1
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Gallo E, De Renzis S, Sharpe J, Mayor R, Hartmann J. Versatile system cores as a conceptual basis for generality in cell and developmental biology. Cell Syst 2024:S2405-4712(24)00209-6. [PMID: 39236709 DOI: 10.1016/j.cels.2024.08.001] [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: 08/16/2023] [Revised: 05/26/2024] [Accepted: 08/07/2024] [Indexed: 09/07/2024]
Abstract
The discovery of general principles underlying the complexity and diversity of cellular and developmental systems is a central and long-standing aim of biology. While new technologies collect data at an ever-accelerating rate, there is growing concern that conceptual progress is not keeping pace. We contend that this is due to a paucity of conceptual frameworks that support meaningful generalizations. This led us to develop the core and periphery (C&P) hypothesis, which posits that many biological systems can be decomposed into a highly versatile core with a large behavioral repertoire and a specific periphery that configures said core to perform one particular function. Versatile cores tend to be widely reused across biology, which confers generality to theories describing them. Here, we introduce this concept and describe examples at multiple scales, including Turing patterning, actomyosin dynamics, multi-cellular morphogenesis, and vertebrate gastrulation. We also sketch its evolutionary basis and discuss key implications and open questions. We propose that the C&P hypothesis could unlock new avenues of conceptual progress in mesoscale biology.
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Affiliation(s)
- Elisa Gallo
- Institute of Molecular Life Sciences, University of Zurich (UZH), 8057 Zurich, Switzerland
| | - Stefano De Renzis
- Developmental Biology Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany
| | - James Sharpe
- EMBL Barcelona, European Molecular Biology Laboratory (EMBL), 08003 Barcelona, Spain; Institució Catalana de Recerca i Estudis Avançats, 08010 Barcelona, Spain
| | - Roberto Mayor
- Department of Cell and Developmental Biology, University College London, London WC1E 6BT, UK
| | - Jonas Hartmann
- Institute of Molecular Life Sciences, University of Zurich (UZH), 8057 Zurich, Switzerland; Developmental Biology Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany; EMBL Barcelona, European Molecular Biology Laboratory (EMBL), 08003 Barcelona, Spain; Department of Cell and Developmental Biology, University College London, London WC1E 6BT, UK; Northwestern Institute on Complex Systems, Northwestern University, Evanston, IL 60208, USA; Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL 60208, USA.
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2
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Hartmann J, Mayor R. Self-organized collective cell behaviors as design principles for synthetic developmental biology. Semin Cell Dev Biol 2023; 141:63-73. [PMID: 35450765 DOI: 10.1016/j.semcdb.2022.04.009] [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: 01/23/2022] [Accepted: 04/12/2022] [Indexed: 10/18/2022]
Abstract
Over the past two decades, molecular cell biology has graduated from a mostly analytic science to one with substantial synthetic capability. This success is built on a deep understanding of the structure and function of biomolecules and molecular mechanisms. For synthetic biology to achieve similar success at the scale of tissues and organs, an equally deep understanding of the principles of development is required. Here, we review some of the central concepts and recent progress in tissue patterning, morphogenesis and collective cell migration and discuss their value for synthetic developmental biology, emphasizing in particular the power of (guided) self-organization and the role of theoretical advances in making developmental insights applicable in synthesis.
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Affiliation(s)
- Jonas Hartmann
- Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK.
| | - Roberto Mayor
- Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK.
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3
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Cockerell A, Wright L, Dattani A, Guo G, Smith A, Tsaneva-Atanasova K, Richards DM. Biophysical models of early mammalian embryogenesis. Stem Cell Reports 2023; 18:26-46. [PMID: 36630902 PMCID: PMC9860129 DOI: 10.1016/j.stemcr.2022.11.021] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 11/02/2022] [Accepted: 11/24/2022] [Indexed: 01/12/2023] Open
Abstract
Embryo development is a critical and fascinating stage in the life cycle of many organisms. Despite decades of research, the earliest stages of mammalian embryogenesis are still poorly understood, caused by a scarcity of high-resolution spatial and temporal data, the use of only a few model organisms, and a paucity of truly multidisciplinary approaches that combine biological research with biophysical modeling and computational simulation. Here, we explain the theoretical frameworks and biophysical processes that are best suited to modeling the early mammalian embryo, review a comprehensive list of previous models, and discuss the most promising avenues for future work.
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Affiliation(s)
- Alaina Cockerell
- Living Systems Institute, University of Exeter, Stocker Road, Exeter EX4 4QD, UK
| | - Liam Wright
- Department of Mathematics, University of Exeter, North Park Road, Exeter EX4 4QF, UK
| | - Anish Dattani
- Living Systems Institute, University of Exeter, Stocker Road, Exeter EX4 4QD, UK
| | - Ge Guo
- Living Systems Institute, University of Exeter, Stocker Road, Exeter EX4 4QD, UK
| | - Austin Smith
- Living Systems Institute, University of Exeter, Stocker Road, Exeter EX4 4QD, UK
| | - Krasimira Tsaneva-Atanasova
- Living Systems Institute, University of Exeter, Stocker Road, Exeter EX4 4QD, UK; Department of Mathematics, University of Exeter, North Park Road, Exeter EX4 4QF, UK; EPSRC Hub for Quantitative Modelling in Healthcare, University of Exeter, Exeter EX4 4QJ, UK; Department of Bioinformatics and Mathematical Modelling, Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, 105 Acad. G. Bonchev Street, 1113 Sofia, Bulgaria
| | - David M Richards
- Living Systems Institute, University of Exeter, Stocker Road, Exeter EX4 4QD, UK; Department of Physics and Astronomy, University of Exeter, North Park Road, Exeter EX4 4QL, UK.
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4
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Umetsu D. Cell mechanics and cell-cell recognition controls by Toll-like receptors in tissue morphogenesis and homeostasis. Fly (Austin) 2022; 16:233-247. [PMID: 35579305 PMCID: PMC9116419 DOI: 10.1080/19336934.2022.2074783] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Signal transduction by the Toll-like receptors (TLRs) is conserved and essential for innate immunity in metazoans. The founding member of the TLR family, Drosophila Toll-1, was initially identified for its role in dorsoventral axis formation in early embryogenesis. The Drosophila genome encodes nine TLRs that display dynamic expression patterns during development, suggesting their involvement in tissue morphogenesis and homeostasis. Recent progress on the developmental functions of TLRs beyond dorsoventral patterning has revealed not only their diverse functions in various biological processes, but also unprecedented molecular mechanisms in directly regulating cell mechanics and cell-cell recognition independent of the canonical signal transduction pathway involving transcriptional regulation of target genes. In this review, I feature and discuss the non-immune functions of TLRs in the control of epithelial tissue homeostasis, tissue morphogenesis, and cell-cell recognition between cell populations with different cell identities.
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Affiliation(s)
- Daiki Umetsu
- Graduate School of Life Sciences, Tohoku University, Sendai, Japan
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5
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Kindberg AA, Srivastava V, Muncie JM, Weaver VM, Gartner ZJ, Bush JO. EPH/EPHRIN regulates cellular organization by actomyosin contractility effects on cell contacts. J Cell Biol 2021; 220:e202005216. [PMID: 33798261 PMCID: PMC8025214 DOI: 10.1083/jcb.202005216] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 02/02/2021] [Accepted: 03/03/2021] [Indexed: 02/06/2023] Open
Abstract
EPH/EPHRIN signaling is essential to many aspects of tissue self-organization and morphogenesis, but little is known about how EPH/EPHRIN signaling regulates cell mechanics during these processes. Here, we use a series of approaches to examine how EPH/EPHRIN signaling drives cellular self-organization. Contact angle measurements reveal that EPH/EPHRIN signaling decreases the stability of heterotypic cell:cell contacts through increased cortical actomyosin contractility. We find that EPH/EPHRIN-driven cell segregation depends on actomyosin contractility but occurs independently of directed cell migration and without changes in cell adhesion. Atomic force microscopy and live cell imaging of myosin localization support that EPH/EPHRIN signaling results in increased cortical tension. Interestingly, actomyosin contractility also nonautonomously drives increased EPHB2:EPHB2 homotypic contacts. Finally, we demonstrate that changes in tissue organization are driven by minimization of heterotypic contacts through actomyosin contractility in cell aggregates and by mouse genetics experiments. These data elucidate the biomechanical mechanisms driving EPH/EPHRIN-based cell segregation wherein differences in interfacial tension, regulated by actomyosin contractility, govern cellular self-organization.
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Affiliation(s)
- Abigail A. Kindberg
- Program in Craniofacial Biology, University of California, San Francisco, San Francisco, CA
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, CA
- Institute for Human Genetics, University of California, San Francisco, San Francisco, CA
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, CA
- Biomedical Sciences Graduate Program, University of California, San Francisco, San Francisco, CA
| | - Vasudha Srivastava
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA
| | - Jonathon M. Muncie
- Center for Bioengineering and Tissue Regeneration, University of California, San Francisco, San Francisco, CA
- Department of Surgery, University of California, San Francisco, San Francisco, CA
- Helen Diller Family Cancer Research Center, University of California, San Francisco, San Francisco, CA
- Graduate Program in Bioengineering, University of California, San Francisco, and University of California, Berkeley, San Francisco, CA
| | - Valerie M. Weaver
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, CA
- Center for Bioengineering and Tissue Regeneration, University of California, San Francisco, San Francisco, CA
- Department of Surgery, University of California, San Francisco, San Francisco, CA
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA
- Department of Anatomy, University of California, San Francisco, San Francisco, CA
- Department of Radiation Oncology, University of California, San Francisco, San Francisco, CA
- UCSF Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA
- Helen Diller Family Cancer Research Center, University of California, San Francisco, San Francisco, CA
| | - Zev J. Gartner
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA
- Center for Cellular Construction, University of California, San Francisco, San Francisco, CA
- Chan Zuckerberg Biohub, San Francisco, CA
| | - Jeffrey O. Bush
- Program in Craniofacial Biology, University of California, San Francisco, San Francisco, CA
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, CA
- Institute for Human Genetics, University of California, San Francisco, San Francisco, CA
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, CA
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6
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Iijima N, Sato K, Kuranaga E, Umetsu D. Differential cell adhesion implemented by Drosophila Toll corrects local distortions of the anterior-posterior compartment boundary. Nat Commun 2020; 11:6320. [PMID: 33303753 PMCID: PMC7729853 DOI: 10.1038/s41467-020-20118-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Accepted: 11/16/2020] [Indexed: 11/25/2022] Open
Abstract
Maintaining lineage restriction boundaries in proliferating tissues is vital to animal development. A long-standing thermodynamics theory, the differential adhesion hypothesis, attributes cell sorting phenomena to differentially expressed adhesion molecules. However, the contribution of the differential adhesion system during tissue morphogenesis has been unsubstantiated despite substantial theoretical support. Here, we report that Toll-1, a transmembrane receptor protein, acts as a differentially expressed adhesion molecule that straightens the fluctuating anteroposterior compartment boundary in the abdominal epidermal epithelium of the Drosophila pupa. Toll-1 is expressed across the entire posterior compartment under the control of the selector gene engrailed and displays a sharp expression boundary that coincides with the compartment boundary. Toll-1 corrects local distortions of the boundary in the absence of cable-like Myosin II enrichment along the boundary. The reinforced adhesion of homotypic cell contacts, together with pulsed cell contraction, achieves a biased vertex sliding action by resisting the separation of homotypic cell contacts in boundary cells. This work reveals a self-organizing system that integrates a differential adhesion system with pulsed contraction of cells to maintain lineage restriction boundaries.
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Affiliation(s)
- Norihiro Iijima
- Laboratory for Histogenetic Dynamics, Graduate School of Life Sciences, Tohoku University, Sendai, 980-8578, Japan
| | - Katsuhiko Sato
- Research Institute for Electronic Science, Hokkaido University, Sapporo, 001-0020, Japan
- Global Station for Soft Matter, Global Institution for Collaborative Research and Education, Hokkaido University, Sapporo, 001-0020, Japan
| | - Erina Kuranaga
- Laboratory for Histogenetic Dynamics, Graduate School of Life Sciences, Tohoku University, Sendai, 980-8578, Japan.
| | - Daiki Umetsu
- Laboratory for Histogenetic Dynamics, Graduate School of Life Sciences, Tohoku University, Sendai, 980-8578, Japan.
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7
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Sharrock TE, Sanson B. Cell sorting and morphogenesis in early Drosophila embryos. Semin Cell Dev Biol 2020; 107:147-160. [PMID: 32807642 DOI: 10.1016/j.semcdb.2020.07.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 07/13/2020] [Accepted: 07/14/2020] [Indexed: 12/25/2022]
Abstract
The regionalisation of growing tissues into compartments that do not mix is thought to be a common motif of animal development. Compartments and compartmental boundaries were discovered by lineage studies in the model organism Drosophila. Since then, many compartment boundaries have been identified in developing tissues, from insects to vertebrates. These are important for animal development, because boundaries localize signalling centres that control tissue morphogenesis. Compartment boundaries are boundaries of lineage restriction, where specific mechanisms keep boundaries straight and cells segregated. Here, we review the mechanisms of cell sorting at boundaries found in early Drosophila embryos. The parasegmental boundaries, separating anterior from posterior compartments in the embryo, keep cells segregated by increasing actomyosin contractility at boundary cell-cell interfaces. Differential actomyosin contractility in turn promotes fold formation and orients cell division. Earlier in development, actomyosin differentials are also important for cell sorting during axis extension. Specific cell surface asymmetries and signalling pathways are required to initiate and maintain these actomyosin differentials.
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Affiliation(s)
- Thomas E Sharrock
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK
| | - Bénédicte Sanson
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK.
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8
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Winklbauer R. Dynamic cell–cell adhesion mediated by pericellular matrix interaction – a hypothesis. J Cell Sci 2019; 132:132/16/jcs231597. [DOI: 10.1242/jcs.231597] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
ABSTRACT
Cell–cell adhesion strength, measured as tissue surface tension, spans an enormous 1000-fold range when different cell types are compared. However, the examination of basic mechanical principles of cell adhesion indicates that cadherin-based and related mechanisms are not able to promote the high-strength adhesion experimentally observed in many late embryonic or malignant tissues. Therefore, the hypothesis is explored that the interaction of the pericellular matrices of cells generates strong adhesion by a mechanism akin to the self-adhesion/self-healing of dynamically cross-linked hydrogels. Quantitative data from biofilm matrices support this model. The mechanism links tissue surface tension to pericellular matrix stiffness. Moreover, it explains the wide, matrix-filled spaces around cells in liquid-like, yet highly cohesive, tissues, and it rehabilitates aspects of the original interpretation of classical cell sorting experiments, as expressed in Steinberg's differential adhesion hypothesis: that quantitative differences in adhesion energies between cells are sufficient to drive sorting.
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Affiliation(s)
- Rudolf Winklbauer
- Department of Cell and Systems Biology, University of Toronto, 25 Harbord Street, Toronto, Ontario, M5S 3G5, Canada
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9
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Wu Z, Ashlin TG, Xu Q, Wilkinson DG. Role of forward and reverse signaling in Eph receptor and ephrin mediated cell segregation. Exp Cell Res 2019; 381:57-65. [PMID: 31075258 PMCID: PMC6546932 DOI: 10.1016/j.yexcr.2019.04.040] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 04/29/2019] [Accepted: 04/30/2019] [Indexed: 12/02/2022]
Abstract
Eph receptor and ephrin signaling has a major role in segregating distinct cell populations to form sharp borders. Expression of interacting Ephs and ephrins typically occurs in complementary regions, such that polarised activation of both components occurs at the interface. Forward signaling through Eph receptors can drive cell segregation, but it is unclear whether reverse signaling through ephrins can also contribute. We have tested the role of reverse signaling, and of polarised versus non-polarised activation, in assays in which contact repulsion drives cell segregation and border sharpening. We find that polarised forward signaling drives stronger segregation than polarised reverse signaling. Nevertheless, reverse signaling contributes since bidirectional Eph and ephrin activation drives stronger segregation than unidirectional forward signaling alone. In contrast, non-polarised Eph activation drives little segregation. We propose that although polarised forward signaling is the principal driver of segregation, reverse signaling enables bidirectional repulsion which prevents mingling of each population into the other.
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Affiliation(s)
- Zhonglin Wu
- The Francis Crick Institute, London, NW1 1AT, UK
| | - Tim G Ashlin
- The Francis Crick Institute, London, NW1 1AT, UK
| | - Qiling Xu
- The Francis Crick Institute, London, NW1 1AT, UK
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10
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McCleery WT, Veldhuis J, Bennett ME, Lynch HE, Ma X, Brodland GW, Hutson MS. Elongated Cells Drive Morphogenesis in a Surface-Wrapped Finite-Element Model of Germband Retraction. Biophys J 2019; 117:157-169. [PMID: 31229244 DOI: 10.1016/j.bpj.2019.05.023] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 05/13/2019] [Accepted: 05/20/2019] [Indexed: 10/26/2022] Open
Abstract
During Drosophila embryogenesis, the germband first extends to curl around the posterior end of the embryo and then retracts back; however, retraction is not simply the reversal of extension. At a tissue level, extension is coincident with ventral furrow formation, and at a cellular level, extension occurs via convergent cell neighbor exchanges in the germband, whereas retraction involves only changes in cell shape. To understand how cell shapes, tissue organization, and cellular forces drive germband retraction, we investigate this process using a whole-embryo, surface-wrapped cellular finite-element model. This model represents two key epithelial tissues-amnioserosa and germband-as adjacent sheets of two-dimensional cellular finite elements that are wrapped around an ellipsoidal three-dimensional approximation of an embryo. The model reproduces the detailed kinematics of in vivo retraction by fitting just one free model parameter, the tension along germband cell interfaces; all other cellular forces are constrained to follow ratios inferred from experimental observations. With no additional parameter adjustments, the model also reproduces quantitative assessments of mechanical stress using laser dissection and failures of retraction when amnioserosa cells are removed via mutations or microsurgery. Surprisingly, retraction in the model is robust to changes in cellular force values but is critically dependent on starting from a configuration with highly elongated amnioserosa cells. Their extreme cellular elongation is established during the prior process of germband extension and is then used to drive retraction. The amnioserosa is the one tissue whose cellular morphogenesis is reversed from germband extension to retraction, and this reversal coordinates the forces needed to retract the germband back to its pre-extension position and shape. In this case, cellular force strengths are less important than the carefully established cell shapes that direct them. VIDEO ABSTRACT.
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Affiliation(s)
- W Tyler McCleery
- Department of Physics & Astronomy, Vanderbilt University, Nashville, Tennessee
| | - Jim Veldhuis
- Department of Civil & Environmental Engineering, University of Waterloo, Waterloo, Ontario, Canada
| | - Monica E Bennett
- Department of Physics & Astronomy, Vanderbilt University, Nashville, Tennessee
| | - Holley E Lynch
- Department of Physics, Stetson University, DeLand, Florida
| | - Xiaoyan Ma
- Department of Physics & Astronomy, Vanderbilt University, Nashville, Tennessee
| | - G Wayne Brodland
- Department of Civil & Environmental Engineering, University of Waterloo, Waterloo, Ontario, Canada
| | - M Shane Hutson
- Department of Physics & Astronomy, Vanderbilt University, Nashville, Tennessee; Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee.
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11
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ya||a: GPU-Powered Spheroid Models for Mesenchyme and Epithelium. Cell Syst 2019; 8:261-266.e3. [DOI: 10.1016/j.cels.2019.02.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 08/03/2018] [Accepted: 02/19/2019] [Indexed: 11/20/2022]
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12
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Chen Z, Zou Y. A multiscale model for heterogeneous tumor spheroid in vitro. MATHEMATICAL BIOSCIENCES AND ENGINEERING : MBE 2018; 15:361-392. [PMID: 29161840 DOI: 10.3934/mbe.2018016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In this paper, a novel multiscale method is proposed for the study of heterogeneous tumor spheroid growth in vitro. The entire tumor spheroid is described by an ellipsoid-based model while nutrient and other environmental factors are treated as continua. The ellipsoid-based discrete component is capable of incorporating mechanical effects and deformability, while keeping a minimum set of free variables to describe complex shape variations. Moreover, our purely cell-based description of tumor avoids the complex mutual conversion between a cell-based model and continuum model within a tumor, such as force and mass transformation. This advantage makes it highly suitable for the study of tumor spheroids in vitro whose size are normally less than 800 μm in diameter. In addition, our numerical scheme provides two computational options depending on tumor size. For a small or medium tumor spheroid, a three-dimensional (3D) numerical model can be directly applied. For a large spheroid, we suggest the use of a 3D-adapted 2D cross section configuration, which has not yet been explored in the literature, as an alternative for the theoretical investigation to bridge the gap between the 2D and 3D models. Our model and its implementations have been validated and applied to various studies given in the paper. The simulation results fit corresponding in vitro experimental observations very well.
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Affiliation(s)
- Zhan Chen
- Department of Mathematical Sciences, Georgia Southern University, Statesboro, GA, 30460, United States
| | - Yuting Zou
- Department of Mathematical Sciences, Georgia Southern University, Statesboro, GA, 30460, United States
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13
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Veldhuis JH, Ehsandar A, Maître JL, Hiiragi T, Cox S, Brodland GW. Inferring cellular forces from image stacks. Philos Trans R Soc Lond B Biol Sci 2017; 372:rstb.2016.0261. [PMID: 28348259 DOI: 10.1098/rstb.2016.0261] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/03/2016] [Indexed: 12/18/2022] Open
Abstract
Although the importance of cellular forces to a wide range of embryogenesis and disease processes is widely recognized, measuring these forces is challenging, especially in three dimensions. Here, we introduce CellFIT-3D, a force inference technique that allows tension maps for three-dimensional cellular systems to be estimated from image stacks. Like its predecessors, video force microscopy and CellFIT, this cell mechanics technique assumes boundary-specific interfacial tensions to be the primary drivers, and it constructs force-balance equations based on triple junction (TJ) dihedral angles. The technique involves image processing, segmenting of cells, grouping of cell outlines, calculation of dihedral planes, averaging along three-dimensional TJs, and matrix equation assembly and solution. The equations tend to be strongly overdetermined, allowing indistinct TJs to be ignored and solution error estimates to be determined. Application to clean and noisy synthetic data generated using Surface Evolver gave tension errors of 1.6-7%, and analyses of eight-cell murine embryos gave estimated errors smaller than the 10% uncertainty of companion aspiration experiments. Other possible areas of application include morphogenesis, cancer metastasis and tissue engineering.This article is part of the themed issue 'Systems morphodynamics: understanding the development of tissue hardware'.
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Affiliation(s)
- Jim H Veldhuis
- Department of Civil and Environmental Engineering, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1
| | - Ahmad Ehsandar
- Department of Civil and Environmental Engineering, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1
| | - Jean-Léon Maître
- Department of Genetics and Developmental Biology, Institut Curie, 26 rue d'Ulm, 75248 Paris Cedex 05, France
| | - Takashi Hiiragi
- Developmental Biology Unit, European Molecular Biology Laboratory, Meyerhofstraße 1, 69117 Heidelberg, Germany
| | - Simon Cox
- Department of Mathematics, Aberystwyth University, Aberystwyth, Ceredigion SY23 3BZ, UK
| | - G Wayne Brodland
- Department of Civil and Environmental Engineering, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1 .,Centre for Bioengineering and Biotechnology, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1
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14
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Fletcher AG, Cooper F, Baker RE. Mechanocellular models of epithelial morphogenesis. Philos Trans R Soc Lond B Biol Sci 2017; 372:rstb.2015.0519. [PMID: 28348253 DOI: 10.1098/rstb.2015.0519] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/31/2016] [Indexed: 01/13/2023] Open
Abstract
Embryonic epithelia achieve complex morphogenetic movements, including in-plane reshaping, bending and folding, through the coordinated action and rearrangement of individual cells. Technical advances in molecular and live-imaging studies of epithelial dynamics provide a very real opportunity to understand how cell-level processes facilitate these large-scale tissue rearrangements. However, the large datasets that we are now able to generate require careful interpretation. In combination with experimental approaches, computational modelling allows us to challenge and refine our current understanding of epithelial morphogenesis and to explore experimentally intractable questions. To this end, a variety of cell-based modelling approaches have been developed to describe cell-cell mechanical interactions, ranging from vertex and 'finite-element' models that approximate each cell geometrically by a polygon representing the cell's membrane, to immersed boundary and subcellular element models that allow for more arbitrary cell shapes. Here, we review how these models have been used to provide insights into epithelial morphogenesis and describe how such models could help future efforts to decipher the forces and mechanical and biochemical feedbacks that guide cell and tissue-level behaviour. In addition, we discuss current challenges associated with using computational models of morphogenetic processes in a quantitative and predictive way.This article is part of the themed issue 'Systems morphodynamics: understanding the development of tissue hardware'.
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Affiliation(s)
- Alexander G Fletcher
- School of Mathematics and Statistics, University of Sheffield, Sheffield S3 7RH, UK .,Bateson Centre, University of Sheffield, Sheffield S10 2TN, UK
| | - Fergus Cooper
- Mathematical Institute, University of Oxford, Oxford OX2 6GG, UK
| | - Ruth E Baker
- Mathematical Institute, University of Oxford, Oxford OX2 6GG, UK
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15
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Krens SFG, Veldhuis JH, Barone V, Čapek D, Maître JL, Brodland GW, Heisenberg CP. Interstitial fluid osmolarity modulates the action of differential tissue surface tension in progenitor cell segregation during gastrulation. Development 2017; 144:1798-1806. [PMID: 28512197 PMCID: PMC5450835 DOI: 10.1242/dev.144964] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 03/29/2017] [Indexed: 12/11/2022]
Abstract
The segregation of different cell types into distinct tissues is a fundamental process in metazoan development. Differences in cell adhesion and cortex tension are commonly thought to drive cell sorting by regulating tissue surface tension (TST). However, the role that differential TST plays in cell segregation within the developing embryo is as yet unclear. Here, we have analyzed the role of differential TST for germ layer progenitor cell segregation during zebrafish gastrulation. Contrary to previous observations that differential TST drives germ layer progenitor cell segregation in vitro, we show that germ layers display indistinguishable TST within the gastrulating embryo, arguing against differential TST driving germ layer progenitor cell segregation in vivo. We further show that the osmolarity of the interstitial fluid (IF) is an important factor that influences germ layer TST in vivo, and that lower osmolarity of the IF compared with standard cell culture medium can explain why germ layers display differential TST in culture but not in vivo. Finally, we show that directed migration of mesendoderm progenitors is required for germ layer progenitor cell segregation and germ layer formation. Highlighted Article: Segregation of the germ layer progenitors in the zebrafish gastrula is driven by directed cell migration, rather than differential tissue surface tension.
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Affiliation(s)
- S F Gabriel Krens
- Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria
| | - Jim H Veldhuis
- Department of Civil and Environmental Engineering, University of Waterloo, Waterloo N2L 3G1, Canada
| | - Vanessa Barone
- Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria
| | - Daniel Čapek
- Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria
| | - Jean-Léon Maître
- Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria
| | - G Wayne Brodland
- Department of Civil and Environmental Engineering, University of Waterloo, Waterloo N2L 3G1, Canada
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16
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Buttenschön A, Hillen T, Gerisch A, Painter KJ. A space-jump derivation for non-local models of cell-cell adhesion and non-local chemotaxis. J Math Biol 2017; 76:429-456. [PMID: 28597056 DOI: 10.1007/s00285-017-1144-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Revised: 05/08/2017] [Indexed: 12/31/2022]
Abstract
Cellular adhesion provides one of the fundamental forms of biological interaction between cells and their surroundings, yet the continuum modelling of cellular adhesion has remained mathematically challenging. In 2006, Armstrong et al. proposed a mathematical model in the form of an integro-partial differential equation. Although successful in applications, a derivation from an underlying stochastic random walk has remained elusive. In this work we develop a framework by which non-local models can be derived from a space-jump process. We show how the notions of motility and a cell polarization vector can be naturally included. With this derivation we are able to include microscopic biological properties into the model. We show that particular choices yield the original Armstrong model, while others lead to more general models, including a doubly non-local adhesion model and non-local chemotaxis models. Finally, we use random walk simulations to confirm that the corresponding continuum model represents the mean field behaviour of the stochastic random walk.
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Affiliation(s)
- Andreas Buttenschön
- Department of Mathematical and Statistical Sciences, Centre for Mathematical Biology, University of Alberta, Edmonton, AB, T6G 2G1, Canada.
| | - Thomas Hillen
- Department of Mathematical and Statistical Sciences, Centre for Mathematical Biology, University of Alberta, Edmonton, AB, T6G 2G1, Canada
| | - Alf Gerisch
- Fachbereich Mathematik, Technische Universität Darmstadt, Dolivostr. 15, 64293, Darmstadt, Germany
| | - Kevin J Painter
- Department of Mathematics and Maxwell Institute for Mathematical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UK.,Department of Mathematical Sciences, Politecnico di Torino, 10129, Turin, Italy
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17
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Winklbauer R, Parent SE. Forces driving cell sorting in the amphibian embryo. Mech Dev 2017; 144:81-91. [DOI: 10.1016/j.mod.2016.09.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 08/18/2016] [Accepted: 09/29/2016] [Indexed: 01/05/2023]
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18
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Osborne JM, Fletcher AG, Pitt-Francis JM, Maini PK, Gavaghan DJ. Comparing individual-based approaches to modelling the self-organization of multicellular tissues. PLoS Comput Biol 2017; 13:e1005387. [PMID: 28192427 PMCID: PMC5330541 DOI: 10.1371/journal.pcbi.1005387] [Citation(s) in RCA: 107] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2016] [Revised: 02/28/2017] [Accepted: 01/28/2017] [Indexed: 12/28/2022] Open
Abstract
The coordinated behaviour of populations of cells plays a central role in tissue growth and renewal. Cells react to their microenvironment by modulating processes such as movement, growth and proliferation, and signalling. Alongside experimental studies, computational models offer a useful means by which to investigate these processes. To this end a variety of cell-based modelling approaches have been developed, ranging from lattice-based cellular automata to lattice-free models that treat cells as point-like particles or extended shapes. However, it remains unclear how these approaches compare when applied to the same biological problem, and what differences in behaviour are due to different model assumptions and abstractions. Here, we exploit the availability of an implementation of five popular cell-based modelling approaches within a consistent computational framework, Chaste (http://www.cs.ox.ac.uk/chaste). This framework allows one to easily change constitutive assumptions within these models. In each case we provide full details of all technical aspects of our model implementations. We compare model implementations using four case studies, chosen to reflect the key cellular processes of proliferation, adhesion, and short- and long-range signalling. These case studies demonstrate the applicability of each model and provide a guide for model usage.
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Affiliation(s)
- James M. Osborne
- School of Mathematics and Statistics, University of Melbourne, Parkville, Victoria, Australia
| | - Alexander G. Fletcher
- School of Mathematics and Statistics, University of Sheffield, Sheffield, United Kingdom
- Bateson Centre, University of Sheffield, Sheffield, United Kingdom
| | - Joe M. Pitt-Francis
- Department of Computer Science, University of Oxford, Oxford, United Kingdom
| | - Philip K. Maini
- Wolfson Centre for Mathematical Biology, Mathematical Institute, University of Oxford, Oxford, United Kingdom
| | - David J. Gavaghan
- Department of Computer Science, University of Oxford, Oxford, United Kingdom
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19
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Winklbauer R. Cell adhesion strength from cortical tension - an integration of concepts. J Cell Sci 2016; 128:3687-93. [PMID: 26471994 DOI: 10.1242/jcs.174623] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Morphogenetic mechanisms such as cell movement or tissue separation depend on cell attachment and detachment processes, which involve adhesion receptors as well as the cortical cytoskeleton. The interplay between the two components is of stunning complexity. Most strikingly, the binding energy of adhesion molecules is usually too small for substantial cell-cell attachment, pointing to a main deficit in our present understanding of adhesion. In this Opinion article, I integrate recent findings and conceptual advances in the field into a coherent framework for cell adhesion. I argue that active cortical tension is best viewed as an integral part of adhesion, and propose on this basis a non-arbitrary measure of adhesion strength - the tissue surface tension of cell aggregates. This concept of adhesion integrates heterogeneous molecular inputs into a single mechanical property and simplifies the analysis of attachment-detachment processes. It draws attention to the enormous variation of adhesion strengths among tissues, whose origin and function is little understood.
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Affiliation(s)
- Rudolf Winklbauer
- Department of Cell and Systems Biology, University of Toronto, 25 Harbord Street, Toronto, Ontario M5S 3G5, Canada
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20
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Abstract
Compaction is a critical first morphological event in the preimplantation development of the mammalian embryo. Characterized by the transformation of the embryo from a loose cluster of spherical cells into a tightly packed mass, compaction is a key step in the establishment of the first tissue-like structures of the embryo. Although early investigation of the mechanisms driving compaction implicated changes in cell-cell adhesion, recent work has identified essential roles for cortical tension and a compaction-specific class of filopodia. During the transition from 8 to 16 cells, as the embryo is compacting, it must also make fundamental decisions regarding cell position, polarity, and fate. Understanding how these and other processes are integrated with compaction requires further investigation. Emerging imaging-based techniques that enable quantitative analysis from the level of cell-cell interactions down to the level of individual regulatory molecules will provide a greater understanding of how compaction shapes the early mammalian embryo.
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Affiliation(s)
- M D White
- Institute of Molecular and Cell Biology, A*STAR, Singapore, Singapore
| | - S Bissiere
- Institute of Molecular and Cell Biology, A*STAR, Singapore, Singapore
| | - Y D Alvarez
- Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, CONICET, Buenos Aires, Argentina
| | - N Plachta
- Institute of Molecular and Cell Biology, A*STAR, Singapore, Singapore.
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21
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A Sawtooth Pattern of Cadherin 2 Stability Mechanically Regulates Somite Morphogenesis. Curr Biol 2016; 26:542-9. [PMID: 26853361 DOI: 10.1016/j.cub.2015.12.055] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Revised: 11/23/2015] [Accepted: 12/21/2015] [Indexed: 01/09/2023]
Abstract
Differential cadherin (Cdh) expression is a classical mechanism for in vitro cell sorting. Studies have explored the roles of differential Cdh levels in cell aggregates and during vertebrate gastrulation, but the role of differential Cdh activity in forming in vivo tissue boundaries and boundary extracellular matrix (ECM) is unclear. Here, we examine the interactions between cell-cell and cell-ECM adhesion during somitogenesis, the formation of the segmented embryonic precursors of the vertebral column and musculature. We identify a sawtooth pattern of stable Cdh2 adhesions in which there is a posterior-to-anterior gradient of stable Cdh2 within each somite, while there is a step-like drop in stable Cdh2 along the somite boundary. Moreover, we find that the posterior somite boundary cells with high levels of stable Cdh2 have the most columnar morphology. Cdh2 is required for maximal cell aspect ratio and thus full epithelialization of the posterior somite. Loss-of-function analysis also indicates that Cdh2 acts with the fibronectin (FN) receptor integrin α5 (Itgα5) to promote somite boundary formation. Using genetic mosaics, we demonstrate that differential Cdh2 levels are sufficient to induce boundary formation, Itgα5 activation, and FN matrix assembly in the paraxial mesoderm. Elevated cytoskeletal contractility is sufficient to replace differential Cdh2 levels in genetic mosaics, suggesting that Cdh2 promotes ECM assembly by increasing cytoskeletal and tissue stiffness along the posterior somite boundary. Throughout somitogenesis, Cdh2 promotes ECM assembly along tissue boundaries and inhibits ECM assembly in the tissue mesenchyme.
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22
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Oldewurtel ER, Kouzel N, Dewenter L, Henseler K, Maier B. Differential interaction forces govern bacterial sorting in early biofilms. eLife 2015; 4. [PMID: 26402455 PMCID: PMC4625442 DOI: 10.7554/elife.10811] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Accepted: 09/23/2015] [Indexed: 12/30/2022] Open
Abstract
Bacterial biofilms can generate micro-heterogeneity in terms of surface structures. However, little is known about the associated changes in the physics of cell–cell interaction and its impact on the architecture of biofilms. In this study, we used the type IV pilus of Neisseria gonorrhoeae to test whether variation of surface structures induces cell-sorting. We show that the rupture forces between pili are fine-tuned by post-translational modification. Bacterial sorting was dependent on pilus post-translational modification and pilus density. Active force generation was necessary for defined morphologies of mixed microcolonies. The observed morphotypes were in remarkable agreement with the differential strength of adhesion hypothesis proposing that a tug-of-war among surface structures of different cells governs cell sorting. We conclude that in early biofilms the density and rupture force of bacterial surface structures can trigger cell sorting based on similar physical principles as in developing embryos. DOI:http://dx.doi.org/10.7554/eLife.10811.001 Communities of bacterial cells can live together embedded within a slime-like molecular matrix as a biofilm. This allows the bacteria to hide from external stresses. A single bacterium can replicate itself and develop into a biofilm, and over time the bacterial cells in specific regions of the biofilm will start to interact with their neighbors in different ways. These interactions occur via structures on the surface of the bacterial cells, and the differences in these interactions resemble those that occur as cells specialize during the development of animal embryos. Previous research into embryonic development has shown how differences in the physical interactions between embryonic cells are essential for sorting the cells into their correct locations and shaping the embryo. However, little is known about which processes govern the development of biofilms. Now, Oldewurtel et al. have asked whether differences in the physical interactions between bacteria trigger cell sorting during the early stages of biofilm development. The experiments involved measuring the force required to break the cell–cell connections (called the ‘rupture force’) in biofilms of a bacterium called Neisseria gonorrhoeae. Oldewurtel et al. found that, in agreement with previous predictions, physical interactions were important for sorting bacterial cells into clusters based on the structures on their surfaces. Bacterial cells actively pull on the surface structures of their neighbors, which allows the cells to sort themselves in a tug-of-war fashion. This means that a cell will move in the direction where it can pull the strongest (i.e., in the direction where the rupture force is highest). While bacteria and embryos use different molecules to generate these pulling forces, these findings indicate that the basic physical principles are similar in both systems. One of the next challenges will be to evaluate how biofilms might benefit from the structures that develop due to cell sorting. DOI:http://dx.doi.org/10.7554/eLife.10811.002
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Affiliation(s)
| | - Nadzeya Kouzel
- Department of Physics, University of Cologne, Cologne, Germany
| | - Lena Dewenter
- Department of Physics, University of Cologne, Cologne, Germany
| | - Katja Henseler
- Department of Physics, University of Cologne, Cologne, Germany
| | - Berenike Maier
- Department of Physics, University of Cologne, Cologne, Germany
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23
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McMillen P, Holley SA. Integration of cell-cell and cell-ECM adhesion in vertebrate morphogenesis. Curr Opin Cell Biol 2015; 36:48-53. [PMID: 26189063 DOI: 10.1016/j.ceb.2015.07.002] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 07/01/2015] [Accepted: 07/01/2015] [Indexed: 01/08/2023]
Abstract
In this review, we highlight recent re-evaluations of the classical cell sorting models and their application to understanding embryonic morphogenesis. Modern genetic and biophysical techniques reveal that tissue self-assembly is not solely a result of differential adhesion, but rather incorporates dynamic cytoskeletal tension and extracellular matrix assembly. There is growing evidence that these biomechanical modules cooperate to organize developing tissues. We describe the contributions of Cadherins and Integrins to tissue assembly and propose a model in which these very different adhesive regimes affect the same outcome through separate but convergent mechanisms.
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Affiliation(s)
- Patrick McMillen
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520, United States
| | - Scott A Holley
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520, United States.
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24
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Perrone MC, Veldhuis JH, Brodland GW. Non-straight cell edges are important to invasion and engulfment as demonstrated by cell mechanics model. Biomech Model Mechanobiol 2015; 15:405-18. [PMID: 26148533 PMCID: PMC4792343 DOI: 10.1007/s10237-015-0697-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Accepted: 06/23/2015] [Indexed: 11/28/2022]
Abstract
Computational models of cell–cell mechanical interactions typically simulate sorting and certain other motions well, but as demands on these models continue to grow, discrepancies between the cell shapes, contact angles and behaviours they predict and those that occur in real cells have come under increased scrutiny. To investigate whether these discrepancies are a direct result of the straight cell–cell edges generally assumed in these models, we developed a finite element model that approximates cell boundaries using polylines with an arbitrary number of segments. We then compared the predictions of otherwise identical polyline and monoline (straight-edge) models in a variety of scenarios, including annealing, single- and multi-cell engulfment, sorting, and two forms of mixing—invasion and checkerboard pattern formation. Keeping cell–cell edges straight influences cell motion, cell shape, contact angle, and boundary length, especially in cases where one cell type is pulled between or around cells of a different type, as in engulfment or invasion. These differences arise because monoline cells have restricted deformation modes. Polyline cells do not face these restrictions, and with as few as three segments per edge yielded realistic edge shapes and contact angle errors one-tenth of those produced by monoline models, making them considerably more suitable for situations where angles and shapes matter, such as validation of cellular force–inference techniques. The findings suggest that non-straight cell edges are important both in modelling and in nature.
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Affiliation(s)
- Matthew C Perrone
- Department of Civil and Environmental Engineering, University of Waterloo, Waterloo, ON, N2L 3G1, Canada
| | - Jim H Veldhuis
- Department of Civil and Environmental Engineering, University of Waterloo, Waterloo, ON, N2L 3G1, Canada
| | - G Wayne Brodland
- Department of Civil and Environmental Engineering, University of Waterloo, Waterloo, ON, N2L 3G1, Canada.
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25
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Fletcher AG, Osterfield M, Baker RE, Shvartsman SY. Vertex models of epithelial morphogenesis. Biophys J 2015; 106:2291-304. [PMID: 24896108 DOI: 10.1016/j.bpj.2013.11.4498] [Citation(s) in RCA: 289] [Impact Index Per Article: 32.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2012] [Revised: 11/06/2013] [Accepted: 11/08/2013] [Indexed: 01/06/2023] Open
Abstract
The dynamic behavior of epithelial cell sheets plays a central role during numerous developmental processes. Genetic and imaging studies of epithelial morphogenesis in a wide range of organisms have led to increasingly detailed mechanisms of cell sheet dynamics. Computational models offer a useful means by which to investigate and test these mechanisms, and have played a key role in the study of cell-cell interactions. A variety of modeling approaches can be used to simulate the balance of forces within an epithelial sheet. Vertex models are a class of such models that consider cells as individual objects, approximated by two-dimensional polygons representing cellular interfaces, in which each vertex moves in response to forces due to growth, interfacial tension, and pressure within each cell. Vertex models are used to study cellular processes within epithelia, including cell motility, adhesion, mitosis, and delamination. This review summarizes how vertex models have been used to provide insight into developmental processes and highlights current challenges in this area, including progressing these models from two to three dimensions and developing new tools for model validation.
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Affiliation(s)
- Alexander G Fletcher
- Wolfson Centre for Mathematical Biology, Mathematical Institute, University of Oxford, Oxford, United Kingdom.
| | - Miriam Osterfield
- Lewis-Sigler Institute for Integrative Genomics, Princeton, New Jersey
| | - Ruth E Baker
- Wolfson Centre for Mathematical Biology, Mathematical Institute, University of Oxford, Oxford, United Kingdom.
| | - Stanislav Y Shvartsman
- Lewis-Sigler Institute for Integrative Genomics, Princeton, New Jersey; Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey.
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26
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Fletcher AG, Osborne JM, Maini PK, Gavaghan DJ. Implementing vertex dynamics models of cell populations in biology within a consistent computational framework. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2013; 113:299-326. [DOI: 10.1016/j.pbiomolbio.2013.09.003] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2012] [Revised: 09/18/2013] [Accepted: 09/25/2013] [Indexed: 10/26/2022]
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Lu K, Gordon R, Cao T. Reverse engineering the mechanical and molecular pathways in stem cell morphogenesis. J Tissue Eng Regen Med 2013; 9:169-73. [DOI: 10.1002/term.1672] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2011] [Revised: 10/05/2012] [Accepted: 11/05/2012] [Indexed: 01/28/2023]
Affiliation(s)
- Kai Lu
- Institute for Integrated Cell-Material Sciences; Kyoto University; Japan
| | - Richard Gordon
- Embryogenesis Center; Gulf Specimen Marine Laboratory; Panacea FL 32346 USA
| | - Tong Cao
- Stem Cell Laboratory, Faculty of Dentistry; National University of Singapore
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28
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Wyczalkowski MA, Chen Z, Filas BA, Varner VD, Taber LA. Computational models for mechanics of morphogenesis. ACTA ACUST UNITED AC 2012; 96:132-52. [PMID: 22692887 DOI: 10.1002/bdrc.21013] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
In the developing embryo, tissues differentiate, deform, and move in an orchestrated manner to generate various biological shapes driven by the complex interplay between genetic, epigenetic, and environmental factors. Mechanics plays a key role in regulating and controlling morphogenesis, and quantitative models help us understand how various mechanical forces combine to shape the embryo. Models allow for the quantitative, unbiased testing of physical mechanisms, and when used appropriately, can motivate new experimentaldirections. This knowledge benefits biomedical researchers who aim to prevent and treat congenital malformations, as well as engineers working to create replacement tissues in the laboratory. In this review, we first give an overview of fundamental mechanical theories for morphogenesis, and then focus on models for specific processes, including pattern formation, gastrulation, neurulation, organogenesis, and wound healing. The role of mechanical feedback in development is also discussed. Finally, some perspectives aregiven on the emerging challenges in morphomechanics and mechanobiology.
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29
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30
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Smallwood R. Computational modeling of epithelial tissues. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2011; 1:191-201. [PMID: 20835991 DOI: 10.1002/wsbm.18] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
There is an extensive literature on the computational modeling of epithelial tissues at all levels from subcellular to whole tissue. This review concentrates on behavior at the individual cell to whole tissue level, and particularly on organizational aspects, and provides an indication of where information from other areas, such as the modeling of angiogenesis, is relevant. The skin, and the lining of all of the body cavities (lung, gut, cervix, bladder etc) are epithelial tissues, which in a topological sense are the boundary between inside and outside the body. They are thin sheets of cells (usually of the order of 0.5 mm thick) without extracellular matrix, have a relatively simple structure, and contain few types of cells. They have important barrier, secretory and transport functions, which are essential for the maintenance of life, so homeostasis and wound healing are important aspects of the behavior of epithelial tissues. Carcinomas originate in epithelial tissues.There are essentially two approaches to modeling tissues--to start at the level of the tissue (i.e., a length scale of the order of 1 mm) and develop generalized equations for behavior (a continuum approach); or to start at the level of the cell (i.e., a length scale of the order of 10 µm) and develop tissue behavior as an emergent property of cellular behavior (an individual-based approach). As will be seen, these are not mutually exclusive approaches, and they come in a variety of flavors.
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Affiliation(s)
- Rod Smallwood
- Department of Computer Science, University of Sheffield, Regent Court, 211 Portobello, Sheffield S1 4DP, UK
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31
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Abstract
During the development of multicellular organisms, cell fate specification is followed by the sorting of different cell types into distinct domains from where the different tissues and organs are formed. Cell sorting involves both the segregation of a mixed population of cells with different fates and properties into distinct domains, and the active maintenance of their segregated state. Because of its biological importance and apparent resemblance to fluid segregation in physics, cell sorting was extensively studied by both biologists and physicists over the last decades. Different theories were developed that try to explain cell sorting on the basis of the physical properties of the constituent cells. However, only recently the molecular and cellular mechanisms that control the physical properties driving cell sorting, have begun to be unraveled. In this review, we will provide an overview of different cell-sorting processes in development and discuss how these processes can be explained by the different sorting theories, and how these theories in turn can be connected to the molecular and cellular mechanisms driving these processes.
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Affiliation(s)
- S F Gabby Krens
- Institute of Science and Technology Austria, Klosterneuburg, Austria
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32
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Leung TKS, Veldhuis JH, Krens SFG, Heisenberg CP, Brodland GW. Identifying same-cell contours in image stacks: a key step in making 3D reconstructions. Ann Biomed Eng 2010; 39:698-705. [PMID: 21103934 DOI: 10.1007/s10439-010-0198-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2010] [Accepted: 10/19/2010] [Indexed: 11/30/2022]
Abstract
Identification of contours belonging to the same cell is a crucial step in the analysis of confocal stacks and other image sets in which cell outlines are visible, and it is central to the making of 3D cell reconstructions. When the cells are close packed, the contour grouping problem is more complex than that found in medical imaging, for example, because there are multiple regions of interest, the regions are not separable from each other by an identifiable background and regions cannot be distinguished by intensity differences. Here, we present an algorithm that uses three primary metrics-overlap of contour areas in adjacent images, co-linearity of the centroids of these areas across three images in a stack, and cell taper-to assign cells to groups. Decreasing thresholds are used to successively assign contours whose membership is less obvious. In a final step, remaining contours are assigned to existing groups by setting all thresholds to zero and groups having strong hour-glass shapes are partitioned. When applied to synthetic data from isotropic model aggregates, a curved model epithelium in which the long axes of the cells lie at all possible angles to the transection plane, and a confocal image stack, algorithm assignments were between 97 and 100% accurate in sets having at least four contours per cell. The algorithm is not particularly sensitive to the thresholds used, and a single set of parameters was used for all of the tests. The algorithm, which could be extended to time-lapse data, solves a key problem in the translation of image data into cell information.
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Affiliation(s)
- Tony Kin Shun Leung
- Department of Civil and Environmental Engineering, University of Waterloo, Waterloo, Ontario, Canada
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33
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Wan LQ, Kang SM, Eng G, Grayson WL, Lu XL, Huo B, Gimble J, Guo XE, Mow VC, Vunjak-Novakovic G. Geometric control of human stem cell morphology and differentiation. Integr Biol (Camb) 2010; 2:346-53. [PMID: 20652175 DOI: 10.1039/c0ib00016g] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
During tissue morphogenesis, stem cells and progenitor cells migrate, proliferate, and differentiate, with striking changes in cell shape, size, and acting mechanical stresses. The local cellular function depends on the spatial distribution of cytokines as well as local mechanical microenvironments in which the cells reside. In this study, we controlled the organization of human adipose derived stem cells using micro-patterning technologies, to investigate the influence of multi-cellular form on spatial distribution of cellular function at an early stage of cell differentiation. The underlying role of cytoskeletal tension was probed through drug treatment. Our results show that the cultivation of stem cells on geometric patterns resulted in pattern- and position-specific cell morphology, proliferation and differentiation. The highest cell proliferation occurred in the regions with large, spreading cells (such as the outer edge of a ring and the short edges of rectangles). In contrast, stem cell differentiation co-localized with the regions containing small, elongated cells (such as the inner edge of a ring and the regions next to the short edges of rectangles). The application of drugs that inhibit the formation of actomyosin resulted in the lack of geometrically specific differentiation patterns. This study confirms the role of substrate geometry on stem cell differentiation, through associated physical forces, and provides a simple and controllable system for studying biophysical regulation of cell function.
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Affiliation(s)
- Leo Q Wan
- Department of Biomedical Engineering, Columbia University, 351 Engineering Terrace, 1210 Amsterdam Avenue, New York, NY 10027, USA
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Abstract
Together with cell growth, division and death, changes in cell shape are of central importance for tissue morphogenesis during development. Cell shape is the product of a cell's material and active properties balanced by external forces. Control of cell shape, therefore, relies on both tight regulation of intracellular mechanics and the cell's physical interaction with its environment. In this review, we first discuss the biological and physical mechanisms of cell shape control. We next examine a number of developmental processes in which cell shape change - either individually or in a coordinated manner - drives embryonic morphogenesis and discuss how cell shape is controlled in these processes. Finally, we emphasize that cell shape control during tissue morphogenesis can only be fully understood by using a combination of cellular, molecular, developmental and biophysical approaches.
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Affiliation(s)
- Ewa Paluch
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany.
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35
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Biomechanics: cell research and applications for the next decade. Ann Biomed Eng 2009; 37:847-59. [PMID: 19259817 DOI: 10.1007/s10439-009-9661-x] [Citation(s) in RCA: 126] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2008] [Accepted: 02/21/2009] [Indexed: 12/18/2022]
Abstract
With the recent revolution in Molecular Biology and the deciphering of the Human Genome, understanding of the building blocks that comprise living systems has advanced rapidly. We have yet to understand, however, how the physical forces that animate life affect the synthesis, folding, assembly, and function of these molecular building blocks. We are equally uncertain as to how these building blocks interact dynamically to create coupled regulatory networks from which integrative biological behaviors emerge. Here we review recent advances in the field of biomechanics at the cellular and molecular levels, and set forth challenges confronting the field. Living systems work and move as multi-molecular collectives, and in order to understand key aspects of health and disease we must first be able to explain how physical forces and mechanical structures contribute to the active material properties of living cells and tissues, as well as how these forces impact information processing and cellular decision making. Such insights will no doubt inform basic biology and rational engineering of effective new approaches to clinical therapy.
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36
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Mechanical determinants of epithelium thickness in early-stage embryos. J Mech Behav Biomed Mater 2008; 2:494-501. [PMID: 19627856 DOI: 10.1016/j.jmbbm.2008.12.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2008] [Revised: 11/20/2008] [Accepted: 12/05/2008] [Indexed: 11/21/2022]
Abstract
To address the fundamental question, "How is the thickness of an embryonic epithelium determined?" equations of force equilibrium are derived and used to construct a theory applicable to embryonic epithelia and other labile monolayers, including confluent cultured cells. Under typical physiological conditions, the underlying mathematical relationships can be reworked into one simple algebraic equation. The theory shows that sheet thickness is determined by mechanical interactions between microfilaments, microtubules, cell adhesion systems and in-plane loading. It also explains the perplexing negative in-plane Poisson's ratio observed in some uniaxial tensile tests of embryonic epithelia. Thickness anomalies can affect phenotype, and the equations make it possible to calculate the degree to which gene expression, signalling pathways or other factors must alter the forces at work in order to produce a specified change in sheet thicknesses. Key findings are confirmed using a cell-based finite element model.
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Morishita Y, Iwasa Y. Growth based morphogenesis of vertebrate limb bud. Bull Math Biol 2008; 70:1957-78. [PMID: 18668295 PMCID: PMC2792361 DOI: 10.1007/s11538-008-9334-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2007] [Accepted: 04/29/2008] [Indexed: 11/03/2022]
Abstract
Many genes and their regulatory relationships are involved in developmental phenomena. However, by chemical information alone, we cannot fully understand changing organ morphologies through tissue growth because deformation and growth of the organ are essentially mechanical processes. Here, we develop a mathematical model to describe the change of organ morphologies through cell proliferation. Our basic idea is that the proper specification of localized volume source (e.g., cell proliferation) is able to guide organ morphogenesis, and that the specification is given by chemical gradients. We call this idea "growth-based morphogenesis." We find that this morphogenetic mechanism works if the tissue is elastic for small deformation and plastic for large deformation. To illustrate our concept, we study the development of vertebrate limb buds, in which a limb bud protrudes from a flat lateral plate and extends distally in a self-organized manner. We show how the proportion of limb bud shape depends on different parameters and also show the conditions needed for normal morphogenesis, which can explain abnormal morphology of some mutants. We believe that the ideas shown in the present paper are useful for the morphogenesis of other organs.
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Affiliation(s)
- Yoshihiro Morishita
- PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho Kawaguchi, Saitama, Japan.
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38
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Chen X, Wayne Brodland G. Multi-scale finite element modeling allows the mechanics of amphibian neurulation to be elucidated. Phys Biol 2008; 5:015003. [DOI: 10.1088/1478-3975/5/1/015003] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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39
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Viens D, Brodland GW. A three-dimensional finite element model for the mechanics of cell-cell interactions. J Biomech Eng 2007; 129:651-7. [PMID: 17887890 DOI: 10.1115/1.2768375] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Technical challenges, including significant ones associated with cell rearrangement, have hampered the development of three-dimensional finite element models for the mechanics of embryonic cells. These challenges have been overcome by a new formulation in which the contents of each cell, assumed to have a viscosity mu, are modeled using a system of orthogonal dashpots. This approach overcomes a stiffening artifact that affects more traditional models, in which space-filling viscous elements are used to model the cytoplasm. Cells are assumed to be polyhedral in geometry, and each n-sided polygonal face is subdivided into n triangles with a common node at the face center so that it needs not remain flat. A constant tension gamma is assumed to act along each cell-cell interface, and cell rearrangements occur through one of two complementary topological transformations. The formulation predicts mechanical interactions between pairs of similar or dissimilar cells that are consistent with experiments, two-dimensional simulations, contact angle theory, and intracellular pressure calculations. Simulations of the partial engulfment of one tissue type by another show that the formulation is able to model aggregates of several hundred cells without difficulty. Simulations carried out using this formulation suggest new experimental approaches for measuring cell surface tensions and interfacial tensions. The formulation holds promise as a tool for gaining insight into the mechanics of isolated or aggregated embryonic cells and for the design and interpretation of experiments that involve them.
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Affiliation(s)
- Denis Viens
- Department of Civil and Environmental Engineering, University of Waterloo, Waterloo, Ontario N2T 2N4, Canada
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40
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N/A. N/A. Shijie Huaren Xiaohua Zazhi 2005; 13:2057-2060. [DOI: 10.11569/wcjd.v13.i17.2057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/26/2023] Open
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41
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Honda H, Tanemura M, Nagai T. A three-dimensional vertex dynamics cell model of space-filling polyhedra simulating cell behavior in a cell aggregate. J Theor Biol 2004; 226:439-53. [PMID: 14759650 DOI: 10.1016/j.jtbi.2003.10.001] [Citation(s) in RCA: 132] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2003] [Revised: 10/05/2003] [Accepted: 10/06/2003] [Indexed: 11/30/2022]
Abstract
We developed a three-dimensional (3D) cell model of a multicellular aggregate consisting of several polyhedral cells to investigate the deformation and rearrangement of cells under the influence of external forces. The polyhedral cells fill the space in the aggregate without gaps or overlaps, consist of contracting interfaces and maintain their volumes. The interfaces and volumes were expressed by 3D vertex coordinates. Vertex movements obey equations of motion that rearrange the cells to minimize total free energy, and undergo an elementary process that exchanges vertex pair connections when vertices approach each other. The total free energy includes the interface energy of cells and the compression or expansion energy of cells. Computer simulations provided the following results: An aggregate of cells becomes spherical to minimize individual cell surface areas; Polygonal interfaces of cells remain flat; Cells within the 3D cell aggregate can move and rearrange despite the absence of free space. We examined cell rearrangement to elucidate the viscoelastic properties of the aggregate, e.g. when an external force flattens a cell aggregate (e.g. under centrifugation) its component cells quickly flatten. Under a continuous external force, the cells slowly rearrange to recover their original shape although the cell aggregate remains flat. The deformation and rearrangement of individual cells is a two-step process with a time lag. Our results showed that morphological and viscoelastic properties of the cell aggregate with long relaxation time are based on component cells where minimization of interfacial energy of cells provides a motive force for cell movement.
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Affiliation(s)
- Hisao Honda
- Institute of Statistical Mathematics, Minami-Azabu 4-6-7, Minato-ku, Tokyo 106-8569, Japan.
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42
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Brodland GW, Veldhuis JH. Computer simulations of mitosis and interdependencies between mitosis orientation, cell shape and epithelia reshaping. J Biomech 2002; 35:673-81. [PMID: 11955507 DOI: 10.1016/s0021-9290(02)00006-4] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Finite element-based computer simulations are used to investigate mitosis and how mitosis, cell shape, and epithelium reshaping depend on each other. Frame- and cell-oriented patterns of mitosis with growing and non-growing daughter cells are considered. Previous simulations have shown that applied stresses or strains can reshape cells so that their long axes are aligned in the principal stretch direction. The simulations reported here show that this can produce global alignment of the mitosis cleavage planes. Other simulations reported here show that mitoses with suitably aligned cleavage planes can drive epithelium reshaping. Formulas that quantify these and other dependencies are derived. These formulas provide quantitative relationships against which current hypotheses regarding epithelia reshaping in real biological systems can be evaluated.
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Affiliation(s)
- G Wayne Brodland
- Department of Civil Engineering, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1.
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43
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Brodland GW. The Differential Interfacial Tension Hypothesis (DITH): a comprehensive theory for the self-rearrangement of embryonic cells and tissues. J Biomech Eng 2002; 124:188-97. [PMID: 12002128 DOI: 10.1115/1.1449491] [Citation(s) in RCA: 176] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A comprehensive theory, herein named the Differential Interfacial Tension Hypothesis for the self-rearrangement of embryonic cells and tissues is presented. These rearrangements include sorting, mixing and formation of checkerboard patterns in heterotypic aggregates of embryonic cells, and total or partial engulfment, separation and dissociation of tissues. This broadly-based theory accounts for the action of all currently known cytoskeletal components and cell adhesion mechanisms. The theory is used to derive conditions for the cell and tissue rearrangements named above. Finite element-based computer simulations involving two or more cell types confirm these conditions.
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Affiliation(s)
- G Wayne Brodland
- Department of Civil Engineering, University of Waterloo, ON, Canada.
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Honda H, Mochizuki A. Formation and maintenance of distinctive cell patterns by coexpression of membrane-bound ligands and their receptors. Dev Dyn 2002; 223:180-92. [PMID: 11836783 DOI: 10.1002/dvdy.10042] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
We show that graded or checkerboard-like cell patterns, and segmental domains along a body axis, can be generated by cell behaviors involving differences in intercellular repulsion. A membrane-bound signal transduction system mediating contact-dependent cell interactions includes membrane-bound ligands (ephrins) and their receptors with tyrosine-kinase activity (Eph proteins). These molecules mediate both repulsive and attractive interactions under bilateral threshold control, i.e., cells expressing the receptors adhere to a surface bearing a critical density of ligand reciprocal to the density of receptor but are repelled by a surface with other densities of ligand (Honda [1998] J. Theor. Biol. 192:235-246). We extend this model. General membrane-bound ligands (not always ephrins) and their receptors are presumably coexpressed in a single cell under bilateral threshold control. Computer simulations of cell pattern formation showed that when coexpression of the ligand and receptor is reciprocal, the cells self-organize into a pattern of segmental domains or a graded cell arrangement along the body axis. The latter process interprets positional information in terms of protein molecules. When coexpression of the two species of molecules is not always reciprocal, the cells generate various patterns including checkerboard and kagome (star) patterns. The case of separate expression of ligands and receptors in different cells is also examined. The mechanism of differences in cell repulsion is compared with the differential cell adhesion hypothesis, which has been used to explain cell sorting.
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Affiliation(s)
- Hisao Honda
- Faculty of Health Science, Hyogo University, Kakogawa, Hyogo, Japan.
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45
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Brodland GW, Chen HH. The mechanics of heterotypic cell aggregates: insights from computer simulations. J Biomech Eng 2000; 122:402-7. [PMID: 11036564 DOI: 10.1115/1.1288205] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Finite element-based computer simulations are used to investigate a number of phenomena, including tissue engulfment, cell sorting, and checkerboard-pattern formation, exhibited by heterotypic cell aggregates. The simulations show that these phenomena can be driven by a single equivalent force, namely a surface (or interfacial) tension, that results from cytoskeletal components and cell-cell adhesions. They also reveal that tissue engulfment, cell sorting, and checkerboard-pattern formation involve several discernible mechanical features or stages. With the aid of analytical arguments, we identify the conditions necessary for each of these phenomena. These findings are consistent with previous experimental investigations and computer simulations, but pose significant challenges to current theories of cell sorting and tissue engulfment.
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Affiliation(s)
- G W Brodland
- Department of Civil Engineering, University of Waterloo, ON, Canada.
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