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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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2
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Panganiban RAM, Yang Z, Sun M, Park CY, Kasahara DI, Schaible N, Krishnan R, Kho AT, Israel E, Hershenson MB, Weiss ST, Himes BE, Fredberg JJ, Tantisira KG, Shore SA, Lu Q. Antagonizing cholecystokinin A receptor in the lung attenuates obesity-induced airway hyperresponsiveness. Nat Commun 2023; 14:47. [PMID: 36599824 PMCID: PMC9813361 DOI: 10.1038/s41467-022-35739-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Accepted: 12/21/2022] [Indexed: 01/06/2023] Open
Abstract
Obesity increases asthma prevalence and severity. However, the underlying mechanisms are poorly understood, and consequently, therapeutic options for asthma patients with obesity remain limited. Here we report that cholecystokinin-a metabolic hormone best known for its role in signaling satiation and fat metabolism-is increased in the lungs of obese mice and that pharmacological blockade of cholecystokinin A receptor signaling reduces obesity-associated airway hyperresponsiveness. Activation of cholecystokinin A receptor by the hormone induces contraction of airway smooth muscle cells. In vivo, cholecystokinin level is elevated in the lungs of both genetically and diet-induced obese mice. Importantly, intranasal administration of cholecystokinin A receptor antagonists (proglumide and devazepide) suppresses the airway hyperresponsiveness in the obese mice. Together, our results reveal an unexpected role for cholecystokinin in the lung and support the repurposing of cholecystokinin A receptor antagonists as a potential therapy for asthma patients with obesity.
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Affiliation(s)
- Ronald Allan M Panganiban
- Program in Molecular and Integrative Physiological Sciences, Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA, 02115, USA
| | - Zhiping Yang
- Program in Molecular and Integrative Physiological Sciences, Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA, 02115, USA
| | - Maoyun Sun
- Program in Molecular and Integrative Physiological Sciences, Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA, 02115, USA
| | - Chan Young Park
- Program in Molecular and Integrative Physiological Sciences, Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA, 02115, USA
| | - David I Kasahara
- Program in Molecular and Integrative Physiological Sciences, Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA, 02115, USA
| | - Niccole Schaible
- Emergency Medicine, Beth Israel Deaconess Medical Center, Boston, MA, 02115, USA
| | - Ramaswamy Krishnan
- Emergency Medicine, Beth Israel Deaconess Medical Center, Boston, MA, 02115, USA
| | - Alvin T Kho
- Computational Health informatics Program, Boston Children's Hospital, Boston, MA, 02115, USA
| | - Elliot Israel
- Asthma Research Center, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, 02115, USA
| | - Marc B Hershenson
- Department of Pediatrics and Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | - Scott T Weiss
- Channing Division of Network Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, 02115, USA
| | - Blanca E Himes
- Department of Biostatistics, Epidemiology and Informatics, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Jeffrey J Fredberg
- Program in Molecular and Integrative Physiological Sciences, Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA, 02115, USA
| | - Kelan G Tantisira
- Division of Pediatric Respiratory Medicine, University of California San Diego and Rady Children's Hospital, San Diego, CA, 92123, USA
| | - Stephanie A Shore
- Program in Molecular and Integrative Physiological Sciences, Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA, 02115, USA
| | - Quan Lu
- Program in Molecular and Integrative Physiological Sciences, Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA, 02115, USA.
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3
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Deviri D, Safran SA. Balance of osmotic pressures determines the nuclear-to-cytoplasmic volume ratio of the cell. Proc Natl Acad Sci U S A 2022; 119:e2118301119. [PMID: 35580183 PMCID: PMC9173802 DOI: 10.1073/pnas.2118301119] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 04/05/2022] [Indexed: 01/06/2023] Open
Abstract
The volume of the cell nucleus varies across cell types and species and is commonly thought to be determined by the size of the genome and degree of chromatin compaction. However, this notion has been challenged over the years by much experimental evidence. Here, we consider the physical condition of mechanical force balance as a determining condition of the nuclear volume and use quantitative, order-of-magnitude analysis to estimate the forces from different sources of nuclear and cytoplasmic pressure. Our estimates suggest that the dominant pressure within the nucleus and cytoplasm of nonstriated muscle cells originates from the osmotic pressure of proteins and RNA molecules that are localized to the nucleus or cytoplasm by out-of-equilibrium, active nucleocytoplasmic transport rather than from chromatin or its associated ions. This motivates us to formulate a physical model for the ratio of the cell and nuclear volumes in which osmotic pressures of localized proteins determine the relative volumes. In accordance with unexplained observations that are a century old, our model predicts that the ratio of the cell and nuclear volumes is a constant, robust to a wide variety of biochemical and biophysical manipulations, and is changed only if gene expression or nucleocytoplasmic transport is modulated.
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Affiliation(s)
- Dan Deviri
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovet 76100, Israel
| | - Samuel A. Safran
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovet 76100, Israel
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In silico stress fibre content affects peak strain in cytoplasm and nucleus but not in the membrane for uniaxial substrate stretch. Med Biol Eng Comput 2021; 59:1933-1944. [PMID: 34392447 DOI: 10.1007/s11517-021-02393-z] [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: 09/03/2020] [Accepted: 06/13/2021] [Indexed: 10/20/2022]
Abstract
Existing in silico models for single cell mechanics feature limited representations of cytoskeletal structures that contribute substantially to the mechanics of a cell. We propose a micromechanical hierarchical approach to capture the mechanical contribution of actin stress fibres. For a cell-specific fibroblast geometry with membrane, cytoplasm and nucleus, the Mori-Tanaka homogenization method was employed to describe cytoplasmic inhomogeneities and constitutive contribution of actin stress fibres. The homogenization was implemented in a finite element model of the fibroblast attached to a substrate through focal adhesions. Strain in cell membrane, cytoplasm and nucleus due to uniaxial substrate stretch was assessed for different stress fibre volume fractions and different elastic modulus of the substrate. A considerable decrease of the peak strain with increasing stress fibre content was observed in cytoplasm and nucleus but not the membrane, whereas the peak strain in cytoplasm, nucleus and membrane increased for increasing elastic modulus of the substrate. Finite element mesh of reconstructed human fibroblast and intracellular strain distribution in cell subjected to substrate stretch.
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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: 15] [Impact Index Per Article: 5.0] [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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6
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Wang H, Zhang H, Da B, Lu D, Tamura R, Goto K, Watanabe I, Fujita D, Hanagata N, Kano J, Nakagawa T, Noguchi M. Mechanomics Biomarker for Cancer Cells Unidentifiable through Morphology and Elastic Modulus. NANO LETTERS 2021; 21:1538-1545. [PMID: 33476166 DOI: 10.1021/acs.nanolett.1c00003] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Cellular mechanical properties are potential cancer biomarkers used for objective cytology to replace the current subjective method relying on cytomorphology. However, heterogeneity among intra/intercellular mechanics and the interplay between cytoskeletal prestress and elastic modulus obscured the difference detectable between malignant and benign cells. In this work, we collected high density nanoscale prestress and elastic modulus data from a single cell by AFM indentation to generate a cellular mechanome. Such high dimensional mechanome data was used to train a malignancy classifier through machine learning. The classifier was tested on 340 single cells of various origins, malignancy, and degrees of similarity in morphology and elastic modulus. The classifier showed instrument-independent robustness and classification accuracy of 89% with an AUC-ROC value of 93%. A signal-to-noise ratio 8 times that of the human-cytologist-based morphological method was also demonstrated, in differentiating precancerous hyperplasia cells from normal cells derived from the same lung cancer patient.
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Affiliation(s)
- Hongxin Wang
- Research Center for Advanced Measurement and Characterization, National Institute for Materials Science, Tsukuba, Ibaraki, Japan
| | - Han Zhang
- Research Center for Advanced Measurement and Characterization, National Institute for Materials Science, Tsukuba, Ibaraki, Japan
| | - Bo Da
- Research and Services Division of Materials Data and Integrated System, National Institute for Materials Science, Tsukuba, Ibaraki, Japan
| | - Dabao Lu
- Research and Services Division of Materials Data and Integrated System, National Institute for Materials Science, Tsukuba, Ibaraki, Japan
| | - Ryo Tamura
- International Center for Materials Architectonics, National Institute for Materials Science, Tsukuba, Ibaraki, Japan
| | - Kenta Goto
- International Center for Young Scientists, National Institute for Materials Science, Tsukuba, Ibaraki, Japan
| | - Ikumu Watanabe
- Research Center for Structural Materials, National Institute for Materials Science, Tsukuba, Ibaraki, Japan
| | - Daisuke Fujita
- Research Center for Advanced Measurement and Characterization, National Institute for Materials Science, Tsukuba, Ibaraki, Japan
| | - Nobutaka Hanagata
- Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Ibaraki, Japan
| | - Junko Kano
- Department of Diagnostic Pathology, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Tomoki Nakagawa
- Department of Diagnostic Pathology, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Masayuki Noguchi
- Department of Diagnostic Pathology, University of Tsukuba, Tsukuba, Ibaraki, Japan
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Barreto YB, Suki B, Alencar AM. Random-walk model of cotransport. Phys Rev E 2020; 102:022403. [PMID: 32942367 DOI: 10.1103/physreve.102.022403] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 07/15/2020] [Indexed: 06/11/2023]
Abstract
We present a statistical mechanical model to describe the dynamics of an arbitrary cotransport system. Our starting point was the alternating access mechanism, which suggests the existence of six states for the cotransport cycle. Then we determined the 14 transition probabilities between these states, including a leak pathway, and used them to write a set of Master Equations for describing the time evolution of the system. The agreement between the asymptotic behavior of this set of equations and the result obtained from thermodynamics is a confirmation that leakage is compatible with the static head equilibrium condition and that our model has captured the essential physics of cotransport. In addition, the model correctly reproduced the transport dynamics found in the literature.
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Affiliation(s)
- Yan B Barreto
- Instituto de Física, Universidade de São Paulo, 05508-090 São Paulo, São Paulo, Brazil
| | - Béla Suki
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts 02215, USA
| | - Adriano M Alencar
- Instituto de Física, Universidade de São Paulo, 05508-090 São Paulo, São Paulo, Brazil
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Vahabikashi A, Gelman A, Dong B, Gong L, Cha EDK, Schimmel M, Tamm ER, Perkumas K, Stamer WD, Sun C, Zhang HF, Gong H, Johnson M. Increased stiffness and flow resistance of the inner wall of Schlemm's canal in glaucomatous human eyes. Proc Natl Acad Sci U S A 2019; 116:26555-26563. [PMID: 31806762 PMCID: PMC6936716 DOI: 10.1073/pnas.1911837116] [Citation(s) in RCA: 71] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The cause of the elevated outflow resistance and consequent ocular hypertension characteristic of glaucoma is unknown. To investigate possible causes for this flow resistance, we used atomic force microscopy (AFM) with 10-µm spherical tips to probe the stiffness of the inner wall of Schlemm's canal as a function of distance from the tissue surface in normal and glaucomatous postmortem human eyes, and 1-µm spherical AFM tips to probe the region immediately below the tissue surface. To localize flow resistance, perfusion and imaging methods were used to characterize the pressure drop in the immediate vicinity of the inner wall using giant vacuoles that form in Schlemm's canal cells as micropressure sensors. Tissue stiffness increased with increasing AFM indentation depth. Tissues from glaucomatous eyes were stiffer compared with normal eyes, with greatly increased stiffness residing within ∼1 µm of the inner-wall surface. Giant vacuole size and density were similar in normal and glaucomatous eyes despite lower flow rate through the latter due to their higher flow resistance. This implied that the elevated flow resistance found in the glaucomatous eyes was localized to the same region as the increased tissue stiffness. Our findings implicate pathological changes to biophysical characteristics of Schlemm's canal endothelia and/or their immediate underlying extracellular matrix as cause for ocular hypertension in glaucoma.
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Affiliation(s)
- Amir Vahabikashi
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60201
| | - Ariel Gelman
- Department of Ophthalmology, Boston University School of Medicine, Boston, MA 02118
| | - Biqin Dong
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60201
- Department of Mechanical Engineering, Northwestern University, Evanston, IL 60201
| | - Lihua Gong
- Department of Ophthalmology, Boston University School of Medicine, Boston, MA 02118
| | - Elliott D. K. Cha
- Department of Ophthalmology, Boston University School of Medicine, Boston, MA 02118
| | - Margit Schimmel
- Institute of Anatomy, University of Regensburg, D-93053 Regensburg, Germany
| | - Ernst R. Tamm
- Institute of Anatomy, University of Regensburg, D-93053 Regensburg, Germany
| | | | - W. Daniel Stamer
- Department of Ophthalmology, Duke University, Durham, NC 27710
- Department of Biomedical Engineering, Duke University, Durham, NC 27708
| | - Cheng Sun
- Department of Mechanical Engineering, Northwestern University, Evanston, IL 60201
| | - Hao F. Zhang
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60201
- Department of Ophthalmology, Northwestern University, Chicago, IL 60611
| | - Haiyan Gong
- Department of Ophthalmology, Boston University School of Medicine, Boston, MA 02118
| | - Mark Johnson
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60201
- Department of Mechanical Engineering, Northwestern University, Evanston, IL 60201
- Department of Ophthalmology, Northwestern University, Chicago, IL 60611
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do Amaral JB, Bloise AC, França CN, Perez-Novo C, Machado-Santelli GM, Alencar AM, Pezato R. Alterations in cellular force parameters and cell projections in Nasal polyps-derived fibroblasts. Auris Nasus Larynx 2019; 47:98-104. [PMID: 31272842 DOI: 10.1016/j.anl.2019.06.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 06/07/2019] [Accepted: 06/20/2019] [Indexed: 02/03/2023]
Abstract
OBJECTIVE Chronic Rhinosinusitis with Nasal Polyps (CRSwNP) is a disease that features a mechanical dysfunction involving chronic inflammation and altered tissue remodeling. In this study, we aim to evaluate the fibroblast morphology and its cellular traction force in primary fibroblasts cell cultures obtained from both healthy individuals (n=7) and patients with CRSwNP (n=8). METHODS Using a Traction-force Microscopy we analyzed parameters of Force/Tension in fibroblasts cultures in both experimental groups. RESULTS The analysis of the Projected Area of Cell revealed that fibroblasts derived from nasal mucosa of healthy individuals have an area on average 39.24% larger than the fibroblasts obtained from the nasal polyp tissue. We also observed that the parameters directly related to the force of the cell, Max Cumulative Force and Net Contractile Moment, presented a high Force/Tension per unit of area in the fibroblasts derived from the healthy nasal mucosa (on average 41% and 52.54% higher than the fibroblasts of the nasal polyp respectively). CONCLUSION Our results demonstrate a cellular mechanism that may be associated with the mechanical dysfunction found in the Nasal Polyp tissue. The weak traction force of nasal polyp-derived fibroblast may, in lower dimensions, impact on the remodeling of nasal mucosa in CRSwNP.
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Affiliation(s)
- Jônatas Bussador do Amaral
- ENT Research Lab., Department of Otorhinolaryngology - Head and Neck Surgery, Federal University of Sao Paulo, Rua Coronel Lisboa, 958, Vila Clementino, São Paulo, SP, 04020-041, Brazil.
| | - Antonio Carlos Bloise
- Institute of Physics, University of Sao Paulo, Rua do Matão, Travessa R Número 187, Cidade Universitária, São Paulo, SP 05508-090, Brazil
| | - Carolina Nunes França
- Universidade Santo Amaro, Pós Graduação em Ciências da Saúde, Rua Enéas de Siqueira Neto, 340 Jardim das Imbuias, São Paulo, SP 04829-300, Brazil
| | - Claudina Perez-Novo
- Laboratory of Proteinchemistry, Proteomics and Epigenetic Signalling Department of Biomedical Sciences, Campus Drie Eiken, building T, first floor Universiteitsplein 1 2610 Wilrijk University of Antwerp, Belgium
| | - Gláucia Maria Machado-Santelli
- Department of Cell and Developmental Biology, Institute of Biomedical Sciences, University of Sao Paulo, Avenida Prof Lineu Prestes, 1524, dade Universitária, Sao Paulo, SP 05508-900, Brazil
| | - Adriano Mesquita Alencar
- Institute of Physics, University of Sao Paulo, Rua do Matão, Travessa R Número 187, Cidade Universitária, São Paulo, SP 05508-090, Brazil
| | - Rogério Pezato
- ENT Research Lab., Department of Otorhinolaryngology - Head and Neck Surgery, Federal University of Sao Paulo, Rua Coronel Lisboa, 958, Vila Clementino, São Paulo, SP, 04020-041, Brazil
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10
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Pezato R, Voegels RL, Pignatari S, Gregório LC, Pinto Bezerra TF, Gregorio L, Balsalobre L, Tepedino MS, Coronel N, Pinna FDR, Mendes Neto J, Oliveira P, Macoto E, Stefanini R, Figueiredo C, Haddad F, Pilan R, Bezerra Soter A, Melo NA, Candido DA, Amaral JD, Santos RDP, Van Zele T, Fujita R, Dreyfuss JL, Chamon W, Alencar AM, Perez-Novo C, Stamm AC. Nasal Polyposis: More than a Chronic Inflammatory Disorder-A Disease of Mechanical Dysfunction-The São Paulo Position. Int Arch Otorhinolaryngol 2019; 23:241-249. [PMID: 30956711 PMCID: PMC6449132 DOI: 10.1055/s-0038-1676659] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 10/21/2018] [Indexed: 01/02/2023] Open
Abstract
Introduction The importance of our study lies in the fact that we have demonstrated the occurrence of mechanical dysfunction within polypoid tissues, which promotes the development of polyps in the nasal cavity. Objective To change the paradigm of nasal polyposis (NP). In this new conception, the chronic nasal inflammatory process that occurs in response to allergies, to pollution, to changes in the epithelial barrier, or to other factors is merely the trigger of the development of the disease in individuals with a genetic predisposition to an abnormal tissue remodeling process, which leads to a derangement of the mechanical properties of the nasal mucosa and, consequently, allows it to grow unchecked. Data Synthesis We propose a fundamentally new approach to intervening in the pathological process of NP, addressing biomechanical properties, fluid dynamics, and the concept of surface tension. Conclusion The incorporation of biomechanical knowledge into our understanding of NP provides a new perspective to help elucidate the physiology and the pathology of nasal polyps, and new avenues for the treatment and cure of NP.
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Affiliation(s)
- Rogerio Pezato
- Department of Otolaryngology - Head and Neck Surgery, Unifesp, São Paulo, SP, Brazil
| | | | - Shirley Pignatari
- Department of Otolaryngology - Head and Neck Surgery, Unifesp, São Paulo, SP, Brazil
| | - Luiz Carlos Gregório
- Department of Otolaryngology - Head and Neck Surgery, Unifesp, São Paulo, SP, Brazil
| | | | - Luciano Gregorio
- Department of Otolaryngology - Head and Neck Surgery, Unifesp, São Paulo, SP, Brazil
| | - Leonardo Balsalobre
- Department of Otolaryngology - Head and Neck Surgery, Unifesp, São Paulo, SP, Brazil
| | | | - Nathália Coronel
- Department of Otolaryngology - Head and Neck Surgery, Unifesp, São Paulo, SP, Brazil
| | | | - José Mendes Neto
- Department of Otolaryngology - Head and Neck Surgery, Unifesp, São Paulo, SP, Brazil
| | - Pedro Oliveira
- Department of Otolaryngology - Head and Neck Surgery, Unifesp, São Paulo, SP, Brazil
| | - Eduardo Macoto
- Department of Otolaryngology - Head and Neck Surgery, Unifesp, São Paulo, SP, Brazil
| | - Renato Stefanini
- Department of Otolaryngology - Head and Neck Surgery, Unifesp, São Paulo, SP, Brazil
| | - Claudia Figueiredo
- Department of Otolaryngology - Head and Neck Surgery, Unifesp, São Paulo, SP, Brazil
| | - Fernanda Haddad
- Department of Otolaryngology - Head and Neck Surgery, Unifesp, São Paulo, SP, Brazil
| | - Renata Pilan
- Department of Otolaryngology, USP, São Paulo, SP, Brazil
| | | | | | | | - Jonatas do Amaral
- Department of Otolaryngology - Head and Neck Surgery, Unifesp, São Paulo, SP, Brazil
| | | | - Thibaut Van Zele
- Ear, Nose and Throat Department,, University of Ghent, Ghent, Belgium
| | - Reginaldo Fujita
- Department of Otolaryngology - Head and Neck Surgery, Unifesp, São Paulo, SP, Brazil
| | | | - Wallace Chamon
- Department of Ophthalmology and Visual Sciences, Unifesp, São Paulo, SP, Brazil.,Department of Ophthalmology and Visual Sciences, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States
| | - Adriano Mesquita Alencar
- Laboratory of Microrheology and Molecular Physiology, Institute of Physics, USP, São Paulo, SP, Brazil
| | - Claudina Perez-Novo
- Proteinscience, Proteomics and Epigenetic Signaling, Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
| | - Aldo Cassol Stamm
- Department of Otolaryngology - Head and Neck Surgery, Unifesp, São Paulo, SP, Brazil
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11
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Vahabikashi A, Park CY, Perkumas K, Zhang Z, Deurloo EK, Wu H, Weitz DA, Stamer WD, Goldman RD, Fredberg JJ, Johnson M. Probe Sensitivity to Cortical versus Intracellular Cytoskeletal Network Stiffness. Biophys J 2019; 116:518-529. [PMID: 30685055 DOI: 10.1016/j.bpj.2018.12.021] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Revised: 12/04/2018] [Accepted: 12/20/2018] [Indexed: 11/19/2022] Open
Abstract
In development, wound healing, and pathology, cell biomechanical properties are increasingly recognized as being of central importance. To measure these properties, experimental probes of various types have been developed, but how each probe reflects the properties of heterogeneous cell regions has remained obscure. To better understand differences attributable to the probe technology, as well as to define the relative sensitivity of each probe to different cellular structures, here we took a comprehensive approach. We studied two cell types-Schlemm's canal endothelial cells and mouse embryonic fibroblasts (MEFs)-using four different probe technologies: 1) atomic force microscopy (AFM) with sharp tip, 2) AFM with round tip, 3) optical magnetic twisting cytometry (OMTC), and 4) traction microscopy (TM). Perturbation of Schlemm's canal cells with dexamethasone treatment, α-actinin overexpression, or RhoA overexpression caused increases in traction reported by TM and stiffness reported by sharp-tip AFM as compared to corresponding controls. By contrast, under these same experimental conditions, stiffness reported by round-tip AFM and by OMTC indicated little change. Knockout (KO) of vimentin in MEFs caused a diminution of traction reported by TM, as well as stiffness reported by sharp-tip and round-tip AFM. However, stiffness reported by OMTC in vimentin-KO MEFs was greater than in wild type. Finite-element analysis demonstrated that this paradoxical OMTC result in vimentin-KO MEFs could be attributed to reduced cell thickness. Our results also suggest that vimentin contributes not only to intracellular network stiffness but also cortex stiffness. Taken together, this evidence suggests that AFM sharp tip and TM emphasize properties of the actin-rich shell of the cell, whereas round-tip AFM and OMTC emphasize those of the noncortical intracellular network.
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Affiliation(s)
- Amir Vahabikashi
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois
| | - Chan Young Park
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, Massachusetts
| | - Kristin Perkumas
- Department of Ophthalmology, Duke University, Durham, North Carolina
| | - Zhiguo Zhang
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, Massachusetts
| | - Emily K Deurloo
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, Massachusetts
| | - Huayin Wu
- School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts
| | - David A Weitz
- School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts; Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, Massachusetts; Department of Physics, Harvard University, Cambridge, Massachusetts
| | - W Daniel Stamer
- Department of Ophthalmology, Duke University, Durham, North Carolina; Department of Biomedical Engineering, Duke University, Durham, North Carolina
| | - Robert D Goldman
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
| | - Jeffrey J Fredberg
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, Massachusetts
| | - Mark Johnson
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois; Department of Ophthalmology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois; Department of Mechanical Engineering, Northwestern University, Evanston, Illinois.
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12
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Miller KE, Suter DM. An Integrated Cytoskeletal Model of Neurite Outgrowth. Front Cell Neurosci 2018; 12:447. [PMID: 30534055 PMCID: PMC6275320 DOI: 10.3389/fncel.2018.00447] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Accepted: 11/07/2018] [Indexed: 12/27/2022] Open
Abstract
Neurite outgrowth underlies the wiring of the nervous system during development and regeneration. Despite a significant body of research, the underlying cytoskeletal mechanics of growth and guidance are not fully understood, and the relative contributions of individual cytoskeletal processes to neurite growth are controversial. Here, we review the structural organization and biophysical properties of neurons to make a semi-quantitative comparison of the relative contributions of different processes to neurite growth. From this, we develop the idea that neurons are active fluids, which generate strong contractile forces in the growth cone and weaker contractile forces along the axon. As a result of subcellular gradients in forces and material properties, actin flows rapidly rearward in the growth cone periphery, and microtubules flow forward in bulk along the axon. With this framework, an integrated model of neurite outgrowth is proposed that hopefully will guide new approaches to stimulate neuronal growth.
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Affiliation(s)
- Kyle E Miller
- Department of Integrative Biology, Michigan State University, East Lansing, MI, United States
| | - Daniel M Suter
- Department of Biological Sciences, Purdue University, West Lafayette, IN, United States.,Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN, United States.,Bindley Bioscience Center, Purdue University, West Lafayette, IN, United States.,Birck Nanotechnology Center, Purdue University, West Lafayette, IN, United States
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13
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Mapping heterogeneity of cellular mechanics by multi-harmonic atomic force microscopy. Nat Protoc 2018; 13:2200-2216. [DOI: 10.1038/s41596-018-0031-8] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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14
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Strohbach A, Pennewitz M, Glaubitz M, Palankar R, Groß S, Lorenz F, Materzok I, Rong A, Busch MC, Felix SB, Delcea M, Busch R. The apelin receptor influences biomechanical and morphological properties of endothelial cells. J Cell Physiol 2018; 233:6250-6261. [PMID: 29369349 DOI: 10.1002/jcp.26496] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Accepted: 01/22/2018] [Indexed: 12/20/2022]
Abstract
The adaption of endothelial cells to local flow conditions is a multifunctional process which leads to distinct alterations in cell shape, the subcellular distribution of structural proteins, and cellular function. G-protein-coupled receptors (GPCRs) have been identified to be fundamentally involved in such processes. Recently, we and others have shown that the expression of the endothelial GPCR apelin receptor (APJ) is regulated by fluid flow and that activation of APJ participates in signaling pathways which are related to processes of mechanotransduction. The present study aims to illuminate these findings by further visualization of APJ function. We show that APJ is located to the cellular junctions and might thus be associated with platelet endothelial cell adhesion molecule-1 (PECAM-1) in human umbilical vein endothelial cells (HUVEC). Furthermore, siRNA-mediated silencing of APJ expression influences the shear-induced adaption of HUVEC in terms of cytoskeletal remodeling, cellular elasticity, cellular motility, attachment, and distribution of adhesion complexes. Taken together, our results demonstrate that APJ is crucial for complemented endothelial adaption to local flow conditions.
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Affiliation(s)
- Anne Strohbach
- Clinic for Internal Medicine B (Cardiology), University of Greifswald, Ferdinand-Sauerbruch-Strasse, Greifswald, Germany.,DZHK (German Centre for Cardiovascular Research), Greifswald, Germany
| | - Malte Pennewitz
- Clinic for Internal Medicine B (Cardiology), University of Greifswald, Ferdinand-Sauerbruch-Strasse, Greifswald, Germany.,DZHK (German Centre for Cardiovascular Research), Greifswald, Germany
| | - Michael Glaubitz
- ZIK HIKE (Innovation Center- Humoral Immune Reactions in Cardiovascular Diseases), University of Greifswald, Greifswald, Germany
| | - Raghavendra Palankar
- Institute for Immunology and Transfusion Medicine, University Medicine Greifswald, Greifswald, Germany
| | - Stefan Groß
- Clinic for Internal Medicine B (Cardiology), University of Greifswald, Ferdinand-Sauerbruch-Strasse, Greifswald, Germany.,DZHK (German Centre for Cardiovascular Research), Greifswald, Germany
| | - Florian Lorenz
- Clinic for Internal Medicine B (Cardiology), University of Greifswald, Ferdinand-Sauerbruch-Strasse, Greifswald, Germany.,DZHK (German Centre for Cardiovascular Research), Greifswald, Germany
| | - Ilka Materzok
- Clinic for Internal Medicine B (Cardiology), University of Greifswald, Ferdinand-Sauerbruch-Strasse, Greifswald, Germany.,DZHK (German Centre for Cardiovascular Research), Greifswald, Germany
| | - Alena Rong
- ZIK HIKE (Innovation Center- Humoral Immune Reactions in Cardiovascular Diseases), University of Greifswald, Greifswald, Germany
| | - Mathias C Busch
- Clinic for Internal Medicine B (Cardiology), University of Greifswald, Ferdinand-Sauerbruch-Strasse, Greifswald, Germany.,DZHK (German Centre for Cardiovascular Research), Greifswald, Germany
| | - Stephan B Felix
- Clinic for Internal Medicine B (Cardiology), University of Greifswald, Ferdinand-Sauerbruch-Strasse, Greifswald, Germany.,DZHK (German Centre for Cardiovascular Research), Greifswald, Germany.,ZIK HIKE (Innovation Center- Humoral Immune Reactions in Cardiovascular Diseases), University of Greifswald, Greifswald, Germany
| | - Mihaela Delcea
- DZHK (German Centre for Cardiovascular Research), Greifswald, Germany.,ZIK HIKE (Innovation Center- Humoral Immune Reactions in Cardiovascular Diseases), University of Greifswald, Greifswald, Germany
| | - Raila Busch
- Clinic for Internal Medicine B (Cardiology), University of Greifswald, Ferdinand-Sauerbruch-Strasse, Greifswald, Germany.,DZHK (German Centre for Cardiovascular Research), Greifswald, Germany
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15
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Disease-causing mutation in α-actinin-4 promotes podocyte detachment through maladaptation to periodic stretch. Proc Natl Acad Sci U S A 2018; 115:1517-1522. [PMID: 29378953 DOI: 10.1073/pnas.1717870115] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
α-Actinin-4 (ACTN4) bundles and cross-links actin filaments to confer mechanical resilience to the reconstituted actin network. How this resilience is built and dynamically regulated in the podocyte, and the cause of its failure in ACTN4 mutation-associated focal segmental glomerulosclerosis (FSGS), remains poorly defined. Using primary podocytes isolated from wild-type (WT) and FSGS-causing point mutant Actn4 knockin mice, we report responses to periodic stretch. While WT cells largely maintained their F-actin cytoskeleton and contraction, mutant cells developed extensive and irrecoverable reductions in these same properties. This difference was attributable to both actin material changes and a more spatially correlated intracellular stress in mutant cells. When stretched cells were further challenged using a cell adhesion assay, mutant cells were more likely to detach. Together, these data suggest a mechanism for mutant podocyte dysfunction and loss in FSGS-it is a direct consequence of mechanical responses of a cytoskeleton that is brittle.
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16
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Jensen L, Neri E, Bassaneze V, De Almeida Oliveira NC, Dariolli R, Turaça LT, Levy D, Veronez D, Ferraz MSA, Alencar AM, Bydlowski SP, Cestari IA, Krieger JE. Integrated molecular, biochemical, and physiological assessment unravels key extraction method mediated influences on rat neonatal cardiomyocytes. J Cell Physiol 2018; 233:5420-5430. [PMID: 29219187 DOI: 10.1002/jcp.26380] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 12/04/2017] [Indexed: 12/29/2022]
Abstract
Neonatal cardiomyocytes are instrumental for disease modeling, but the effects of different cell extraction methods on basic cell biological processes remain poorly understood. We assessed the influence of two popular methods to extract rat neonatal cardiomyocytes, Pre-plating (PP), and Percoll (PC) on cell structure, metabolism, and function. Cardiomyocytes obtained from PP showed higher gene expression for troponins, titin, and potassium and sodium channels compared to PC. Also, PP cells displayed higher levels of troponin I protein. Cells obtained from PC displayed higher lactate dehydrogenase activity and lactate production than PP cells, indicating higher anaerobic metabolism after 8 days of culture. In contrast, reactive oxygen species levels were higher in PP cells as indicated by ethidium and hydroxyethidium production. Consistent with these data, protein nitration was higher in PP cells, as well as nitrite accumulation in cell medium. Moreover, PP cells showed higher global intracellular calcium under basal and 1 mM isoprenaline conditions. In a calcium-transient assessment under electrical stimulation (0.5 Hz), PP cells displayed higher calcium amplitude than cardiomyocytes obtained from PC and using a traction force microscope technique we observed that PP cardiomyocytes showed the highest relaxation. Collectively, we demonstrated that extraction methods influence parameters related to cell structure, metabolism, and function. Overall, PP derived cells are more active and mature than PC cells, displaying higher contractile function and generating more reactive oxygen species. On the other hand, PC derived cells display higher anaerobic metabolism, despite comparable high yields from both protocols.
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Affiliation(s)
- Leonardo Jensen
- Laboratory of Genetics and Molecular Cardiology/LIM 13, Heart Institute (InCor), University of São Paulo Medical School, São Paulo, Brazil
| | - Elida Neri
- Laboratory of Genetics and Molecular Cardiology/LIM 13, Heart Institute (InCor), University of São Paulo Medical School, São Paulo, Brazil
| | - Vinicius Bassaneze
- Laboratory of Genetics and Molecular Cardiology/LIM 13, Heart Institute (InCor), University of São Paulo Medical School, São Paulo, Brazil
| | - Nathalia C De Almeida Oliveira
- Laboratory of Genetics and Molecular Cardiology/LIM 13, Heart Institute (InCor), University of São Paulo Medical School, São Paulo, Brazil
| | - Rafael Dariolli
- Laboratory of Genetics and Molecular Cardiology/LIM 13, Heart Institute (InCor), University of São Paulo Medical School, São Paulo, Brazil
| | - Lauro T Turaça
- Laboratory of Genetics and Molecular Cardiology/LIM 13, Heart Institute (InCor), University of São Paulo Medical School, São Paulo, Brazil
| | - Débora Levy
- Laboratory of Genetics and Molecular Hematology/LIM 31, Clinics Hospital (HC), University of São Paulo Medical School, São Paulo, Brazil
| | - Douglas Veronez
- Bioengineering Division, Heart Institute (InCor), University of São Paulo Medical School, São Paulo, Brazil
| | - Mariana S A Ferraz
- Laboratory of Microrheology and Molecular Physiology, Institute of Physics, University of São Paulo, São Paulo, Brazil
| | - Adriano M Alencar
- Laboratory of Microrheology and Molecular Physiology, Institute of Physics, University of São Paulo, São Paulo, Brazil
| | - Sérgio P Bydlowski
- Laboratory of Genetics and Molecular Hematology/LIM 31, Clinics Hospital (HC), University of São Paulo Medical School, São Paulo, Brazil
| | - Idágene A Cestari
- Bioengineering Division, Heart Institute (InCor), University of São Paulo Medical School, São Paulo, Brazil
| | - José Eduardo Krieger
- Laboratory of Genetics and Molecular Cardiology/LIM 13, Heart Institute (InCor), University of São Paulo Medical School, São Paulo, Brazil
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17
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Cai P, Takahashi R, Kuribayashi-Shigetomi K, Subagyo A, Sueoka K, Maloney JM, Van Vliet KJ, Okajima T. Temporal Variation in Single-Cell Power-Law Rheology Spans the Ensemble Variation of Cell Population. Biophys J 2017; 113:671-678. [PMID: 28793221 DOI: 10.1016/j.bpj.2017.06.025] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 06/11/2017] [Accepted: 06/13/2017] [Indexed: 01/08/2023] Open
Abstract
Changes in the cytoskeletal organization within cells can be characterized by large spatial and temporal variations in rheological properties of the cell (e.g., the complex shear modulus G∗). Although the ensemble variation in G∗ of single cells has been elucidated, the detailed temporal variation of G∗ remains unknown. In this study, we investigated how the rheological properties of individual fibroblast cells change under a spatially confined environment in which the cell translational motion is highly restricted and the whole cell shape remains unchanged. The temporal evolution of single-cell rheology was probed at the same measurement location within the cell, using atomic force microscopy-based oscillatory deformation. The measurements reveal that the temporal variation in the power-law rheology of cells is quantitatively consistent with the ensemble variation, indicating that the cell system satisfies an ergodic hypothesis in which the temporal statistics are identical to the ensemble statistics. The autocorrelation of G∗ implies that the cell mechanical state evolves in the ensemble of possible states with a characteristic timescale.
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Affiliation(s)
- PingGen Cai
- Graduate School of Information Science and Technology, Hokkaido University, Sapporo, Japan
| | - Ryosuke Takahashi
- Graduate School of Information Science and Technology, Hokkaido University, Sapporo, Japan
| | | | - Agus Subagyo
- Graduate School of Information Science and Technology, Hokkaido University, Sapporo, Japan
| | - Kazuhisa Sueoka
- Graduate School of Information Science and Technology, Hokkaido University, Sapporo, Japan
| | - John M Maloney
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Krystyn J Van Vliet
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts; Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Takaharu Okajima
- Graduate School of Information Science and Technology, Hokkaido University, Sapporo, Japan.
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18
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Zhou Z, Sun X, Ma J, Tong M, To S, Wong A, Ngan A. Actin cytoskeleton stiffness grades metastatic potential of ovarian carcinoma Hey A8 cells via nanoindentation mapping. J Biomech 2017; 60:219-226. [DOI: 10.1016/j.jbiomech.2017.06.040] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Revised: 05/24/2017] [Accepted: 06/25/2017] [Indexed: 02/03/2023]
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19
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Suki B, Hu Y, Murata N, Imsirovic J, Mondoñedo JR, de Oliveira CLN, Schaible N, Allen PG, Krishnan R, Bartolák-Suki E. A microfluidic chamber-based approach to map the shear moduli of vascular cells and other soft materials. Sci Rep 2017; 7:2305. [PMID: 28536424 PMCID: PMC5442161 DOI: 10.1038/s41598-017-02659-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Accepted: 04/18/2017] [Indexed: 11/09/2022] Open
Abstract
There is growing interest in quantifying vascular cell and tissue stiffness. Most measurement approaches, however, are incapable of assessing stiffness in the presence of physiological flows. We developed a microfluidic approach which allows measurement of shear modulus (G) during flow. The design included a chamber with glass windows allowing imaging with upright or inverted microscopes. Flow was controlled gravitationally to push culture media through the chamber. Fluorescent beads were conjugated to the sample surface and imaged before and during flow. Bead displacements were calculated from images and G was computed as the ratio of imposed shear stress to measured shear strain. Fluid-structure simulations showed that shear stress on the surface did not depend on sample stiffness. Our approach was verified by measuring the moduli of polyacrylamide gels of known stiffness. In human pulmonary microvascular endothelial cells, G was 20.4 ± 12 Pa and decreased by 20% and 22% with increasing shear stress and inhibition of non-muscle myosin II motors, respectively. The G showed a larger intra- than inter-cellular variability and it was mostly determined by the cytosol. Our shear modulus microscopy can thus map the spatial distribution of G of soft materials including gels, cells and tissues while allowing the visualization of microscopic structures such as the cytoskeleleton.
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Affiliation(s)
- Béla Suki
- Department of Biomedical Engineering, Boston University, Boston, MA, 02215, USA.
| | - Yingying Hu
- Department of Biomedical Engineering, Boston University, Boston, MA, 02215, USA
| | - Naohiko Murata
- Department of Biomedical Engineering, Boston University, Boston, MA, 02215, USA
| | - Jasmin Imsirovic
- Department of Biomedical Engineering, Boston University, Boston, MA, 02215, USA
| | - Jarred R Mondoñedo
- Department of Biomedical Engineering, Boston University, Boston, MA, 02215, USA
| | | | - Niccole Schaible
- Center for Vascular Biology Research, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, 02215, USA
| | - Philip G Allen
- Department of Biomedical Engineering, Boston University, Boston, MA, 02215, USA
| | - Ramaswamy Krishnan
- Center for Vascular Biology Research, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, 02215, USA
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20
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Huang C, Liu L, You Z, Wang B, Du Y, Ogawa R. Keloid progression: a stiffness gap hypothesis. Int Wound J 2016; 14:764-771. [PMID: 27995750 DOI: 10.1111/iwj.12693] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Accepted: 11/06/2016] [Indexed: 12/19/2022] Open
Abstract
Keloids are fibroproliferative skin disorders characterised clinically by continuous horizontal progression and post-surgical recurrence and histologically by the accumulation of collagen and fibroblast ingredients. Till now, their aetiology remains clear, which may cover genetic, environmental and metabolic factors. Evidence in the involvement of local mechanics (e.g. predilection site and typical shape) and the progress in mechanobiology have incubated our stiffness gap hypotheses in illustrating the chronic but constant development in keloid. We put forward that the enlarged gap between extracellular matrix (ECM) stiffness and cellular stiffness potentiates keloid progression. Matrix stiffness itself provides organisational guidance cues to regulate the mechanosensitive resident cells (e.g. proliferation, migration and apoptosis). During this dynamic process, the ECM stiffness and cell stiffness are not well balanced, and the continuously enlarged stiffness gap between them potentiates keloid progression. The cushion factors, such as prestress for cell stiffness and topology for ECM stiffness, serve as compensations, the decompensation of which aggravates keloid development. It can well explain the typical shape of keloids, their progression in a horizontal but not vertical direction and the post-surgical recurrence, which were evidenced by our clinical cases. Such a stiffness gap hypothesis might be bridged to mechanotherapeutic approaches for keloid progression.
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Affiliation(s)
- Chenyu Huang
- Department of Dermatology Beijing Tsinghua Changgung Hospital, Tsinghua University, Beijing, China
| | - Longwei Liu
- Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing, China
| | - Zhifeng You
- Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing, China
| | - Bingjie Wang
- Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing, China
| | - Yanan Du
- Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing, China
| | - Rei Ogawa
- Department of Plastic, Reconstructive and Aesthetic Surgery, Nippon Medical School, Tokyo, Japan
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21
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Nguyen AV, Nyberg KD, Scott MB, Welsh AM, Nguyen AH, Wu N, Hohlbauch SV, Geisse NA, Gibb EA, Robertson AG, Donahue TR, Rowat AC. Stiffness of pancreatic cancer cells is associated with increased invasive potential. Integr Biol (Camb) 2016; 8:1232-1245. [PMID: 27761545 PMCID: PMC5866717 DOI: 10.1039/c6ib00135a] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Metastasis is a fundamentally physical process in which cells are required to deform through narrow gaps as they invade surrounding tissues and transit to distant sites. In many cancers, more invasive cells are more deformable than less invasive cells, but the extent to which mechanical phenotype, or mechanotype, can predict disease aggressiveness in pancreatic ductal adenocarcinoma (PDAC) remains unclear. Here we investigate the invasive potential and mechanical properties of immortalized PDAC cell lines derived from primary tumors and a secondary metastatic site, as well as noncancerous pancreatic ductal cells. To investigate how invasive behavior is associated with cell mechanotype, we flow cells through micron-scale pores using parallel microfiltration and microfluidic deformability cytometry; these results show that the ability of PDAC cells to passively transit through pores is only weakly correlated with their invasive potential. We also measure the Young's modulus of pancreatic ductal cells using atomic force microscopy, which reveals that there is a strong association between cell stiffness and invasive potential in PDAC cells. To determine the molecular origins of the variability in mechanotype across our PDAC cell lines, we analyze RNAseq data for genes that are known to regulate cell mechanotype. Our results show that vimentin, actin, and lamin A are among the most differentially expressed mechanoregulating genes across our panel of PDAC cell lines, as well as a cohort of 38 additional PDAC cell lines. We confirm levels of these proteins across our cell panel using immunoblotting, and find that levels of lamin A increase with both invasive potential and Young's modulus. Taken together, we find that stiffer PDAC cells are more invasive than more compliant cells, which challenges the paradigm that decreased cell stiffness is a hallmark of metastatic potential.
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Affiliation(s)
- Angelyn V Nguyen
- Department of Integrative Biology and Physiology, University of California, Los Angeles, USA.
| | - Kendra D Nyberg
- Department of Integrative Biology and Physiology, University of California, Los Angeles, USA. and Department of Bioengineering, University of California, Los Angeles, USA
| | - Michael B Scott
- Department of Integrative Biology and Physiology, University of California, Los Angeles, USA.
| | - Alia M Welsh
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, USA
| | - Andrew H Nguyen
- Department of General Surgery, University of California, Los Angeles, USA
| | - Nanping Wu
- Department of General Surgery, University of California, Los Angeles, USA
| | - Sophia V Hohlbauch
- Asylum Research, an Oxford Instruments Company, Santa Barbara, California, USA
| | - Nicholas A Geisse
- Asylum Research, an Oxford Instruments Company, Santa Barbara, California, USA
| | - Ewan A Gibb
- Canada's Michael Smith Genome Sciences Centre, British Columbia Cancer Agency, Vancouver, BC, Canada
| | - A Gordon Robertson
- Canada's Michael Smith Genome Sciences Centre, British Columbia Cancer Agency, Vancouver, BC, Canada
| | - Timothy R Donahue
- Department of General Surgery, University of California, Los Angeles, USA and Jonsson Comprehensive Cancer Center, University of California, Los Angeles, USA
| | - Amy C Rowat
- Department of Integrative Biology and Physiology, University of California, Los Angeles, USA. and Department of Bioengineering, University of California, Los Angeles, USA and Jonsson Comprehensive Cancer Center, University of California, Los Angeles, USA
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22
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Mapping intracellular mechanics on micropatterned substrates. Proc Natl Acad Sci U S A 2016; 113:E7159-E7168. [PMID: 27799529 DOI: 10.1073/pnas.1605112113] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The mechanical properties of cells impact on their architecture, their migration, intracellular trafficking, and many other cellular functions and have been shown to be modified during cancer progression. We have developed an approach to map the intracellular mechanical properties of living cells by combining micropatterning and optical tweezers-based active microrheology. We optically trap micrometer-sized beads internalized in cells plated on crossbow-shaped adhesive micropatterns and track their displacement following a step displacement of the cell. The local intracellular complex shear modulus is measured from the relaxation of the bead position assuming that the intracellular microenvironment of the bead obeys power-law rheology. We also analyze the data with a standard viscoelastic model and compare with the power-law approach. We show that the shear modulus decreases from the cell center to the periphery and from the cell rear to the front along the polarity axis of the micropattern. We use a variety of inhibitors to quantify the spatial contribution of the cytoskeleton, intracellular membranes, and ATP-dependent active forces to intracellular mechanics and apply our technique to differentiate normal and cancer cells.
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23
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Alencar AM, Ferraz MSA, Park CY, Millet E, Trepat X, Fredberg JJ, Butler JP. Non-equilibrium cytoquake dynamics in cytoskeletal remodeling and stabilization. SOFT MATTER 2016; 12:8506-8511. [PMID: 27722665 PMCID: PMC5123702 DOI: 10.1039/c6sm01041e] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The cytoskeleton (CSK) is a tensed fiber framework that supports, shapes and stabilizes the cell. The CSK is in a constant state of remodeling, moreover, which is an active non-equilibrium thermodynamic process. We report here that cytoskeletal remodeling involves reconfigurations that are not only sudden but also are transmitted to great distances within the cell in a fashion reminiscent of quakes in the Earth's crust. Remarkably, these events in the cell conform both qualitatively and quantitatively to empirical laws typical of earthquakes, including hierarchical fault structures, cumulative energy distributions following the Gutenberg-Richter law, and rate of after-shocks following Omori's law. While it is well-established that remodeling and stabilization of the cytoskeleton are non-equilibrium process, these new unanticipated observations establish that these processes are also remarkably non-local and strongly cooperative.
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Affiliation(s)
| | | | - Chan Young Park
- Molecular and Integrative Physiological Sciences, Department of Environmental Health, Harvard School of Public Health, Boston, MA, USA
| | - Emil Millet
- Molecular and Integrative Physiological Sciences, Department of Environmental Health, Harvard School of Public Health, Boston, MA, USA
| | - Xavier Trepat
- Institució Catalana de Recerca i Estudis Avançats, Universitat de Barcelona, Ciber-BBN, and Institute for Bioengineering of Catalonia, 08014 Barcelona, Spain
| | - Jeffrey J Fredberg
- Molecular and Integrative Physiological Sciences, Department of Environmental Health, Harvard School of Public Health, Boston, MA, USA
| | - James P Butler
- Molecular and Integrative Physiological Sciences, Department of Environmental Health, Harvard School of Public Health, Boston, MA, USA and Department Medicine, Harvard Medical School, Boston, MA, USA
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24
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de Saint Vincent MR. Optical twisting to monitor the rheology of single cells. Biorheology 2016; 53:69-80. [DOI: 10.3233/bir-15084] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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25
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Seriani R, de Souza CEC, Krempel PG, Frias DP, Matsuda M, Correia AT, Ferreira MZJ, Alencar AM, Negri EM, Saldiva PHN, Mauad T, Macchione M. Human bronchial epithelial cells exposed in vitro to diesel exhaust particles exhibit alterations in cell rheology and cytotoxicity associated with decrease in antioxidant defenses and imbalance in pro- and anti-apoptotic gene expression. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2016; 23:9862-9870. [PMID: 26856867 DOI: 10.1007/s11356-016-6228-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Accepted: 02/01/2016] [Indexed: 06/05/2023]
Abstract
Diesel exhaust particles (DEPs) from diesel engines produce adverse alterations in cells of the airways by activating intracellular signaling pathways and apoptotic gene overexpression, and also by influencing metabolism and cytoskeleton changes. This study used human bronchial epithelium cells (BEAS-2B) in culture and evaluates their exposure to DEPs (15ug/mL for 1 and 2 h) in order to determine changes to cell rheology (viscoelasticity) and gene expression of the enzymes involved in oxidative stress, apoptosis, and cytotoxicity. BEAS-2B cells exposed to DEPs were found to have a significant loss in stiffness, membrane stability, and mitochondrial activity. The genes involved in apoptosis [B cell lymphoma 2 (BCL-2 and caspase-3)] presented inversely proportional expressions (p = 0.05, p = 0.01, respectively), low expression of the genes involved in antioxidant responses [SOD1 (superoxide dismutase 1); SOD2 (superoxide dismutase 2), and GPx (glutathione peroxidase) (p = 0.01)], along with an increase in cytochrome P450, family 1, subfamily A, polypeptide 1 (CYP1A1) (p = 0.01). These results suggest that alterations in cell rheology and cytotoxicity could be associated with oxidative stress and imbalance between pro- and anti-apoptotic genes.
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Affiliation(s)
- Robson Seriani
- Laboratory of Experimental Air Pollution (LIM05), Department of Pathology, School of Medicine, University of São Paulo, Av. Dr. Arnaldo 455, 1°andar, sala 1150, Cerqueira César, São Paulo, SP, CEP:01246-903, Brazil.
- FAM - Faculdades das Américas, Rua Augusta, 1508, 3°andar, São Paulo, SP, 01304-001, Brazil.
| | - Claudia Emanuele Carvalho de Souza
- Laboratory of Chronopharmacology, Department of Physiology, Institute of Bioscience, University of São Paulo, Rua do Matão - travessa 14, Cidade Universitária, 05508900, São Paulo, SP, Brazil
| | - Paloma Gava Krempel
- Laboratory for Investigations in Ophthalmology (LIM-33), University of São Paulo Medical School São Paulo, Dr. Arnaldo 455, 5°andar, Cerqueira César, São Paulo, SP, CEP:01246-903, Brazil
| | - Daniela Perroni Frias
- Laboratory of Experimental Air Pollution (LIM05), Department of Pathology, School of Medicine, University of São Paulo, Av. Dr. Arnaldo 455, 1°andar, sala 1150, Cerqueira César, São Paulo, SP, CEP:01246-903, Brazil
| | - Monique Matsuda
- Laboratory for Investigations in Ophthalmology (LIM-33), University of São Paulo Medical School São Paulo, Dr. Arnaldo 455, 5°andar, Cerqueira César, São Paulo, SP, CEP:01246-903, Brazil
| | - Aristides Tadeu Correia
- Heart Institute (InCor), Department of Cardiopulmonology, University of São Paulo Medical School, Av. Dr. Enéas de Carvalho Aguiar, 44, Cerqueira Cesar, 05403-000, Sao Paulo, SP, Brazil
| | - Márcia Zotti Justo Ferreira
- Laboratory of Microrheology and Molecular Physiology, Institute of Physics, University of São Paulo, Rua do Matão, Travessa R Número 187, Cidade Universitária, 05508-090, Sao Paulo, SP, Brazil
| | - Adriano Mesquita Alencar
- Laboratory of Microrheology and Molecular Physiology, Institute of Physics, University of São Paulo, Rua do Matão, Travessa R Número 187, Cidade Universitária, 05508-090, Sao Paulo, SP, Brazil
| | - Elnara Marcia Negri
- Laboratory of Experimental Air Pollution (LIM05), Department of Pathology, School of Medicine, University of São Paulo, Av. Dr. Arnaldo 455, 1°andar, sala 1150, Cerqueira César, São Paulo, SP, CEP:01246-903, Brazil
| | - Paulo Hilário Nascimento Saldiva
- Laboratory of Experimental Air Pollution (LIM05), Department of Pathology, School of Medicine, University of São Paulo, Av. Dr. Arnaldo 455, 1°andar, sala 1150, Cerqueira César, São Paulo, SP, CEP:01246-903, Brazil
| | - Thais Mauad
- Laboratory of Experimental Air Pollution (LIM05), Department of Pathology, School of Medicine, University of São Paulo, Av. Dr. Arnaldo 455, 1°andar, sala 1150, Cerqueira César, São Paulo, SP, CEP:01246-903, Brazil
| | - Mariangela Macchione
- Laboratory of Experimental Air Pollution (LIM05), Department of Pathology, School of Medicine, University of São Paulo, Av. Dr. Arnaldo 455, 1°andar, sala 1150, Cerqueira César, São Paulo, SP, CEP:01246-903, Brazil
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O'Toole M, Lamoureux P, Miller KE. Measurement of subcellular force generation in neurons. Biophys J 2016; 108:1027-37. [PMID: 25762315 DOI: 10.1016/j.bpj.2015.01.021] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Revised: 01/19/2015] [Accepted: 01/23/2015] [Indexed: 11/24/2022] Open
Abstract
Forces are important for neuronal outgrowth during the initial wiring of the nervous system and after trauma, yet subcellular force generation over the microtubule-rich region at the rear of the growth cone and along the axon has never, to our knowledge, been directly measured. Because previous studies have indicated microtubule polymerization and the microtubule-associated proteins Kinesin-1 and dynein all generate forces that push microtubules forward, a major question is whether the net forces in these regions are contractile or expansive. A challenge in addressing this is that measuring local subcellular force generation is difficult. Here we develop an analytical mathematical model that describes the relationship between unequal subcellular forces arranged in series within the neuron and the net overall tension measured externally. Using force-calibrated towing needles to measure and apply forces, in combination with docked mitochondria to monitor subcellular strain, we then directly measure force generation over the rear of the growth cone and along the axon of chick sensory neurons. We find the rear of the growth cone generates 2.0 nN of contractile force, the axon generates 0.6 nN of contractile force, and that the net overall tension generated by the neuron is 1.3 nN. This work suggests that the forward bulk flow of the cytoskeletal framework that occurs during axonal elongation and growth-cone pauses arises because strong contractile forces in the rear of the growth cone pull material forward.
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Affiliation(s)
- Matthew O'Toole
- Department of Mathematics, Kettering University, Flint, Michigan
| | - Phillip Lamoureux
- Department of Zoology, Michigan State University, East Lansing, Michigan
| | - Kyle E Miller
- Department of Zoology, Michigan State University, East Lansing, Michigan.
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Smoking and Female Sex: Independent Predictors of Human Vascular Smooth Muscle Cells Stiffening. PLoS One 2015; 10:e0145062. [PMID: 26661469 PMCID: PMC4678027 DOI: 10.1371/journal.pone.0145062] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Accepted: 11/29/2015] [Indexed: 11/23/2022] Open
Abstract
Aims Recent evidence shows the rigidity of vascular smooth muscle cells (VSMC) contributes to vascular mechanics. Arterial rigidity is an independent cardiovascular risk factor whose associated modifications in VSMC viscoelasticity have never been investigated. This study’s objective was to evaluate if the arterial rigidity risk factors aging, African ancestry, female sex, smoking and diabetes mellitus are associated with VMSC stiffening in an experimental model using a human derived vascular smooth muscle primary cell line repository. Methods Eighty patients subjected to coronary artery bypass surgery were enrolled. VSMCs were extracted from internal thoracic artery fragments and mechanically evaluated using Optical Magnetic Twisting Cytometry assay. The obtained mechanical variables were correlated with the clinical variables: age, gender, African ancestry, smoking and diabetes mellitus. Results The mechanical variables Gr, G’r and G”r had a normal distribution, demonstrating an inter-individual variability of VSMC viscoelasticity, which has never been reported before. Female sex and smoking were independently associated with VSMC stiffening: Gr (apparent cell stiffness) p = 0.022 and p = 0.018, R2 0.164; G’r (elastic modulus) p = 0.019 and p = 0.009, R2 0.184 and G”r (dissipative modulus) p = 0.011 and p = 0.66, R2 0.141. Conclusion Female sex and smoking are independent predictors of VSMC stiffening. This pro-rigidity effect represents an important element for understanding the vascular rigidity observed in post-menopausal females and smokers, as well as a potential therapeutic target to be explored in the future. There is a significant inter-individual variation of VSMC viscoelasticity, which is slightly modulated by clinical variables and probably relies on molecular factors.
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Gavara N, Chadwick RS. Relationship between cell stiffness and stress fiber amount, assessed by simultaneous atomic force microscopy and live-cell fluorescence imaging. Biomech Model Mechanobiol 2015. [PMID: 26206449 PMCID: PMC4869747 DOI: 10.1007/s10237-015-0706-9] [Citation(s) in RCA: 98] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Actomyosin stress fibers, one of the main components of the cell’s cytoskeleton, provide mechanical stability to adherent cells by applying and transmitting tensile forces onto the extracellular matrix (ECM) at the sites of cell–ECM adhesion. While it is widely accepted that changes in spatial and temporal distribution of stress fibers affect the cell’s mechanical properties, there is no quantitative knowledge on how stress fiber amount and organization directly modulate cell stiffness. We address this key open question by combining atomic force microscopy with simultaneous fluorescence imaging of living cells, and combine for the first time reliable quantitative parameters obtained from both techniques. We show that the amount of myosin and (to a lesser extent) actin assembled in stress fibers directly modulates cell stiffness in adherent mouse fibroblasts (NIH3T3). In addition, the spatial distribution of stress fibers has a second-order modulatory effect. In particular, the presence of either fibers located in the cell periphery, aligned fibers or thicker fibers gives rise to reinforced cell stiffness. Our results provide basic and significant information that will help design optimal protocols to regulate the mechanical properties of adherent cells via pharmacological interventions that alter stress fiber assembly or via micropatterning techniques that restrict stress fiber spatial organization.
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Affiliation(s)
- Núria Gavara
- School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London, E1 3NS, UK.
| | - Richard S Chadwick
- Auditory Mechanics Section, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Building 10 Rm. 5D49, 10 Center Drive, MSC-1417, Bethesda, MD, 20892, USA
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Rigato A, Rico F, Eghiaian F, Piel M, Scheuring S. Atomic Force Microscopy Mechanical Mapping of Micropatterned Cells Shows Adhesion Geometry-Dependent Mechanical Response on Local and Global Scales. ACS NANO 2015; 9:5846-56. [PMID: 26013956 PMCID: PMC5382230 DOI: 10.1021/acsnano.5b00430] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
In multicellular organisms, cell shape and organization are dictated by cell-cell or cell-extracellular matrix adhesion interactions. Adhesion complexes crosstalk with the cytoskeleton enabling cells to sense their mechanical environment. Unfortunately, most of cell biology studies, and cell mechanics studies in particular, are conducted on cultured cells adhering to a hard, homogeneous, and unconstrained substrate with nonspecific adhesion sites, thus far from physiological and reproducible conditions. Here, we grew cells on three different fibronectin patterns with identical overall dimensions but different geometries (▽, T, and Y), and investigated their topography and mechanics by atomic force microscopy (AFM). The obtained mechanical maps were reproducible for cells grown on patterns of the same geometry, revealing pattern-specific subcellular differences. We found that local Young's moduli variations are related to the cell adhesion geometry. Additionally, we detected local changes of cell mechanical properties induced by cytoskeletal drugs. We thus provide a method to quantitatively and systematically investigate cell mechanics and their variations, and present further evidence for a tight relation between cell adhesion and mechanics.
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Affiliation(s)
- Annafrancesca Rigato
- Bio-AFM-Lab, BIO-AFM-LAB Bio Atomic Force Microscopy Laboratory
Aix Marseille Université - UMR S_1006Institut National de la Santé et de la Recherche Médicale - U1006Parc scientifique et technologique de Luminy - 163, avenue de Luminy - Case 1006 - 13288 Marseille Cedex 09
| | - Felix Rico
- Bio-AFM-Lab, BIO-AFM-LAB Bio Atomic Force Microscopy Laboratory
Aix Marseille Université - UMR S_1006Institut National de la Santé et de la Recherche Médicale - U1006Parc scientifique et technologique de Luminy - 163, avenue de Luminy - Case 1006 - 13288 Marseille Cedex 09
| | - Frédéric Eghiaian
- Bio-AFM-Lab, BIO-AFM-LAB Bio Atomic Force Microscopy Laboratory
Aix Marseille Université - UMR S_1006Institut National de la Santé et de la Recherche Médicale - U1006Parc scientifique et technologique de Luminy - 163, avenue de Luminy - Case 1006 - 13288 Marseille Cedex 09
| | - Mathieu Piel
- CDC, Compartimentation et dynamique cellulaires
Université Pierre et Marie Curie - Paris 6 - INSTITUT CURIE - Centre National de la Recherche Scientifique - UMR14426 rue d'Ulm 75248 Paris Cedex 05
| | - Simon Scheuring
- Bio-AFM-Lab, BIO-AFM-LAB Bio Atomic Force Microscopy Laboratory
Aix Marseille Université - UMR S_1006Institut National de la Santé et de la Recherche Médicale - U1006Parc scientifique et technologique de Luminy - 163, avenue de Luminy - Case 1006 - 13288 Marseille Cedex 09
- * Correspondence should be addressed to Simon Scheuring
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30
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Hecht FM, Rheinlaender J, Schierbaum N, Goldmann WH, Fabry B, Schäffer TE. Imaging viscoelastic properties of live cells by AFM: power-law rheology on the nanoscale. SOFT MATTER 2015; 11:4584-4591. [PMID: 25891371 DOI: 10.1039/c4sm02718c] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
We developed force clamp force mapping (FCFM), an atomic force microscopy (AFM) technique for measuring the viscoelastic creep behavior of live cells with sub-micrometer spatial resolution. FCFM combines force-distance curves with an added force clamp phase during tip-sample contact. From the creep behavior measured during the force clamp phase, quantitative viscoelastic sample properties are extracted. We validate FCFM on soft polyacrylamide gels. We find that the creep behavior of living cells conforms to a power-law material model. By recording short (50-60 ms) force clamp measurements in rapid succession, we generate, for the first time, two-dimensional maps of power-law exponent and modulus scaling parameter. Although these maps reveal large spatial variations of both parameters across the cell surface, we obtain robust mean values from the several hundreds of measurements performed on each cell. Measurements on mouse embryonic fibroblasts show that the mean power-law exponents and the mean modulus scaling parameters differ greatly among individual cells, but both parameters are highly correlated: stiffer cells consistently show a smaller power-law exponent. This correlation allows us to distinguish between wild-type cells and cells that lack vinculin, a dominant protein of the focal adhesion complex, even though the mean values of viscoelastic properties between wildtype and knockout cells did not differ significantly. Therefore, FCFM spatially resolves viscoelastic sample properties and can uncover subtle mechanical signatures of proteins in living cells.
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Affiliation(s)
- Fabian M Hecht
- Institute of Applied Physics, University of Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany.
| | - Johannes Rheinlaender
- Institute of Applied Physics, University of Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany.
| | - Nicolas Schierbaum
- Institute of Applied Physics, University of Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany.
| | - Wolfgang H Goldmann
- Department of Physics, University of Erlangen-Nuremberg, Henkestraße 91, 91052 Erlangen, Germany
| | - Ben Fabry
- Department of Physics, University of Erlangen-Nuremberg, Henkestraße 91, 91052 Erlangen, Germany
| | - Tilman E Schäffer
- Institute of Applied Physics, University of Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany.
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31
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Park CY, Zhou EH, Tambe D, Chen B, Lavoie T, Dowell M, Simeonov A, Maloney DJ, Marinkovic A, Tschumperlin DJ, Burger S, Frykenberg M, Butler JP, Stamer WD, Johnson M, Solway J, Fredberg JJ, Krishnan R. High-throughput screening for modulators of cellular contractile force. Integr Biol (Camb) 2015; 7:1318-24. [PMID: 25953078 DOI: 10.1039/c5ib00054h] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
When cellular contractile forces are central to pathophysiology, these forces comprise a logical target of therapy. Nevertheless, existing high-throughput screens are limited to upstream signalling intermediates with poorly defined relationships to such a physiological endpoint. Using cellular force as the target, here we report a new screening technology and demonstrate its applications using human airway smooth muscle cells in the context of asthma and Schlemm's canal endothelial cells in the context of glaucoma. This approach identified several drug candidates for both asthma and glaucoma. We attained rates of 1000 compounds per screening day, thus establishing a force-based cellular platform for high-throughput drug discovery.
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Affiliation(s)
- Chan Young Park
- Molecular and Integrative Physiological Sciences, Harvard School of Public Health, 665 Huntington Avenue, Boston, MA 02115, USA
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Enriched inorganic compounds in diesel exhaust particles induce mitogen-activated protein kinase activation, cytoskeleton instability, and cytotoxicity in human bronchial epithelial cells. ACTA ACUST UNITED AC 2015; 67:323-9. [PMID: 25769681 DOI: 10.1016/j.etp.2015.02.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Accepted: 02/20/2015] [Indexed: 11/23/2022]
Abstract
This study assessed the effects of the diesel exhaust particles on ERK and JNK MAPKs activation, cell rheology (viscoelasticity), and cytotoxicity in bronchial epithelial airway cells (BEAS-2B). Crude DEP and DEP after extraction with hexane (DEP/HEX) were utilized. The partial reduction of some DEP/HEX organics increased the biodisponibility of many metallic elements. JNK and ERK were activated simultaneously by crude DEP with no alterations in viscoelasticity of the cells. Mitochondrial activity, however, revealed a decrease through the MTT assay. DEP/HEX treatment increased viscoelasticity and cytotoxicity (membrane damage), and also activated JNK. Our data suggest that the greater bioavailability of metals could be involved in JNK activation and, consequently, in the reduction of fiber coherence and increase in the viscoelasticity and cytotoxicity of BEAS cells. The adverse findings detected after exposure to crude DEP and to DEP/HEX reflect the toxic potential of diesel compounds. Considering the fact that the cells of the respiratory epithelium are the first line of defense between the body and the environment, our data contribute to a better understanding of the pathways leading to respiratory cell injury and provide evidence for the onset of or worsening of respiratory diseases caused by inorganic compounds present in DEP.
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33
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Lim YC, Cooling MT, Long DS. Computational models of the primary cilium and endothelial mechanotransmission. Biomech Model Mechanobiol 2014; 14:665-78. [PMID: 25366114 DOI: 10.1007/s10237-014-0629-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Accepted: 10/20/2014] [Indexed: 12/31/2022]
Abstract
In endothelial cells (ECs), the mechanotransduction of fluid shear stress is partially dependent on the transmission of force from the fluid into the cell (mechanotransmission). The role of the primary cilium in EC mechanotransmission is not yet known. To motivate a framework towards quantifying cilia contribution to EC mechanotransmission, we have reviewed mechanical models of both (1) the primary cilium (three-dimensional and lower-dimensional) and (2) whole ECs (finite element, non-finite element, and tensegrity). Both the primary cilia and whole EC models typically incorporate fluid-induced wall shear stress and spatial geometry based on experimentally acquired images of cells. This paper presents future modelling directions as well as the major goals towards integrating primary cilium models into a multi-component EC mechanical model. Finally, we outline how an integrated cilium-EC model can be used to better understand mechanotransduction in the endothelium.
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Affiliation(s)
- Yi Chung Lim
- Auckland Bioengineering Institute, University of Auckland, 70 Symonds St, Auckland, 1010, New Zealand
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34
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A microwell pattern for C17.2 cell aggregate formation with concave cylindrical surface induced cell peeling. Biomaterials 2014; 35:9423-37. [DOI: 10.1016/j.biomaterials.2014.07.046] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Accepted: 07/23/2014] [Indexed: 01/17/2023]
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35
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Stiffness versus prestress relationship at subcellular length scale. J Biomech 2014; 47:3222-5. [PMID: 25138630 DOI: 10.1016/j.jbiomech.2014.08.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Accepted: 08/01/2014] [Indexed: 11/21/2022]
Abstract
Local intracellular variations of cell mechanical properties, which are essential for vital cellular functions, have not been well characterized and are poorly understood. Here, we used results from our previous biomechanical imaging study to obtain relationships between intracellular shear modulus and prestress. We found that the subcellular shear modulus vs. prestress relationships exhibited positive linear correlations, consistent with previously observed behaviors at the whole cell and tissue levels. This, in turn, suggests that the prestress may be a unifying factor that determines material properties of living matter at different length scales.
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36
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Cai P, Mizutani Y, Tsuchiya M, Maloney JM, Fabry B, Van Vliet KJ, Okajima T. Quantifying cell-to-cell variation in power-law rheology. Biophys J 2014; 105:1093-102. [PMID: 24010652 DOI: 10.1016/j.bpj.2013.07.035] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2013] [Revised: 06/15/2013] [Accepted: 07/12/2013] [Indexed: 11/17/2022] Open
Abstract
Among individual cells of the same source and type, the complex shear modulus G(∗) exhibits a large log-normal distribution that is the result of spatial, temporal, and intrinsic variations. Such large distributions complicate the statistical evaluation of pharmacological treatments and the comparison of different cell states. However, little is known about the characteristic features of cell-to-cell variation. In this study, we investigated how this variation depends on the spatial location within the cell and on the actin filament cytoskeleton, the organization of which strongly influences cell mechanics. By mechanically probing fibroblasts arranged on a microarray, via atomic force microscopy, we observed that the standard deviation σ of G(∗) was significantly reduced among cells in which actin filaments were depolymerized. The parameter σ also exhibited a subcellular spatial dependence. Based on our findings regarding the frequency dependence of σ of the storage modulus G('), we proposed two types of cell-to-cell variation in G(') that arise from the purely elastic and the frequency-dependent components in terms of the soft glassy rheology model of cell deformability. We concluded that the latter inherent cell-to-cell variation can be reduced greatly by disrupting actin networks, by probing at locations within the cell nucleus boundaries distant from the cell center, and by measuring at high loading frequencies.
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Affiliation(s)
- PingGen Cai
- Graduate School of Information Science and Technology, Hokkaido University, Sapporo, Japan
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37
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Ingber DE, Wang N, Stamenović D. Tensegrity, cellular biophysics, and the mechanics of living systems. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2014; 77:046603. [PMID: 24695087 PMCID: PMC4112545 DOI: 10.1088/0034-4885/77/4/046603] [Citation(s) in RCA: 227] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The recent convergence between physics and biology has led many physicists to enter the fields of cell and developmental biology. One of the most exciting areas of interest has been the emerging field of mechanobiology that centers on how cells control their mechanical properties, and how physical forces regulate cellular biochemical responses, a process that is known as mechanotransduction. In this article, we review the central role that tensegrity (tensional integrity) architecture, which depends on tensile prestress for its mechanical stability, plays in biology. We describe how tensional prestress is a critical governor of cell mechanics and function, and how use of tensegrity by cells contributes to mechanotransduction. Theoretical tensegrity models are also described that predict both quantitative and qualitative behaviors of living cells, and these theoretical descriptions are placed in context of other physical models of the cell. In addition, we describe how tensegrity is used at multiple size scales in the hierarchy of life—from individual molecules to whole living organisms—to both stabilize three-dimensional form and to channel forces from the macroscale to the nanoscale, thereby facilitating mechanochemical conversion at the molecular level.
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Affiliation(s)
- Donald E. Ingber
- Wyss Institute for Biologically Inspired Engineering at Harvard University, Harvard Medical School, Harvard School of Engineering and Applied Sciences, and Boston Children’s Hospital, 3 Blackfan Circle, CLSB5, Boston, MA 02115
| | - Ning Wang
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, 1206 W. Green St, Urbana, IL 61801
| | - Dimitrije Stamenović
- Department of Biomedical Engineering, and Division of Material Science and Engineering, College of Engineering, Boston University, 44 Cummington Mall, Boston, MA 02215
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38
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Pritchard RH, Huang YYS, Terentjev EM. Mechanics of biological networks: from the cell cytoskeleton to connective tissue. SOFT MATTER 2014; 10:1864-84. [PMID: 24652375 DOI: 10.1039/c3sm52769g] [Citation(s) in RCA: 107] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
From the cell cytoskeleton to connective tissues, fibrous networks are ubiquitous in metazoan life as the key promoters of mechanical strength, support and integrity. In recent decades, the application of physics to biological systems has made substantial strides in elucidating the striking mechanical phenomena observed in such networks, explaining strain stiffening, power law rheology and cytoskeletal fluidisation - all key to the biological function of individual cells and tissues. In this review we focus on the current progress in the field, with a primer into the basic physics of individual filaments and the networks they form. This is followed by a discussion of biological networks in the context of a broad spread of recent in vitro and in vivo experiments.
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Affiliation(s)
- Robyn H Pritchard
- Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE, UK.
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39
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Microtubules mediate changes in membrane cortical elasticity during contractile activation. Exp Cell Res 2014; 322:21-9. [DOI: 10.1016/j.yexcr.2013.12.027] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Revised: 12/17/2013] [Accepted: 12/31/2013] [Indexed: 12/20/2022]
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40
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Dinardo CL, Venturini G, Zhou EH, Watanabe IS, Campos LCG, Dariolli R, da Motta-Leal-Filho JM, Carvalho VM, Cardozo KHM, Krieger JE, Alencar AM, Pereira AC. Variation of mechanical properties and quantitative proteomics of VSMC along the arterial tree. Am J Physiol Heart Circ Physiol 2014; 306:H505-16. [DOI: 10.1152/ajpheart.00655.2013] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Vascular smooth muscle cells (VSMCs) are thought to assume a quiescent and homogeneous mechanical behavior after arterial tree development phase. However, VSMCs are known to be molecularly heterogeneous in other aspects and their mechanics may play a role in pathological situations. Our aim was to evaluate VSMCs from different arterial beds in terms of mechanics and proteomics, as well as investigate factors that may influence this phenotype. VSMCs obtained from seven arteries were studied using optical magnetic twisting cytometry (both in static state and after stretching) and shotgun proteomics. VSMC mechanical data were correlated with anatomical parameters and ultrastructural images of their vessels of origin. Femoral, renal, abdominal aorta, carotid, mammary, and thoracic aorta exhibited descending order of stiffness (G, P < 0.001). VSMC mechanical data correlated with the vessel percentage of elastin and amount of surrounding extracellular matrix (ECM), which decreased with the distance from the heart. After 48 h of stretching simulating regional blood flow of elastic arteries, VSMCs exhibited a reduction in basal rigidity. VSMCs from the thoracic aorta expressed a significantly higher amount of proteins related to cytoskeleton structure and organization vs. VSMCs from the femoral artery. VSMCs are heterogeneous in terms of mechanical properties and expression/organization of cytoskeleton proteins along the arterial tree. The mechanical phenotype correlates with the composition of ECM and can be modulated by cyclic stretching imposed on VSMCs by blood flow circumferential stress.
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Affiliation(s)
- Carla Luana Dinardo
- Heart Institute (InCor), University of São Paulo Medical School, São Paulo, Brazil
| | - Gabriela Venturini
- Heart Institute (InCor), University of São Paulo Medical School, São Paulo, Brazil
| | - Enhua H. Zhou
- Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts
| | - Ii Sei Watanabe
- Institute of Biomedical Sciences, Department of Anatomy, University of São Paulo, São Paulo, Brazil
| | | | - Rafael Dariolli
- Heart Institute (InCor), University of São Paulo Medical School, São Paulo, Brazil
| | | | | | | | - José Eduardo Krieger
- Heart Institute (InCor), University of São Paulo Medical School, São Paulo, Brazil
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41
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Biomechanical imaging of cell stiffness and prestress with subcellular resolution. Biomech Model Mechanobiol 2013; 13:665-78. [DOI: 10.1007/s10237-013-0526-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2013] [Accepted: 08/28/2013] [Indexed: 10/26/2022]
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42
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Head DA, Mizuno D. Local mechanical response in semiflexible polymer networks subjected to an axisymmetric prestress. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 88:022717. [PMID: 24032874 DOI: 10.1103/physreve.88.022717] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2013] [Revised: 07/12/2013] [Indexed: 06/02/2023]
Abstract
Analytical and numerical calculations are presented for the mechanical response of fiber networks in a state of axisymmetric prestress, in the limit where geometric nonlinearities such as fiber rotation are negligible. This allows us to focus on the anisotropy deriving purely from the nonlinear force-extension curves of individual fibers. The number of independent elastic coefficients for isotropic, axisymmetric, and fully anisotropic networks are enumerated before deriving expressions for the response to a locally applied force that can be tested against, e.g., microrheology experiments. Localized forces can generate anisotropy away from the point of application, so numerical integration of nonlinear continuum equations is employed to determine the stress field, and induced mechanical anisotropy, at points located directly behind and in front of a force monopole. Results are presented for the wormlike chain model in normalized forms, allowing them to be easily mapped to a range of systems. Finally, the relevance of these findings to naturally occurring systems and directions for future investigation are discussed.
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Affiliation(s)
- David A Head
- School of Computing, Leeds University, Leeds LS2 9JT, United Kingdom
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43
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Hardin C, Rajendran K, Manomohan G, Tambe DT, Butler JP, Fredberg JJ, Martinelli R, Carman CV, Krishnan R. Glassy dynamics, cell mechanics, and endothelial permeability. J Phys Chem B 2013; 117:12850-6. [PMID: 23638866 DOI: 10.1021/jp4020965] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
A key feature of all inflammatory processes is disruption of the vascular endothelial barrier. Such disruption is initiated in part through active contraction of the cytoskeleton of the endothelial cell (EC). Because contractile forces are propagated from cell to cell across a great many cell-cell junctions, this contractile process is strongly cooperative and highly nonlocal. We show here that the characteristic length scale of propagation is modulated by agonists and antagonists that impact permeability of the endothelial barrier. In the presence of agonists including thrombin, histamine, and H2O2, force correlation length increases, whereas in the presence of antagonists including sphingosine-1-phosphate, hepatocyte growth factor, and the rho kinase inhibitor, Y27632, force correlation length decreases. Intercellular force chains and force clusters are also evident, both of which are reminiscent of soft glassy materials approaching a glass transition.
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Affiliation(s)
- Corey Hardin
- Division of Pulmonary and Critical Care Medicine, Massachusetts General Hospital , Boston, Massachusetts
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44
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Tambe DT, Croutelle U, Trepat X, Park CY, Kim JH, Millet E, Butler JP, Fredberg JJ. Monolayer stress microscopy: limitations, artifacts, and accuracy of recovered intercellular stresses. PLoS One 2013; 8:e55172. [PMID: 23468843 PMCID: PMC3585344 DOI: 10.1371/journal.pone.0055172] [Citation(s) in RCA: 121] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2012] [Accepted: 12/19/2012] [Indexed: 12/18/2022] Open
Abstract
In wound healing, tissue growth, and certain cancers, the epithelial or the endothelial monolayer sheet expands. Within the expanding monolayer sheet, migration of the individual cell is strongly guided by physical forces imposed by adjacent cells. This process is called plithotaxis and was discovered using Monolayer Stress Microscopy (MSM). MSM rests upon certain simplifying assumptions, however, concerning boundary conditions, cell material properties and system dimensionality. To assess the validity of these assumptions and to quantify associated errors, here we report new analytical, numerical, and experimental investigations. For several commonly used experimental monolayer systems, the simplifying assumptions used previously lead to errors that are shown to be quite small. Out-of-plane components of displacement and traction fields can be safely neglected, and characteristic features of intercellular stresses that underlie plithotaxis remain largely unaffected. Taken together, these findings validate Monolayer Stress Microscopy within broad but well-defined limits of applicability.
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Affiliation(s)
- Dhananjay T Tambe
- Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, USA.
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45
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Han SJ, Bielawski KS, Ting LH, Rodriguez ML, Sniadecki NJ. Decoupling substrate stiffness, spread area, and micropost density: a close spatial relationship between traction forces and focal adhesions. Biophys J 2013; 103:640-8. [PMID: 22947925 DOI: 10.1016/j.bpj.2012.07.023] [Citation(s) in RCA: 130] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2011] [Revised: 07/03/2012] [Accepted: 07/18/2012] [Indexed: 01/30/2023] Open
Abstract
Mechanical cues can influence the manner in which cells generate traction forces and form focal adhesions. The stiffness of a cell's substrate and the available area on which it can spread can influence its generation of traction forces, but to what extent these factors are intertwined is unclear. In this study, we used microcontact printing and micropost arrays to control cell spreading, substrate stiffness, and post density to assess their effect on traction forces and focal adhesions. We find that both the spread area and the substrate stiffness influence traction forces in an independent manner, but these factors have opposite effects: cells on stiffer substrates produce higher average forces, whereas cells with larger spread areas generate lower average forces. We show that post density influences the generation of traction forces in a manner that is more dominant than the effect of spread area. Additionally, we observe that focal adhesions respond to spread area, substrate stiffness, and post density in a manner that closely matches the trends seen for traction forces. This work supports the notion that traction forces and focal adhesions have a close relationship in their response to mechanical cues.
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Affiliation(s)
- Sangyoon J Han
- Department of Mechanical Engineering, University of Washington, Seattle, Washington, USA
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46
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Wood ST, Dean BC, Dean D. A computational approach to understand phenotypic structure and constitutive mechanics relationships of single cells. Ann Biomed Eng 2012. [PMID: 23180027 DOI: 10.1007/s10439-012-0690-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The goal of this study is to construct a representative 3D finite element model (FEM) of individual cells based on their sub-cellular structures that predicts cell mechanical behavior. The FEM simulations replicate atomic force microscopy (AFM) nanoindentation experiments on live vascular smooth muscle cells. Individual cells are characterized mechanically with AFM and then imaged in 3D using a spinning disc confocal microscope. Using these images, geometries for the FEM are automatically generated via image segmentation and linear programming algorithms. The geometries consist of independent structures representing the nucleus, actin stress fiber network, and cytoplasm. These are imported into commercial software for mesh refinement and analysis. The FEM presented here is capable of predicting AFM results well for 500 nm indentations. The FEM results are relatively insensitive to both the exact number and diameter of fibers used. Despite the localized nature of AFM nanoindentation, the model predicts that stresses are distributed in an anisotropic manner throughout the cell body via the actin stress fibers. This pattern of stress distribution is likely a result of the geometric arrangement of the actin network.
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Affiliation(s)
- Scott T Wood
- Department of Bioengineering, Clemson University, 301 Rhodes Research Center, Clemson, SC 29634, USA
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47
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Oh MJ, Kuhr F, Byfield F, Levitan I. Micropipette aspiration of substrate-attached cells to estimate cell stiffness. J Vis Exp 2012:3886. [PMID: 23051713 PMCID: PMC3490255 DOI: 10.3791/3886] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Growing number of studies show that biomechanical properties of individual cells play major roles in multiple cellular functions, including cell proliferation, differentiation, migration and cell-cell interactions. The two key parameters of cellular biomechanics are cellular deformability or stiffness and the ability of the cells to contract and generate force. Here we describe a quick and simple method to estimate cell stiffness by measuring the degree of membrane deformation in response to negative pressure applied by a glass micropipette to the cell surface, a technique that is called Micropipette Aspiration or Microaspiration. Microaspiration is performed by pulling a glass capillary to create a micropipette with a very small tip (2-50 μm diameter depending on the size of a cell or a tissue sample), which is then connected to a pneumatic pressure transducer and brought to a close vicinity of a cell under a microscope. When the tip of the pipette touches a cell, a step of negative pressure is applied to the pipette by the pneumatic pressure transducer generating well-defined pressure on the cell membrane. In response to pressure, the membrane is aspirated into the pipette and progressive membrane deformation or "membrane projection" into the pipette is measured as a function of time. The basic principle of this experimental approach is that the degree of membrane deformation in response to a defined mechanical force is a function of membrane stiffness. The stiffer the membrane is, the slower the rate of membrane deformation and the shorter the steady-state aspiration length. The technique can be performed on isolated cells, both in suspension and substrate-attached, large organelles, and liposomes. Analysis is performed by comparing maximal membrane deformations achieved under a given pressure for different cell populations or experimental conditions. A "stiffness coefficient" is estimated by plotting the aspirated length of membrane deformation as a function of the applied pressure. Furthermore, the data can be further analyzed to estimate the Young's modulus of the cells (E), the most common parameter to characterize stiffness of materials. It is important to note that plasma membranes of eukaryotic cells can be viewed as a bi-component system where membrane lipid bilayer is underlied by the sub-membrane cytoskeleton and that it is the cytoskeleton that constitutes the mechanical scaffold of the membrane and dominates the deformability of the cellular envelope. This approach, therefore, allows probing the biomechanical properties of the sub-membrane cytoskeleton.
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Affiliation(s)
- Myung-Jin Oh
- Section of Respiratory, Critical Care and Sleep Medicine, Department of Medicine, University of Illinois, USA
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48
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Deguchi S, Matsui TS, Sato M. Simultaneous contraction and buckling of stress fibers in individual cells. J Cell Biochem 2012; 113:824-32. [DOI: 10.1002/jcb.23410] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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49
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Matsumoto T, Nagayama K. Tensile properties of vascular smooth muscle cells: bridging vascular and cellular biomechanics. J Biomech 2011; 45:745-55. [PMID: 22177671 DOI: 10.1016/j.jbiomech.2011.11.014] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/30/2011] [Indexed: 01/16/2023]
Abstract
Vascular walls change their dimensions and mechanical properties adaptively in response to blood pressure. Because these responses are driven by the smooth muscle cells (SMCs) in the media, a detailed understanding of the mechanical environment of the SMCs should reveal the mechanism of the adaptation. As the mechanical properties of the media are highly heterogeneous at the microscopic level, the mechanical properties of the cells should be measured directly. The tensile properties of SMCs are, thus, important to reveal the microscopic mechanical environment in vascular tissues; their tensile properties have a close correlation with the distribution and arrangement of elements of the cytoskeletal networks, such as stress fibers and microtubules. In this review, we first introduce the experimental techniques used for tensile testing and discuss the various factors affecting the tensile properties of vascular SMCs. Cytoskeletal networks are particularly important for the mechanical properties of a cell and its mechanism of mechanotransduction; thus, the mechanical properties of cytoskeletal filaments and their effects on whole-cell mechanical properties are discussed with special attention to the balance of intracellular forces among the intracellular components that determines the force applied to each element of the cytoskeletal filaments, which is the key to revealing the mechanotransduction events regulating mechanical adaptation. Lastly, we suggest future directions to connect tissue and cell mechanics and to elucidate the mechanism of mechanical adaptation, one of the key issues of cardiovascular solid biomechanics.
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Affiliation(s)
- Takeo Matsumoto
- Biomechanics Laboratory, Department of Mechanical Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan.
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50
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Deguchi S, Matsui TS, Iio K. The position and size of individual focal adhesions are determined by intracellular stress-dependent positive regulation. Cytoskeleton (Hoboken) 2011; 68:639-51. [DOI: 10.1002/cm.20541] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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