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Buenaventura A, Saito T, Kanao T, Matsunaga D, Matsui TS, Deguchi S. Intracellular Macromolecular Crowding within Individual Stress Fibers Analyzed by Fluorescence Correlation Spectroscopy. Cell Mol Bioeng 2024; 17:165-176. [PMID: 39050511 PMCID: PMC11263330 DOI: 10.1007/s12195-024-00803-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Accepted: 05/06/2024] [Indexed: 07/27/2024] Open
Abstract
Introduction The diffusion of cell components such as proteins is crucial to the function of all living cells. The abundance of macromolecules in cells is likely to cause a state of macromolecular crowding, but its effects on the extent of diffusion remain poorly understood. Methods Here we investigate the diffusion rate in three distinct locations in mesenchymal cell types, namely the open cytoplasm, the stress fibers in the open cytoplasm, and those below the nucleus using three kinds of biologically inert green fluorescent proteins (GFPs), namely a monomer, dimer, and trimer GFP. Fluorescence correlation spectroscopy (FCS) was used to determine the diffusion coefficients. Results We show that diffusion tends to be lowered on average in stress fibers and is significantly lower in those located below the nucleus. Our data suggest that the diffusive properties of GFPs, and potentially other molecules as well, are hindered by macromolecular crowding. However, although the size dependence on protein diffusion was also studied for monomer, dimer, and trimer GFPs, there was no significant difference in the diffusion rates among the GFPs of these sizes. These results could be attributed to the lack of significant change in protein size among the selected GFP multimers. Conclusion The data presented here would provide a basis for better understanding of the complex protein diffusion in the nonuniform cytoplasm, shedding light on cellular responses to mechanical stress, their local mechanical properties, and reduced turnover in senescent cells.
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Affiliation(s)
- Aria Buenaventura
- Division of Bioengineering, Osaka University, Toyonaka, 560-0043 Japan
| | - Takumi Saito
- Division of Bioengineering, Osaka University, Toyonaka, 560-0043 Japan
- Graduate School of Biomedical Engineering, Tohoku University, Sendai, 980-0812 Japan
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, USA
- Nanobiology Institute, Yale University, West Haven, USA
| | - Taiga Kanao
- Division of Bioengineering, Osaka University, Toyonaka, 560-0043 Japan
| | - Daiki Matsunaga
- Division of Bioengineering, Osaka University, Toyonaka, 560-0043 Japan
| | - Tsubasa S. Matsui
- Division of Bioengineering, Osaka University, Toyonaka, 560-0043 Japan
| | - Shinji Deguchi
- Division of Bioengineering, Osaka University, Toyonaka, 560-0043 Japan
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2
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Cao R, Tian H, Tian Y, Fu X. A Hierarchical Mechanotransduction System: From Macro to Micro. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2302327. [PMID: 38145330 PMCID: PMC10953595 DOI: 10.1002/advs.202302327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Revised: 10/27/2023] [Indexed: 12/26/2023]
Abstract
Mechanotransduction is a strictly regulated process whereby mechanical stimuli, including mechanical forces and properties, are sensed and translated into biochemical signals. Increasing data demonstrate that mechanotransduction is crucial for regulating macroscopic and microscopic dynamics and functionalities. However, the actions and mechanisms of mechanotransduction across multiple hierarchies, from molecules, subcellular structures, cells, tissues/organs, to the whole-body level, have not been yet comprehensively documented. Herein, the biological roles and operational mechanisms of mechanotransduction from macro to micro are revisited, with a focus on the orchestrations across diverse hierarchies. The implications, applications, and challenges of mechanotransduction in human diseases are also summarized and discussed. Together, this knowledge from a hierarchical perspective has the potential to refresh insights into mechanotransduction regulation and disease pathogenesis and therapy, and ultimately revolutionize the prevention, diagnosis, and treatment of human diseases.
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Affiliation(s)
- Rong Cao
- Department of Endocrinology and MetabolismCenter for Diabetes Metabolism ResearchState Key Laboratory of Biotherapy and Cancer CenterWest China Medical SchoolWest China HospitalSichuan University and Collaborative Innovation CenterChengduSichuan610041China
| | - Huimin Tian
- Department of Endocrinology and MetabolismCenter for Diabetes Metabolism ResearchState Key Laboratory of Biotherapy and Cancer CenterWest China Medical SchoolWest China HospitalSichuan University and Collaborative Innovation CenterChengduSichuan610041China
| | - Yan Tian
- Department of Endocrinology and MetabolismCenter for Diabetes Metabolism ResearchState Key Laboratory of Biotherapy and Cancer CenterWest China Medical SchoolWest China HospitalSichuan University and Collaborative Innovation CenterChengduSichuan610041China
| | - Xianghui Fu
- Department of Endocrinology and MetabolismCenter for Diabetes Metabolism ResearchState Key Laboratory of Biotherapy and Cancer CenterWest China Medical SchoolWest China HospitalSichuan University and Collaborative Innovation CenterChengduSichuan610041China
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3
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Manifacier I, Carlin G, Liu D, Vassaux M, Pieuchot L, Luchnikov V, Anselme K, Milan JL. In silico analysis shows that dynamic changes in curvature guide cell migration over long distances. Biomech Model Mechanobiol 2024; 23:315-333. [PMID: 37875692 DOI: 10.1007/s10237-023-01777-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Accepted: 09/24/2023] [Indexed: 10/26/2023]
Abstract
In vitro experiments have shown that cell scale curvatures influence cell migration; cells avoid convex hills and settle in concave valleys. However, it is not known whether dynamic changes in curvature can guide cell migration. This study extends a previous in-silico model to explore the effects over time of changing the substrate curvature on cell migration guidance. By simulating a dynamic surface curvature using traveling wave patterns, we investigate the influence of wave height and speed, and find that long-distance cell migration guidance can be achieved on specific wave patterns. We propose a mechanistic explanation of what we call dynamic curvotaxis and highlight those cellular features that may be involved. Our results open a new area of study for understanding cell mobility in dynamic environments, from single-cell in vitro experiments to multi-cellular in vivo mechanisms.
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Affiliation(s)
- Ian Manifacier
- Aix Marseille Univ, CNRS, ISM, Marseille, France
- APHM, Institute for Locomotion, Department of Orthopaedics and Traumatology, St Marguerite Hospital, Marseille, France
| | - Gildas Carlin
- Aix Marseille Univ, CNRS, ISM, Marseille, France
- APHM, Institute for Locomotion, Department of Orthopaedics and Traumatology, St Marguerite Hospital, Marseille, France
| | - Dongshu Liu
- Aix Marseille Univ, CNRS, ISM, Marseille, France
- APHM, Institute for Locomotion, Department of Orthopaedics and Traumatology, St Marguerite Hospital, Marseille, France
| | - Maxime Vassaux
- Univ Rennes, CNRS, IPR (Institut de Physique de Rennes) - UMR 6251, 35000, Rennes, France
| | - Laurent Pieuchot
- Université de Haute-Alsace, CNRS, IS2M UMR 7361, Mulhouse, 68100, France
| | - Valeriy Luchnikov
- Université de Haute-Alsace, CNRS, IS2M UMR 7361, Mulhouse, 68100, France
| | - Karine Anselme
- Université de Haute-Alsace, CNRS, IS2M UMR 7361, Mulhouse, 68100, France
| | - Jean-Louis Milan
- Aix Marseille Univ, CNRS, ISM, Marseille, France.
- APHM, Institute for Locomotion, Department of Orthopaedics and Traumatology, St Marguerite Hospital, Marseille, France.
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4
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Giverso C, Loy N, Lucci G, Preziosi L. Cell orientation under stretch: A review of experimental findings and mathematical modelling. J Theor Biol 2023; 572:111564. [PMID: 37391125 DOI: 10.1016/j.jtbi.2023.111564] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2023] [Accepted: 06/15/2023] [Indexed: 07/02/2023]
Abstract
The key role of electro-chemical signals in cellular processes had been known for many years, but more recently the interplay with mechanics has been put in evidence and attracted substantial research interests. Indeed, the sensitivity of cells to mechanical stimuli coming from the microenvironment turns out to be relevant in many biological and physiological circumstances. In particular, experimental evidence demonstrated that cells on elastic planar substrates undergoing periodic stretches, mimicking native cyclic strains in the tissue where they reside, actively reorient their cytoskeletal stress fibres. At the end of the realignment process, the cell axis forms a certain angle with the main stretching direction. Due to the importance of a deeper understanding of mechanotransduction, such a phenomenon was studied both from the experimental and the mathematical modelling point of view. The aim of this review is to collect and discuss both the experimental results on cell reorientation and the fundamental features of the mathematical models that have been proposed in the literature.
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Affiliation(s)
- Chiara Giverso
- Department of Mathematical Sciences "G.L. Lagrange", Politecnico di Torino, Corso Duca degli Abruzzi 24, Turin, 10126, Italy.
| | - Nadia Loy
- Department of Mathematical Sciences "G.L. Lagrange", Politecnico di Torino, Corso Duca degli Abruzzi 24, Turin, 10126, Italy.
| | - Giulio Lucci
- Department of Mathematical Sciences "G.L. Lagrange", Politecnico di Torino, Corso Duca degli Abruzzi 24, Turin, 10126, Italy.
| | - Luigi Preziosi
- Department of Mathematical Sciences "G.L. Lagrange", Politecnico di Torino, Corso Duca degli Abruzzi 24, Turin, 10126, Italy.
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5
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Ruppel A, Wörthmüller D, Misiak V, Kelkar M, Wang I, Moreau P, Méry A, Révilloud J, Charras G, Cappello G, Boudou T, Schwarz US, Balland M. Force propagation between epithelial cells depends on active coupling and mechano-structural polarization. eLife 2023; 12:e83588. [PMID: 37548995 PMCID: PMC10511242 DOI: 10.7554/elife.83588] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Accepted: 08/07/2023] [Indexed: 08/08/2023] Open
Abstract
Cell-generated forces play a major role in coordinating the large-scale behavior of cell assemblies, in particular during development, wound healing, and cancer. Mechanical signals propagate faster than biochemical signals, but can have similar effects, especially in epithelial tissues with strong cell-cell adhesion. However, a quantitative description of the transmission chain from force generation in a sender cell, force propagation across cell-cell boundaries, and the concomitant response of receiver cells is missing. For a quantitative analysis of this important situation, here we propose a minimal model system of two epithelial cells on an H-pattern ('cell doublet'). After optogenetically activating RhoA, a major regulator of cell contractility, in the sender cell, we measure the mechanical response of the receiver cell by traction force and monolayer stress microscopies. In general, we find that the receiver cells show an active response so that the cell doublet forms a coherent unit. However, force propagation and response of the receiver cell also strongly depend on the mechano-structural polarization in the cell assembly, which is controlled by cell-matrix adhesion to the adhesive micropattern. We find that the response of the receiver cell is stronger when the mechano-structural polarization axis is oriented perpendicular to the direction of force propagation, reminiscent of the Poisson effect in passive materials. We finally show that the same effects are at work in small tissues. Our work demonstrates that cellular organization and active mechanical response of a tissue are key to maintain signal strength and lead to the emergence of elasticity, which means that signals are not dissipated like in a viscous system, but can propagate over large distances.
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Affiliation(s)
- Artur Ruppel
- Université Grenoble Alpes, CNRS, LIPhyGrenobleFrance
| | - Dennis Wörthmüller
- Institute for Theoretical Physics, Heidelberg UniversityHeidelbergGermany
- BioQuant–Center for Quantitative Biology, Heidelberg UniversityHeidelbergGermany
| | | | - Manasi Kelkar
- London Centre for Nanotechnology, University College LondonLondonUnited Kingdom
| | - Irène Wang
- Université Grenoble Alpes, CNRS, LIPhyGrenobleFrance
| | | | - Adrien Méry
- Université Grenoble Alpes, CNRS, LIPhyGrenobleFrance
| | | | - Guillaume Charras
- London Centre for Nanotechnology, University College LondonLondonUnited Kingdom
- Department of Cell and Developmental Biology, University College LondonLondonUnited Kingdom
- Institute for the Physics of Living Systems, University College LondonLondonUnited Kingdom
| | | | - Thomas Boudou
- Université Grenoble Alpes, CNRS, LIPhyGrenobleFrance
| | - Ulrich S Schwarz
- Institute for Theoretical Physics, Heidelberg UniversityHeidelbergGermany
- BioQuant–Center for Quantitative Biology, Heidelberg UniversityHeidelbergGermany
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6
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Mahutga RR, Barocas VH, Alford PW. The non-affine fiber network solver: A multiscale fiber network material model for finite-element analysis. J Mech Behav Biomed Mater 2023; 144:105967. [PMID: 37329673 PMCID: PMC10330778 DOI: 10.1016/j.jmbbm.2023.105967] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2023] [Revised: 06/01/2023] [Accepted: 06/06/2023] [Indexed: 06/19/2023]
Abstract
Multiscale mechanical models in biomaterials research have largely relied on simplifying the microstructure in order to make large-scale simulations tractable. The microscale simplifications often rely on approximations of the constituent distributions and assumptions on the deformation of the constituents. Of particular interest in biomechanics are fiber embedded materials, where simplified fiber distributions and assumed affinity in the fiber deformation greatly influence the mechanical behavior. The consequences of these assumptions are problematic when dealing with microscale mechanical phenomena such as cellular mechanotransduction in growth and remodeling, and fiber-level failure events during tissue failure. In this work, we propose a technique for coupling non-affine network models to finite element solvers, allowing for simulation of discrete microstructural phenomena within macroscopically complex geometries. The developed plugin is readily available as an open-source library for use with the bio-focused finite element software FEBio, and the description of the implementation allows for the adaptation to other finite element solvers.
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Affiliation(s)
- Ryan R Mahutga
- Department of Biomedical Engineering, University of Minnesota - Twin Cities, Minneapolis, MN, USA.
| | - Victor H Barocas
- Department of Biomedical Engineering, University of Minnesota - Twin Cities, Minneapolis, MN, USA
| | - Patrick W Alford
- Department of Biomedical Engineering, University of Minnesota - Twin Cities, Minneapolis, MN, USA
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7
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Karkhaneh Yousefi AA, Petit C, Ben Hassine A, Avril S. Stiffness sensing by smooth muscle cells: Continuum mechanics modeling of the acto-myosin role. J Mech Behav Biomed Mater 2023; 144:105990. [PMID: 37385127 DOI: 10.1016/j.jmbbm.2023.105990] [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: 02/20/2023] [Revised: 05/30/2023] [Accepted: 06/23/2023] [Indexed: 07/01/2023]
Abstract
Aortic smooth muscle cells (SMCs) play a vital role in maintaining homeostasis in the aorta by sensing and responding to mechanical stimuli. However, the mechanisms that underlie the ability of SMCs to sense and respond to stiffness change in their environment are still partially unclear. In this study, we focus on the role of acto-myosin contractility in stiffness sensing and introduce a novel continuum mechanics approach based on the principles of thermal strains. Each stress fiber satisfies a universal stress-strain relationship driven by a Young's modulus, a contraction coefficient scaling the fictitious thermal strain, a maximum contraction stress and a softening parameter describing the sliding effects between actin and myosin filaments. To account for the inherent variability of cellular responses, large populations of SMCs are modeled with the finite-element method, each cell having a random number and a random arrangement of stress fibers. Moreover, the level of myosin activation in each stress fiber satisfies a Weibull probability density function. Model predictions are compared to traction force measurements on different SMC lineages. It is demonstrated that the model not only predicts well the effects of substrate stiffness on cellular traction, but it can also successfully approximate the statistical variations of cellular tractions induced by intercellular variability. Finally, stresses in the nuclear envelope and in the nucleus are computed with the model, showing that the variations of cytoskeletal forces induced by substrate stiffness directly induce deformations of the nucleus which can potentially alter gene expression. The predictability of the model combined to its relative simplicity are promising assets for further investigation of stiffness sensing in 3D environments. Eventually, this could contribute to decipher the effects of mechanosensitivity impairment, which are known to be at the root of aortic aneurysms.
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Affiliation(s)
| | - Claudie Petit
- Mines Saint-Etienne, Université Jean Monnet, INSERM, U1059 SAINBIOSE, 42023, Saint-Etienne, France
| | - Amira Ben Hassine
- Mines Saint-Etienne, Université Jean Monnet, INSERM, U1059 SAINBIOSE, 42023, Saint-Etienne, France
| | - Stéphane Avril
- Mines Saint-Etienne, Université Jean Monnet, INSERM, U1059 SAINBIOSE, 42023, Saint-Etienne, France.
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8
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Xu J, Wang Q, Li X, Zheng Y, Ji B. Cellular mechanisms of wound closure under cyclic stretching. Biophys J 2023; 122:2404-2420. [PMID: 36966361 PMCID: PMC10322892 DOI: 10.1016/j.bpj.2023.03.034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2022] [Revised: 02/23/2023] [Accepted: 03/22/2023] [Indexed: 03/27/2023] Open
Abstract
Wound closure is a fundamental process in many physiological and pathological processes, but the regulating effects of external force on the closure process are still unclear. Here, we systematically studied the closure process of wounds of different shape under cyclic stretching. We found that the stretching amplitude and direction had significant effect on the healing speed and healing mode. For instance, there was a biphasic dependence of the healing speed on the stretching amplitude. That is, the wound closure was faster under relatively small and large amplitude, while it was slower under intermediate amplitude. At the same time, the stretching could regulate the healing pattern. We showed that the stretching would increase the healing speed along the direction perpendicular to the stretching direction. Specifically, when the stretching was along the major axis of the wound, it accelerated the healing speed along the short axis, which induced a rosette to stitching-line mode transition. In contrast, stretching along the minor axis accelerated the healing speed along the long axis, inducing a stitching-line to rosette mode transition. Our theoretical analyses demonstrated that the wound closure process was coregulated by the mechanical factors including prestress in the cytoskeleton, the protrusion of cells, and the contraction of the actin ring, as well as the geometry of the wound. The cyclic stretch could further modulate the roles of these factors. For example, the stretching changed the stress field in the cell layer, and switched the direction of cell protrusions. This article reveals important cellular mechanisms of the wound healing process under cyclic stretching, and provides an insight into possible approaches of regulating cell collective behaviors via mechanical forces.
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Affiliation(s)
- Jiayi Xu
- Department of Applied Mechanics, Beijing Institute of Technology, Beijing, China; Wenzhou Key Laboratory of Biophysics, Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou, China
| | - Qianchun Wang
- Wenzhou Key Laboratory of Biophysics, Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou, China
| | - Xiaojun Li
- Department of Applied Mechanics, Beijing Institute of Technology, Beijing, China
| | - Yifei Zheng
- Institute of Biomechanics and Applications, Department of Engineering Mechanics, Zhejiang University, Hangzhou, China
| | - Baohua Ji
- Institute of Biomechanics and Applications, Department of Engineering Mechanics, Zhejiang University, Hangzhou, China.
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9
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Ni H, Ni Q, Papoian GA, Trache A, Jiang Y. Myosin and [Formula: see text]-actinin regulation of stress fiber contractility under tensile stress. Sci Rep 2023; 13:8662. [PMID: 37248294 PMCID: PMC10227020 DOI: 10.1038/s41598-023-35675-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Accepted: 05/19/2023] [Indexed: 05/31/2023] Open
Abstract
Stress fibers are actomyosin bundles that regulate cellular mechanosensation and force transduction. Interacting with the extracellular matrix through focal adhesion complexes, stress fibers are highly dynamic structures regulated by myosin motors and crosslinking proteins. Under external mechanical stimuli such as tensile forces, the stress fiber remodels its architecture to adapt to external cues, displaying properties of viscoelastic materials. How the structural remodeling of stress fibers is related to the generation of contractile force is not well understood. In this work, we simulate mechanochemical dynamics and force generation of stress fibers using the molecular simulation platform MEDYAN. We model stress fiber as two connecting bipolar bundles attached at the ends to focal adhesion complexes. The simulated stress fibers generate contractile force that is regulated by myosin motors and [Formula: see text]-actinin crosslinkers. We find that stress fibers enhance contractility by reducing the distance between actin filaments to increase crosslinker binding, and this structural remodeling ability depends on the crosslinker turnover rate. Under tensile pulling force, the stress fiber shows an instantaneous increase of the contractile forces followed by a slow relaxation into a new steady state. While the new steady state contractility after pulling depends only on the overlap between actin bundles, the short-term contractility enhancement is sensitive to the tensile pulling distance. We further show that this mechanical response is also sensitive to the crosslinker turnover rate. Our results provide new insights into the stress fiber mechanics that have significant implications for understanding cellular adaptation to mechanical signaling.
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Affiliation(s)
- Haoran Ni
- Institute for Physical Science and Technology, University of Maryland, College Park, MD, USA
| | - Qin Ni
- Institute for NanoBioTechnology, Johns Hopkins University, Baltimore, MD, USA
| | - Garegin A. Papoian
- Institute for Physical Science and Technology, University of Maryland, College Park, MD, USA
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD, USA
| | - Andreea Trache
- Department of Medical Physiology, Texas A &M University Health Science Center, Bryan, TX, USA
- Department of Biomedical Engineering, Texas A &M University, College Station, TX, USA
| | - Yi Jiang
- Department of Mathematics and Statistics, Georgia State University, Atlanta, GA, USA
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10
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Saito T, Deguchi S. CM-FRAP-Continuum Mechanics-Based Fluorescence Recovery After Photobleaching. Curr Protoc 2023; 3:e655. [PMID: 36689324 DOI: 10.1002/cpz1.655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Fluorescence recovery after photobleaching (FRAP) is widely used to evaluate intracellular molecular turnover or repeated translocation of molecules using confocal laser scanning microscopy. While numerous models have been developed for the analysis of FRAP responses, in which chemical interactions and/or fast diffusion processes are involved, it is inherently difficult to evaluate the long-term behavior of molecular turnover because of the presence of intracellular flow and microscopic deformation of bleached regions. To overcome these difficulties, we have developed a novel continuum mechanics-based FRAP (CM-FRAP) approach that enables simultaneous evaluation of long-term molecular turnover and intracellular flow/deformation. Here we demonstrate the utility of CM-FRAP by using actin molecules associated with stress fibers in rat aortic smooth muscle cells with clarification of the experimental setup and data analysis. © 2023 Wiley Periodicals LLC. Basic Protocol 1: Plasmid construction and sample preparation Basic Protocol 2: How to perform FRAP experiments Basic Protocol 3: Data analysis based on CM-FRAP.
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Affiliation(s)
- Takumi Saito
- Division of Bioengineering, Graduate School of Engineering Science, Osaka University, Japan.,Graduate School of Biomedical Engineering, Tohoku University, Japan.,Department of Molecular Biophysics and Biochemistry, Yale University, USA.,Nanobiology Institute, Yale University, USA
| | - Shinji Deguchi
- Division of Bioengineering, Graduate School of Engineering Science, Osaka University, Japan
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11
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Saito T, Matsunaga D, Deguchi S. Long-term molecular turnover of actin stress fibers revealed by advection-reaction analysis in fluorescence recovery after photobleaching. PLoS One 2022; 17:e0276909. [PMCID: PMC9639824 DOI: 10.1371/journal.pone.0276909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2022] [Accepted: 10/15/2022] [Indexed: 11/09/2022] Open
Abstract
Fluorescence recovery after photobleaching (FRAP) is a versatile technique to evaluate the intracellular molecular exchange called turnover. Mechanochemical models of FRAP typically consider the molecular diffusion and chemical reaction that simultaneously occur on a time scale of seconds to minutes. Particularly for long-term measurements, however, a mechanical advection effect can no longer be ignored, which transports the proteins in specific directions within the cells and accordingly shifts the spatial distribution of the local chemical equilibrium. Nevertheless, existing FRAP models have not considered the spatial shift, and as such, the turnover rate is often analyzed without considering the spatiotemporally updated chemical equilibrium. Here we develop a new FRAP model aimed at long-term measurements to quantitatively determine the two distinct effects of the advection and chemical reaction, i.e., the different major sources of the change in fluorescence intensity. To validate this approach, we carried out FRAP experiments on actin in stress fibers over a time period of more than 900 s, and the advection rate was shown to be comparable in magnitude to the chemical dissociation rate. We further found that the actin–myosin interaction and actin polymerization differently affect the advection and chemical dissociation. Our results suggest that the distinction between the two effects is indispensable to extract the intrinsic chemical properties of the actin cytoskeleton from the observations of complicated turnover in cells.
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Affiliation(s)
- Takumi Saito
- Division of Bioengineering, Graduate School of Engineering Science, Osaka University, Osaka, Japan
- Graduate School of Biomedical Engineering, Tohoku University, Tohoku, Japan
- JSPS Research Fellowship for Young Scientists, Tokyo, Japan
| | - Daiki Matsunaga
- Division of Bioengineering, Graduate School of Engineering Science, Osaka University, Osaka, Japan
| | - Shinji Deguchi
- Division of Bioengineering, Graduate School of Engineering Science, Osaka University, Osaka, Japan
- * E-mail:
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12
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Pajic-Lijakovic I, Milivojevic M. Marangoni effect and cell spreading. EUROPEAN BIOPHYSICS JOURNAL : EBJ 2022; 51:419-429. [PMID: 35930028 DOI: 10.1007/s00249-022-01612-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Accepted: 07/25/2022] [Indexed: 06/15/2023]
Abstract
Cells are very sensitive to the shear stress (SS). However, undesirable SS is generated during physiological process such as collective cell migration (CCM) and influences the biological processes such as morphogenesis, wound healing and cancer invasion. Despite extensive research devoted to study the SS generation caused by CCM, we still do not fully understand the main cause of SS appearance. An attempt is made here to offer some answers to these questions by considering the rearrangement of cell monolayers. The SS generation represents a consequence of natural and forced convection. While forced convection is dependent on cell speed, the natural convection is induced by the gradient of tissue surface tension. The phenomenon is known as the Marangoni effect. The gradient of tissue surface tension induces directed cell spreading from the regions of lower tissue surface tension to the regions of higher tissue surface tension and leads to the cell sorting. This directional cell migration is described by the Marangoni flux. The phenomenon has been recognized during the rearrangement of (1) epithelial cell monolayers and (2) mixed cell monolayers made by epithelial and mesenchymal cells. The consequence of the Marangoni effect is an intensive spreading of cancer cells through an epithelium. In this work, a review of existing literature about SS generation caused by CCM is given along with the assortment of published experimental findings, to invite experimentalists to test given theoretical considerations in multicellular systems.
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Affiliation(s)
- Ivana Pajic-Lijakovic
- Faculty of Technology and Metallurgy, Department of Chemical Engineering, University of Belgrade, Belgrade, Serbia.
| | - Milan Milivojevic
- Faculty of Technology and Metallurgy, Department of Chemical Engineering, University of Belgrade, Belgrade, Serbia
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13
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A statistical mechanics model for determining the length distribution of actin filaments under cellular tensional homeostasis. Sci Rep 2022; 12:14466. [PMID: 36002503 PMCID: PMC9402564 DOI: 10.1038/s41598-022-18833-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 08/22/2022] [Indexed: 11/08/2022] Open
Abstract
Tensional homeostasis is a cellular process whereby nonmuscle cells such as fibroblasts keep a constant level of intracellular tension and signaling activities. Cells are allowed thanks to tensional homeostasis to adapt to mechanical stress, but the detailed mechanism remains unclear. Here we address from a theoretical point of view what is required for maintaining cellular tensional homeostasis. A constrained optimization problem is formulated to analytically determine the probability function of the length of individual actin filaments (AFs) responsible for sustaining cellular tension. An objective function composed of two entropic quantities measuring the extent of formation and dispersion of AFs within cells is optimized under two constraint functions dictating a constant amount of actin molecules and tension that are arguably the two most salient features of tensional homeostasis. We then derive a specific probability function of AFs that is qualitatively consistent with previous experimental observations, in which short AF populations preferably appear. Regarding the underlying mechanism, our analyses suggest that the constraint for keeping the constant tension level makes long AF populations smaller in number because long AFs have a higher chance to be involved in bearing larger forces. The specific length distribution of AFs is thus required for achieving the constrained objectives, by which individual cells are endowed with the ability to stably maintain a homeostatic tension throughout the cell, thereby potentially allowing cells to locally detect deviation in the tension, keep resulting biological functions, and hence enable subsequent adaptation to mechanical stress. Although minimal essential factors are included given the actual complexity of cells, our approach would provide a theoretical basis for understanding complicated homeostatic and adaptive behavior of the cell.
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14
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Benvenuti E, Reho GA, Palumbo S, Fraldi M. Pre-strains and buckling in mechanosensitivity of contractile cells and focal adhesions: A tensegrity model. J Mech Behav Biomed Mater 2022; 135:105413. [PMID: 36057207 DOI: 10.1016/j.jmbbm.2022.105413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Revised: 08/04/2022] [Accepted: 08/05/2022] [Indexed: 10/31/2022]
Abstract
We demonstrate that several key aspects of the contractile activity of a cell interacting with the substrate can be captured by means of a non linear elastic tensegrity mechanical system made of a tensile element in parallel with a buckling-prone component, and exchanging forces with the surroundings through an extracellular matrix-focal adhesion complex. Mechanosensitivity of the focal adhesion plaque is triggered by pre-strain-driven buckling of the system induced either by pre-contraction or pre-polymerization of the constituents. The impact of pre-polymerization on the mechanical force and the implications of using linear and nonlinear elasticity for the focal adhesion plaque are assessed.
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Affiliation(s)
- E Benvenuti
- Engineering Department, University of Ferrara, Italy.
| | - G A Reho
- Engineering Department, University of Ferrara, Italy
| | - S Palumbo
- Department of Structures for Engineering and Architecture, University of Napoli Federico II, Italy
| | - M Fraldi
- Department of Structures for Engineering and Architecture, University of Napoli Federico II, Italy.
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15
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Ebben A, Dabagh M. Mechanotransduction in Endothelial Cells in Vicinity of Cancer Cells. Cell Mol Bioeng 2022; 15:313-330. [DOI: 10.1007/s12195-022-00728-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2021] [Accepted: 06/14/2022] [Indexed: 11/30/2022] Open
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16
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Palumbo S, Benvenuti E, Fraldi M. Actomyosin contractility and buckling of microtubules in nucleation, growth and disassembling of focal adhesions. Biomech Model Mechanobiol 2022; 21:1187-1200. [PMID: 35614374 PMCID: PMC9283365 DOI: 10.1007/s10237-022-01584-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Accepted: 04/08/2022] [Indexed: 11/24/2022]
Abstract
Building up and maintenance of cytoskeletal structure in living cells are force-dependent processes involving a dynamic chain of polymerization and depolymerization events, which are also at the basis of cells’ remodelling and locomotion. All these phenomena develop by establishing cell–matrix interfaces made of protein complexes, known as focal adhesions, which govern mechanosensing and mechanotransduction mechanisms mediated by stress transmission between cell interior and external environment. Within this framework, by starting from a work by Cao et al. (Biophys J 109:1807–1817, 2015), we here investigate the role played by actomyosin contractility of stress fibres in nucleation, growth and disassembling of focal adhesions. In particular, we propose a tensegrity model of an adherent cell incorporating nonlinear elasticity and unstable behaviours, which provides a new kinematical interpretation of cellular contractile forces and describes how stress fibres, microtubules and adhesion plaques interact mechanobiologically. The results confirm some experimental evidences and suggest how the actomyosin contraction level could be exploited by cells to actively control their adhesion, eventually triggering cytoskeleton reconfigurations and migration processes observed in both physiological conditions and diseases.
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Affiliation(s)
- S Palumbo
- Department of Structures for Engineering and Architecture, University of Napoli "Federico II", Napoli, Italy
| | - E Benvenuti
- Department of Engineering, University of Ferrara, Ferrara, Italy
| | - M Fraldi
- Department of Structures for Engineering and Architecture, University of Napoli "Federico II", Napoli, Italy.
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17
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The Effect of Magnetic Field Gradient and Gadolinium-Based MRI Contrast Agent Dotarem on Mouse Macrophages. Cells 2022; 11:cells11050757. [PMID: 35269379 PMCID: PMC8909262 DOI: 10.3390/cells11050757] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 02/10/2022] [Accepted: 02/14/2022] [Indexed: 02/04/2023] Open
Abstract
Magnetic resonance imaging (MRI) is widely used in diagnostic medicine. MRI uses the static magnetic field to polarize nuclei spins, fast-switching magnetic field gradients to generate temporal and spatial resolution, and radiofrequency (RF) electromagnetic waves to control the spin orientation. All these forms of magnetic static and electromagnetic RF fields interact with human tissue and cells. However, reports on the MRI technique's effects on the cells and human body are often inconsistent or contradictory. In both research and clinical MRI, recent progress in improving sensitivity and resolution is associated with the increased magnetic field strength of MRI magnets. Additionally, to improve the contrast of the images, the MRI technique often employs contrast agents, such as gadolinium-based Dotarem, with effects on cells and organs that are still disputable and not fully understood. Application of higher magnetic fields requires revisiting previously observed or potentially possible bio-effects. This article focuses on the influence of a static magnetic field gradient with and without a gadolinium-based MRI contrast agent (Dotarem) and the cellular and molecular effects of Dotarem on macrophages.
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18
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Sutton AA, Molter CW, Amini A, Idicula J, Furman M, Tirgar P, Tao Y, Ghagre A, Koushki N, Khavari A, Ehrlicher AJ. Cell monolayer deformation microscopy reveals mechanical fragility of cell monolayers following EMT. Biophys J 2022; 121:629-643. [PMID: 34999131 PMCID: PMC8873957 DOI: 10.1016/j.bpj.2022.01.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 11/26/2021] [Accepted: 01/05/2022] [Indexed: 11/24/2022] Open
Abstract
Tissue and cell mechanics are crucial factors in maintaining homeostasis and in development, with aberrant mechanics contributing to many diseases. During the epithelial-to-mesenchymal transition (EMT), a highly conserved cellular program in organismal development and cancer metastasis, cells gain the ability to detach from their original location and autonomously migrate. While a great deal of biochemical and biophysical changes at the single-cell level have been revealed, how the physical properties of multicellular assemblies change during EMT, and how this may affect disease progression, is unknown. Here we introduce cell monolayer deformation microscopy (CMDM), a new methodology to measure the planar mechanical properties of cell monolayers by locally applying strain and measuring their resistance to deformation. We employ this new method to characterize epithelial multicellular mechanics at early and late stages of EMT, finding the epithelial monolayers to be relatively compliant, ductile, and mechanically homogeneous. By comparison, the transformed mesenchymal monolayers, while much stiffer, were also more brittle, mechanically heterogeneous, displayed more viscoelastic creep, and showed sharp yield points at significantly lower strains. Here, CMDM measurements identify specific biophysical functional states of EMT and offer insight into how cell aggregates fragment under mechanical stress. This mechanical fingerprinting of multicellular assemblies using new quantitative metrics may also offer new diagnostic applications in healthcare to characterize multicellular mechanical changes in disease.
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Affiliation(s)
- Amy A. Sutton
- Department of Bioengineering, McGill University, Montreal, Quebec, Canada
| | - Clayton W. Molter
- Department of Bioengineering, McGill University, Montreal, Quebec, Canada
| | - Ali Amini
- Department of Mechanical Engineering, McGill University, Montreal, Quebec, Canada
| | - Johanan Idicula
- Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, Canada
| | - Max Furman
- Department of Bioengineering, McGill University, Montreal, Quebec, Canada
| | - Pouria Tirgar
- Department of Bioengineering, McGill University, Montreal, Quebec, Canada
| | - Yuanyuan Tao
- Department of Bioengineering, McGill University, Montreal, Quebec, Canada
| | - Ajinkya Ghagre
- Department of Bioengineering, McGill University, Montreal, Quebec, Canada
| | - Newsha Koushki
- Department of Bioengineering, McGill University, Montreal, Quebec, Canada
| | - Adele Khavari
- Department of Bioengineering, McGill University, Montreal, Quebec, Canada
| | - Allen J. Ehrlicher
- Department of Bioengineering, McGill University, Montreal, Quebec, Canada,Department of Mechanical Engineering, McGill University, Montreal, Quebec, Canada,Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, Canada,Department of Biomedical Engineering, McGill University, Montreal, Quebec, Canada,Centre for Structural Biology, McGill University, Montreal, Quebec, Canada,Goodman Cancer Research Centre, McGill University, Montreal, Quebec, Canada,Corresponding author
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19
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Modulus adaptive lubricating prototype inspired by instant muscle hardening mechanism of catfish skin. Nat Commun 2022; 13:377. [PMID: 35046391 PMCID: PMC8770490 DOI: 10.1038/s41467-022-28038-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2021] [Accepted: 01/05/2022] [Indexed: 12/21/2022] Open
Abstract
In nature, living organisms evolve unique functional components with mechanically adaptive compatibility to cater dynamic change of interface friction/lubrication. This mechanism can be used for developing intelligent artificial lubrication-regulation systems. Inspired by the muscle hardening-triggered lubrication of longsnout catfish, here we report a modulus adaptive lubricating hydrogel prototype consisting of top mucus-like hydrophilic lubricating layer and muscle-like bottom hydrogel that can stiffen via thermal-triggered phase separation. It exhibits instant switch from soft/high frictional state (~0.3 MPa, μ~0.37) to stiff/lubricating state (~120 MPa, μ~0.027) in water upon heating up. Such switchable lubrication is effective for wide range of normal loads and attributed to the modulus-dominated adaptive contact mechanism. As a proof-of-concept, switchable lubricating hydrogel bullets and patches are engineered for realizing controllable interface movements. These important results demonstrate potential applications in the fields of intelligent motion devices and soft robots. Stimuli responsive materials are interesting for applications in different technological fields, but realizing controllable surface friction-control based on the change of the modulus of a material is less investigated. Here the authors demonstrate a lubrication regulating strategy and prototype based on thermally triggered changes of the modulus of a hydrogel.
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20
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Do TD, Katsuyoshi J, Cai H, Ohashi T. Mechanical Properties of Isolated Primary Cilia Measured by Micro-tensile Test and Atomic Force Microscopy. Front Bioeng Biotechnol 2021; 9:753805. [PMID: 34858960 PMCID: PMC8632022 DOI: 10.3389/fbioe.2021.753805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 10/18/2021] [Indexed: 11/29/2022] Open
Abstract
Mechanotransduction is a well-known mechanism by which cells sense their surrounding mechanical environment, convert mechanical stimuli into biochemical signals, and eventually change their morphology and functions. Primary cilia are believed to be mechanosensors existing on the surface of the cell membrane and support cells to sense surrounding mechanical signals. Knowing the mechanical properties of primary cilia is essential to understand their responses, such as sensitivity to mechanical stimuli. Previous studies have so far conducted flow experiments or optical trap techniques to measure the flexural rigidity EI (E: Young’s modulus, I: second moment of inertia) of primary cilia; however, the flexural rigidity is not a material property of materials and depends on mathematical models used in the determination, leading to a discrepancy between studies. For better characterization of primary cilia mechanics, Young’s modulus should be directly and precisely measured. In this study, the tensile Young’s modulus of isolated primary cilia is, for the first time, measured by using an in-house micro-tensile tester. The different strain rates of 0.01–0.3 s−1 were applied to isolated primary cilia, which showed a strain rate–dependent Young’s modulus in the range of 69.5–240.0 kPa on average. Atomic force microscopy was also performed to measure the local Young’s modulus of primary cilia, showing the Young’s modulus within the order of tens to hundreds of kPa. This study could directly provide the global and local Young’s moduli, which will benefit better understanding of primary cilia mechanics.
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Affiliation(s)
- Tien-Dung Do
- Division of Human Mechanical Systems and Design, Graduate School of Engineering, Hokkaido University, Sapporo, Japan
| | - Jimuro Katsuyoshi
- Division of Human Mechanical Systems and Design, Graduate School of Engineering, Hokkaido University, Sapporo, Japan
| | - Haonai Cai
- Division of Human Mechanical Systems and Design, Graduate School of Engineering, Hokkaido University, Sapporo, Japan
| | - Toshiro Ohashi
- Division of Mechanical and Aerospace Engineering, Faculty of Engineering, Hokkaido University, Sapporo, Japan
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21
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Liu S, Matsui TS, Kang N, Deguchi S. Analysis of senescence-responsive stress fiber proteome reveals reorganization of stress fibers mediated by elongation factor eEF2 in HFF-1 cells. Mol Biol Cell 2021; 33:ar10. [PMID: 34705524 PMCID: PMC8886821 DOI: 10.1091/mbc.e21-05-0229] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Stress fibers (SFs), which are actomyosin structures, reorganize in response to various cues to maintain cellular homeostasis. Currently, the protein components of SFs are only partially identified, limiting our understanding of their responses. Here we isolate SFs from human fibroblasts HFF-1 to determine with proteomic analysis the whole protein components and how they change with replicative senescence (RS), a state where cells decline in the ability to replicate after repeated divisions. We found that at least 135 proteins are associated with SFs, and 63 of them are up-regulated with RS, by which SFs become larger in size. Among them, we focused on eEF2 (eukaryotic translation elongation factor 2) as it exhibited on RS the most significant increase in abundance. We show that eEF2 is critical to the reorganization and stabilization of SFs in senescent fibroblasts. Our findings provide a novel molecular basis for SFs to be reinforced to resist cellular senescence.
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Affiliation(s)
- Shiyou Liu
- Division of Bioengineering, Graduate School of Engineering Science, Osaka University, Japan
| | - Tsubasa S Matsui
- Division of Bioengineering, Graduate School of Engineering Science, Osaka University, Japan
| | - Na Kang
- Division of Bioengineering, Graduate School of Engineering Science, Osaka University, Japan
| | - Shinji Deguchi
- Division of Bioengineering, Graduate School of Engineering Science, Osaka University, Japan
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22
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Cook BL, Chao CJ, Alford PW. Architecture-Dependent Mechano-Adaptation in Single Vascular Smooth Muscle Cells. J Biomech Eng 2021; 143:101002. [PMID: 33972987 DOI: 10.1115/1.4051117] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Indexed: 01/03/2023]
Abstract
Arteries grow and remodel following mechanical perturbation. Vascular smooth muscle cells (VSMCs) within the artery undergo hyperplasia, hypertrophy, or change their contractility following sustained changes in loading. Experimental evidence in vivo and in vitro suggests that VSMCs grow and remodel to maintain a constant transmural stress, or "target" stress. This behavior is often described using a stress-dependent finite growth framework. Typically, computational models of arterial growth and remodeling account for VSMC behavior in a constrained mixture formulation that incorporates behavior of each component of the artery. However, these models do not account for differential VSMC architecture observed in situ, which may significantly influence growth and remodeling behavior. Here, we used cellular microbiaxial stretching (CμBS) to characterize how VSMCs with different cytoskeletal architectures respond to a sustained step change in strain. We find that VSMC F-actin architecture becomes more aligned following stretch and retains this alignment after 24 h. Further, we find that VSMC stress magnitude depends on cellular architecture. Qualitatively, however, stress behavior following stretch is consistent across cell architectures-stress increases following stretch and returns to prestretch magnitudes after 24 h. Finally, we formulated an architecture-dependent targeted growth law that accounts for experimentally measured cytoskeletal alignment and attributes stress evolution to individual fiber growth and find that this model robustly captures long-term stress evolution in single VSMCs. These results suggest that VSMC mechano-adaptation depends on cellular architecture, which has implications for growth and remodeling in regions of arteries with differential architecture, such as at bifurcations.
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Affiliation(s)
- Bernard L Cook
- Department of Biomedical Engineering, University of Minnesota, Nils Hasselmo Hall, Room 7-105 312 Church Street SE, Minneapolis, MN 55455
| | - Christina J Chao
- Department of Biomedical Engineering, University of Minnesota, Nils Hasselmo Hall, Room 7-105 312 Church Street SE, Minneapolis, MN 55455
| | - Patrick W Alford
- Department of Biomedical Engineering, University of Minnesota, Nils Hasselmo Hall, Room 7-105 312 Church Street SE, Minneapolis, MN 55455
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23
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Dey K, Roca E, Ramorino G, Sartore L. Progress in the mechanical modulation of cell functions in tissue engineering. Biomater Sci 2021; 8:7033-7081. [PMID: 33150878 DOI: 10.1039/d0bm01255f] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
In mammals, mechanics at multiple stages-nucleus to cell to ECM-underlie multiple physiological and pathological functions from its development to reproduction to death. Under this inspiration, substantial research has established the role of multiple aspects of mechanics in regulating fundamental cellular processes, including spreading, migration, growth, proliferation, and differentiation. However, our understanding of how these mechanical mechanisms are orchestrated or tuned at different stages to maintain or restore the healthy environment at the tissue or organ level remains largely a mystery. Over the past few decades, research in the mechanical manipulation of the surrounding environment-known as substrate or matrix or scaffold on which, or within which, cells are seeded-has been exceptionally enriched in the field of tissue engineering and regenerative medicine. To do so, traditional tissue engineering aims at recapitulating key mechanical milestones of native ECM into a substrate for guiding the cell fate and functions towards specific tissue regeneration. Despite tremendous progress, a big puzzle that remains is how the cells compute a host of mechanical cues, such as stiffness (elasticity), viscoelasticity, plasticity, non-linear elasticity, anisotropy, mechanical forces, and mechanical memory, into many biological functions in a cooperative, controlled, and safe manner. High throughput understanding of key cellular decisions as well as associated mechanosensitive downstream signaling pathway(s) for executing these decisions in response to mechanical cues, solo or combined, is essential to address this issue. While many reports have been made towards the progress and understanding of mechanical cues-particularly, substrate bulk stiffness and viscoelasticity-in regulating the cellular responses, a complete picture of mechanical cues is lacking. This review highlights a comprehensive view on the mechanical cues that are linked to modulate many cellular functions and consequent tissue functionality. For a very basic understanding, a brief discussion of the key mechanical players of ECM and the principle of mechanotransduction process is outlined. In addition, this review gathers together the most important data on the stiffness of various cells and ECM components as well as various tissues/organs and proposes an associated link from the mechanical perspective that is not yet reported. Finally, beyond addressing the challenges involved in tuning the interplaying mechanical cues in an independent manner, emerging advances in designing biomaterials for tissue engineering are also explored.
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Affiliation(s)
- Kamol Dey
- Department of Applied Chemistry and Chemical Engineering, Faculty of Science, University of Chittagong, Bangladesh
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24
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Determining the domain-level reaction-diffusion properties of an actin-binding protein transgelin-2 within cells. Exp Cell Res 2021; 404:112619. [PMID: 33965400 DOI: 10.1016/j.yexcr.2021.112619] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 03/18/2021] [Accepted: 04/19/2021] [Indexed: 11/21/2022]
Abstract
Proteins in cells undergo repeated binding to other molecules, thereby reducing the apparent extent of their intracellular diffusion. While much effort has been made to analytically decouple these combined effects of pure diffusion and chemical binding, it is difficult with conventional approaches to attribute the measured quantities to the nature of specific domains of the proteins. Motivated by the common goal in cell signaling research aimed at identifying the domains responsible for particular intermolecular interactions, here we describe a framework for determining the local physicochemical properties of cellular proteins associated with immobile scaffolds. To validate this new approach, we apply it to transgelin-2, an actin-binding protein whose intracellular dynamics remains elusive. We develop a fluorescence recovery after photobleaching (FRAP)-based framework, in which comprehensive combinations of domain-deletion mutants are created, and the difference among them in FRAP response is analyzed. We demonstrate that transgelin-2 in actin stress fibers (SFs) interacts with F-actin via two separate domains, and the chemical properties are determined for the individual domains. Its pure diffusion properties independent of the association to F-actin is also obtained. Our approach will thus be useful, as presented here for transgelin-2, in addressing the signaling mechanism of cellular proteins associated with SFs.
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25
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Migliorini E, Cavalcanti-Adam EA, Uva AE, Fiorentino M, Gattullo M, Manghisi VM, Vaiani L, Boccaccio A. Nanoindentation of mesenchymal stem cells using atomic force microscopy: effect of adhesive cell-substrate structures. NANOTECHNOLOGY 2021; 32:215706. [PMID: 33596559 DOI: 10.1088/1361-6528/abe748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 02/17/2021] [Indexed: 06/12/2023]
Abstract
The procedure commonly adopted to characterize cell materials using atomic force microscopy neglects the stress state induced in the cell by the adhesion structures that anchor it to the substrate. In several studies, the cell is considered as made from a single material and no specific information is provided regarding the mechanical properties of subcellular components. Here we present an optimization algorithm to determine separately the material properties of subcellular components of mesenchymal stem cells subjected to nanoindentation measurements. We assess how these properties change if the adhesion structures at the cell-substrate interface are considered or not in the algorithm. In particular, among the adhesion structures, the focal adhesions and the stress fibers were simulated. We found that neglecting the adhesion structures leads to underestimate the cell mechanical properties thus making errors up to 15%. This result leads us to conclude that the action of adhesion structures should be taken into account in nanoindentation measurements especially for cells that include a large number of adhesions to the substrate.
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Affiliation(s)
| | - Elisabetta Ada Cavalcanti-Adam
- Max Planck Institute for Medical Research, D-69120 Heidelberg, Germany
- Heidelberg University, D-69120 Heidelberg, Germany
| | - Antonio Emmanuele Uva
- Dipartimento di Meccanica, Matematica e Management, Politecnico di Bari, Bari, Italy
| | - Michele Fiorentino
- Dipartimento di Meccanica, Matematica e Management, Politecnico di Bari, Bari, Italy
| | - Michele Gattullo
- Dipartimento di Meccanica, Matematica e Management, Politecnico di Bari, Bari, Italy
| | - Vito Modesto Manghisi
- Dipartimento di Meccanica, Matematica e Management, Politecnico di Bari, Bari, Italy
| | - Lorenzo Vaiani
- Dipartimento di Meccanica, Matematica e Management, Politecnico di Bari, Bari, Italy
| | - Antonio Boccaccio
- Dipartimento di Meccanica, Matematica e Management, Politecnico di Bari, Bari, Italy
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26
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Affiliation(s)
- Guillaume Charras
- London Centre for Nanotechnology, University College London, London, UK.
- Department of Cell and Developmental Biology, University College London, London, UK.
- Institute for the Physics of Living Systems, University College London, London, UK.
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27
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Li XJ, Wang M, Xue Y, Duan D, Li C, Ye J, Han X, Qiao R, Wang K, Li XL. Characterization and comparison of the bacterial community between complete intensive and extensive feeding patterns in pigs. AMB Express 2021; 11:32. [PMID: 33630191 PMCID: PMC7907295 DOI: 10.1186/s13568-021-01191-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Accepted: 02/09/2021] [Indexed: 12/26/2022] Open
Abstract
To investigate and compare the gut microbiota structures in complete intensive feeding pattern (CP) and extensive feeding pattern (EP) groups, a total of 20 pigs were divided into two groups and fed the same diet. The fecal microbial composition was profiled using 16S rRNA gene sequencing. Our results showed that seventeen predominant genera were present in each pig sample and constituted the phylogenetic core of the microbiota at the class level. The abundance of most of the core microbial flora were significantly higher in the CP group than in the EP group (P < 0.05), while the abundance of Gammaproteobacteria was significantly lower in the CP group than in the EP group (P < 0.05). The CP group had significantly greater community diversity, richness, and evenness than the EP group (P < 0.05). Functional prediction analysis indicated that intestinal microbial species potentially led to faster growth and an increased fat accumulation capacity in the CP group; however, disease resistance was weaker in the CP group than in the EP group. In conclusion, EP pigs have a wider range of activity and better animal welfare than CP pigs, which helps reduce the occurrence of diseases and neurological symptoms. To explore the effect of intestinal flora on disease resistance in pigs at the molecular level, Coprococcus, which is a key gut bacterium in the intestine, was selected for isolation and purification and cocultured with intestinal epithelial cells. qPCR was performed to determine the effect of Coprococcus on SLA-DRB gene expression in intestinal epithelial cells. The results showed that Coprococcus enhanced SLA-DRB gene expression in intestinal epithelial cells. The results provide useful reference data for further study on the relationship between intestinal flora and pig disease resistance.
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28
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Vaiani L, Migliorini E, Cavalcanti-Adam EA, Uva AE, Fiorentino M, Gattullo M, Manghisi VM, Boccaccio A. Coarse-grained elastic network modelling: A fast and stable numerical tool to characterize mesenchymal stem cells subjected to AFM nanoindentation measurements. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2021; 121:111860. [PMID: 33579492 DOI: 10.1016/j.msec.2020.111860] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 12/23/2020] [Accepted: 12/26/2020] [Indexed: 12/11/2022]
Abstract
The knowledge of the mechanical properties is the starting point to study the mechanobiology of mesenchymal stem cells and to understand the relationships linking biophysical stimuli to the cellular differentiation process. In experimental biology, Atomic Force Microscopy (AFM) is a common technique for measuring these mechanical properties. In this paper we present an alternative approach for extracting common mechanical parameters, such as the Young's modulus of cell components, starting from AFM nanoindentation measurements conducted on human mesenchymal stem cells. In a virtual environment, a geometrical model of a stem cell was converted in a highly deformable Coarse-Grained Elastic Network Model (CG-ENM) to reproduce the real AFM experiment and retrieve the related force-indentation curve. An ad-hoc optimization algorithm perturbed the local stiffness values of the springs, subdivided in several functional regions, until the computed force-indentation curve replicated the experimental one. After this curve matching, the extraction of global Young's moduli was performed for different stem cell samples. The algorithm was capable to distinguish the material properties of different subcellular components such as the cell cortex and the cytoskeleton. The numerical results predicted with the elastic network model were then compared to those obtained from hertzian contact theory and Finite Element Method (FEM) for the same case studies, showing an optimal agreement and a highly reduced computational cost. The proposed simulation flow seems to be an accurate, fast and stable method for understanding the mechanical behavior of soft biological materials, even for subcellular levels of detail. Moreover, the elastic network modelling allows shortening the computational times to approximately 33% of the time required by a traditional FEM simulation performed using elements with size comparable to that of springs.
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Affiliation(s)
- L Vaiani
- Dipartimento di Meccanica, Matematica e Management, Politecnico di Bari, Bari 70126, Italy
| | | | - E A Cavalcanti-Adam
- Max Planck Institute for Medical Research, D-69120 Heidelberg, Germany; Heidelberg University, D-69120 Heidelberg, Germany
| | - A E Uva
- Dipartimento di Meccanica, Matematica e Management, Politecnico di Bari, Bari 70126, Italy
| | - M Fiorentino
- Dipartimento di Meccanica, Matematica e Management, Politecnico di Bari, Bari 70126, Italy
| | - M Gattullo
- Dipartimento di Meccanica, Matematica e Management, Politecnico di Bari, Bari 70126, Italy
| | - V M Manghisi
- Dipartimento di Meccanica, Matematica e Management, Politecnico di Bari, Bari 70126, Italy
| | - A Boccaccio
- Dipartimento di Meccanica, Matematica e Management, Politecnico di Bari, Bari 70126, Italy.
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29
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Lin J, Li X, Yin J, Qian J. Effect of Cyclic Stretch on Neuron Reorientation and Axon Outgrowth. Front Bioeng Biotechnol 2020; 8:597867. [PMID: 33425865 PMCID: PMC7793818 DOI: 10.3389/fbioe.2020.597867] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2020] [Accepted: 11/23/2020] [Indexed: 01/30/2023] Open
Abstract
The directional alignment and outgrowth of neurons is a critical step of nerve regeneration and functional recovery of nerve systems, where neurons are exposed to a complex mechanical environment with subcellular structures such as stress fibers and focal adhesions acting as the key mechanical transducer. In this paper, we investigate the effects of cyclic stretch on neuron reorientation and axon outgrowth with a feasible stretching device that controls stretching amplitude and frequency. Statistical results indicate an evident frequency and amplitude dependence of neuron reorientation, that is, neurons tend to align away from stretch direction when stretching amplitude and frequency are large enough. On the other hand, axon elongation under cyclic stretch is very close to the reference case where neurons are not stretched. A mechanochemical framework is proposed by connecting the evolution of cellular configuration to the microscopic dynamics of subcellular structures, including stress fiber, focal adhesion, and microtubule, yielding theoretical predictions that are consistent with the experimental observations. The theoretical work provides an explanation of the neuron's mechanical response to cyclic stretch, suggesting that the contraction force generated by stress fiber plays an essential role in both neuron reorientation and axon elongation. This combined experimental and theoretical study on stretch-induced neuron reorientation may have potential applications in neurodevelopment and neuron regeneration.
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Affiliation(s)
- Ji Lin
- Key Laboratory of Soft Machines and Smart Devices of Zhejiang Province, Department of Engineering Mechanics, Zhejiang University, Hangzhou, China
| | - Xiaokeng Li
- State Key Laboratory of Fluid Power and Mechatronic Systems, Key Laboratory of 3D Printing Process and Equipment of Zhejiang Province, School of Mechanical Engineering, Zhejiang University, Hangzhou, China
| | - Jun Yin
- State Key Laboratory of Fluid Power and Mechatronic Systems, Key Laboratory of 3D Printing Process and Equipment of Zhejiang Province, School of Mechanical Engineering, Zhejiang University, Hangzhou, China
| | - Jin Qian
- Key Laboratory of Soft Machines and Smart Devices of Zhejiang Province, Department of Engineering Mechanics, Zhejiang University, Hangzhou, China
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30
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Li XJ, Wang M, Xue Y, Duan D, Li C, Han X, Wang K, Qiao R, Li XL. Identification of microflora related to growth performance in pigs based on 16S rRNA sequence analyses. AMB Express 2020; 10:192. [PMID: 33123840 PMCID: PMC7596147 DOI: 10.1186/s13568-020-01130-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 10/18/2020] [Indexed: 12/13/2022] Open
Abstract
Intestinal microorganisms have been shown to be important factors affecting the growth performance of pigs. Therefore, to investigate the effect of the intestinal microflora structure on the growth performance of pigs, samples from Duroc (n = 10), Landrace (n = 9) and Yorkshire (n = 21) pigs under the same diet and feeding conditions were collected. The fecal microbial composition was profiled via 16S ribosomal RNA (rRNA) gene sequencing. We also analyzed their growth performance. We found that Duroc and Landrace pigs had significant differences in average daily gain (ADG), feed efficiency ratio (FER), growth index (GI), and number of days taken to reach 100 kg (P < 0.05). Moreover, through analysis of the intestinal flora, we also identified 18 species of intestinal flora with significant differences between Duroc and Landrace pigs (P < 0.05). To eliminate the influence of genetic background, the differential intestinal flora of 21 Yorkshire pigs with differences in growth performance was analyzed. The results showed that there were significant correlations between Barnesiella, Dorea, Clostridium and Lactobacillus and pig growth performance. To explore the effect of the intestinal flora on the growth performance of pigs at the molecular level, Lactobacillus, which is the most abundant in the intestine, was selected for isolation and purification and cocultured with intestinal epithelial cells. qPCR was used to determine the effect of Lactobacillus on MC4R gene expression in intestinal epithelial cells. The results showed that Lactobacillus inhibited MC4R gene expression in these cells. The results provide a useful reference for further study of the relationship between the intestinal flora and pig growth performance.
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31
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Asgharzadeh P, Birkhold AI, Trivedi Z, Özdemir B, Reski R, Röhrle O. A NanoFE simulation-based surrogate machine learning model to predict mechanical functionality of protein networks from live confocal imaging. Comput Struct Biotechnol J 2020; 18:2774-2788. [PMID: 33101614 PMCID: PMC7559262 DOI: 10.1016/j.csbj.2020.09.024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 09/12/2020] [Accepted: 09/13/2020] [Indexed: 02/07/2023] Open
Abstract
Sub-cellular mechanics plays a crucial role in a variety of biological functions and dysfunctions. Due to the strong structure-function relationship in cytoskeletal protein networks, light can be shed on their mechanical functionality by investigating their structures. Here, we present a data-driven approach employing a combination of confocal live imaging of fluorescent tagged protein networks, in silico mechanical experiments and machine learning to investigate this relationship. Our designed image processing and nanoFE mechanical simulation framework resolves the structure and mechanical behaviour of cytoskeletal networks and the developed gradient boosting surrogate models linking network structure to its functionality. In this study, for the first time, we perform mechanical simulations of Filamentous Temperature Sensitive Z (FtsZ) complex protein networks with realistic network geometry depicting its skeletal functionality inside organelles (here, chloroplasts) of the moss Physcomitrella patens. Training on synthetically produced simulation data enables predicting the mechanical characteristics of FtsZ network purely based on its structural features (R2⩾0.93), therefore allowing to extract structural principles enabling specific mechanical traits of FtsZ, such as load bearing and resistance to buckling failure in case of large network deformation.
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Affiliation(s)
- Pouyan Asgharzadeh
- Institute for Modelling and Simulation of Biomechanical Systems, University of Stuttgart, Stuttgart, Germany.,Stuttgart Center for Simulation Science (SC SimTech), Stuttgart, Germany
| | - Annette I Birkhold
- Institute for Modelling and Simulation of Biomechanical Systems, University of Stuttgart, Stuttgart, Germany.,Stuttgart Center for Simulation Science (SC SimTech), Stuttgart, Germany
| | - Zubin Trivedi
- Institute for Modelling and Simulation of Biomechanical Systems, University of Stuttgart, Stuttgart, Germany
| | - Bugra Özdemir
- Plant Biotechnology, Faculty of Biology, University of Freiburg, Freiburg, Germany.,Signalling Research Centres BIOSS and CIBSS, Freiburg, Germany
| | - Ralf Reski
- Plant Biotechnology, Faculty of Biology, University of Freiburg, Freiburg, Germany.,Signalling Research Centres BIOSS and CIBSS, Freiburg, Germany.,Cluster of Excellence livMatS @ FIT - Freiburg Centre for Interactive Materials and Bioinspired Technologies, Freiburg, Germany
| | - Oliver Röhrle
- Institute for Modelling and Simulation of Biomechanical Systems, University of Stuttgart, Stuttgart, Germany.,Stuttgart Center for Simulation Science (SC SimTech), Stuttgart, Germany
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32
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A Stochastic Modelling Framework for Single Cell Migration: Coupling Contractility and Focal Adhesions. Symmetry (Basel) 2020. [DOI: 10.3390/sym12081348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The interaction of the actin cytoskeleton with cell–substrate adhesions is necessary for cell migration. While the trajectories of motile cells have a stochastic character, investigations of cell motility mechanisms rarely elaborate on the origins of the observed randomness. Here, guided by a few fundamental attributes of cell motility, I construct a minimal stochastic cell migration model from ground-up. The resulting model couples a deterministic actomyosin contractility mechanism with stochastic cell–substrate adhesion kinetics, and yields a well-defined piecewise deterministic process. Numerical simulations reproduce several experimentally observed results, including anomalous diffusion, tactic migration and contact guidance. This work provides a basis for the development of cell–cell collision and population migration models.
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33
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Saito T, Huang W, Matsui TS, Kuragano M, Takahashi M, Deguchi S. What factors determine the number of nonmuscle myosin II in the sarcomeric unit of stress fibers? Biomech Model Mechanobiol 2020; 20:155-166. [PMID: 32776260 DOI: 10.1007/s10237-020-01375-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 08/01/2020] [Indexed: 01/05/2023]
Abstract
Actin stress fibers (SFs), a contractile apparatus in nonmuscle cells, possess a contractile unit that is apparently similar to the sarcomere of myofibrils in muscles. The function of SFs has thus often been addressed based on well-characterized properties of muscles. However, unlike the fixed number of myosin molecules in myofibrils, the number of nonmuscle myosin II (NMII) within the contractile sarcomeric unit in SFs is quite low and variable for some reason. Here we address what factors may determine the specific number of NMII in SFs. We suggest with a theoretical model that the number lies just in between the function of SFs for bearing cellular tension under static conditions and for promptly disintegrating upon forced cell shortening. We monitored shortening-induced disintegration of SFs in human osteosarcoma U2OS cells expressing mutants of myosin regulatory light chain that virtually regulates the interaction of NMII with actin filaments, and the behaviors observed were indeed consistent with the theoretical consequences. This situation-specific nature of SFs may allow nonmuscle cells to respond adaptively to mechanical stress to circumvent activation of pro-inflammatory signals as previously indicated, i.e., a behavior distinct from that of muscles that are basically specialized for exhibiting contractile activity.
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Affiliation(s)
- Takumi Saito
- Division of Bioengineering, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka, 560-8531, Japan.,Japan Society for the Promotion of Science, Tokyo, Japan
| | - Wenjing Huang
- Department of Bioengineering, Graduate School of Engineering, The University of Tokyo, Tokyo, Japan
| | - Tsubasa S Matsui
- Division of Bioengineering, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka, 560-8531, Japan
| | - Masahiro Kuragano
- Graduate School of Engineering, Muroran Institute of Technology, Muroran, Japan
| | - Masayuki Takahashi
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, Japan
| | - Shinji Deguchi
- Division of Bioengineering, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka, 560-8531, Japan.
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34
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Hajjarian Z, Nadkarni SK. Tutorial on laser speckle rheology: technology, applications, and opportunities. JOURNAL OF BIOMEDICAL OPTICS 2020; 25:1-19. [PMID: 32358928 PMCID: PMC7195443 DOI: 10.1117/1.jbo.25.5.050801] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Accepted: 04/10/2020] [Indexed: 05/27/2023]
Abstract
SIGNIFICANCE The onset of several diseases is frequently marked with anomalous mechanical alteration of the affected tissue at the intersection of cells and their microenvironment. Therefore, mapping the micromechanical attributes of the tissues could enhance our understanding of the etiology of human disease, improve the diagnosis, and help stratify therapies that target these mechanical aberrations. AIM We review the tremendous opportunities offered through using optics for imaging the micromechanical properties, at length scales inaccessible to other modalities, in both basic research and clinical medicine. We specifically focus on laser speckle rheology (LSR), a technology that quantifies the mechanical properties of tissues in a rapid, noncontact manner. APPROACH In LSR, the shear viscoelastic modulus is measured from the time-variant speckle intensity fluctuations reflected off the tissue. The LSR technology is engineered and configured into several embodiments, including bench-top optical systems, endoscopes for minimally invasive procedures, portable point-of-care devices, and microscopes. RESULTS These technological nuances have primed the LSR for widespread applications in diagnosis and therapeutic monitoring, as demonstrated here, in cardiovascular disease, coagulation disorders, and tumor malignancies. CONCLUSION The fast-paced technological advancements, elaborated here, position the LSR as a competent candidate for many more exciting opportunities in basic research and medicine.
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Affiliation(s)
- Zeinab Hajjarian
- Massachusetts General Hospital, Harvard Medical School, Wellman Center for Photomedicine, Boston, Massachusetts, United States
| | - Seemantini K. Nadkarni
- Massachusetts General Hospital, Harvard Medical School, Wellman Center for Photomedicine, Boston, Massachusetts, United States
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35
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He S, Green Y, Saeidi N, Li X, Fredberg JJ, Ji B, Pismen LM. A theoretical model of collective cell polarization and alignment. JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS 2020; 137:103860. [PMID: 33518805 PMCID: PMC7842695 DOI: 10.1016/j.jmps.2019.103860] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Collective cell polarization and alignment play important roles in tissue morphogenesis, wound healing and cancer metastasis. How cells sense the direction and position in these processes, however, has not been fully understood. Here we construct a theoretical model based on describing cell layer as a nemato-elastic medium, by which the cell polarization, cell alignment and cell active contraction are explicitly expressed as functions of components of the nematic order parameter. To determine the order parameter we derive two sets of governing equations, one for the force equilibrium of the system, and the other for the minimization of the system's free energy including the energy of cell polarization and alignment. By solving these coupled governing equations, we can predict the effects of substrate stiffness, geometries of cell layers, external forces and myosin activity on the direction- and position-dependent cell aspect ratio and cell orientation. Moreover, the axisymmetric problem with cells on a ring-like pattern is solved analytically, and the analytical solution for cell aspect ratio are governed by parameter groups which include the stiffness of the cell and the substrate, the strength of myosin activity and the external forces. Our predictions of the cell aspect ratio and orientation are generally comparable to experimental observations. These results show that the pattern of cell polarization is determined by the anisotropic degree of active contractile stress, and suggest a stress-driven polarization mechanism that enables cells to sense their spatial positions to develop direction- and position-dependent behavior. This, in turn, sheds light on the ways to control pattern formation in tissue engineering for potential biomedical applications.
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Affiliation(s)
- Shijie He
- Department of Applied Mechanics, School of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081, China
- Center for Engineering in Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Yoav Green
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
- Department of Mechanical Engineering, Ben-Gurion University of the Negev, Beersheva 8410501, Israel
| | - Nima Saeidi
- Center for Engineering in Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Xiaojun Li
- Department of Applied Mechanics, School of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081, China
| | - Jeffrey J. Fredberg
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
| | - Baohua Ji
- Department of Applied Mechanics, School of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081, China
- Department of Engineering Mechanics, Zhejiang University, Hangzhou 310027, China
- Corresponding authors. (B. Ji), (L.M. Pismen)
| | - Len M. Pismen
- Department of Chemical Engineering, Technion – Israel Institute of Technology, Haifa 32000, Israel
- Corresponding authors. (B. Ji), (L.M. Pismen)
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36
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Helical structure of actin stress fibers and its possible contribution to inducing their direction-selective disassembly upon cell shortening. Biomech Model Mechanobiol 2019; 19:543-555. [PMID: 31549258 DOI: 10.1007/s10237-019-01228-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Accepted: 09/10/2019] [Indexed: 12/21/2022]
Abstract
Mechanisms of the assembly of actin stress fibers (SFs) have been extensively studied, while those of the disassembly-particularly cell shortening-induced ones-remain unclear. Here, we show that SFs have helical structures composed of multi-subbundles, and they tend to be delaminated upon cell shortening. Specifically, we observed with atomic force microscopy delamination of helical SFs into their subbundles. We physically caught individual SFs using a pair of glass needles to observe rotational deformations during stretching as well as ATP-driven active contraction, suggesting that they deform in a manner reflecting their intrinsic helical structure. A minimal analytical model was then developed based on the Frenet-Serret formulas with force-strain measurement data to suggest that helical SFs can be delaminated into the constituent subbundles upon axial shortening. Given that SFs are large molecular clusters that bear cellular tension but must promptly disassemble upon loss of the tension, the resulting increase in their surface area due to the shortening-induced delamination may facilitate interaction with surrounding molecules to aid subsequent disintegration. Thus, our results suggest a new mechanism of the disassembly that occurs only in the specific SFs exposed to forced shortening.
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37
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Manifacier I, Beussman KM, Han SJ, Sniadecki NJ, About I, Milan JL. The consequence of substrates of large-scale rigidity on actin network tension in adherent cells. Comput Methods Biomech Biomed Engin 2019; 22:1073-1082. [PMID: 31204851 DOI: 10.1080/10255842.2019.1629428] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
There is compelling evidence that substrate stiffness affects cell adhesion as well as cytoskeleton organization and contractile activity. This work was designed to study the cytoskeletal contractile activity of single cells plated on micropost substrates of different stiffness using a numerical model simulating the intracellular tension of individual cells. We allowed cells to adhere onto micropost substrates of various rigidities and used experimental traction force data to infer cell contractility using a numerical model. The model shows that higher substrate stiffness leads to an increase in intracellular tension. The strength of this model is its ability to calculate the mechanical state of each cell in accordance to its individual cytoskeletal structure. This is achieved by regenerating a numerical cytoskeleton based on microscope images of the actin network of each cell. The resulting numerical structure consequently represents pulling characteristics on its environment similar to those generated by the cell in-vivo. From actin imaging we can calculate and better understand how forces are transmitted throughout the cell.
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Affiliation(s)
- Ian Manifacier
- Aix Marseille Univ, CNRS, ISM , Marseille , France.,Aix Marseille University, APHM, CNRS, ISM, Sainte-Marguerite Hospital, Institute for Locomotion , Marseille , France
| | - Kevin M Beussman
- Department of Mechanical Engineering, University of Washington , Seattle , WA , USA.,Center for Cardiovascular Biology, University of Washington , Seattle , WA , USA.,Institute for Stem Cell and Regenerative Medicine, University of Washington , Seattle , WA , USA
| | - Sangyoon J Han
- Department of Cell Biology, Harvard Medical School , Boston , WA , USA.,Department of Cell Biology, University of Texas Southwestern Medical Center at Dallas , Dallas , TX
| | - Nathan J Sniadecki
- Department of Mechanical Engineering, University of Washington , Seattle , WA , USA.,Center for Cardiovascular Biology, University of Washington , Seattle , WA , USA.,Institute for Stem Cell and Regenerative Medicine, University of Washington , Seattle , WA , USA.,Department of Bioengineering, University of Washington , Seattle , WA, USA
| | - Imad About
- Aix Marseille Univ, CNRS, ISM , Marseille , France
| | - Jean-Louis Milan
- Aix Marseille Univ, CNRS, ISM , Marseille , France.,Aix Marseille University, APHM, CNRS, ISM, Sainte-Marguerite Hospital, Institute for Locomotion , Marseille , France
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38
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The Cytoskeleton-A Complex Interacting Meshwork. Cells 2019; 8:cells8040362. [PMID: 31003495 PMCID: PMC6523135 DOI: 10.3390/cells8040362] [Citation(s) in RCA: 181] [Impact Index Per Article: 36.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 04/15/2019] [Accepted: 04/15/2019] [Indexed: 12/22/2022] Open
Abstract
The cytoskeleton of animal cells is one of the most complicated and functionally versatile structures, involved in processes such as endocytosis, cell division, intra-cellular transport, motility, force transmission, reaction to external forces, adhesion and preservation, and adaptation of cell shape. These functions are mediated by three classical cytoskeletal filament types, as follows: Actin, microtubules, and intermediate filaments. The named filaments form a network that is highly structured and dynamic, responding to external and internal cues with a quick reorganization that is orchestrated on the time scale of minutes and has to be tightly regulated. Especially in brain tumors, the cytoskeleton plays an important role in spreading and migration of tumor cells. As the cytoskeletal organization and regulation is complex and many-faceted, this review aims to summarize the findings about cytoskeletal filament types, including substructures formed by them, such as lamellipodia, stress fibers, and interactions between intermediate filaments, microtubules and actin. Additionally, crucial regulatory aspects of the cytoskeletal filaments and the formed substructures are discussed and integrated into the concepts of cell motility. Even though little is known about the impact of cytoskeletal alterations on the progress of glioma, a final point discussed will be the impact of established cytoskeletal alterations in the cellular behavior and invasion of glioma.
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39
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Zaidi KF, Agrawal N. Microstencil-based spatial immobilization of individual cells for single cell analysis. BIOMICROFLUIDICS 2018; 12:064104. [PMID: 30867865 PMCID: PMC6404921 DOI: 10.1063/1.5061922] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Accepted: 11/05/2018] [Indexed: 05/04/2023]
Abstract
Cells exhibit biologically heterogeneous phenotypes, particularly in pathogenic states. To study cell behavior at the single cell level, a variety of micropatterning techniques have been proposed that allow the spatial organization of cells with great control over cell volume, morphology, and intercellular interactions. Among these strategies, microstencil patterning has traditionally been eschewed due to fragility of membranes and lack of control over cell configurations within patterns. Here, we present a simple and reproducible strategy to create robust microstencils and achieve consistent and efficient cell patterns requiring less than 4 μl of cell solution. Polydimethylsiloxane microstencils fabricated with this technique can be used dozens of times over the course of several months with minimal wear or degradation. Characterization of pattern size, cell suspension density, and droplet volume allows on-demand configurations of singlets, doublets, triplets, or multiple cells per individual space. In addition, a novel technique to suppress evaporative convection provides precise and repeatable results, with a twofold increase in patterning efficacy. Selective dual surface modification to create hydrophilic islands on a hydrophobic substrate facilitates a significantly longer and healthier lifespan of cells without crossover of pattern boundaries. The ability to pattern individual cells with or without an extracellular matrix substrate and to control the magnitude of cell-cell contact as well as spread area provides a powerful approach to monitoring cell functions such as proliferation and intercellular signaling.
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Affiliation(s)
- Khadija F. Zaidi
- Department of Bioengineering, George Mason University, Fairfax, Virginia 22033, USA
| | - Nitin Agrawal
- Department of Bioengineering, George Mason University, Fairfax, Virginia 22033, USA
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40
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Kong D, Peng L, Di Cio S, Novak P, Gautrot JE. Stem Cell Expansion and Fate Decision on Liquid Substrates Are Regulated by Self-Assembled Nanosheets. ACS NANO 2018; 12:9206-9213. [PMID: 30178996 DOI: 10.1021/acsnano.8b03865] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
The culture of adherent cells is overwhelmingly relying on the use of solid substrates to support cell adhesion. Indeed, it is typically thought that relatively strong bulk mechanical properties (bulk moduli in the range of kPa to GPa) are essential to promote cell adhesion and, in turn, regulate cell expansion and fate decision. In this report, we show that adherent stem cells such as mesenchymal stem cells and primary keratinocytes can be cultured at the surface of liquid substrates and that this phenomenon is mediated by the assembly of polymer nanosheets at the liquid-liquid interface. We use interfacial rheology to quantify this assembly and demonstrate the strong mechanical properties of such nanosheets. Importantly, we show that cell adhesion to such quasi-2D materials is mediated by the classical integrin/acto-myosin machinery, despite the absence of bulk mechanical properties of the underlying liquid substrate. Finally, we show that stem cell proliferation and fate decision are also regulated by the mechanical properties of these self-assembled protein nanosheets. Liquid substrates offer attractive features for the culture of adherent cells and stem cells, and the development of novel stem cell technologies, such as liquid-liquid systems, are particularly well-adapted to automated parallel processing and scale up.
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41
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Collective cell polarization and alignment on curved surfaces. J Mech Behav Biomed Mater 2018; 88:330-339. [PMID: 30196189 DOI: 10.1016/j.jmbbm.2018.08.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Revised: 05/31/2018] [Accepted: 08/17/2018] [Indexed: 01/06/2023]
Abstract
Curvature as an important topological parameter of 3D extra-cellular matrix has drawn growing attention in recent years. But the underlying mechanism that curvature influences cell behaviors has remained unknown. In this study, we seeded cells on semi-cylindrical and hemispheric surfaces and tested cell alignment and polarization. We found that the surface curvature has profound effect on cell behaviors. With the decrease of diameter of the cylinder/sphere (i.e. increase of curvature), the cells would more preferentially align and polarize with large aspect ratio in the axial/peripheral direction. And the behaviors of the alignment and polarization were position-dependent. For example, at the end of the cylinder, the cells preferred to align circumferentially; while in the interior region, the cells preferred to align in the axial direction. We showed that the cell polarization and alignment were closely correlated with the in-plane stresses in cell layer. That is, the cell polarization and alignment were controlled by the maximum shear stress, which drove cells to align and polarize along the maximum principal stress. The curvature could influence the magnitude of the maximum shear stress and thus regulate cell behaviors. This study provided important insights into the mechanisms of surface curvature influencing cell behaviors in tissue morphogenesis. In addition, our theory of the stress dependent cellular polarity provides a generalized interpretation of the curvature and edge effects which might be extended to understand other steric effects in cell behaviors.
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42
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De R. A general model of focal adhesion orientation dynamics in response to static and cyclic stretch. Commun Biol 2018; 1:81. [PMID: 30271962 PMCID: PMC6123675 DOI: 10.1038/s42003-018-0084-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Accepted: 06/03/2018] [Indexed: 12/11/2022] Open
Abstract
Understanding cellular response to mechanical forces is immensely important for a plethora of biological processes. Focal adhesions are multimolecular protein assemblies that connect the cell to the extracellular matrix and play a pivotal role in cell mechanosensing. Under time-varying stretches, focal adhesions dynamically reorganize and reorient and as a result, regulate the response of cells in tissues. Here I present a simple theoretical model based on, to my knowledge, a novel approach in the understanding of stretch-sensitive bond association and dissociation processes together with the elasticity of the cell-substrate system to predict the growth, stability, and the orientation of focal adhesions in the presence of static as well as cyclically varying stretches. The model agrees well with several experimental observations; most importantly, it explains the puzzling observations of parallel orientation of focal adhesions under static stretch and nearly perpendicular orientation in response to fast varying cyclic stretch. Rumi De presents a model for focal adhesion dynamics under static stretch and cyclic stretch conditions. The predictions agree with prior observations and may explain the puzzling observation that focal adhesions orient toward the parallel direction in the presence of static or quasi-static stretch, but toward the perpendicular direction under fast varying cyclic stretch.
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Affiliation(s)
- Rumi De
- Department of Physical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, 741246, West Bengal, India.
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Robertson SN, Campsie P, Childs PG, Madsen F, Donnelly H, Henriquez FL, Mackay WG, Salmerón-Sánchez M, Tsimbouri MP, Williams C, Dalby MJ, Reid S. Control of cell behaviour through nanovibrational stimulation: nanokicking. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2018; 376:20170290. [PMID: 29661978 PMCID: PMC5915650 DOI: 10.1098/rsta.2017.0290] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 03/07/2018] [Indexed: 05/05/2023]
Abstract
Mechanical signals are ubiquitous in our everyday life and the process of converting these mechanical signals into a biological signalling response is known as mechanotransduction. Our understanding of mechanotransduction, and its contribution to vital cellular responses, is a rapidly expanding field of research involving complex processes that are still not clearly understood. The use of mechanical vibration as a stimulus of mechanotransduction, including variation of frequency and amplitude, allows an alternative method to control specific cell behaviour without chemical stimulation (e.g. growth factors). Chemical-independent control of cell behaviour could be highly advantageous for fields including drug discovery and clinical tissue engineering. In this review, a novel technique is described based on nanoscale sinusoidal vibration. Using finite-element analysis in conjunction with laser interferometry, techniques that are used within the field of gravitational wave detection, optimization of apparatus design and calibration of vibration application have been performed. We further discuss the application of nanovibrational stimulation, or 'nanokicking', to eukaryotic and prokaryotic cells including the differentiation of mesenchymal stem cells towards an osteoblast cell lineage. Mechanotransductive mechanisms are discussed including mediation through the Rho-A kinase signalling pathway. Optimization of this technique was first performed in two-dimensional culture using a simple vibration platform with an optimal frequency and amplitude of 1 kHz and 22 nm. A novel bioreactor was developed to scale up cell production, with recent research demonstrating that mesenchymal stem cell differentiation can be efficiently triggered in soft gel constructs. This important step provides first evidence that clinically relevant (three-dimensional) volumes of osteoblasts can be produced for the purpose of bone grafting, without complex scaffolds and/or chemical induction. Initial findings have shown that nanovibrational stimulation can also reduce biofilm formation in a number of clinically relevant bacteria. This demonstrates additional utility of the bioreactor to investigate mechanotransduction in other fields of research.This article is part of a discussion meeting issue 'The promises of gravitational-wave astronomy'.
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Affiliation(s)
- Shaun N Robertson
- SUPA, Department of Biomedical Engineering, University of Strathclyde, Graham Hills, 50 George Street, Glasgow G1 1QE, UK
| | - Paul Campsie
- SUPA, Department of Biomedical Engineering, University of Strathclyde, Graham Hills, 50 George Street, Glasgow G1 1QE, UK
| | - Peter G Childs
- Division of Biomedical Engineering, School of Engineering, University of Glasgow, Glasgow G12 8QQ, UK
| | - Fiona Madsen
- Institute of Healthcare, Policy and Practice, School of Health, Nursing and Midwifery, University of the West of Scotland, Paisley PA1 2BE, UK
| | - Hannah Donnelly
- Centre for Cell Engineering, Institute for Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Fiona L Henriquez
- Institute of Biomedical and Environmental Health Research, School of Science and Sport, University of the West of Scotland, Paisley PA1 2BE, UK
| | - William G Mackay
- Institute of Healthcare, Policy and Practice, School of Health, Nursing and Midwifery, University of the West of Scotland, Paisley PA1 2BE, UK
| | - Manuel Salmerón-Sánchez
- Division of Biomedical Engineering, School of Engineering, University of Glasgow, Glasgow G12 8QQ, UK
| | - Monica P Tsimbouri
- Centre for Cell Engineering, Institute for Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Craig Williams
- Institute of Healthcare, Policy and Practice, School of Health, Nursing and Midwifery, University of the West of Scotland, Paisley PA1 2BE, UK
| | - Matthew J Dalby
- Centre for Cell Engineering, Institute for Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Stuart Reid
- SUPA, Department of Biomedical Engineering, University of Strathclyde, Graham Hills, 50 George Street, Glasgow G1 1QE, UK
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Fan N, Jiang H, Ye Z, Wu G, Kang Y, Wang Q, Ran X, Guo J, Zhang G, Wang G, Peng B. The Insertion Mechanism of a Living Cell Determined by the Stress Segmentation Effect of the Cell Membrane during the Tip-Cell Interaction. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2018; 14:e1703868. [PMID: 29717805 DOI: 10.1002/smll.201703868] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 03/11/2018] [Indexed: 06/08/2023]
Abstract
Atomic force microscopy probes are proved to be powerful tools to measure and manipulate the individual cell, providing potential applications for the controlled drug/protein delivery. However, the measured insertion efficiency varies dramatically from 20 to 80%, in some cases, the nanotip can never penetrate the cell membrane no matter how much force is applied to it. Thus, the insertion mechanism of a living cell during the tip-cell interaction must be thoroughly investigated before this technology comes into practical applications. In this work, a multistructural cell model is established to study the tip-membrane interaction. The simulation results show that the stress of the cell membrane can be divided into two stages by the stress segmentation point S. After point S, the stress of the cell membrane increases slightly and most of the indentation force is allocated to the cytoskeleton. This phenomenon is called "stress segmentation effect of the cell membrane," which confirms the hypothesis based on the experimental studies. Moreover, according to the experimental and numerical studies, the hypothesis of the stress segmentation effect also explains the reason that modifying the cell membrane or using the manmade sharpened nanotip can increase the insertion efficiency.
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Affiliation(s)
- Na Fan
- School of Mechanical and Electrical Engineering, University of Electronic Science and Technology of China, Chengdu, Sichuan, 611731, P. R. China
| | - Hai Jiang
- School of Mechanical and Electrical Engineering, University of Electronic Science and Technology of China, Chengdu, Sichuan, 611731, P. R. China
| | - Zhiyi Ye
- Key Laboratory of Biorheological Science and Technology of Ministry of Education, College of Bioengineering, Chongqing University, Chongqing, 400044, P. R. China
| | - Guiyong Wu
- School of Mechanical and Electrical Engineering, University of Electronic Science and Technology of China, Chengdu, Sichuan, 611731, P. R. China
| | - Yuejun Kang
- Institute for Clean Energy & Advanced Materials, Southwest University, Chongqing, 400715, P. R. China
| | - Qun Wang
- School of Mechanical and Electrical Engineering, University of Electronic Science and Technology of China, Chengdu, Sichuan, 611731, P. R. China
| | - Xiaolin Ran
- Key Laboratory of Biorheological Science and Technology of Ministry of Education, College of Bioengineering, Chongqing University, Chongqing, 400044, P. R. China
| | - Jian Guo
- School of Mechanical Engineering, University of South China, Hengyang, Hunan, 421001, P. R. China
| | - Guocheng Zhang
- School of Mechanical and Electrical Engineering, University of Electronic Science and Technology of China, Chengdu, Sichuan, 611731, P. R. China
| | - Guixue Wang
- Key Laboratory of Biorheological Science and Technology of Ministry of Education, College of Bioengineering, Chongqing University, Chongqing, 400044, P. R. China
| | - Bei Peng
- School of Mechanical and Electrical Engineering, University of Electronic Science and Technology of China, Chengdu, Sichuan, 611731, P. R. China
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Kong D, Megone W, Nguyen KDQ, Di Cio S, Ramstedt M, Gautrot JE. Protein Nanosheet Mechanics Controls Cell Adhesion and Expansion on Low-Viscosity Liquids. NANO LETTERS 2018; 18:1946-1951. [PMID: 29411615 DOI: 10.1021/acs.nanolett.7b05339] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Adherent cell culture typically requires cell spreading at the surface of solid substrates to sustain the formation of stable focal adhesions and assembly of a contractile cytoskeleton. However, a few reports have demonstrated that cell culture is possible on liquid substrates such as silicone and fluorinated oils, even displaying very low viscosities (0.77 cSt). Such behavior is surprising as low viscosity liquids are thought to relax much too fast (<ms) to enable the stabilization of focal adhesions (with lifetimes on the order of minutes to hours). Here we show that cell spreading and proliferation at the surface of low viscosity liquids are enabled by the self-assembly of mechanically strong protein nanosheets at these interfaces. We propose that this phenomenon results from the denaturation of globular proteins, such as albumin, in combination with the coupling of surfactant molecules to the resulting protein nanosheets. We use interfacial rheology and atomic force microscopy indentation to characterize the mechanical properties of protein nanosheets and associated liquid-liquid interfaces. We identify a direct relationship between interfacial mechanics and the association of surfactant molecules with proteins and polymers assembled at liquid-liquid interfaces. In addition, our data indicate that cells primarily sense in-plane mechanical properties of interfaces, rather than relying on surface tension to sustain spreading, as in the spreading of water striders. These findings demonstrate that bulk and nanoscale mechanical properties may be designed independently, to provide structure and regulate cell phenotype, therefore calling for a paradigm shift for the design of biomaterials in regenerative medicine.
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Dabagh M, Jalali P, Butler PJ, Randles A, Tarbell JM. Mechanotransmission in endothelial cells subjected to oscillatory and multi-directional shear flow. J R Soc Interface 2018; 14:rsif.2017.0185. [PMID: 28515328 DOI: 10.1098/rsif.2017.0185] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Accepted: 04/21/2017] [Indexed: 12/27/2022] Open
Abstract
Local haemodynamics are linked to the non-uniform distribution of atherosclerosic lesions in arteries. Low and oscillatory (reversing in the axial flow direction) wall shear stress (WSS) induce inflammatory responses in endothelial cells (ECs) mediating disease localization. The objective of this study is to investigate computationally how the flow direction (reflected in WSS variation on the EC surface over time) influences the forces experienced by structural components of ECs that are believed to play important roles in mechanotransduction. A three-dimensional, multi-scale, multi-component, viscoelastic model of focally adhered ECs is developed, in which oscillatory WSS (reversing or non-reversing) parallel to the principal flow direction, or multi-directional oscillatory WSS with reversing axial and transverse components are applied over the EC surface. The computational model includes the glycocalyx layer, actin cortical layer, nucleus, cytoskeleton, focal adhesions (FAs), stress fibres and adherens junctions (ADJs). We show the distinct effects of atherogenic flow profiles (reversing unidirectional flow and reversing multi-directional flow) on subcellular structures relative to non-atherogenic flow (non-reversing flow). Reversing flow lowers stresses and strains due to viscoelastic effects, and multi-directional flow alters stress on the ADJs perpendicular to the axial flow direction. The simulations predict forces on integrins, ADJ filaments and other substructures in the range that activate mechanotransduction.
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Affiliation(s)
- Mahsa Dabagh
- Department of Biomedical Engineering, Duke University, Durham, NC, USA .,School of Energy Systems, Lappeenranta University of Technology, Lappeenranta, Finland
| | - Payman Jalali
- School of Energy Systems, Lappeenranta University of Technology, Lappeenranta, Finland
| | - Peter J Butler
- Department of Biomedical Engineering, The Pennsylvania State University, Pennsylvania, PA, USA
| | - Amanda Randles
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - John M Tarbell
- Department of Biomedical Engineering, The City College of New York, New York, NY, USA
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Abstract
The focus of this paper is to describe the mechanism and behavior of two-dimensional in vitro cell stretch platforms, as well as discussing designs for the evaluation of mechanical properties of cells. It is extremely important to understand the cellular response to extrinsic mechanical forces as living biological system is constantly subjected to mechanical forces in vivo. In addition, this mechanistic understanding of cellular response will provide valuable information towards the design and fabrication of bioengineered tissues and organs, which are expected to replace and/or aid bodily functions. This paper will primarily focus on the development, advantages and limitations of two-dimensional cell stretch platforms.
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Affiliation(s)
- H. GHAZIZADEH
- Joint School of Nanoscience and Nanoengineering, North Carolina A&T State University, 2907 East Gate City Blvd., Greensboro, NC 27401, USA
| | - S. ARAVAMUDHAN
- Joint School of Nanoscience and Nanoengineering, North Carolina A&T State University, 2907 East Gate City Blvd., Greensboro, NC 27401, USA
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48
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Sakamoto Y, Buchanan RM, Sanchez-Adams J, Guilak F, Sacks MS. On the Functional Role of Valve Interstitial Cell Stress Fibers: A Continuum Modeling Approach. J Biomech Eng 2017; 139:2595420. [PMID: 28024085 DOI: 10.1115/1.4035557] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Indexed: 01/20/2023]
Abstract
The function of the heart valve interstitial cells (VICs) is intimately connected to heart valve tissue remodeling and repair, as well as the onset and progression of valvular pathological processes. There is yet only very limited knowledge and extant models for the complex three-dimensional VIC internal stress-bearing structures, the associated cell-level biomechanical behaviors, and how they change under varying activation levels. Importantly, VICs are known to exist and function within the highly dynamic valve tissue environment, including very high physiological loading rates. Yet we have no knowledge on how these factors affect VIC function. To this end, we extended our previous VIC computational continuum mechanics model (Sakamoto, et al., 2016, "On Intrinsic Stress Fiber Contractile Forces in Semilunar Heart Valve Interstitial Cells Using a Continuum Mixture Model," J. Mech. Behav. Biomed. Mater., 54(244-258)). to incorporate realistic stress-fiber geometries, force-length relations (Hill model for active contraction), explicit α-smooth muscle actin (α-SMA) and F-actin expression levels, and strain rate. Novel micro-indentation measurements were then performed using cytochalasin D (CytoD), variable KCl molar concentrations, both alone and with transforming growth factor β1 (TGF-β1) (which emulates certain valvular pathological processes) to explore how α-SMA and F-actin expression levels influenced stress fiber responses under quasi-static and physiological loading rates. Simulation results indicated that both F-actin and α-SMA contributed substantially to stress fiber force generation, with the highest activation state (90 mM KCL + TGF-β1) inducing the largest α-SMA levels and associated force generation. Validation was performed by comparisons to traction force microscopy studies, which showed very good agreement. Interestingly, only in the highest activation state was strain rate sensitivity observed, which was captured successfully in the simulations. These unique findings demonstrated that only VICs with high levels of αSMA expression exhibited significant viscoelastic effects. Implications of this study include greater insight into the functional role of α-SMA and F-actin in VIC stress fiber function, and the potential for strain rate-dependent effects in pathological states where high levels of α-SMA occur, which appear to be unique to the valvular cellular in vivo microenvironment.
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Affiliation(s)
- Yusuke Sakamoto
- Center for Cardiovascular Simulation, Institute for Computational Engineering and Sciences, Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX 78712
| | - Rachel M Buchanan
- Center for Cardiovascular Simulation, Institute for Computational Engineering and Sciences, Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX 78712
| | - Johannah Sanchez-Adams
- Departments of Orthopaedic Surgery, Duke University Medical Center, Durham, NC 27710;Departments of Biomedical Engineering, Duke University Medical Center, Durham, NC 27710
| | - Farshid Guilak
- Departments of Orthopaedic Surgery, Washington University, St. Louis, MO 63110;Departments of Biomedical Engineering, Washington University, St. Louis, MO 63110;Departments of Developmental Biology, Washington University, St. Louis, MO 63110
| | - Michael S Sacks
- W. A. "Tex" Moncrief, Jr. Simulation-Based Engineering Science Chair I Center for Cardiovascular Simulation, Institute for Computational Engineering and Sciences, Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX 78712 e-mail:
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49
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Sander M, Dobicki H, Ott A. Large Amplitude Oscillatory Shear Rheology of Living Fibroblasts: Path-Dependent Steady States. Biophys J 2017; 113:1561-1573. [PMID: 28978448 PMCID: PMC5627183 DOI: 10.1016/j.bpj.2017.07.032] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Revised: 06/12/2017] [Accepted: 07/10/2017] [Indexed: 01/16/2023] Open
Abstract
Mechanical properties of biological cells play a role in cell locomotion, embryonic tissue formation, and tumor migration among many other processes. Cells exhibit a complex nonlinear response to mechanical cues that is not understood. Cells may stiffen as well as soften, depending on the exact type of stimulus. Here we apply large-amplitude oscillatory shear to a monolayer of separated fibroblast cells suspended between two plates. Although we apply identical steady-state excitations, in response we observe different typical regimes that exhibit cell softening or cell stiffening to varying degrees. This degeneracy of the cell response can be linked to the initial paths that the instrument takes to go from cell rest to steady state. A model of cross-linked, force-bearing filaments submitted to steady-state excitation renders the different observed regimes with minor changes in parameters if the filaments are permitted to self-organize and form different spatially organized structures. We suggest that rather than a complex viscoelastic or plastic response, the different observed regimes reflect the emergence of different steady-state cytoskeletal conformations. A high sensitivity of the cytoskeletal rheology and structure to minor changes in parameters or initial conditions enables a cell to respond to mechanical requirements quickly and in various ways with only minor biochemical intervention. Probing path-dependent rheological changes constitutes a possibly very sensitive assessment of the cell cytoskeleton as a possible tool for medical diagnosis. Our observations show that the memory of subtle differences in earlier deformation paths must be taken into account when deciphering the cell mechanical response to large-amplitude deformations.
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Affiliation(s)
- Mathias Sander
- Biological Experimental Physics, Department of Physics, Saarland University, Saarbruecken, Germany
| | - Heike Dobicki
- Biological Experimental Physics, Department of Physics, Saarland University, Saarbruecken, Germany
| | - Albrecht Ott
- Biological Experimental Physics, Department of Physics, Saarland University, Saarbruecken, Germany.
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PETROVA MARGARITA, GAO ZHIWEN, LIU YAN, GAO YANFEI, HE WEI. COHESIVE FINITE ELEMENT SIMULATIONS OF CONTRACTION AND SHAPE EFFECTS ON CELL DE-ADHESION. J MECH MED BIOL 2017. [DOI: 10.1142/s0219519417500919] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Cohesive-interface-based finite element simulations were conducted to investigate the critical shear stress required for cell de-adhesion from extracellular substrates. The interface ligand–receptor bonds are modeled by a cohesive interface model with initial stiffness, interface strength, and fracture energy as the governing parameters. The ratio of the cell modulus to the interface stiffness defines a length scale. If this length is much less than the contact size, the de-adhesion process can be modeled by the linear elastic fracture mechanics, while the opposite limit leads to the concurrent sliding of the cell or, equivalently, debonding of all the interface ligand–receptor pairs. Since it generates additional shear-stress concentration along the interface, cell contraction generally reduces the critical de-adhesion stress. Cell de-adhesion is more prone to take place for three-dimensional irregular cell shapes because of the much easier failure in the anti-plane Mode III shear, as well as the additional stress concentration in these geometric irregularities.
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Affiliation(s)
- MARGARITA PETROVA
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996, USA
| | - ZHIWEN GAO
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996, USA
- Key Laboratory of Mechanics on Disaster and Environment in Western China Attached to the Ministry of Education of China, Lanzhou University, Lanzhou, Gansu Province, 730000, P. R. China
- Department of Mechanics and Engineering Science, College of Civil Engineering and Mechanics, Lanzhou University, Lanzhou, Gansu Province, 73000, P. R. China
| | - YAN LIU
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996, USA
- Tianjin First Central Hospital, Tianjin Medical University, Tianjin 300192, P. R. China
| | - YANFEI GAO
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996, USA
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - WEI HE
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996, USA
- State Key Laboratory of Fine Chemicals, Department of Polymer Science and Engineering, Dalian University of Technology, Dalian, Liaoning Province, 116023, P. R. China
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