1
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Zhang H, Hang JT, Chang Z, Yu S, Yang H, Xu GK. Scaling-law mechanical marker for liver fibrosis diagnosis and drug screening through machine learning. Front Bioeng Biotechnol 2024; 12:1404508. [PMID: 39081332 PMCID: PMC11286496 DOI: 10.3389/fbioe.2024.1404508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2024] [Accepted: 06/28/2024] [Indexed: 08/02/2024] Open
Abstract
Studies of cell and tissue mechanics have shown that significant changes in cell and tissue mechanics during lesions and cancers are observed, which provides new mechanical markers for disease diagnosis based on machine learning. However, due to the lack of effective mechanic markers, only elastic modulus and iconographic features are currently used as markers, which greatly limits the application of cell and tissue mechanics in disease diagnosis. Here, we develop a liver pathological state classifier through a support vector machine method, based on high dimensional viscoelastic mechanical data. Accurate diagnosis and grading of hepatic fibrosis facilitates early detection and treatment and may provide an assessment tool for drug development. To this end, we used the viscoelastic parameters obtained from the analysis of creep responses of liver tissues by a self-similar hierarchical model and built a liver state classifier based on machine learning. Using this classifier, we implemented a fast classification of healthy, diseased, and mesenchymal stem cells (MSCs)-treated fibrotic live tissues, and our results showed that the classification accuracy of healthy and diseased livers can reach 0.99, and the classification accuracy of the three liver tissues mixed also reached 0.82. Finally, we provide screening methods for markers in the context of massive data as well as high-dimensional viscoelastic variables based on feature ablation for drug development and accurate grading of liver fibrosis. We propose a novel classifier that uses the dynamical mechanical variables as input markers, which can identify healthy, diseased, and post-treatment liver tissues.
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Affiliation(s)
- Honghao Zhang
- School of Mechanical Engineering, Northwestern Polytechnical University, Xi’an, China
| | - Jiu-Tao Hang
- Department of Engineering Mechanics, SVL, School of Aerospace Engineering, Xi’an Jiaotong University, Xi’an, China
| | - Zhuo Chang
- Department of Engineering Mechanics, SVL, School of Aerospace Engineering, Xi’an Jiaotong University, Xi’an, China
| | - Suihuai Yu
- School of Mechanical Engineering, Northwestern Polytechnical University, Xi’an, China
| | - Hui Yang
- School of Life Sciences, Northwestern Polytechnical University, Xi’an, China
| | - Guang-Kui Xu
- Department of Engineering Mechanics, SVL, School of Aerospace Engineering, Xi’an Jiaotong University, Xi’an, China
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2
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Chang Z, Li LY, Shi ZJ, Liu W, Xu GK. Beyond stiffness: Multiscale viscoelastic features as biomechanical markers for assessing cell types and states. Biophys J 2024; 123:1869-1881. [PMID: 38835167 PMCID: PMC11267428 DOI: 10.1016/j.bpj.2024.05.033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Revised: 05/14/2024] [Accepted: 05/30/2024] [Indexed: 06/06/2024] Open
Abstract
Cell mechanics are pivotal in regulating cellular activities, diseases progression, and cancer development. However, the understanding of how cellular viscoelastic properties vary in physiological and pathological stimuli remains scarce. Here, we develop a hybrid self-similar hierarchical theory-microrheology approach to accurately and efficiently characterize cellular viscoelasticity. Focusing on two key cell types associated with livers fibrosis-the capillarized liver sinusoidal endothelial cells and activated hepatic stellate cells-we uncover a universal two-stage power-law rheology characterized by two distinct exponents, αshort and αlong. The mechanical profiles derived from both exponents exhibit significant potential for discriminating among diverse cells. This finding suggests a potential common dynamic creep characteristic across biological systems, extending our earlier observations in soft tissues. Using a tailored hierarchical model for cellular mechanical structures, we discern significant variations in the viscoelastic properties and their distribution profiles across different cell types and states from the cytoplasm (elastic stiffness E1 and viscosity η), to a single cytoskeleton fiber (elastic stiffness E2), and then to the cell level (transverse expansion stiffness E3). Importantly, we construct a logistic-regression-based machine-learning model using the dynamic parameters that outperforms conventional cell-stiffness-based classifiers in assessing cell states, achieving an area under the curve of 97% vs. 78%. Our findings not only advance a robust framework for monitoring intricate cell dynamics but also highlight the crucial role of cellular viscoelasticity in discerning cell states across a spectrum of liver diseases and prognosis, offering new avenues for developing diagnostic and therapeutic strategies based on cellular viscoelasticity.
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Affiliation(s)
- Zhuo Chang
- Laboratory for Multiscale Mechanics and Medical Science, Department of Engineering Mechanics, State Key Laboratory for Strength and Vibration of Mechanical Structures, School of Aerospace Engineering, Xi'an Jiaotong University, Xi'an, China
| | - Li-Ya Li
- Institute for Stem Cell & Regenerative Medicine, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Zhi-Jun Shi
- Laboratory for Multiscale Mechanics and Medical Science, Department of Engineering Mechanics, State Key Laboratory for Strength and Vibration of Mechanical Structures, School of Aerospace Engineering, Xi'an Jiaotong University, Xi'an, China
| | - Wenjia Liu
- Institute for Stem Cell & Regenerative Medicine, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China.
| | - Guang-Kui Xu
- Laboratory for Multiscale Mechanics and Medical Science, Department of Engineering Mechanics, State Key Laboratory for Strength and Vibration of Mechanical Structures, School of Aerospace Engineering, Xi'an Jiaotong University, Xi'an, China.
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3
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Handler C, Testi C, Scarcelli G. Advantages of integrating Brillouin microscopy in multimodal mechanical mapping of cells and tissues. Curr Opin Cell Biol 2024; 88:102341. [PMID: 38471195 DOI: 10.1016/j.ceb.2024.102341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2023] [Revised: 01/15/2024] [Accepted: 02/01/2024] [Indexed: 03/14/2024]
Abstract
Recent research has highlighted the growing significance of the mechanical properties of cells and tissues in the proper execution of physiological functions within an organism; alterations to these properties can potentially result in various diseases. These mechanical properties can be assessed using various techniques that vary in spatial and temporal resolutions as well as applications. Due to the wide range of mechanical behaviors exhibited by cells and tissues, a singular mapping technique may be insufficient in capturing their complexity and nuance. Consequently, by utilizing a combination of methods-multimodal mechanical mapping-researchers can achieve a more comprehensive characterization of mechanical properties, encompassing factors such as stiffness, modulus, viscoelasticity, and forces. Furthermore, different mapping techniques can provide complementary information and enable the exploration of spatial and temporal variations to enhance our understanding of cellular dynamics and tissue mechanics. By capitalizing on the unique strengths of each method while mitigating their respective limitations, a more precise and holistic understanding of cellular and tissue mechanics can be obtained. Here, we spotlight Brillouin microscopy (BM) as a noncontact, noninvasive, and label-free mechanical mapping modality to be coutilized alongside established mechanical probing methods. This review summarizes some of the most widely adopted individual mechanical mapping techniques and highlights several recent multimodal approaches demonstrating their utility. We envision that future studies aim to adopt multimodal techniques to drive advancements in the broader realm of mechanobiology.
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Affiliation(s)
- Chenchen Handler
- Department of Mechanical Engineering, A. James Clark School of Engineering, University of Maryland, College Park, MD 20742, USA
| | - Claudia Testi
- Fischell Department of Bioengineering, A. James Clark School of Engineering, University of Maryland, College Park, MD 20742, USA; Center for Life Nano- and Neuro- Science, Istituto Italiano di Tecnologia, Viale Regina Elena 291, Rome 00161, Italy
| | - Giuliano Scarcelli
- Fischell Department of Bioengineering, A. James Clark School of Engineering, University of Maryland, College Park, MD 20742, USA.
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4
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Lima I, Silva A, Sousa F, Ferreira W, Freire R, de Oliveira C, de Sousa J. Measuring the viscoelastic relaxation function of cells with a time-dependent interpretation of the Hertz-Sneddon indentation model. Heliyon 2024; 10:e30623. [PMID: 38770291 PMCID: PMC11103437 DOI: 10.1016/j.heliyon.2024.e30623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Revised: 04/15/2024] [Accepted: 04/30/2024] [Indexed: 05/22/2024] Open
Abstract
The Hertz-Sneddon elastic indentation model is widely adopted in the biomechanical investigation of living cells and other soft materials using atomic force microscopy despite the explicit viscoelastic nature of these materials. In this work, we demonstrate that an exact analytical viscoelastic force model for power-law materials, can be interpreted as a time-dependent Hertz-Sneddon-like model. Characterizing fibroblasts (L929) and osteoblasts (OFCOLII) demonstrates the model's accuracy. Our results show that the difference between Young's modulus E Y obtained by fitting force curves with the Hertz-Sneddon model and the effective Young's modulus derived from the viscoelastic force model is less than 3%, even when cells are probed at large forces where nonlinear deformation effects become significant. We also propose a measurement protocol that involves probing samples at different indentation speeds and forces, enabling the construction of the average viscoelastic relaxation function of samples by conveniently fitting the force curves with the Hertz-Sneddon model.
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Affiliation(s)
- I.V.M. Lima
- Departamento de Física, Universidade Federal do Ceará, Fortaleza, 60440-900, Ceará, Brazil
| | - A.V.S. Silva
- Departamento de Física, Universidade Federal do Ceará, Fortaleza, 60440-900, Ceará, Brazil
- Instituto Federal do Rio Grande do Norte, Pau dos Ferros, 59900-000, Rio Grande do Norte, Brazil
| | - F.D. Sousa
- Núcleo de Biologia Experimental, Universidade de Fortaleza, Fortaleza, 60811-905, Ceará, Brazil
| | - W.P. Ferreira
- Departamento de Física, Universidade Federal do Ceará, Fortaleza, 60440-900, Ceará, Brazil
| | - R.S. Freire
- Central Analítica, Universidade Federal do Ceará, Fortaleza, 60440-900, Ceará, Brazil
| | - C.L.N. de Oliveira
- Departamento de Física, Universidade Federal do Ceará, Fortaleza, 60440-900, Ceará, Brazil
| | - J.S. de Sousa
- Departamento de Física, Universidade Federal do Ceará, Fortaleza, 60440-900, Ceará, Brazil
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5
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Hang JT, Wang H, Wang BC, Xu GK. Anisotropic power-law viscoelasticity of living cells is dominated by cytoskeletal network structure. Acta Biomater 2024; 180:197-205. [PMID: 38599439 DOI: 10.1016/j.actbio.2024.04.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2023] [Revised: 03/19/2024] [Accepted: 04/01/2024] [Indexed: 04/12/2024]
Abstract
During physiological and pathological processes, cells experience significant morphological alterations with the re-arrangement of cytoskeletal filaments, resulting in anisotropic viscoelasticity. Here, a structure-based cell model is proposed to study the anisotropic viscoelastic mechanical behaviors of living cells. We investigate how cell shape affects its creep responses in longitudinal and perpendicular directions. It is shown that cells exhibit power-law rheological behavior in both longitudinal and perpendicular directions under step stress, with a more solid-like behavior along the longitudinal direction. We reveal that the cell volume and cytoskeletal filament orientation, which have been neglected in most existing models, play a critical role in regulating cellular anisotropic viscoelasticity. The stiffness of the cell in both directions increases linearly with increasing its aspect ratio, due to the decrease of cell volume. Moreover, the increase in the cell's aspect ratio produces the aggregation of cytoskeletal filaments along the longitudinal direction, resulting in higher stiffness in this direction. It is also shown that the increase in cell's aspect ratio corresponds to a process of cellular ordering, which can be quantitatively characterized by the orientational entropy of cytoskeletal filaments. In addition, we present a simple yet robust method to establish the relationship between cell's aspect ratio and cell volume, thus providing a theoretical framework to capture the anisotropic viscoelastic behavior of cells. This study suggests that the structure-based cell models may be further developed to investigate cellular rheological responses to external mechanical stimuli and may be extended to the tissue scale. STATEMENT OF SIGNIFICANCE: The viscoelastic behaviors of cells hold significant importance in comprehending the roles of mechanical forces in embryo development, invasion, and metastasis of cancer cells. Here, a structure-based cell model is proposed to study the anisotropic viscoelastic mechanical behaviors of living cells. Our study highlights the crucial role of previously neglected factors, such as cell volume and cytoskeletal filament orientation, in regulating cellular anisotropic viscoelasticity. We further propose an orientational entropy of cytoskeletal filaments to quantitatively characterize the ordering process of cells with increasing aspect ratios. Moreover, we derived the analytical interrelationships between cell aspect ratio, cell stiffness, cell volume, and cytoskeletal fiber orientation. This study provides a theoretical framework to describe the anisotropic viscoelastic mechanical behavior of cells.
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Affiliation(s)
- Jiu-Tao Hang
- Laboratory for Multiscale Mechanics and Medical Science, Department of Engineering Mechanics, SVL, School of Aerospace Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - Huan Wang
- Laboratory for Multiscale Mechanics and Medical Science, Department of Engineering Mechanics, SVL, School of Aerospace Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - Bi-Cong Wang
- Laboratory for Multiscale Mechanics and Medical Science, Department of Engineering Mechanics, SVL, School of Aerospace Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - Guang-Kui Xu
- Laboratory for Multiscale Mechanics and Medical Science, Department of Engineering Mechanics, SVL, School of Aerospace Engineering, Xi'an Jiaotong University, Xi'an 710049, China.
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6
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Woolley L, Burbidge A, Vermant J, Christakopoulos F. A microrheological examination of insulin-secreting β-cells in healthy and diabetic-like conditions. SOFT MATTER 2024; 20:3464-3472. [PMID: 38573072 DOI: 10.1039/d3sm01141k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/05/2024]
Abstract
Pancreatic β-cells regulate glucose homeostasis through glucose-stimulated insulin secretion, which is hindered in type-2 diabetes. Transport of the insulin vesicles is expected to be affected by changes in the viscoelastic and transport properties of the cytoplasm. These are evaluated in situ through particle-tracking measurements using a rat insulinoma β-cell line. The use of inert probes assists in decoupling the material properties of the cytoplasm from the active transport through cellular processes. The effect of glucose-stimulated insulin secretion is examined, and the subsequent remodeling of the cytoskeleton, at constant effects of cell activity, is shown to result in reduced mobility of the tracer particles. Induction of diabetic-like conditions is identified to alter the mean-squared displacement of the passive particles in the cytoplasm and diminish its reaction to glucose stimulation.
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Affiliation(s)
- Lukas Woolley
- Department of Materials, ETH Zurich, Vladimir-Prelog-Weg 5, 8093 Zurich, Switzerland.
| | - Adam Burbidge
- Nestlé Research, Route de Jorat 57, vers-chez-les Blanc, 1000 Lausanne, Switzerland
| | - Jan Vermant
- Department of Materials, ETH Zurich, Vladimir-Prelog-Weg 5, 8093 Zurich, Switzerland.
| | - Fotis Christakopoulos
- Department of Materials, ETH Zurich, Vladimir-Prelog-Weg 5, 8093 Zurich, Switzerland.
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7
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Herzog S, Fläschner G, Incaviglia I, Arias JC, Ponti A, Strohmeyer N, Nava MM, Müller DJ. Monitoring the mass, eigenfrequency, and quality factor of mammalian cells. Nat Commun 2024; 15:1751. [PMID: 38409119 PMCID: PMC10897412 DOI: 10.1038/s41467-024-46056-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 02/06/2024] [Indexed: 02/28/2024] Open
Abstract
The regulation of mass is essential for the development and homeostasis of cells and multicellular organisms. However, cell mass is also tightly linked to cell mechanical properties, which depend on the time scales at which they are measured and change drastically at the cellular eigenfrequency. So far, it has not been possible to determine cell mass and eigenfrequency together. Here, we introduce microcantilevers oscillating in the Ångström range to monitor both fundamental physical properties of the cell. If the oscillation frequency is far below the cellular eigenfrequency, all cell compartments follow the cantilever motion, and the cell mass measurements are accurate. Yet, if the oscillating frequency approaches or lies above the cellular eigenfrequency, the mechanical response of the cell changes, and not all cellular components can follow the cantilever motions in phase. This energy loss caused by mechanical damping within the cell is described by the quality factor. We use these observations to examine living cells across externally applied mechanical frequency ranges and to measure their total mass, eigenfrequency, and quality factor. The three parameters open the door to better understand the mechanobiology of the cell and stimulate biotechnological and medical innovations.
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Affiliation(s)
- Sophie Herzog
- Department of Biosystems Science and Engineering, Eidgenössische Technische Hochschule (ETH) Zurich, Klingelbergstrasse 48, 4056, Basel, Switzerland
| | - Gotthold Fläschner
- Department of Biosystems Science and Engineering, Eidgenössische Technische Hochschule (ETH) Zurich, Klingelbergstrasse 48, 4056, Basel, Switzerland.
- Nanosurf AG, Gräubernstrasse 12, 4410, Liestal, Switzerland.
| | - Ilaria Incaviglia
- Department of Biosystems Science and Engineering, Eidgenössische Technische Hochschule (ETH) Zurich, Klingelbergstrasse 48, 4056, Basel, Switzerland
| | - Javier Casares Arias
- Department of Biosystems Science and Engineering, Eidgenössische Technische Hochschule (ETH) Zurich, Klingelbergstrasse 48, 4056, Basel, Switzerland
| | - Aaron Ponti
- Department of Biosystems Science and Engineering, Eidgenössische Technische Hochschule (ETH) Zurich, Klingelbergstrasse 48, 4056, Basel, Switzerland
| | - Nico Strohmeyer
- Department of Biosystems Science and Engineering, Eidgenössische Technische Hochschule (ETH) Zurich, Klingelbergstrasse 48, 4056, Basel, Switzerland
| | - Michele M Nava
- Department of Biosystems Science and Engineering, Eidgenössische Technische Hochschule (ETH) Zurich, Klingelbergstrasse 48, 4056, Basel, Switzerland
| | - Daniel J Müller
- Department of Biosystems Science and Engineering, Eidgenössische Technische Hochschule (ETH) Zurich, Klingelbergstrasse 48, 4056, Basel, Switzerland.
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8
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Atia L, Fredberg JJ. A life off the beaten track in biomechanics: Imperfect elasticity, cytoskeletal glassiness, and epithelial unjamming. BIOPHYSICS REVIEWS 2023; 4:041304. [PMID: 38156333 PMCID: PMC10751956 DOI: 10.1063/5.0179719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Accepted: 11/17/2023] [Indexed: 12/30/2023]
Abstract
Textbook descriptions of elasticity, viscosity, and viscoelasticity fail to account for certain mechanical behaviors that typify soft living matter. Here, we consider three examples. First, strong empirical evidence suggests that within lung parenchymal tissues, the frictional stresses expressed at the microscale are fundamentally not of viscous origin. Second, the cytoskeleton (CSK) of the airway smooth muscle cell, as well as that of all eukaryotic cells, is more solid-like than fluid-like, yet its elastic modulus is softer than the softest of soft rubbers by a factor of 104-105. Moreover, the eukaryotic CSK expresses power law rheology, innate malleability, and fluidization when sheared. For these reasons, taken together, the CSK of the living eukaryotic cell is reminiscent of the class of materials called soft glasses, thus likening it to inert materials such as clays, pastes slurries, emulsions, and foams. Third, the cellular collective comprising a confluent epithelial layer can become solid-like and jammed, fluid-like and unjammed, or something in between. Esoteric though each may seem, these discoveries are consequential insofar as they impact our understanding of bronchospasm and wound healing as well as cancer cell invasion and embryonic development. Moreover, there are reasons to suspect that certain of these phenomena first arose in the early protist as a result of evolutionary pressures exerted by the primordial microenvironment. We have hypothesized, further, that each then became passed down virtually unchanged to the present day as a conserved core process. These topics are addressed here not only because they are interesting but also because they track the journey of one laboratory along a path less traveled by.
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Affiliation(s)
- Lior Atia
- Ben Gurion University of the Negev, Beer Sheva, Israel
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9
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Li SH, Xu GK. Topological mechanism in the nonlinear power-law relaxation of cell cortex. Phys Rev E 2023; 108:064408. [PMID: 38243511 DOI: 10.1103/physreve.108.064408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2023] [Accepted: 11/16/2023] [Indexed: 01/21/2024]
Abstract
Different types of cells exhibit a universal power-law rheology, but the mechanism underneath is still unclear. Based on the exponential distribution of actin filament length, we treat the cell cortex as a collection of chains of crosslinkers with exponentially distributed binding energy, and show that the power-law exponent of its stress relaxation should scale with the chain length. Through this model, we are able to explain how the exponent can be regulated by the crosslinker number and imposed strain during cortex relaxation. Network statistics show that the average length of filament-crosslinker chains decreases with the crosslinker number, which endows a denser network with lower exponent. Due to gradual molecular alignment with the stretch direction, the number of effectively stretched crosslinkers in the network is found to increase with the imposed strain. This effective growth in network density diminishes the exponent under large strain. By incorporating the inclined angle of crosslinkers into the model without in-series structure, we show that the exponent cannot be altered by crosslinker rotation directly, refining our previous conjectures. This work may help to understand cellular mechanics from the molecular perspective.
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Affiliation(s)
- Shao-Heng Li
- Laboratory for Multiscale Mechanics and Medical Science, Department of Engineering Mechanics, State Key Laboratory for Strength and Vibration of Mechanical Structures, School of Aerospace Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - Guang-Kui Xu
- Laboratory for Multiscale Mechanics and Medical Science, Department of Engineering Mechanics, State Key Laboratory for Strength and Vibration of Mechanical Structures, School of Aerospace Engineering, Xi'an Jiaotong University, Xi'an 710049, China
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10
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Umeda K, Nishizawa K, Nagao W, Inokuchi S, Sugino Y, Ebata H, Mizuno D. Activity-dependent glassy cell mechanics II: Nonthermal fluctuations under metabolic activity. Biophys J 2023; 122:4395-4413. [PMID: 37865819 PMCID: PMC10698330 DOI: 10.1016/j.bpj.2023.10.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 08/28/2023] [Accepted: 10/18/2023] [Indexed: 10/23/2023] Open
Abstract
The glassy cytoplasm, crowded with bio-macromolecules, is fluidized in living cells by mechanical energy derived from metabolism. Characterizing the living cytoplasm as a nonequilibrium system is crucial in elucidating the intricate mechanism that relates cell mechanics to metabolic activities. In this study, we conducted active and passive microrheology in eukaryotic cells, and quantified nonthermal fluctuations by examining the violation of the fluctuation-dissipation theorem. The power spectral density of active force generation was estimated following the Langevin theory extended to nonequilibrium systems. However, experiments performed while regulating cellular metabolic activity showed that the nonthermal displacement fluctuation, rather than the active nonthermal force, is linked to metabolism. We discuss that mechano-enzymes in living cells do not act as microscopic objects. Instead, they generate meso-scale collective fluctuations with displacements controlled by enzymatic activity. The activity induces structural relaxations in glassy cytoplasm. Even though the autocorrelation of nonthermal fluctuations is lost at long timescales due to the structural relaxations, the nonthermal displacement fluctuation remains regulated by metabolic reactions. Our results therefore demonstrate that nonthermal fluctuations serve as a valuable indicator of a cell's metabolic activities, regardless of the presence or absence of structural relaxations.
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Affiliation(s)
| | | | - Wataru Nagao
- Department of Physics, Kyushu University, Fukuoka, Japan
| | - Shono Inokuchi
- Department of Physics, Kyushu University, Fukuoka, Japan
| | - Yujiro Sugino
- Department of Physics, Kyushu University, Fukuoka, Japan
| | - Hiroyuki Ebata
- Department of Physics, Kyushu University, Fukuoka, Japan
| | - Daisuke Mizuno
- Department of Physics, Kyushu University, Fukuoka, Japan.
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11
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Fielding SM, Cochran JO, Huang J, Bi D, Marchetti MC. Constitutive model for the rheology of biological tissue. Phys Rev E 2023; 108:L042602. [PMID: 37978678 DOI: 10.1103/physreve.108.l042602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Accepted: 09/13/2023] [Indexed: 11/19/2023]
Abstract
The rheology of biological tissue is key to processes such as embryo development, wound healing, and cancer metastasis. Vertex models of confluent tissue monolayers have uncovered a spontaneous liquid-solid transition tuned by cell shape; and a shear-induced solidification transition of an initially liquidlike tissue. Alongside this jamming/unjamming behavior, biological tissue also displays an inherent viscoelasticity, with a slow time and rate-dependent mechanics. With this motivation, we combine simulations and continuum theory to examine the rheology of the vertex model in nonlinear shear across a full range of shear rates from quastistatic to fast, elucidating its nonlinear stress-strain curves after the inception of shear of finite rate, and its steady state flow curves of stress as a function of strain rate. We formulate a rheological constitutive model that couples cell shape to flow and captures both the tissue solid-liquid transition and its rich linear and nonlinear rheology.
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Affiliation(s)
- Suzanne M Fielding
- Department of Physics, Durham University, Science Laboratories, South Road, Durham DH1 3LE, UK
| | - James O Cochran
- Department of Physics, Durham University, Science Laboratories, South Road, Durham DH1 3LE, UK
| | - Junxiang Huang
- Department of Physics, Northeastern University, Massachusetts 02115, USA
| | - Dapeng Bi
- Department of Physics, Northeastern University, Massachusetts 02115, USA
| | - M Cristina Marchetti
- Department of Physics, University of California, Santa Barbara, California 93106, USA
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12
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Goldner AN, Fessehaye SM, Rodriguez N, Mapes KA, Osterfield M, Doubrovinski K. Evidence that tissue recoil in the early Drosophila embryo is a passive not active process. Mol Biol Cell 2023; 34:br16. [PMID: 37405768 PMCID: PMC10551697 DOI: 10.1091/mbc.e22-09-0409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Revised: 06/26/2023] [Accepted: 06/28/2023] [Indexed: 07/06/2023] Open
Abstract
Understanding tissue morphogenesis is impossible without knowing the mechanical properties of the tissue being shaped. Although techniques for measuring tissue material properties are continually being developed, methods for determining how individual proteins contribute to mechanical properties are very limited. Here, we developed two complementary techniques for the acute inactivation of spaghetti squash (the Drosophila myosin regulatory light chain), one based on the recently introduced (auxin-inducible degron 2 (AID2) system, and the other based on a novel method for conditional protein aggregation that results in nearly instantaneous protein inactivation. Combining these techniques with rheological measurements, we show that passive material properties of the cellularization-stage Drosophila embryo are essentially unaffected by myosin activity. These results suggest that this tissue is elastic, not predominantly viscous, on the developmentally relevant timescale.
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Affiliation(s)
- Amanda Nicole Goldner
- Department of Biophysics and Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Salena M. Fessehaye
- Department of Biophysics and Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Nataly Rodriguez
- Department of Biophysics and Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Kelly Ann Mapes
- Department of Biophysics and Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Miriam Osterfield
- Department of Biophysics and Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Konstantin Doubrovinski
- Department of Biophysics and Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
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13
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Dubay R, Darling EM, Fiering J. Microparticles with tunable, cell-like properties for quantitative acoustic mechanophenotyping. MICROSYSTEMS & NANOENGINEERING 2023; 9:90. [PMID: 37448969 PMCID: PMC10336031 DOI: 10.1038/s41378-023-00556-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 04/21/2023] [Accepted: 05/08/2023] [Indexed: 07/18/2023]
Abstract
Mechanical properties of biological cells have been shown to correlate with their biomolecular state and function, and therefore methods to measure these properties at scale are of interest. Emerging microfluidic technologies can measure the mechanical properties of cells at rates over 20,000 cells/s, which is more than four orders of magnitude faster than conventional instrumentation. However, precise and repeatable means to calibrate and test these new tools remain lacking, since cells themselves are by nature variable. Commonly, microfluidic tools use rigid polymer microspheres for calibration because they are widely available in cell-similar sizes, but conventional microspheres do not fully capture the physiological range of other mechanical properties that are equally important to device function (e.g., elastic modulus and density). Here, we present for the first time development of monodisperse polyacrylamide microparticles with both tunable elasticity and tunable density. Using these size, elasticity, and density tunable particles, we characterized a custom acoustic microfluidic device that makes single-cell measurements of mechanical properties. We then applied the approach to measure the distribution of the acoustic properties within samples of human leukocytes and showed that the system successfully discriminates lymphocytes from other leukocytes. This initial demonstration shows how the tunable microparticles with properties within the physiologically relevant range can be used in conjunction with microfluidic devices for efficient high-throughput measurements of mechanical properties at single-cell resolution.
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Affiliation(s)
- Ryan Dubay
- Center for Biomedical Engineering, Brown University, Providence, RI 02912 USA
- Biological Microsystems, Draper, Cambridge, MA 02139 USA
| | - Eric M. Darling
- Center for Biomedical Engineering, Brown University, Providence, RI 02912 USA
- Department of Pathology and Laboratory Medicine, Brown University, Providence, RI 02912 USA
- School of Engineering, Brown University, Providence, RI 02912 USA
- Department of Orthopaedics, Brown University, Providence, RI 02912 USA
| | - Jason Fiering
- Biological Microsystems, Draper, Cambridge, MA 02139 USA
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14
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Ebata H, Umeda K, Nishizawa K, Nagao W, Inokuchi S, Sugino Y, Miyamoto T, Mizuno D. Activity-dependent glassy cell mechanics Ⅰ: Mechanical properties measured with active microrheology. Biophys J 2023; 122:1781-1793. [PMID: 37050875 PMCID: PMC10209042 DOI: 10.1016/j.bpj.2023.04.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 01/27/2023] [Accepted: 04/07/2023] [Indexed: 04/14/2023] Open
Abstract
Active microrheology was conducted in living cells by applying an optical-trapping force to vigorously fluctuating tracer beads with feedback-tracking technology. The complex shear modulus G(ω)=G'(ω)-iG″(ω) was measured in HeLa cells in an epithelial-like confluent monolayer. We found that G(ω)∝(-iω)1/2 over a wide range of frequencies (1 Hz < ω/2π < 10 kHz). Actin disruption and cell-cycle progression from G1 to S and G2 phases only had a limited effect on G(ω) in living cells. On the other hand, G(ω) was found to be dependent on cell metabolism; ATP-depleted cells showed an increased elastic modulus G'(ω) at low frequencies, giving rise to a constant plateau such that G(ω)=G0+A(-iω)1/2. Both the plateau and the additional frequency dependency ∝(-iω)1/2 of ATP-depleted cells are consistent with a rheological response typical of colloidal jamming. On the other hand, the plateau G0 disappeared in ordinary metabolically active cells, implying that living cells fluidize their internal states such that they approach the critical jamming point.
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Affiliation(s)
- Hiroyuki Ebata
- Department of Physics, Kyushu University, Fukuoka, Japan
| | | | - Kenji Nishizawa
- Institute of Developmental Biology of Marseille, Marseille, France
| | - Wataru Nagao
- Department of Physics, Kyushu University, Fukuoka, Japan
| | - Shono Inokuchi
- Department of Physics, Kyushu University, Fukuoka, Japan
| | - Yujiro Sugino
- Department of Physics, Kyushu University, Fukuoka, Japan
| | - Takafumi Miyamoto
- Department of Endocrinology and Metabolism, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan; Transborder Medical Research Center, University of Tsukuba, Ibaraki, Japan
| | - Daisuke Mizuno
- Department of Physics, Kyushu University, Fukuoka, Japan.
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15
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Lee S, Jung I, Lee S, Shin J, Cho E, Jung S, Ih S, Kim YG, Hong S, Choi YL, Park S. Plasmonic-Magnetic Active Nanorheology for Intracellular Viscosity. NANO LETTERS 2023; 23:2031-2038. [PMID: 36695563 DOI: 10.1021/acs.nanolett.2c04761] [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: 06/17/2023]
Abstract
We demonstrate active plasmonic systems where plasmonic signals are repeatedly modulated by changing the orientation of nanoprobes under an external magnetic field, which is a prerequisite for in situ active nanorheology in intracellular viscosity measurements. Au/Ni/Au nanorods act as "nanotransmitters", which transmit the mechanical motion of nanorods to an electromagnetic radiation signal as a periodic sine function. This fluctuating optical response is transduced to frequency peaks via Fourier transform surface plasmon resonance (FTSPR). As a driving frequency of the external magnetic field applied to the Au/Ni/Au nanorods increases and reaches above a critical threshold, there is a transition from the synchronous motion of nanorods to asynchronous responses, leading to the disappearance of the FTSPR peak, which allows us to measure the local viscosity of the complex fluids. Using this ensemble-based method with plasmonic functional nanomaterials, we measure the intracellular viscosity of cancer cells and normal cells in a reliable and reproducible manner.
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Affiliation(s)
- Sungwoo Lee
- Department of Chemistry, Sungkyunkwan University (SKKU), Suwon 16419, Republic of Korea
- Institute of Basic Science, Sungkyunkwan University (SKKU), Suwon 16419, Republic of Korea
| | - Insub Jung
- Department of Chemistry, Sungkyunkwan University (SKKU), Suwon 16419, Republic of Korea
- Institute of Basic Science, Sungkyunkwan University (SKKU), Suwon 16419, Republic of Korea
| | - Soohyun Lee
- Department of Chemistry, Sungkyunkwan University (SKKU), Suwon 16419, Republic of Korea
| | - Junghyun Shin
- Department of Physics and Astronomy, Institute of Applied Physics, Seoul National University (SNU), Seoul 08826, Republic of Korea
| | - Eunbyeol Cho
- Department of Chemistry, Sungkyunkwan University (SKKU), Suwon 16419, Republic of Korea
| | - Sangbaek Jung
- Department of Chemistry, Sungkyunkwan University (SKKU), Suwon 16419, Republic of Korea
| | - Seongkeun Ih
- Department of Chemistry, Sungkyunkwan University (SKKU), Suwon 16419, Republic of Korea
| | - Yang-Gyun Kim
- Department of Chemistry, Sungkyunkwan University (SKKU), Suwon 16419, Republic of Korea
| | - Seunghun Hong
- Department of Physics and Astronomy, Institute of Applied Physics, Seoul National University (SNU), Seoul 08826, Republic of Korea
| | - Yoon-La Choi
- Department of Health Sciences and Technology, SAIHST, Sungkyunkwan University (SKKU), Seoul 06355, Republic of Korea
- Department of Pathology and Translational Genomics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 06351, Republic of Korea
| | - Sungho Park
- Department of Chemistry, Sungkyunkwan University (SKKU), Suwon 16419, Republic of Korea
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16
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Li SH, Gao H, Xu GK. Network dynamics of the nonlinear power-law relaxation of cell cortex. Biophys J 2022; 121:4091-4098. [PMID: 36171727 PMCID: PMC9675028 DOI: 10.1016/j.bpj.2022.09.035] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 09/09/2022] [Accepted: 09/26/2022] [Indexed: 11/17/2022] Open
Abstract
Living cells are known to exhibit universal power-law rheological behaviors, but their underlying biomechanical principles are still not fully understood. Here, we present a network dynamics picture to decipher the nonlinear power-law relaxation of cortical cytoskeleton. Under step strains, we present a scaling relation between instantaneous differential stiffness and external stress as a result of chain reorientation. Then, during the relaxation, we show how the scaling law theoretically originates from an exponential form of cortical disorder, with the scaling exponent decreased by the imposed strain or crosslinker density in the nonlinear regime. We attribute this exponent variation to the molecular realignment along the stretch direction or the transition of network structure from in-series to in-parallel modes, both solidifying the network toward our one-dimensional theoretical limit. In addition, the rebinding of crosslinkers is found to be crucial for moderating the relaxation speed under small strains. Together with the disorder nature, we demonstrate that the structural effects of networks provide a unified interpretation for the nonlinear power-law relaxation of cell cortex, and may help to understand cell mechanics from the molecular scale.
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Affiliation(s)
- Shao-Heng Li
- Laboratory for Multiscale Mechanics and Medical Science, Department of Engineering Mechanics, SVL, School of Aerospace Engineering, Xi'an Jiaotong University, Xi'an, China
| | - Huajian Gao
- School of Mechanical and Aerospace Engineering, College of Engineering, Nanyang Technological University, Singapore, Singapore; Institute of High Performance Computing, A(∗)STAR, Singapore, Singapore.
| | - Guang-Kui Xu
- Laboratory for Multiscale Mechanics and Medical Science, Department of Engineering Mechanics, SVL, School of Aerospace Engineering, Xi'an Jiaotong University, Xi'an, China.
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17
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Su Z, Chen Z, Ma K, Chen H, Ho JWK. Molecular determinants of intrinsic cellular stiffness in health and disease. Biophys Rev 2022; 14:1197-1209. [PMID: 36345276 PMCID: PMC9636357 DOI: 10.1007/s12551-022-00997-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Accepted: 09/11/2022] [Indexed: 10/14/2022] Open
Abstract
In recent years, the role of intrinsic biophysical features, especially cellular stiffness, in diverse cellular and disease processes is being increasingly recognized. New high throughput techniques for the quantification of cellular stiffness facilitate the study of their roles in health and diseases. In this review, we summarized recent discovery about how cellular stiffness is involved in cell stemness, tumorigenesis, and blood diseases. In addition, we review the molecular mechanisms underlying the gene regulation of cellular stiffness in health and disease progression. Finally, we discussed the current understanding on how the cytoskeleton structure and the regulation of these genes contribute to cellular stiffness, highlighting where the field of cellular stiffness is headed.
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Affiliation(s)
- Zezhuo Su
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong, SAR China
- Laboratory of Data Discovery for Health Limited (D24H), Hong Kong Science Park, Hong Kong, SAR China
| | - Zhenlin Chen
- Department of Biomedical Engineering, College of Engineering, City University of Hong Kong, Kowloon, Hong Kong, SAR China
| | - Kun Ma
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong, SAR China
- Laboratory of Data Discovery for Health Limited (D24H), Hong Kong Science Park, Hong Kong, SAR China
| | - Huaying Chen
- School of Mechanical Engineering and Automation, Harbin Institute of Technology, Shenzhen, Shenzhen, 518055 China
| | - Joshua W. K. Ho
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong, SAR China
- Laboratory of Data Discovery for Health Limited (D24H), Hong Kong Science Park, Hong Kong, SAR China
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18
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Matsumoto M, Tsuru H, Suginobe H, Narita J, Ishii R, Hirose M, Hashimoto K, Wang R, Yoshihara C, Ueyama A, Tanaka R, Ozono K, Okajima T, Ishida H. Atomic force microscopy identifies the alteration of rheological properties of the cardiac fibroblasts in idiopathic restrictive cardiomyopathy. PLoS One 2022; 17:e0275296. [PMID: 36174041 PMCID: PMC9522286 DOI: 10.1371/journal.pone.0275296] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Accepted: 09/13/2022] [Indexed: 11/29/2022] Open
Abstract
Restrictive cardiomyopathy (RCM) is a rare disease characterized by increased ventricular stiffness and preserved ventricular contraction. Various sarcomere gene variants are known to cause RCM; however, more than a half of patients do not harbor such pathogenic variants. We recently demonstrated that cardiac fibroblasts (CFs) play important roles in inhibiting the diastolic function of cardiomyocytes via humoral factors and direct cell–cell contact regardless of sarcomere gene mutations. However, the mechanical properties of CFs that are crucial for intercellular communication and the cardiomyocyte microenvironment remain less understood. In this study, we evaluated the rheological properties of CFs derived from pediatric patients with RCM and healthy control CFs via atomic force microscopy. Then, we estimated the cellular modulus scale factor related to the cell stiffness, fluidity, and Newtonian viscosity of single cells based on the single power-law rheology model and analyzed the comprehensive gene expression profiles via RNA-sequencing. RCM-derived CFs showed significantly higher stiffness and viscosity and lower fluidity compared to healthy control CFs. Furthermore, RNA-sequencing revealed that the signaling pathways associated with cytoskeleton elements were affected in RCM CFs; specifically, cytoskeletal actin-associated genes (ACTN1, ACTA2, and PALLD) were highly expressed in RCM CFs, whereas several tubulin genes (TUBB3, TUBB, TUBA1C, and TUBA1B) were down-regulated. These results implies that the signaling pathways associated with cytoskeletal elements alter the rheological properties of RCM CFs, particularly those related to CF–cardiomyocyte interactions, thereby leading to diastolic cardiac dysfunction in RCM.
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Affiliation(s)
- Mizuki Matsumoto
- Graduate School of Information Science and Technology, Hokkaido University, Sapporo, Japan
| | - Hirofumi Tsuru
- Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan
- Department of Pediatrics, Niigata University School of Medicine, Niigata, Japan
| | - Hidehiro Suginobe
- Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Jun Narita
- Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Ryo Ishii
- Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Masaki Hirose
- Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Kazuhisa Hashimoto
- Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Renjie Wang
- Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Chika Yoshihara
- Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Atsuko Ueyama
- Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Ryosuke Tanaka
- Graduate School of Information Science and Technology, Hokkaido University, Sapporo, Japan
| | - Keiichi Ozono
- Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Takaharu Okajima
- Graduate School of Information Science and Technology, Hokkaido University, Sapporo, Japan
- * E-mail: (HI); (TO)
| | - Hidekazu Ishida
- Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan
- * E-mail: (HI); (TO)
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19
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Li Y, Wong IY, Guo M. Reciprocity of Cell Mechanics with Extracellular Stimuli: Emerging Opportunities for Translational Medicine. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2107305. [PMID: 35319155 PMCID: PMC9463119 DOI: 10.1002/smll.202107305] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Revised: 02/20/2022] [Indexed: 06/14/2023]
Abstract
Human cells encounter dynamic mechanical cues in healthy and diseased tissues, which regulate their molecular and biophysical phenotype, including intracellular mechanics as well as force generation. Recent developments in bio/nanomaterials and microfluidics permit exquisitely sensitive measurements of cell mechanics, as well as spatiotemporal control over external mechanical stimuli to regulate cell behavior. In this review, the mechanobiology of cells interacting bidirectionally with their surrounding microenvironment, and the potential relevance for translational medicine are considered. Key fundamental concepts underlying the mechanics of living cells as well as the extracelluar matrix are first introduced. Then the authors consider case studies based on 1) microfluidic measurements of nonadherent cell deformability, 2) cell migration on micro/nano-topographies, 3) traction measurements of cells in three-dimensional (3D) matrix, 4) mechanical programming of organoid morphogenesis, as well as 5) active mechanical stimuli for potential therapeutics. These examples highlight the promise of disease diagnosis using mechanical measurements, a systems-level understanding linking molecular with biophysical phenotype, as well as therapies based on mechanical perturbations. This review concludes with a critical discussion of these emerging technologies and future directions at the interface of engineering, biology, and medicine.
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Affiliation(s)
- Yiwei Li
- Department of Biomedical Engineering, College of Life Science and Technology, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, Hubei, 430074, China
| | - Ian Y Wong
- School of Engineering, Center for Biomedical Engineering, Joint Program in Cancer Biology, Brown University, 184 Hope St Box D, Providence, RI, 02912, USA
| | - Ming Guo
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
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20
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Mao Y, Nielsen P, Ali J. Passive and Active Microrheology for Biomedical Systems. Front Bioeng Biotechnol 2022; 10:916354. [PMID: 35866030 PMCID: PMC9294381 DOI: 10.3389/fbioe.2022.916354] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2022] [Accepted: 06/08/2022] [Indexed: 12/12/2022] Open
Abstract
Microrheology encompasses a range of methods to measure the mechanical properties of soft materials. By characterizing the motion of embedded microscopic particles, microrheology extends the probing length scale and frequency range of conventional bulk rheology. Microrheology can be characterized into either passive or active methods based on the driving force exerted on probe particles. Tracer particles are driven by thermal energy in passive methods, applying minimal deformation to the assessed medium. In active techniques, particles are manipulated by an external force, most commonly produced through optical and magnetic fields. Small-scale rheology holds significant advantages over conventional bulk rheology, such as eliminating the need for large sample sizes, the ability to probe fragile materials non-destructively, and a wider probing frequency range. More importantly, some microrheological techniques can obtain spatiotemporal information of local microenvironments and accurately describe the heterogeneity of structurally complex fluids. Recently, there has been significant growth in using these minimally invasive techniques to investigate a wide range of biomedical systems both in vitro and in vivo. Here, we review the latest applications and advancements of microrheology in mammalian cells, tissues, and biofluids and discuss the current challenges and potential future advances on the horizon.
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Affiliation(s)
- Yating Mao
- Department of Chemical and Biomedical Engineering, FAMU-FSU College of Engineering, Tallahassee, FL, United States
- National High Magnetic Field Laboratory, Tallahassee, FL, United States
| | - Paige Nielsen
- Department of Chemical and Biomedical Engineering, FAMU-FSU College of Engineering, Tallahassee, FL, United States
- National High Magnetic Field Laboratory, Tallahassee, FL, United States
| | - Jamel Ali
- Department of Chemical and Biomedical Engineering, FAMU-FSU College of Engineering, Tallahassee, FL, United States
- National High Magnetic Field Laboratory, Tallahassee, FL, United States
- *Correspondence: Jamel Ali,
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21
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Shi Y, Sivarajan S, Crocker JC, Reich DH. Measuring Cytoskeletal Mechanical Fluctuations and Rheology with Active Micropost Arrays. Curr Protoc 2022; 2:e433. [PMID: 35612274 PMCID: PMC9321978 DOI: 10.1002/cpz1.433] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The dynamics of the cellular actomyosin cytoskeleton are crucial to many aspects of cellular function. Here, we describe techniques that employ active micropost array detectors (AMPADs) to measure cytoskeletal rheology and mechanical force fluctuations. The AMPADS are arrays of flexible poly(dimethylsiloxane) (PDMS) microposts with magnetic nanowires embedded in a subset of microposts to enable actuation of those posts via an externally applied magnetic field. Techniques are described to track the magnetic microposts' motion with nanometer precision at up to 100 video frames per second to measure the local cellular rheology at well-defined positions. Application of these high-precision tracking techniques to the full array of microposts in contact with a cell also enables mapping of the cytoskeletal mechanical fluctuation dynamics with high spatial and temporal resolution. This article describes (1) the fabrication of magnetic micropost arrays, (2) measurement protocols for both local rheology and cytoskeletal force fluctuation mapping, and (3) special-purpose software routines to reduce and analyze these data. © 2022 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Fabrication of magnetic micropost arrays Basic Protocol 2: Data acquisition for cellular force fluctuations on non-magnetic micropost arrays Basic Protocol 3: Data acquisition for local cellular rheology measurements with magnetic microposts Basic Protocol 4: Data reduction: determining microposts' motion Basic Protocol 5: Data analysis: determining local rheology from magnetic microposts Basic Protocol 6: Data analysis for force fluctuation measurements Support Protocol 1: Fabrication of magnetic Ni nanowires by electrodeposition Support Protocol 2: Configuring Streampix for magnetic rheology measurements.
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Affiliation(s)
- Yu Shi
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland.,Current address: Department of Biomedical Engineering, University of North Carolina, Chapel Hill, North Carolina
| | - Shankar Sivarajan
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland
| | - John C Crocker
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Daniel H Reich
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland
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22
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Hang JT, Xu GK, Gao H. Frequency-dependent transition in power-law rheological behavior of living cells. SCIENCE ADVANCES 2022; 8:eabn6093. [PMID: 35522746 PMCID: PMC9075802 DOI: 10.1126/sciadv.abn6093] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Living cells are active viscoelastic materials exhibiting diverse mechanical behaviors at different time scales. However, dynamical rheological characteristics of cells in frequency range spanning many orders of magnitude, especially in high frequencies, remain poorly understood. Here, we show that a self-similar hierarchical model can capture cell's power-law rheological characteristics in different frequency scales. In low-frequency scales, the storage and loss moduli exhibit a weak power-law dependence on frequency with same exponent. In high-frequency scales, the storage modulus becomes a constant, while the loss modulus shows a power-law dependence on frequency with an exponent of 1.0. The transition between low- and high-frequency scales is defined by a transition frequency based on cell's mechanical parameters. The cytoskeletal differences of different cell types or states can be characterized by changes in mechanical parameters in the model. This study provides valuable insights into potentially using mechanics-based markers for cell classification and cancer diagnosis.
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Affiliation(s)
- Jiu-Tao Hang
- Laboratory for Multiscale Mechanics and Medical Science, Department of Engineering Mechanics, SVL, School of Aerospace Engineering, Xi’an Jiaotong University, Xi’an 710049, China
| | - Guang-Kui Xu
- Laboratory for Multiscale Mechanics and Medical Science, Department of Engineering Mechanics, SVL, School of Aerospace Engineering, Xi’an Jiaotong University, Xi’an 710049, China
- Corresponding author. (G.-K.X.); (H.G.)
| | - Huajian Gao
- School of Mechanical and Aerospace Engineering, College of Engineering, Nanyang Technological University, Singapore 639798, Singapore
- Institute of High Performance Computing, A*STAR, Singapore 138632, Singapore
- Corresponding author. (G.-K.X.); (H.G.)
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23
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Vakhrusheva A, Murashko A, Trifonova E, Efremov Y, Timashev P, Sokolova O. Role of Actin-binding Proteins in the Regulation of Cellular Mechanics. Eur J Cell Biol 2022; 101:151241. [DOI: 10.1016/j.ejcb.2022.151241] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Revised: 04/18/2022] [Accepted: 05/19/2022] [Indexed: 12/25/2022] Open
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24
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Huang J, Cochran JO, Fielding SM, Marchetti MC, Bi D. Shear-Driven Solidification and Nonlinear Elasticity in Epithelial Tissues. PHYSICAL REVIEW LETTERS 2022; 128:178001. [PMID: 35570431 DOI: 10.1103/physrevlett.128.178001] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Accepted: 03/31/2022] [Indexed: 06/15/2023]
Abstract
Biological processes, from morphogenesis to tumor invasion, spontaneously generate shear stresses inside living tissue. The mechanisms that govern the transmission of mechanical forces in epithelia and the collective response of the tissue to bulk shear deformations remain, however, poorly understood. Using a minimal cell-based computational model, we investigate the constitutive relation of confluent tissues under simple shear deformation. We show that an initially undeformed fluidlike tissue acquires finite rigidity above a critical applied strain. This is akin to the shear-driven rigidity observed in other soft matter systems. Interestingly, shear-driven rigidity can be understood by a critical scaling analysis in the vicinity of the second order critical point that governs the liquid-solid transition of the undeformed system. We further show that a solidlike tissue responds linearly only to small strains and but then switches to a nonlinear response at larger stains, with substantial stiffening. Finally, we propose a mean-field formulation for cells under shear that offers a simple physical explanation of shear-driven rigidity and nonlinear response in a tissue.
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Affiliation(s)
- Junxiang Huang
- Department of Physics, Northeastern University, Boston, Massachusetts 02115, USA
| | - James O Cochran
- Department of Physics, Durham University, Science Laboratories, South Road, Durham DH1 3LE, United Kingdom
| | - Suzanne M Fielding
- Department of Physics, Durham University, Science Laboratories, South Road, Durham DH1 3LE, United Kingdom
| | - M Cristina Marchetti
- Department of Physics, University of California, Santa Barbara, California 93106, USA
| | - Dapeng Bi
- Department of Physics, Northeastern University, Boston, Massachusetts 02115, USA
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25
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Sun W, Gao X, Lei H, Wang W, Cao Y. Biophysical Approaches for Applying and Measuring Biological Forces. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2105254. [PMID: 34923777 PMCID: PMC8844594 DOI: 10.1002/advs.202105254] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Indexed: 05/13/2023]
Abstract
Over the past decades, increasing evidence has indicated that mechanical loads can regulate the morphogenesis, proliferation, migration, and apoptosis of living cells. Investigations of how cells sense mechanical stimuli or the mechanotransduction mechanism is an active field of biomaterials and biophysics. Gaining a further understanding of mechanical regulation and depicting the mechanotransduction network inside cells require advanced experimental techniques and new theories. In this review, the fundamental principles of various experimental approaches that have been developed to characterize various types and magnitudes of forces experienced at the cellular and subcellular levels are summarized. The broad applications of these techniques are introduced with an emphasis on the difficulties in implementing these techniques in special biological systems. The advantages and disadvantages of each technique are discussed, which can guide readers to choose the most suitable technique for their questions. A perspective on future directions in this field is also provided. It is anticipated that technical advancement can be a driving force for the development of mechanobiology.
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Affiliation(s)
- Wenxu Sun
- School of SciencesNantong UniversityNantong226019P. R. China
| | - Xiang Gao
- Key Laboratory of Intelligent Optical Sensing and IntegrationNational Laboratory of Solid State Microstructureand Department of PhysicsCollaborative Innovation Center of Advanced MicrostructuresNanjing UniversityNanjing210023P. R. China
- Institute of Brain ScienceNanjing UniversityNanjing210023P. R. China
| | - Hai Lei
- Key Laboratory of Intelligent Optical Sensing and IntegrationNational Laboratory of Solid State Microstructureand Department of PhysicsCollaborative Innovation Center of Advanced MicrostructuresNanjing UniversityNanjing210023P. R. China
- Institute of Brain ScienceNanjing UniversityNanjing210023P. R. China
- Chemistry and Biomedicine Innovation CenterNanjing UniversityNanjing210023P. R. China
| | - Wei Wang
- Key Laboratory of Intelligent Optical Sensing and IntegrationNational Laboratory of Solid State Microstructureand Department of PhysicsCollaborative Innovation Center of Advanced MicrostructuresNanjing UniversityNanjing210023P. R. China
- Institute of Brain ScienceNanjing UniversityNanjing210023P. R. China
| | - Yi Cao
- Key Laboratory of Intelligent Optical Sensing and IntegrationNational Laboratory of Solid State Microstructureand Department of PhysicsCollaborative Innovation Center of Advanced MicrostructuresNanjing UniversityNanjing210023P. R. China
- Institute of Brain ScienceNanjing UniversityNanjing210023P. R. China
- MOE Key Laboratory of High Performance Polymer Materials and TechnologyDepartment of Polymer Science & EngineeringCollege of Chemistry & Chemical EngineeringNanjing UniversityNanjing210023P. R. China
- Chemistry and Biomedicine Innovation CenterNanjing UniversityNanjing210023P. R. China
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26
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Rosen ME, Grant CP, Dallon JC. Mean square displacement for a discrete centroid model of cell motion. PLoS One 2021; 16:e0261021. [PMID: 34928985 PMCID: PMC8687545 DOI: 10.1371/journal.pone.0261021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Accepted: 11/22/2021] [Indexed: 11/18/2022] Open
Abstract
The mean square displacement (MSD) is an important statistical measure on a stochastic process or a trajectory. In this paper we find an approximation to the mean square displacement for a model of cell motion. The model is a discrete-time jump process which approximates a force-based model for cell motion. In cell motion, the mean square displacement not only gives a measure of overall drift, but it is also an indicator of mode of transport. The key to finding the approximation is to find the mean square displacement for a subset of the state space and use it as an approximation for the entire state space. We give some intuition as to why this is an unexpectedly good approximation. A lower bound and upper bound for the mean square displacement are also given. We show that, although the upper bound is far from the computed mean square displacement, in rare cases the large displacements are approached.
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Affiliation(s)
- Mary Ellen Rosen
- Department of Mathematics, Brigham Young University, Provo, Utah, United States of America
| | - Christopher P. Grant
- Department of Mathematics, Brigham Young University, Provo, Utah, United States of America
| | - J. C. Dallon
- Department of Mathematics, Brigham Young University, Provo, Utah, United States of America
- * E-mail:
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27
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The confined Generalized Stokes-Einstein relation and its consequence on intracellular two-point microrheology. J Colloid Interface Sci 2021; 609:423-433. [PMID: 34906914 DOI: 10.1016/j.jcis.2021.11.037] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 11/06/2021] [Accepted: 11/08/2021] [Indexed: 01/14/2023]
Abstract
Two-point microrheology (TPM) is used to infer material properties of complex fluids from the correlated motion of hydrodynamically interacting probes embedded in the medium. The mechanistic connection between probe motion and material properties is propagation of disturbance flows, encoded in current TPM theory for unconfined materials. However, confined media e.g. biological cells and particle-laden droplets, require theory that encodes confinement into the flow propagator (Green's function). To test this idea, we use Confined Stokesian Dynamics simulations to explicitly represent many-body hydrodynamic couplings between colloids and with the enclosing cavity at arbitrary concentration and cavity size. We find that previous TPM theory breaks down in confinement, and we identify and replace the underlying key elements. We put forth a Confined Generalized Stokes-Einstein Relation and report the viscoelastic spectrum. We find that confinement alters particle dynamics and increases viscosity, owing to hydrodynamic and entropic coupling with the cavity. The new theory produces a master curve for all cavity sizes and concentrations and reveals that for colloids larger than 0.005 times the enclosure size, the new model is required.
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28
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Shi Y, Sivarajan S, Xiang KM, Kostecki GM, Tung L, Crocker JC, Reich DH. Pervasive cytoquakes in the actomyosin cortex across cell types and substrate stiffness. Integr Biol (Camb) 2021; 13:246-257. [PMID: 34875067 DOI: 10.1093/intbio/zyab017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 10/25/2021] [Accepted: 11/02/2021] [Indexed: 11/14/2022]
Abstract
The actomyosin cytoskeleton enables cells to resist deformation, crawl, change their shape and sense their surroundings. Despite decades of study, how its molecular constituents can assemble together to form a network with the observed mechanics of cells remains poorly understood. Recently, it has been shown that the actomyosin cortex of quiescent cells can undergo frequent, abrupt reconfigurations and displacements, called cytoquakes. Notably, such fluctuations are not predicted by current physical models of actomyosin networks, and their prevalence across cell types and mechanical environments has not previously been studied. Using micropost array detectors, we have performed high-resolution measurements of the dynamic mechanical fluctuations of cells' actomyosin cortex and stress fiber networks. This reveals cortical dynamics dominated by cytoquakes-intermittent events with a fat-tailed distribution of displacements, sometimes spanning microposts separated by 4 μm, in all cell types studied. These included 3T3 fibroblasts, where cytoquakes persisted over substrate stiffnesses spanning the tissue-relevant range of 4.3 kPa-17 kPa, and primary neonatal rat cardiac fibroblasts and myofibroblasts, human embryonic kidney cells and human bone osteosarcoma epithelial (U2OS) cells, where cytoquakes were observed on substrates in the same stiffness range. Overall, these findings suggest that the cortex self-organizes into a marginally stable mechanical state whose physics may contribute to cell mechanical properties, active behavior and mechanosensing.
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Affiliation(s)
- Yu Shi
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Shankar Sivarajan
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Katherine M Xiang
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Geran M Kostecki
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Leslie Tung
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21205, USA
| | - John C Crocker
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Daniel H Reich
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218, USA
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29
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Mierke CT. Viscoelasticity Acts as a Marker for Tumor Extracellular Matrix Characteristics. Front Cell Dev Biol 2021; 9:785138. [PMID: 34950661 PMCID: PMC8691700 DOI: 10.3389/fcell.2021.785138] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 11/23/2021] [Indexed: 12/28/2022] Open
Abstract
Biological materials such as extracellular matrix scaffolds, cancer cells, and tissues are often assumed to respond elastically for simplicity; the viscoelastic response is quite commonly ignored. Extracellular matrix mechanics including the viscoelasticity has turned out to be a key feature of cellular behavior and the entire shape and function of healthy and diseased tissues, such as cancer. The interference of cells with their local microenvironment and the interaction among different cell types relies both on the mechanical phenotype of each involved element. However, there is still not yet clearly understood how viscoelasticity alters the functional phenotype of the tumor extracellular matrix environment. Especially the biophysical technologies are still under ongoing improvement and further development. In addition, the effect of matrix mechanics in the progression of cancer is the subject of discussion. Hence, the topic of this review is especially attractive to collect the existing endeavors to characterize the viscoelastic features of tumor extracellular matrices and to briefly highlight the present frontiers in cancer progression and escape of cancers from therapy. Finally, this review article illustrates the importance of the tumor extracellular matrix mechano-phenotype, including the phenomenon viscoelasticity in identifying, characterizing, and treating specific cancer types.
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Affiliation(s)
- Claudia Tanja Mierke
- Faculty of Physics and Earth Science, Peter Debye Institute of Soft Matter Physics, Biological Physics Division, University of Leipzig, Leipzig, Germany
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30
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Fodor É, Souslov A. Optimal power and efficiency of odd engines. Phys Rev E 2021; 104:L062602. [PMID: 35030849 DOI: 10.1103/physreve.104.l062602] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2021] [Accepted: 12/09/2021] [Indexed: 11/07/2022]
Abstract
Odd materials feature antisymmetric response to perturbations. This anomalous property can stem from the nonequilibrium activity of their components, which is sustained by an external energy supply. These materials open the door to designing innovative engines which extract work by applying cyclic deformations, without any equivalent in equilibrium. Here, we reveal that the efficiency of such energy conversion, from local activity to macroscopic work, can be arbitrarily close to unity when the cycles of deformation are properly designed. We illustrate these principles in some canonical viscoelastic materials, which leads us to identify strategies for optimizing power and efficiency according to material properties and to delineate guidelines for the design of more complex odd engines.
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Affiliation(s)
- Étienne Fodor
- Department of Physics and Materials Science, University of Luxembourg, L-1511 Luxembourg
| | - Anton Souslov
- Department of Physics, University of Bath, Claverton Down, Bath BA2 7AY, United Kingdom
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31
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Wei X, Fang C, Gong B, Yao J, Qian J, Lin Y. Viscoelasticity of 3D actin networks dictated by the mechanochemical characteristics of cross-linkers. SOFT MATTER 2021; 17:10177-10185. [PMID: 33646227 DOI: 10.1039/d0sm01558j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
In this study, we report a computational investigation on how the mechanochemical characteristics of crosslinking molecules influence the viscoelasticity of three dimensional F-actin networks, an issue of key interest in analyzing the behavior of living cells and biological gels. In particular, it was found that the continuous breakage and rebinding of cross-linkers result in a locally peaked loss modulus in the rheology spectrum of the network, reflecting the fact that maximum energy dissipation is achieved when the driving frequency of the applied oscillating shear becomes comparable to the dissociation/association rate of crosslinking molecules. In addition, we showed that when subjected to constant rate of shear, an actin network can exhibit either strain hardening or softening depending on the ratio between the loading rate and unbinding speed of cross-linkers. A criterion for predicting the transition from softening to hardening was also obtained, in agreement with recent experiments. Finally, significant structural evolution was found to occur in random networks undergoing mechanical "training" (i.e. under a constant applied shear stress over a period of time), eventually leading to a pronounced anisotropic response of the network afterward which again is consistent with experimental observations.
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Affiliation(s)
- X Wei
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, China.
- HKU-Shenzhen Institute of Research and Innovation (HKU-SIRI), Guangdong, China
| | - C Fang
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, China.
- HKU-Shenzhen Institute of Research and Innovation (HKU-SIRI), Guangdong, China
| | - B Gong
- Department of Engineering Mechanics, Key Laboratory of Soft Machines and Smart Devices of Zhejiang Province, Zhejiang University, Hangzhou, Zhejiang, China.
| | - J Yao
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, China.
- HKU-Shenzhen Institute of Research and Innovation (HKU-SIRI), Guangdong, China
| | - J Qian
- Department of Engineering Mechanics, Key Laboratory of Soft Machines and Smart Devices of Zhejiang Province, Zhejiang University, Hangzhou, Zhejiang, China.
| | - Y Lin
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, China.
- HKU-Shenzhen Institute of Research and Innovation (HKU-SIRI), Guangdong, China
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32
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Abstract
The eukaryotic cell's cytoskeleton is a prototypical example of an active material: objects embedded within it are driven by molecular motors acting on the cytoskeleton, leading to anomalous diffusive behavior. Experiments tracking the behavior of cell-attached objects have observed anomalous diffusion with a distribution of displacements that is non-Gaussian, with heavy tails. This has been attributed to "cytoquakes" or other spatially extended collective effects. We show, using simulations and analytical theory, that a simple continuum active gel model driven by fluctuating force dipoles naturally creates heavy power-law tails in cytoskeletal displacements. We predict that this power law exponent should depend on the geometry and dimensionality of where force dipoles are distributed through the cell; we find qualitatively different results for force dipoles in a 3D cytoskeleton and a quasi-two-dimensional cortex. We then discuss potential applications of this model both in cells and in synthetic active gels.
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Affiliation(s)
- Daniel W Swartz
- Department of Physics and Astronomy, Johns Hopkins University, USA
- Department of Physics, Massachusetts Institute of Technology, USA
| | - Brian A Camley
- Department of Physics and Astronomy, Johns Hopkins University, USA
- Department of Biophysics, Johns Hopkins University, USA
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33
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Bhide S, Gombalova D, Mönke G, Stegmaier J, Zinchenko V, Kreshuk A, Belmonte JM, Leptin M. Mechanical competition alters the cellular interpretation of an endogenous genetic program. J Cell Biol 2021; 220:212605. [PMID: 34449835 PMCID: PMC8406609 DOI: 10.1083/jcb.202104107] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2021] [Revised: 07/26/2021] [Accepted: 07/30/2021] [Indexed: 12/16/2022] Open
Abstract
The intrinsic genetic program of a cell is not sufficient to explain all of the cell's activities. External mechanical stimuli are increasingly recognized as determinants of cell behavior. In the epithelial folding event that constitutes the beginning of gastrulation in Drosophila, the genetic program of the future mesoderm leads to the establishment of a contractile actomyosin network that triggers apical constriction of cells and thereby tissue folding. However, some cells do not constrict but instead stretch, even though they share the same genetic program as their constricting neighbors. We show here that tissue-wide interactions force these cells to expand even when an otherwise sufficient amount of apical, active actomyosin is present. Models based on contractile forces and linear stress-strain responses do not reproduce experimental observations, but simulations in which cells behave as ductile materials with nonlinear mechanical properties do. Our models show that this behavior is a general emergent property of actomyosin networks in a supracellular context, in accordance with our experimental observations of actin reorganization within stretching cells.
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Affiliation(s)
- Sourabh Bhide
- Director's Research Unit, European Molecular Biology Laboratory, Heidelberg, Germany.,Collaboration for Joint PhD Degree between European Molecular Biology Laboratory and Faculty of Biosciences, Heidelberg University, Heidelberg, Germany
| | - Denisa Gombalova
- Director's Research Unit, European Molecular Biology Laboratory, Heidelberg, Germany.,Collaboration for Joint PhD Degree between European Molecular Biology Laboratory and Faculty of Biosciences, Heidelberg University, Heidelberg, Germany
| | - Gregor Mönke
- Director's Research Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Johannes Stegmaier
- Institute of Imaging and Computer Vision, Rheinisch-Westfälische Technische Hochschule Aachen University, Aachen, Germany
| | - Valentyna Zinchenko
- Collaboration for Joint PhD Degree between European Molecular Biology Laboratory and Faculty of Biosciences, Heidelberg University, Heidelberg, Germany.,Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Anna Kreshuk
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Julio M Belmonte
- Department of Physics, North Carolina State University, Raleigh, NC.,Quantitative and Computational Developmental Biology Cluster, North Carolina State University, Raleigh, NC
| | - Maria Leptin
- Director's Research Unit, European Molecular Biology Laboratory, Heidelberg, Germany.,European Molecular Biology Organization, Heidelberg, Germany
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34
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Hang JT, Kang Y, Xu GK, Gao H. A hierarchical cellular structural model to unravel the universal power-law rheological behavior of living cells. Nat Commun 2021; 12:6067. [PMID: 34663821 PMCID: PMC8523554 DOI: 10.1038/s41467-021-26283-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 09/27/2021] [Indexed: 11/15/2022] Open
Abstract
Living cells are a complex soft material with fascinating mechanical properties. A striking feature is that, regardless of their types or states, cells exhibit a universal power-law rheological behavior which to this date still has not been captured by a single theoretical model. Here, we propose a cellular structural model that accounts for the essential mechanical responses of cell membrane, cytoplasm and cytoskeleton. We demonstrate that this model can naturally reproduce the universal power-law characteristics of cell rheology, as well as how its power-law exponent is related to cellular stiffness. More importantly, the power-law exponent can be quantitatively tuned in the range of 0.1 ~ 0.5, as found in most types of cells, by varying the stiffness or architecture of the cytoskeleton. Based on the structural characteristics, we further develop a self-similar hierarchical model that can spontaneously capture the power-law characteristics of creep compliance over time and complex modulus over frequency. The present model suggests that mechanical responses of cells may depend primarily on their generic architectural mechanism, rather than specific molecular properties. Different types of cells exhibit a universal power-law rheological behavior which to this date has not been captured by a single theoretical model. Here, the authors propose a self-similar hierarchical cellular model that can naturally reproduce the universal power-law characteristics of cell rheology.
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Affiliation(s)
- Jiu-Tao Hang
- Laboratory for Multiscale Mechanics and Medical Science, Department of Engineering Mechanics, SVL, School of Aerospace Engineering, Xi'an Jiaotong University, 710049, Xi'an, China
| | - Yu Kang
- College of Pharmaceutical Sciences, Zhejiang University, 310058, Hangzhou, China
| | - Guang-Kui Xu
- Laboratory for Multiscale Mechanics and Medical Science, Department of Engineering Mechanics, SVL, School of Aerospace Engineering, Xi'an Jiaotong University, 710049, Xi'an, China.
| | - Huajian Gao
- School of Mechanical and Aerospace Engineering, College of Engineering, Nanyang Technological University, 639798, Singapore, Singapore. .,Institute of High Performance Computing, A*STAR, 138632, Singapore, Singapore.
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35
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Li Y, Tang W, Guo M. The Cell as Matter: Connecting Molecular Biology to Cellular Functions. MATTER 2021; 4:1863-1891. [PMID: 35495565 PMCID: PMC9053450 DOI: 10.1016/j.matt.2021.03.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Viewing cell as matter to understand the intracellular biomolecular processes and multicellular tissue behavior represents an emerging research area at the interface of physics and biology. Cellular material displays various physical and mechanical properties, which can strongly affect both intracellular and multicellular biological events. This review provides a summary of how cells, as matter, connect molecular biology to cellular and multicellular scale functions. As an impact in molecular biology, we review recent progresses in utilizing cellular material properties to direct cell fate decisions in the communities of immune cells, neurons, stem cells, and cancer cells. Finally, we provide an outlook on how to integrate cellular material properties in developing biophysical methods for engineered living systems, regenerative medicine, and disease treatments.
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Affiliation(s)
- Yiwei Li
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Wenhui Tang
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Ming Guo
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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36
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Chowdhury F, Huang B, Wang N. Cytoskeletal prestress: The cellular hallmark in mechanobiology and mechanomedicine. Cytoskeleton (Hoboken) 2021; 78:249-276. [PMID: 33754478 PMCID: PMC8518377 DOI: 10.1002/cm.21658] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 03/16/2021] [Accepted: 03/17/2021] [Indexed: 12/13/2022]
Abstract
Increasing evidence demonstrates that mechanical forces, in addition to soluble molecules, impact cell and tissue functions in physiology and diseases. How living cells integrate mechanical signals to perform appropriate biological functions is an area of intense investigation. Here, we review the evidence of the central role of cytoskeletal prestress in mechanotransduction and mechanobiology. Elevating cytoskeletal prestress increases cell stiffness and reinforces cell stiffening, facilitates long-range cytoplasmic mechanotransduction via integrins, enables direct chromatin stretching and rapid gene expression, spurs embryonic development and stem cell differentiation, and boosts immune cell activation and killing of tumor cells whereas lowering cytoskeletal prestress maintains embryonic stem cell pluripotency, promotes tumorigenesis and metastasis of stem cell-like malignant tumor-repopulating cells, and elevates drug delivery efficiency of soft-tumor-cell-derived microparticles. The overwhelming evidence suggests that the cytoskeletal prestress is the governing principle and the cellular hallmark in mechanobiology. The application of mechanobiology to medicine (mechanomedicine) is rapidly emerging and may help advance human health and improve diagnostics, treatment, and therapeutics of diseases.
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Affiliation(s)
- Farhan Chowdhury
- Department of Mechanical Engineering and Energy ProcessesSouthern Illinois University CarbondaleCarbondaleIllinoisUSA
| | - Bo Huang
- Department of Immunology, Institute of Basic Medical Sciences & State Key Laboratory of Medical Molecular BiologyChinese Academy of Medical Sciences and Peking Union Medical CollegeBeijingChina
| | - Ning Wang
- Department of Mechanical Science and EngineeringUniversity of Illinois at Urbana‐ChampaignUrbanaIllinoisUSA
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37
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Fläschner G, Roman CI, Strohmeyer N, Martinez-Martin D, Müller DJ. Rheology of rounded mammalian cells over continuous high-frequencies. Nat Commun 2021; 12:2922. [PMID: 34006873 PMCID: PMC8131594 DOI: 10.1038/s41467-021-23158-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Accepted: 04/16/2021] [Indexed: 11/09/2022] Open
Abstract
Understanding the viscoelastic properties of living cells and their relation to cell state and morphology remains challenging. Low-frequency mechanical perturbations have contributed considerably to the understanding, yet higher frequencies promise to elucidate the link between cellular and molecular properties, such as polymer relaxation and monomer reaction kinetics. Here, we introduce an assay, that uses an actuated microcantilever to confine a single, rounded cell on a second microcantilever, which measures the cell mechanical response across a continuous frequency range ≈ 1-40 kHz. Cell mass measurements and optical microscopy are co-implemented. The fast, high-frequency measurements are applied to rheologically monitor cellular stiffening. We find that the rheology of rounded HeLa cells obeys a cytoskeleton-dependent power-law, similar to spread cells. Cell size and viscoelasticity are uncorrelated, which contrasts an assumption based on the Laplace law. Together with the presented theory of mechanical de-embedding, our assay is generally applicable to other rheological experiments.
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Affiliation(s)
- Gotthold Fläschner
- Eidgenössische Technische Hochschule (ETH) Zürich, Department of Biosystems Science and Engineering, Basel, Switzerland
| | - Cosmin I Roman
- Eidgenössische Technische Hochschule (ETH) Zürich, Department of Mechanical and Process Engineering, Zürich, Switzerland
| | - Nico Strohmeyer
- Eidgenössische Technische Hochschule (ETH) Zürich, Department of Biosystems Science and Engineering, Basel, Switzerland
| | - David Martinez-Martin
- Eidgenössische Technische Hochschule (ETH) Zürich, Department of Biosystems Science and Engineering, Basel, Switzerland.,The University of Sydney, School of Biomedical Engineering, NSW, Sydney, Australia
| | - Daniel J Müller
- Eidgenössische Technische Hochschule (ETH) Zürich, Department of Biosystems Science and Engineering, Basel, Switzerland.
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38
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Lavrenyuk K, Conway D, Dahl KN. Imaging methods in mechanosensing: a historical perspective and visions for the future. Mol Biol Cell 2021; 32:842-854. [PMID: 33788578 PMCID: PMC8108522 DOI: 10.1091/mbc.e20-10-0671] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Over the past three decades, as mechanobiology has become a distinct area of study, researchers have developed novel imaging tools to discover the pathways of biomechanical signaling. Early work with substrate engineering and particle tracking demonstrated the importance of cell–extracellular matrix interactions on the cell cycle as well as the mechanical flux of the intracellular environment. Most recently, tension sensor approaches allowed directly measuring tension in cell–cell and cell–substrate interactions. We retrospectively analyze how these various optical techniques progressed the field and suggest our vision forward for a unified theory of cell mechanics, mapping cellular mechanosensing, and novel biomedical applications for mechanobiology.
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Affiliation(s)
- Kirill Lavrenyuk
- Carnegie Mellon University, College of Engineering, Pittsburgh, PA 15213
| | - Daniel Conway
- Virginia Commonwealth University, College of Engineering, Richmond, VA 23284
| | - Kris Noel Dahl
- Carnegie Mellon University, College of Engineering, Pittsburgh, PA 15213
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39
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Moradi M, Nazockdast E. Cell nucleus as a microrheological probe to study the rheology of the cytoskeleton. Biophys J 2021; 120:1542-1564. [PMID: 33705756 DOI: 10.1016/j.bpj.2021.01.042] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 12/29/2020] [Accepted: 01/11/2021] [Indexed: 01/12/2023] Open
Abstract
Mechanical properties of the cell are important biomarkers for probing its architectural changes caused by cellular processes and/or pathologies. The development of microfluidic technologies has enabled measuring the cell's mechanical properties at high throughput so that mechanical phenotyping can be applied to large samples in reasonable timescales. These studies typically measure the stiffness of the cell as the only mechanical biomarker and do not disentangle the rheological contributions of different structural components of the cell, including the cell cortex, the interior cytoplasm and its immersed cytoskeletal structures, and the nucleus. Recent advancements in high-speed fluorescent imaging have enabled probing the deformations of the cell cortex while also tracking different intracellular components in rates applicable to microfluidic platforms. We present a, to our knowledge, novel method to decouple the mechanics of the cell cortex and the cytoplasm by analyzing the correlation between the cortical deformations that are induced by external microfluidic flows and the nucleus displacements, induced by those cortical deformations, i.e., we use the nucleus as a high-throughput microrheological probe to study the rheology of the cytoplasm, independent of the cell cortex mechanics. To demonstrate the applicability of this method, we consider a proof-of-concept model consisting of a rigid spherical nucleus centered in a spherical cell. We obtain analytical expressions for the time-dependent nucleus velocity as a function of the cell deformations when the interior cytoplasm is modeled as a viscous, viscoelastic, porous, and poroelastic material and demonstrate how the nucleus velocity can be used to characterize the linear rheology of the cytoplasm over a wide range of forces and timescales/frequencies.
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Affiliation(s)
- Moslem Moradi
- UNC Chapel Hill, Applied Physical Sciences, Chapel Hill, North Carolina
| | - Ehssan Nazockdast
- UNC Chapel Hill, Applied Physical Sciences, Chapel Hill, North Carolina.
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40
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Moazzeni S, Demiryurek Y, Yu M, Shreiber DI, Zahn JD, Shan JW, Foty RA, Liu L, Lin H. Single-cell mechanical analysis and tension quantification via electrodeformation relaxation. Phys Rev E 2021; 103:032409. [PMID: 33862816 PMCID: PMC10625872 DOI: 10.1103/physreve.103.032409] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Accepted: 02/24/2021] [Indexed: 02/03/2023]
Abstract
The mechanical behavior and cortical tension of single cells are analyzed using electrodeformation relaxation. Four types of cells, namely, MCF-10A, MCF-7, MDA-MB-231, and GBM, are studied, with pulse durations ranging from 0.01 to 10 s. Mechanical response in the long-pulse regime is characterized by a power-law behavior, consistent with soft glassy rheology resulting from unbinding events within the cortex network. In the subsecond short-pulse regime, a single timescale well describes the process and indicates the naive tensioned (prestressed) state of the cortex with minimal force-induced alteration. A mathematical model is employed and the simple ellipsoidal geometry allows for use of an analytical solution to extract the cortical tension. At the shortest pulse of 0.01 s, tensions for all four cell types are on the order of 10^{-2} N/m.
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Affiliation(s)
- Seyedsajad Moazzeni
- Department of Mechanical and Aerospace Engineering, Rutgers, The State University of New Jersey, 98 Brett Road, Piscataway, New Jersey 08854, USA
| | - Yasir Demiryurek
- Department of Mechanical and Aerospace Engineering, Rutgers, The State University of New Jersey, 98 Brett Road, Piscataway, New Jersey 08854, USA
| | - Miao Yu
- Department of Mechanical and Aerospace Engineering, Rutgers, The State University of New Jersey, 98 Brett Road, Piscataway, New Jersey 08854, USA
| | - David I. Shreiber
- Department of Biomedical Engineering, Rutgers, The State University of New Jersey, 599 Taylor Road, Piscataway, New Jersey 08854, USA
| | - Jeffrey D. Zahn
- Department of Biomedical Engineering, Rutgers, The State University of New Jersey, 599 Taylor Road, Piscataway, New Jersey 08854, USA
| | - Jerry W. Shan
- Department of Mechanical and Aerospace Engineering, Rutgers, The State University of New Jersey, 98 Brett Road, Piscataway, New Jersey 08854, USA
| | - Ramsey A. Foty
- Department of Surgery, Rutgers, The State University of New Jersey, 125 Patterson Street, New Brunswick, New Jersey 08901, USA
| | - Liping Liu
- Department of Mechanical and Aerospace Engineering, Rutgers, The State University of New Jersey, 98 Brett Road, Piscataway, New Jersey 08854, USA
- Department of Mathematics, Rutgers, The State University of New Jersey, 110 Frelinghuysen Road, Piscataway, New Jersey 08901, USA
| | - Hao Lin
- Department of Mechanical and Aerospace Engineering, Rutgers, The State University of New Jersey, 98 Brett Road, Piscataway, New Jersey 08854, USA
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41
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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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42
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Hao Y, Cheng S, Tanaka Y, Hosokawa Y, Yalikun Y, Li M. Mechanical properties of single cells: Measurement methods and applications. Biotechnol Adv 2020; 45:107648. [DOI: 10.1016/j.biotechadv.2020.107648] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 09/11/2020] [Accepted: 10/12/2020] [Indexed: 12/22/2022]
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43
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S Mogre S, Brown AI, Koslover EF. Getting around the cell: physical transport in the intracellular world. Phys Biol 2020; 17:061003. [PMID: 32663814 DOI: 10.1088/1478-3975/aba5e5] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Eukaryotic cells face the challenging task of transporting a variety of particles through the complex intracellular milieu in order to deliver, distribute, and mix the many components that support cell function. In this review, we explore the biological objectives and physical mechanisms of intracellular transport. Our focus is on cytoplasmic and intra-organelle transport at the whole-cell scale. We outline several key biological functions that depend on physically transporting components across the cell, including the delivery of secreted proteins, support of cell growth and repair, propagation of intracellular signals, establishment of organelle contacts, and spatial organization of metabolic gradients. We then review the three primary physical modes of transport in eukaryotic cells: diffusive motion, motor-driven transport, and advection by cytoplasmic flow. For each mechanism, we identify the main factors that determine speed and directionality. We also highlight the efficiency of each transport mode in fulfilling various key objectives of transport, such as particle mixing, directed delivery, and rapid target search. Taken together, the interplay of diffusion, molecular motors, and flows supports the intracellular transport needs that underlie a broad variety of biological phenomena.
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Affiliation(s)
- Saurabh S Mogre
- Department of Physics, University of California, San Diego, San Diego, California 92093, United States of America
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44
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Mukherjee A, Barai A, Singh RK, Yan W, Sen S. Nuclear plasticity increases susceptibility to damage during confined migration. PLoS Comput Biol 2020; 16:e1008300. [PMID: 33035221 PMCID: PMC7577492 DOI: 10.1371/journal.pcbi.1008300] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 10/21/2020] [Accepted: 09/01/2020] [Indexed: 01/07/2023] Open
Abstract
Large nuclear deformations during migration through confined spaces have been associated with nuclear membrane rupture and DNA damage. However, the stresses associated with nuclear damage remain unclear. Here, using a quasi-static plane strain finite element model, we map evolution of nuclear shape and stresses during confined migration of a cell through a deformable matrix. Plastic deformation of the nucleus observed for a cell with stiff nucleus transiting through a stiffer matrix lowered nuclear stresses, but also led to kinking of the nuclear membrane. In line with model predictions, transwell migration experiments with fibrosarcoma cells showed that while nuclear softening increased invasiveness, nuclear stiffening led to plastic deformation and higher levels of DNA damage. In addition to highlighting the advantage of nuclear softening during confined migration, our results suggest that plastic deformations of the nucleus during transit through stiff tissues may lead to bending-induced nuclear membrane disruption and subsequent DNA damage. Stiffness of the nucleus is known to impede migration of cells through dense matrices. Nuclear translocation through small pores is achieved by active deformation of the nucleus by the cytoskeleton. However, stresses on the nucleus during confined migration may lead to nuclear damage, as observed experimentally. However, the factors contributing to nuclear damage remain incompletely understood. Here we show that plastic or permanent nuclear deformation which is necessary for successful migration through small pores in stiff matrices, also leads to bending of the nuclear membrane. We propose that this bending precedes nuclear blebs which are experimentally observed.
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Affiliation(s)
- Abhishek Mukherjee
- IITB-Monash Research Academy, IIT Bombay, Mumbai, India
- Dept. of Mechanical Engineering, IIT Bombay, Mumbai, India
- Dept. of Mechanical and Aerospace Engineering, Monash University, Melbourne, Australia
| | - Amlan Barai
- Dept. of Biosciences & Bioengineering, IIT Bombay, Mumbai, India
| | | | - Wenyi Yan
- Dept. of Mechanical and Aerospace Engineering, Monash University, Melbourne, Australia
- * E-mail: (WY); (SS)
| | - Shamik Sen
- Dept. of Biosciences & Bioengineering, IIT Bombay, Mumbai, India
- * E-mail: (WY); (SS)
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45
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Walker M, Godin M, Harden JL, Pelling AE. Time dependent stress relaxation and recovery in mechanically strained 3D microtissues. APL Bioeng 2020; 4:036107. [PMID: 32984751 PMCID: PMC7500532 DOI: 10.1063/5.0002898] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2020] [Accepted: 08/02/2020] [Indexed: 02/06/2023] Open
Abstract
Characterizing the time-dependent mechanical properties of cells is not only necessary to determine how they deform but also to understand how external forces trigger biochemical-signaling cascades to govern their behavior. At present, mechanical properties are largely assessed by applying local shear or compressive forces on single cells grown in isolation on non-physiological 2D surfaces. In comparison, we developed the microfabricated vacuum actuated stretcher to measure tensile loading of 3D multicellular "microtissue" cultures. Using this approach, we here assessed the time-dependent stress relaxation and recovery responses of microtissues and quantified the spatial viscoelastic deformation following step length changes. Unlike previous results, stress relaxation and recovery in microtissues measured over a range of step amplitudes and pharmacological treatments followed an augmented stretched exponential behavior describing a broad distribution of inter-related timescales. Furthermore, despite the variety of experimental conditions, all responses led to a single linear relationship between the residual elastic stress and the degree of stress relaxation, suggesting that these mechanical properties are coupled through interactions between structural elements and the association of cells with their matrix. Finally, although stress relaxation could be quantitatively and spatially linked to recovery, they differed greatly in their dynamics; while stress recovery acted as a linear process, relaxation time constants changed with an inverse power law with the step size. This assessment of microtissues offers insights into how the collective behavior of cells in a 3D collagen matrix generates the dynamic mechanical properties of tissues, which is necessary to understand how cells deform and sense mechanical forces in vivo.
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Affiliation(s)
- Matthew Walker
- Department of Biology, University of Ottawa, Gendron Hall, 30 Marie Curie, Ottawa, Ontario K1N5N5, Canada
| | | | | | - Andrew E. Pelling
- Author to whom correspondence should be addressed:. Tel.: +1 613 562 5800 ext. 6965. Fax: +1 613 562 5190. URL:http://www.pellinglab.net
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46
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Chaubet L, Chaudhary AR, Heris HK, Ehrlicher AJ, Hendricks AG. Dynamic actin cross-linking governs the cytoplasm's transition to fluid-like behavior. Mol Biol Cell 2020; 31:1744-1752. [PMID: 32579489 PMCID: PMC7521843 DOI: 10.1091/mbc.e19-09-0504] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 06/05/2020] [Accepted: 06/16/2020] [Indexed: 12/21/2022] Open
Abstract
Cells precisely control their mechanical properties to organize and differentiate into tissues. The architecture and connectivity of cytoskeletal filaments change in response to mechanical and biochemical cues, allowing the cell to rapidly tune its mechanics from highly cross-linked, elastic networks to weakly cross-linked viscous networks. While the role of actin cross-linking in controlling actin network mechanics is well-characterized in purified actin networks, its mechanical role in the cytoplasm of living cells remains unknown. Here, we probe the frequency-dependent intracellular viscoelastic properties of living cells using multifrequency excitation and in situ optical trap calibration. At long timescales in the intracellular environment, we observe that the cytoskeleton becomes fluid-like. The mechanics are well-captured by a model in which actin filaments are dynamically connected by a single dominant cross-linker. A disease-causing point mutation (K255E) of the actin cross-linker α-actinin 4 (ACTN4) causes its binding kinetics to be insensitive to tension. Under normal conditions, the viscoelastic properties of wild-type (WT) and K255E+/- cells are similar. However, when tension is reduced through myosin II inhibition, WT cells relax 3× faster to the fluid-like regime while K255E+/- cells are not affected. These results indicate that dynamic actin cross-linking enables the cytoplasm to flow at long timescales.
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Affiliation(s)
- Loïc Chaubet
- Department of Bioengineering, McGill University, Montreal, QC H3A 0C3, Canada
| | | | - Hossein K. Heris
- Department of Bioengineering, McGill University, Montreal, QC H3A 0C3, Canada
| | - Allen J. Ehrlicher
- Department of Bioengineering, McGill University, Montreal, QC H3A 0C3, Canada
| | - Adam G. Hendricks
- Department of Bioengineering, McGill University, Montreal, QC H3A 0C3, Canada
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47
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Bonfanti A, Kaplan JL, Charras G, Kabla A. Fractional viscoelastic models for power-law materials. SOFT MATTER 2020; 16:6002-6020. [PMID: 32638812 DOI: 10.1039/d0sm00354a] [Citation(s) in RCA: 77] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Soft materials often exhibit a distinctive power-law viscoelastic response arising from broad distribution of time-scales present in their complex internal structure. A promising tool to accurately describe the rheological behaviour of soft materials is fractional calculus. However, its use in the scientific community remains limited due to the unusual notation and non-trivial properties of fractional operators. This review aims to provide a clear and accessible description of fractional viscoelastic models for a broad audience and to demonstrate the ability of these models to deliver a unified approach for the characterisation of power-law materials. The use of a consistent framework for the analysis of rheological data would help classify the empirical behaviours of soft and biological materials, and better understand their response.
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Affiliation(s)
- A Bonfanti
- Department of Engineering, University of Cambridge, UK.
| | - J L Kaplan
- Department of Engineering, University of Cambridge, UK.
| | - G Charras
- London Centre for Nanotechnology, University College London, UK and Department of Cell and Developmental Biology, University College London, UK
| | - A Kabla
- Department of Engineering, University of Cambridge, UK.
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48
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Graybill PM, Davalos RV. Cytoskeletal Disruption after Electroporation and Its Significance to Pulsed Electric Field Therapies. Cancers (Basel) 2020; 12:E1132. [PMID: 32366043 PMCID: PMC7281591 DOI: 10.3390/cancers12051132] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 04/24/2020] [Accepted: 04/27/2020] [Indexed: 12/18/2022] Open
Abstract
Pulsed electric fields (PEFs) have become clinically important through the success of Irreversible Electroporation (IRE), Electrochemotherapy (ECT), and nanosecond PEFs (nsPEFs) for the treatment of tumors. PEFs increase the permeability of cell membranes, a phenomenon known as electroporation. In addition to well-known membrane effects, PEFs can cause profound cytoskeletal disruption. In this review, we summarize the current understanding of cytoskeletal disruption after PEFs. Compiling available studies, we describe PEF-induced cytoskeletal disruption and possible mechanisms of disruption. Additionally, we consider how cytoskeletal alterations contribute to cell-cell and cell-substrate disruption. We conclude with a discussion of cytoskeletal disruption-induced anti-vascular effects of PEFs and consider how a better understanding of cytoskeletal disruption after PEFs may lead to more effective therapies.
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Affiliation(s)
- Philip M. Graybill
- BEMS Lab, Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, VA 24061, USA;
- Department of Mechanical Engineering, Virginia Tech, Blacksburg, VA 24061, USA
| | - Rafael V. Davalos
- BEMS Lab, Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, VA 24061, USA;
- Department of Mechanical Engineering, Virginia Tech, Blacksburg, VA 24061, USA
- Virginia Tech–Wake Forest University, School of Biomedical Engineering and Sciences, Blacksburg, VA 24061, USA
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49
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He W, Su Y, Peng HB, Tong P. Dynamic heterogeneity and non-Gaussian statistics for ganglioside GM1s and acetylcholine receptors on live cell membrane. Mol Biol Cell 2020; 31:1380-1391. [PMID: 32348189 PMCID: PMC7353135 DOI: 10.1091/mbc.e19-08-0473] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
We have carried out a comparative study of the lateral motion of ganglioside GM1, which is a glycosphingolipid residing on the outer leaflet of the plasma membrane, and acetylcholine receptor (AChR), which is a well-characterized ion channel. Both the lipid molecules and the transmembrane proteins reside on the plasma membranes of live Xenopus muscle cells. From a thorough analysis of a large volume of individual molecular trajectories obtained from more than 300 live cells over a wide range of sampling rates and long durations, we find that the GM1s and AChRs share the same dynamic heterogeneity and non-Gaussian statistics. Our measurements with the ATP-depleted cells reveal that the diffusion dynamics of the GM1s and AChRs is uniformly affected by the intracellular ATP level of the living muscle cells, further demonstrating that membrane diffusion is strongly coupled to the dynamics of the underlying cortical actin network, as predicted by the dynamic picket-fence model.
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Affiliation(s)
- Wei He
- Nano Science and Technology Program, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
| | - Yun Su
- Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
| | - H Benjamin Peng
- Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
| | - Penger Tong
- Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
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50
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Garcia PD, Guerrero CR, Garcia R. Nanorheology of living cells measured by AFM-based force-distance curves. NANOSCALE 2020; 12:9133-9143. [PMID: 32293616 DOI: 10.1039/c9nr10316c] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Mechanobiology aims to establish functional relationships between the mechanical state of a living a cell and its physiology. The acquisition of force-distance curves with an AFM is by far the dominant method to characterize the nanomechanical properties of living cells. However, theoretical simulations have shown that the contact mechanics models used to determine the Young's modulus from a force-distance curve could be off by a factor 5 from its expected value. The semi-quantitative character arises from the lack of a theory that integrates the AFM data, a realistic viscoelastic model of a cell and its finite-thickness. Here, we develop a method to determine the mechanical response of a cell from a force-distance curve. The method incorporates bottom-effect corrections, a power-law rheology model and the deformation history of the cell. It transforms the experimental data into viscoelastic parameters of the cell as a function of the indentation frequency. The quantitative agreement obtained between the experiments performed on living fibroblast cells and the analytical theory supports the use of force-distance curves to measure the nanorheological properties of cells.
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Affiliation(s)
- Pablo D Garcia
- Instituto de Ciencia de Materiales de Madrid, CSIC, c/ Sor Juana Inés de la Cruz 3, 28049 Madrid, Spain.
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