The Young's moduli exhibited a log-normal distribution for both cell lines. Unlike normal cells, cancer cells demonstrated diverse viscoelastic behavior and different responses to actin cytoskeleton reorganization. They were more resistant to specific formin-dependent nucleation inhibition, and reinforced their cortical actin after detachment from the substrate. This article is part of a Special Issue entitled: Mechanobiology.
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31
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Benitez R, Toca-herrera JL. Looking at cell mechanics with atomic force microscopy: Experiment and theory. Microsc Res Tech 2014; 77:947-58. [DOI: 10.1002/jemt.22419] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Revised: 07/24/2014] [Accepted: 07/25/2014] [Indexed: 11/08/2022]
Affiliation(s)
- Rafael Benitez
- Department of Mathematics; University Center of Plasencia, University of Extremadura, Avda. Virgen del Puerto 2; 10600 Plasencia Spain
| | - José. L. Toca-herrera
- Institute for Biophysics, Department of Nanobiotechnology; University of Natural Resources and Life Sciences Vienna (BOKU), Muthgasse 11; 1190 Vienna Austria
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32
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Maloney JM, Lehnhardt E, Long AF, Van Vliet KJ. Mechanical fluidity of fully suspended biological cells. Biophys J 2014; 105:1767-77. [PMID: 24138852 DOI: 10.1016/j.bpj.2013.08.040] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Revised: 08/01/2013] [Accepted: 08/26/2013] [Indexed: 11/16/2022] Open
Abstract
Mechanical characteristics of single biological cells are used to identify and possibly leverage interesting differences among cells or cell populations. Fluidity-hysteresivity normalized to the extremes of an elastic solid or a viscous liquid-can be extracted from, and compared among, multiple rheological measurements of cells: creep compliance versus time, complex modulus versus frequency, and phase lag versus frequency. With multiple strategies available for acquisition of this nondimensional property, fluidity may serve as a useful and robust parameter for distinguishing cell populations, and for understanding the physical origins of deformability in soft matter. Here, for three disparate eukaryotic cell types deformed in the suspended state via optical stretching, we examine the dependence of fluidity on chemical and environmental influences at a timescale of ∼1 s. We find that fluidity estimates are consistent in the time and frequency domains under a structural damping (power-law or fractional-derivative) model, but not under an equivalent-complexity, lumped-component (spring-dashpot) model; the latter predicts spurious time constants. Although fluidity is suppressed by chemical cross-linking, we find that ATP depletion in the cell does not measurably alter the parameter, and we thus conclude that active ATP-driven events are not a crucial enabler of fluidity during linear viscoelastic deformation of a suspended cell. Finally, by using the capacity of optical stretching to produce near-instantaneous increases in cell temperature, we establish that fluidity increases with temperature-now measured in a fully suspended, sortable cell without the complicating factor of cell-substratum adhesion.
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Affiliation(s)
- John M Maloney
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts
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33
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von Dassow M, Miller CJ, Davidson LA. Biomechanics and the thermotolerance of development. PLoS One 2014; 9:e95670. [PMID: 24776615 PMCID: PMC4002435 DOI: 10.1371/journal.pone.0095670] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2013] [Accepted: 03/31/2014] [Indexed: 11/19/2022] Open
Abstract
Successful completion of development requires coordination of patterning events with morphogenetic movements. Environmental variability challenges this coordination. For example, developing organisms encounter varying environmental temperatures that can strongly influence developmental rates. We hypothesized that the mechanics of morphogenesis would have to be finely adjusted to allow for normal morphogenesis across a wide range of developmental rates. We formulated our hypothesis as a simple model incorporating time-dependent application of force to a viscoelastic tissue. This model suggested that the capacity to maintain normal morphogenesis across a range of temperatures would depend on how both tissue viscoelasticity and the forces that drive deformation vary with temperature. To test this model we investigated how the mechanical behavior of embryonic tissue (Xenopus laevis) changed with temperature; we used a combination of micropipette aspiration to measure viscoelasticity, electrically induced contractions to measure cellular force generation, and confocal microscopy to measure endogenous contractility. Contrary to expectations, the viscoelasticity of the tissues and peak contractile tension proved invariant with temperature even as rates of force generation and gastrulation movements varied three-fold. Furthermore, the relative rates of different gastrulation movements varied with temperature: the speed of blastopore closure increased more slowly with temperature than the speed of the dorsal-to-ventral progression of involution. The changes in the relative rates of different tissue movements can be explained by the viscoelastic deformation model given observed viscoelastic properties, but only if morphogenetic forces increase slowly rather than all at once.
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Affiliation(s)
- Michelangelo von Dassow
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- Duke University Marine Laboratory, Beaufort, North Carolina, United States of America
| | - Callie Johnson Miller
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Lance A. Davidson
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- Department of Developmental Biology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
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34
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Chan CJ, Whyte G, Boyde L, Salbreux G, Guck J. Impact of heating on passive and active biomechanics of suspended cells. Interface Focus 2014; 4:20130069. [PMID: 24748957 PMCID: PMC3982451 DOI: 10.1098/rsfs.2013.0069] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
A cell is a complex material whose mechanical properties are essential for its normal functions. Heating can have a dramatic effect on these mechanical properties, similar to its impact on the dynamics of artificial polymer networks. We investigated such mechanical changes by the use of a microfluidic optical stretcher, which allowed us to probe cell mechanics when the cells were subjected to different heating conditions at different time scales. We find that HL60/S4 myeloid precursor cells become mechanically more compliant and fluid-like when subjected to either a sudden laser-induced temperature increase or prolonged exposure to higher ambient temperature. Above a critical temperature of 52 ± 1°C, we observed active cell contraction, which was strongly correlated with calcium influx through temperature-sensitive transient receptor potential vanilloid 2 (TRPV2) ion channels, followed by a subsequent expansion in cell volume. The change from passive to active cellular response can be effectively described by a mechanical model incorporating both active stress and viscoelastic components. Our work highlights the role of TRPV2 in regulating the thermomechanical response of cells. It also offers insights into how cortical tension and osmotic pressure govern cell mechanics and regulate cell-shape changes in response to heat and mechanical stress.
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Affiliation(s)
- C. J. Chan
- Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, UK
- Biotechnology Center, Technische Universität Dresden, Dresden, Germany
| | - G. Whyte
- Department of Physics and Institute of Medical Biotechnology, University of Erlangen-Nuremberg, Erlangen, Germany
| | - L. Boyde
- Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, UK
| | - G. Salbreux
- Max Planck Institute for the Physics of Complex Systems, Dresden, Germany
| | - J. Guck
- Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, UK
- Biotechnology Center, Technische Universität Dresden, Dresden, Germany
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35
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Zielinski R, Mihai C, Kniss D, Ghadiali SN. Finite element analysis of traction force microscopy: influence of cell mechanics, adhesion, and morphology. J Biomech Eng 2014; 135:71009. [PMID: 23720059 DOI: 10.1115/1.4024467] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Accepted: 05/08/2013] [Indexed: 02/04/2023]
Abstract
The interactions between adherent cells and their extracellular matrix (ECM) have been shown to play an important role in many biological processes, such as wound healing, morphogenesis, differentiation, and cell migration. Cells attach to the ECM at focal adhesion sites and transmit contractile forces to the substrate via cytoskeletal actin stress fibers. This contraction results in traction stresses within the substrate/ECM. Traction force microscopy (TFM) is an experimental technique used to quantify the contractile forces generated by adherent cells. In TFM, cells are seeded on a flexible substrate and displacements of the substrate caused by cell contraction are tracked and converted to a traction stress field. The magnitude of these traction stresses are normally used as a surrogate measure of internal cell contractile force or contractility. We hypothesize that in addition to contractile force, other biomechanical properties including cell stiffness, adhesion energy density, and cell morphology may affect the traction stresses measured by TFM. In this study, we developed finite element models of the 2D and 3D TFM techniques to investigate how changes in several biomechanical properties alter the traction stresses measured by TFM. We independently varied cell stiffness, cell-ECM adhesion energy density, cell aspect ratio, and contractility and performed a sensitivity analysis to determine which parameters significantly contribute to the measured maximum traction stress and net contractile moment. Results suggest that changes in cell stiffness and adhesion energy density can significantly alter measured tractions, independent of contractility. Based on a sensitivity analysis, we developed a correction factor to account for changes in cell stiffness and adhesion and successfully applied this correction factor algorithm to experimental TFM measurements in invasive and noninvasive cancer cells. Therefore, application of these types of corrections to TFM measurements can yield more accurate estimates of cell contractility.
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Affiliation(s)
- Rachel Zielinski
- Biomedical Engineering Department, The Ohio State University, Columbus, OH 43210, USA
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36
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Chiou YW, Lin HK, Tang MJ, Lin HH, Yeh ML. The influence of physical and physiological cues on atomic force microscopy-based cell stiffness assessment. PLoS One 2013; 8:e77384. [PMID: 24194882 PMCID: PMC3806741 DOI: 10.1371/journal.pone.0077384] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Accepted: 09/04/2013] [Indexed: 01/16/2023] Open
Abstract
Atomic force microscopy provides a novel technique for differentiating the mechanical properties of various cell types. Cell elasticity is abundantly used to represent the structural strength of cells in different conditions. In this study, we are interested in whether physical or physiological cues affect cell elasticity in Atomic force microscopy (AFM)-based assessments. The physical cues include the geometry of the AFM tips, the indenting force and the operating temperature of the AFM. All of these cues show a significant influence on the cell elasticity assessment. Sharp AFM tips create a two-fold increase in the value of the effective Young's modulus (E(eff)) relative to that of the blunt tips. Higher indenting force at the same loading rate generates higher estimated cell elasticity. Increasing the operation temperature of the AFM leads to decreases in the cell stiffness because the structure of actin filaments becomes disorganized. The physiological cues include the presence of fetal bovine serum or extracellular matrix-coated surfaces, the culture passage number, and the culture density. Both fetal bovine serum and the extracellular matrix are critical for cells to maintain the integrity of actin filaments and consequently exhibit higher elasticity. Unlike primary cells, mouse kidney progenitor cells can be passaged and maintain their morphology and elasticity for a very long period without a senescence phenotype. Finally, cell elasticity increases with increasing culture density only in MDCK epithelial cells. In summary, for researchers who use AFM to assess cell elasticity, our results provide basic and significant information about the suitable selection of physical and physiological cues.
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Affiliation(s)
- Yu-Wei Chiou
- Department of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan
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37
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Spedden E, Kaplan DL, Staii C. Temperature response of the neuronal cytoskeleton mapped via atomic force and fluorescence microscopy. Phys Biol 2013; 10:056002. [PMID: 23965760 DOI: 10.1088/1478-3975/10/5/056002] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Neuronal cells change their growth properties in response to external physical stimuli such as variations in external temperature, stiffness of the growth substrate, or topographical guidance cues. Detailed knowledge of the mechanisms that control these biomechanical responses is necessary for understanding the basic principles that underlie neuronal growth and regeneration. Here, we present elasticity maps of living cortical neurons (embryonic rat) as a function of temperature, and correlate these maps to the locations of internal structural components of the cytoskeleton. Neurons display a significant increase in the average elastic modulus upon a decrease in ambient temperature from 37 to 25 °C. We demonstrate that the dominant mechanism by which the elasticity of the neurons changes in response to temperature is the stiffening of the actin components of the cytoskeleton induced by myosin II. We also report a reversible shift in the location and composition of the high-stiffness areas of the neuron cytoskeleton with temperature. At 37 °C the areas of the cell displaying high elastic modulus overlap with the tubulin-dense regions, while at 25 °C these high-stiffness areas correspond to the actin-dense regions of the cytoskeleton. These results demonstrate the importance of considering temperature effects when investigating cytoskeletal dynamics in cells.
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Affiliation(s)
- Elise Spedden
- Department of Physics and Astronomy and Center for Nanoscopic Physics, Tufts University, 4 Colby Street, Medford, MA 02155, USA
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38
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Effects of cochlear loading on the motility of active outer hair cells. Proc Natl Acad Sci U S A 2013; 110:5474-9. [PMID: 23509256 DOI: 10.1073/pnas.1302911110] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Outer hair cells (OHCs) power the amplification of sound-induced vibrations in the mammalian inner ear through an active process that involves hair-bundle motility and somatic motility. It is unclear, though, how either mechanism can be effective at high frequencies, especially when OHCs are mechanically loaded by other structures in the cochlea. We address this issue by developing a model of an active OHC on the basis of observations from isolated cells, then we use the model to predict the response of an active OHC in the intact cochlea. We find that active hair-bundle motility amplifies the receptor potential that drives somatic motility. Inertial loading of a hair bundle by the tectorial membrane reduces the bundle's reactive load, allowing the OHC's active motility to influence the motion of the cochlear partition. The system exhibits enhanced sensitivity and tuning only when it operates near a dynamical instability, a Hopf bifurcation. This analysis clarifies the roles of cochlear structures and shows how the two mechanisms of motility function synergistically to create the cochlear amplifier. The results suggest that somatic motility evolved to enhance a preexisting amplifier based on active hair-bundle motility, thus allowing mammals to hear high-frequency sounds.
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39
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Emery MJ, Eveland RL, Min JH, Hildebrandt J, Swenson ER. CO2 relaxation of the rat lung parenchymal strip. Respir Physiol Neurobiol 2013; 186:33-9. [PMID: 23305910 DOI: 10.1016/j.resp.2012.12.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Revised: 12/29/2012] [Accepted: 12/29/2012] [Indexed: 01/13/2023]
Abstract
Evidence from liquid-filled rat lungs supported the presence of CO2-dependent, active relaxation of parenchyma under normoxia by unknown mechanisms (Emery et al., 2007). This response may improve matching of alveolar ventilation (V˙A) to perfusion (Q˙) by increasing compliance and V˙A in overperfused (high CO2) regions, and decrease V˙A in underperfused regions. Here, we have more directly studied CO2-dependent parenchymal relaxation and tested a hypothesized role for actin-myosin interaction in this effect. Lung parenchymal strips (∼1.5mm×1.5mm×15mm) from 16 rats were alternately exposed to normoxic hypocapnia ( [Formula: see text] ) or hypercapnia ( [Formula: see text] ). Seven specimens were used to construct length-tension curves, and nine were tested with and without the myosin blocker 2,3-butanedione monoxime (BDM). The results demonstrate substantial, reversible CO2-dependent changes in parenchyma strip recoil (up to 23%) and BDM eliminates this effect, supporting a potentially important role for parenchymal myosin in V˙A/Q˙ matching.
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Affiliation(s)
- Michael J Emery
- Pulmonary and Critical Care Medicine (S-111-PULM), VA Puget Sound Health Care System, 1660 South Columbian Way, Seattle, WA 98108, USA.
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40
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Matrix rigidity regulates cancer cell growth by modulating cellular metabolism and protein synthesis. PLoS One 2012; 7:e37231. [PMID: 22623999 PMCID: PMC3356407 DOI: 10.1371/journal.pone.0037231] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Accepted: 04/16/2012] [Indexed: 11/19/2022] Open
Abstract
Background Tumor cells in vivo encounter diverse types of microenvironments both at the site of the primary tumor and at sites of distant metastases. Understanding how the various mechanical properties of these microenvironments affect the biology of tumor cells during disease progression is critical in identifying molecular targets for cancer therapy. Methodology/Principal Findings This study uses flexible polyacrylamide gels as substrates for cell growth in conjunction with a novel proteomic approach to identify the properties of rigidity-dependent cancer cell lines that contribute to their differential growth on soft and rigid substrates. Compared to cells growing on more rigid/stiff substrates (>10,000 Pa), cells on soft substrates (150–300 Pa) exhibited a longer cell cycle, due predominantly to an extension of the G1 phase of the cell cycle, and were metabolically less active, showing decreased levels of intracellular ATP and a marked reduction in protein synthesis. Using stable isotope labeling of amino acids in culture (SILAC) and mass spectrometry, we measured the rates of protein synthesis of over 1200 cellular proteins under growth conditions on soft and rigid/stiff substrates. We identified cellular proteins whose syntheses were either preferentially inhibited or preserved on soft matrices. The former category included proteins that regulate cytoskeletal structures (e.g., tubulins) and glycolysis (e.g., phosphofructokinase-1), whereas the latter category included proteins that regulate key metabolic pathways required for survival, e.g., nicotinamide phosphoribosyltransferase, a regulator of the NAD salvage pathway. Conclusions/Significance The cellular properties of rigidity-dependent cancer cells growing on soft matrices are reminiscent of the properties of dormant cancer cells, e.g., slow growth rate and reduced metabolism. We suggest that the use of relatively soft gels as cell culture substrates would allow molecular pathways to be studied under conditions that reflect the different mechanical environments encountered by cancer cells upon metastasis to distant sites.
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41
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Waters CM, Roan E, Navajas D. Mechanobiology in lung epithelial cells: measurements, perturbations, and responses. Compr Physiol 2012; 2:1-29. [PMID: 23728969 PMCID: PMC4457445 DOI: 10.1002/cphy.c100090] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Epithelial cells of the lung are located at the interface between the environment and the organism and serve many important functions including barrier protection, fluid balance, clearance of particulate, initiation of immune responses, mucus and surfactant production, and repair following injury. Because of the complex structure of the lung and its cyclic deformation during the respiratory cycle, epithelial cells are exposed to continuously varying levels of mechanical stresses. While normal lung function is maintained under these conditions, changes in mechanical stresses can have profound effects on the function of epithelial cells and therefore the function of the organ. In this review, we will describe the types of stresses and strains in the lungs, how these are transmitted, and how these may vary in human disease or animal models. Many approaches have been developed to better understand how cells sense and respond to mechanical stresses, and we will discuss these approaches and how they have been used to study lung epithelial cells in culture. Understanding how cells sense and respond to changes in mechanical stresses will contribute to our understanding of the role of lung epithelial cells during normal function and development and how their function may change in diseases such as acute lung injury, asthma, emphysema, and fibrosis.
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42
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Tamura K, Mizutani T, Haga H, Kawabata K. Active fluctuation in the cortical cytoskeleton observed by high-speed live-cell scanning probe microscopy. Acta Biomater 2011; 7:3766-72. [PMID: 21704197 DOI: 10.1016/j.actbio.2011.06.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2011] [Revised: 05/28/2011] [Accepted: 06/08/2011] [Indexed: 11/29/2022]
Abstract
We investigated the dynamics of the cortical cytoskeleton in living cells by analyzing the motion of the endogenous components of the cytoskeleton using scanning probe microscopy (SPM). We performed molecular characterization of the microgranules visualized by SPM in living cells and analyzed the motion of these microgranules via particle tracking. Simultaneous SPM and epifluorescence microscopy observations showed that the microgranules recruited not only actin but also cortactin, which can bind to actin filaments. This indicates condensation of actin filaments at microgranules, leading us to identify them as "cytoskeletal microdomains". High-speed SPM observation and particle-tracking analysis showed that these cytoskeletal microdomains exhibit random walk-like diffusive fluctuations over a timescale of seconds. Inhibition of the molecular motor myosin II, which drives actin filaments, led to subdiffusive fluctuations of the microdomains. These results can be explained by longitudinal sliding of actin filaments stochastically driven by myosin II and the bending motion of the actin filaments in the absence of sliding. Analysis of the cytoskeletal microdomains thus revealed the intrinsic dynamics of the cortical cytoskeleton.
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Affiliation(s)
- Kazushi Tamura
- Graduate School of Science, Hokkaido University, Kita 10 Nishi 8, Kita-ku, Sapporo, Japan.
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43
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Abstract
Morphogenesis takes place against a background of organism-to-organism and environmental variation. Therefore, fundamental questions in the study of morphogenesis include: How are the mechanical processes of tissue movement and deformation affected by that variability, and in turn, how do the mechanic of the system modulate phenotypic variation? We highlight a few key factors, including environmental temperature, embryo size and environmental chemistry that might perturb the mechanics of morphogenesis in natural populations. Then we discuss several ways in which mechanics-including feedback from mechanical cues-might influence intra-specific variation in morphogenesis. To understand morphogenesis it will be necessary to consider whole-organism, environment and evolutionary scales because these larger scales present the challenges that developmental mechanisms have evolved to cope with. Studying the variation organisms express and the variation organisms experience will aid in deciphering the causes of birth defects.
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Affiliation(s)
- Michelangelo von Dassow
- Department of Bioengineering, University of Pittsburgh, 3501 Fifth Ave, 5059-BST3, Pittsburgh, PA 15213, USA.
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44
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Prandi S, Sala GL, Bellocci M, Alessandrini A, Facci P, Bigiani A, Rossini GP. Palytoxin induces cell lysis by priming a two-step process in mcf-7 cells. Chem Res Toxicol 2011; 24:1283-96. [PMID: 21728342 DOI: 10.1021/tx2001866] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The cytolytic action of palytoxin (PlTX) was recognized long ago, but its features have remained largely undetermined. We used biochemical, morphological, physiological, and physical tools, to study the cytolytic response in MCF-7 cells, as our model system. Cytolysis represented a stereotyped response induced by the addition of isotonic phosphate buffer (PBS) to cells that had been exposed to PlTX, after toxin removal and under optimal and suboptimal experimental conditions. Cytolysis was sensitive to osmolytes present during cell exposure to PlTX but not in the course of the lytic phase. Fluorescence microscopy showed that PlTX caused cell rounding and rearrangement of the actin cytoskeleton. Atomic force microscopy (AFM) was used to monitor PlTX effects in real time, and we found that morphological and mechanical properties of MCF-7 cells did not change during toxin exposure, but increased cell height and decreased stiffness at its surface were observed when PBS was added to PlTX-treated cells. The presence of an osmolyte during PlTX treatment prevented the detection of changes in morphological and mechanical properties caused by PBS addition to toxin-treated cells, as detected by AFM. By patch-clamp technique, we confirmed that PlTX action involved the transformation of the Na(+),K(+)-ATPase into a channel and found that cell membrane capacitance was not changed by PlTX, indicating that the membrane surface area was not greatly affected in our model system. Overall, our findings show that the cytolytic response triggered by PlTX in MCF-7 cells includes a first phase, which is toxin-dependent and osmolyte-sensitive, priming cells to lytic events taking place in a separate phase, which does not require the presence of the toxin and is osmolyte-insensitive but is accompanied by marked reorganization of actin-based cytoskeleton and altered mechanical properties at the cell's surface. A model of the two-step process of PlTX-induced cytolysis is presented.
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Affiliation(s)
- Simone Prandi
- Dipartimento di Scienze Biomediche, Università di Modena e Reggio Emilia , Via Campi 287, I-41125 Modena, Italy
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45
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Maloney JM, Nikova D, Lautenschläger F, Clarke E, Langer R, Guck J, Van Vliet KJ. Mesenchymal stem cell mechanics from the attached to the suspended state. Biophys J 2011; 99:2479-87. [PMID: 20959088 DOI: 10.1016/j.bpj.2010.08.052] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2010] [Revised: 08/18/2010] [Accepted: 08/20/2010] [Indexed: 01/01/2023] Open
Abstract
Human mesenchymal stem cells (hMSCs) are therapeutically useful cells that are typically expanded in vitro on stiff substrata before reimplantation. Here we explore MSC mechanical and structural changes via atomic force microscopy and optical stretching during extended passaging, and we demonstrate that cytoskeletal organization and mechanical stiffness of attached MSC populations are strongly modulated over >15 population doublings in vitro. Cytoskeletal actin networks exhibit significant coarsening, attendant with decreasing average mechanical compliance and differentiation potential of these cells, although expression of molecular surface markers does not significantly decline. These mechanical changes are not observed in the suspended state, indicating that the changes manifest themselves as alterations in stress fiber arrangement rather than cortical cytoskeleton arrangement. Additionally, optical stretching is capable of investigating a previously unquantified structural transition: remodeling-induced stiffening over tens of minutes after adherent cells are suspended. Finally, we find that optically stretched hMSCs exhibit power-law rheology during both loading and recovery; this evidence appears to be the first to originate from a biophysical measurement technique not involving cell-probe or cell-substratum contact. Together, these quantitative assessments of attached and suspended MSCs define the extremes of the extracellular environment while probing intracellular mechanisms that contribute to cell mechanical response.
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Affiliation(s)
- John M Maloney
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, USA
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46
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Seow CY, Fredberg JJ. Emergence of airway smooth muscle functions related to structural malleability. J Appl Physiol (1985) 2010; 110:1130-5. [PMID: 21127211 DOI: 10.1152/japplphysiol.01192.2010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The function of a complex system such as a smooth muscle cell is the result of the active interaction among molecules and molecular aggregates. Emergent macroscopic manifestations of these molecular interactions, such as the length-force relationship and its associated length adaptation, are well documented, but the molecular constituents and organization that give rise to these emergent muscle behaviors remain largely unknown. In this minireview, we describe emergent properties of airway smooth muscle that seem to have originated from inherent fragility of the cellular structures, which has been increasingly recognized as a unique and important smooth muscle attribute. We also describe molecular interactions (based on direct and indirect evidence) that may confer malleability on fragile structural elements that in turn may allow the muscle to adapt to large and frequent changes in cell dimensions. Understanding how smooth muscle works may hinge on how well we can relate molecular events to its emergent macroscopic functions.
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Affiliation(s)
- Chun Y Seow
- Department of Pathology, James Hogg Research Centre, University of British Columbia, Vancouver, British Columbia, Canada.
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47
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Tamura K, Mizutani T, Haga H, Kawabata K. Nano-mechanical properties of living cells expressing constitutively active RhoA effectors. Biochem Biophys Res Commun 2010; 403:363-7. [PMID: 21078298 DOI: 10.1016/j.bbrc.2010.11.036] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2010] [Accepted: 11/10/2010] [Indexed: 11/12/2022]
Abstract
Filamentous actin and myosin-II are major determinants of cell mechanics and are tightly regulated by a small guanosine triphosphatase, RhoA, and its downstream effectors. We examined the effects of constitutively active mutants of RhoA effectors, which have not been reported before, on cortical stiffness of living cells by using scanning probe microscopy, fluorescence microscopy, and truncated mutants of RhoA effectors labeled with a fluorescent protein. Our data indicated that expression of a constitutively active mutant of Dia1, a formin-family actin polymerizer, enhanced cortical stiffness and increased actin filament quantity in cells. Furthermore, expression of a constitutively active mutant of Rho-associated coiled-coil kinase, a myosin-II activator, softened the cell cortex but increased myosin-II activity. Our findings provide new insights into anomalous mechanics of cells, which is a topic of current interest in a variety of biological research fields.
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Affiliation(s)
- Kazushi Tamura
- Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan.
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48
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Rico F, Chu C, Abdulreda MH, Qin Y, Moy VT. Temperature modulation of integrin-mediated cell adhesion. Biophys J 2010; 99:1387-96. [PMID: 20816050 PMCID: PMC2931747 DOI: 10.1016/j.bpj.2010.06.037] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2010] [Revised: 06/02/2010] [Accepted: 06/14/2010] [Indexed: 10/19/2022] Open
Abstract
In response to external stimuli, cells modulate their adhesive state by regulating the number and intrinsic affinity of receptor/ligand bonds. A number of studies have shown that cell adhesion is dramatically reduced at room or lower temperatures as compared with physiological temperature. However, the underlying mechanism that modulates adhesion is still unclear. Here, we investigated the adhesion of the monocytic cell line THP-1 to a surface coated with intercellular adhesion molecule-1 (ICAM-1) as a function of temperature. THP-1 cells express the integrin lymphocyte function-associated antigen-1 (LFA-1), a receptor for ICAM-1. Direct force measurements of cell adhesion and cell elasticity were carried out by atomic force microscopy. Force measurements revealed an increase of the work of de-adhesion with temperature that was coupled to a gradual decrease in cellular stiffness. Of interest, single-molecule measurements revealed that the rupture force of the LFA-1/ICAM-1 complex decreased with temperature. A detailed analysis of the force curves indicated that temperature-modulated cell adhesion was mainly due to the enhanced ability of cells to deform and to form a greater number of longer membrane tethers at physiological temperatures. Together, these results emphasize the importance of cell mechanics and membrane-cytoskeleton interaction on the modulation of cell adhesion.
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Affiliation(s)
- Félix Rico
- Department of Physiology and Biophysics, University of Miami, Miller School of Medicine, Miami, Florida, USA.
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49
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Zhou EH, Quek ST, Lim CT. Power-law rheology analysis of cells undergoing micropipette aspiration. Biomech Model Mechanobiol 2010; 9:563-72. [PMID: 20179987 DOI: 10.1007/s10237-010-0197-7] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2009] [Accepted: 02/01/2010] [Indexed: 11/30/2022]
Abstract
Accurate quantification of the mechanical properties of living cells requires the combined use of experimental techniques and theoretical models. In this paper, we investigate the viscoelastic response of suspended NIH 3T3 fibroblasts undergoing micropipette aspiration using power-law rheology model. As an important first step, we examine the pipette size effect on cell deformation and find that pipettes larger than ~7 μm are more suitable for bulk rheological measurements than smaller ones and the cell can be treated as effectively continuum. When the large pipettes are used to apply a constant pressure to a cell, the creep deformation is better fitted with the power-law rheology model than with the liquid drop or spring-dashpot models; magnetic twisting cytometry measurement on the rounded cell confirms the power-law behavior. This finding is further extended to suspended cells treated with drugs targeting their cytoskeleton. As such, our results suggest that the application of relatively large pipettes can provide more effective assessment of the bulk material properties as well as support application of power-law rheology to cells in suspension.
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Affiliation(s)
- E H Zhou
- Department of Mechanical Engineering, National University of Singapore, Singapore.
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50
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Park CY, Tambe D, Alencar AM, Trepat X, Zhou EH, Millet E, Butler JP, Fredberg JJ. Mapping the cytoskeletal prestress. Am J Physiol Cell Physiol 2010; 298:C1245-52. [PMID: 20164383 DOI: 10.1152/ajpcell.00417.2009] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Cell mechanical properties on a whole cell basis have been widely studied, whereas local intracellular variations have been less well characterized and are poorly understood. To fill this gap, here we provide detailed intracellular maps of regional cytoskeleton (CSK) stiffness, loss tangent, and rate of structural rearrangements, as well as their relationships to the underlying regional F-actin density and the local cytoskeletal prestress. In the human airway smooth muscle cell, we used micropatterning to minimize geometric variation. We measured the local cell stiffness and loss tangent with optical magnetic twisting cytometry and the local rate of CSK remodeling with spontaneous displacements of a CSK-bound bead. We also measured traction distributions with traction microscopy and cell geometry with atomic force microscopy. On the basis of these experimental observations, we used finite element methods to map for the first time the regional distribution of intracellular prestress. Compared with the cell center or edges, cell corners were systematically stiffer and more fluidlike and supported higher traction forces, and at the same time had slower remodeling dynamics. Local remodeling dynamics had a close inverse relationship with local cell stiffness. The principal finding, however, is that systematic regional variations of CSK stiffness correlated only poorly with regional F-actin density but strongly and linearly with the regional prestress. Taken together, these findings in the intact cell comprise the most comprehensive characterization to date of regional variations of cytoskeletal mechanical properties and their determinants.
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Affiliation(s)
- Chan Young Park
- Dept. of Environmental Health, Harvard School of Public Health, Boston, MA 02115, USA
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