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Bates JHT, Herrmann J, Casey DT, Suki B. An agent-based model of tissue maintenance and self-repair. Am J Physiol Cell Physiol 2023; 324:C941-C950. [PMID: 36878841 PMCID: PMC10089306 DOI: 10.1152/ajpcell.00531.2022] [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: 11/28/2022] [Revised: 02/10/2023] [Accepted: 03/02/2023] [Indexed: 03/08/2023]
Abstract
We hypothesized that a system that possesses the capacity for ongoing maintenance of its tissues will necessarily also have the capacity to self-heal following a perturbation. We used an agent-based model of tissue maintenance to investigate this idea, and in particular to determine the extent to which the current state of the tissue must influence cell behavior in order for tissue maintenance and self-healing to be stable. We show that a mean level of tissue density is robustly maintained when catabolic agents digest tissue at a rate proportional to local tissue density, but that the spatial heterogeneity of the tissue at homeostasis increases with the rate at which tissue is digested. The rate of self-healing is also increased by increasing either the amount of tissue removed or deposited at each time step by catabolic or anabolic agents, respectively, and by increasing the density of both agent types on the tissue. We also found that tissue maintenance and self-healing are stable with an alternate rule in which cells move preferentially to tissue regions of low density. The most basic form of self-healing can thus be achieved with cells that follow very simple rules of behavior, provided these rules are based in some way on the current state of the local tissue. Straightforward mechanisms can accelerate the rate of self-healing, as might be beneficial to the organism.
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Affiliation(s)
- Jason H T Bates
- Department of Medicine, University of Vermont, Burlington, Vermont, United States
| | - Jacob Herrmann
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts, United States
| | - Dylan T Casey
- Department of Medicine, University of Vermont, Burlington, Vermont, United States
- Complex Systems Center, University of Vermont, Burlington, Vermont, United States
| | - Béla Suki
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts, United States
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Abstract
Background The study of the mechanisms controlling wound healing is an attractive area within the field of biology, with it having a potentially significant impact on the health sector given the current medical burden associated with healing in the elderly population. Healing is a complex process and includes many steps that are regulated by coding and noncoding RNAs, proteins and other molecules. Nitric oxide (NO) is one of these small molecule regulators and its function has already been associated with inflammation and angiogenesis during adult healing. Results Our results showed that NO is also an essential component during embryonic scarless healing and acts via a previously unknown mechanism. NO is mainly produced during the early phase of healing and it is crucial for the expression of genes associated with healing. However, we also observed a late phase of healing, which occurs for several hours after wound closure and takes place under the epidermis and includes tissue remodelling that is dependent on NO. We also found that the NO is associated with multiple cellular metabolic pathways, in particularly the glucose metabolism pathway. This is particular noteworthy as the use of NO donors have already been found to be beneficial for the treatment of chronic healing defects (including those associated with diabetes) and it is possible that its mechanism of action follows those observed during embryonic wound healing. Conclusions Our study describes a new role of NO during healing, which may potentially translate to improved therapeutic treatments, especially for individual suffering with problematic healing.
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Tetley RJ, Staddon MF, Heller D, Hoppe A, Banerjee S, Mao Y. Tissue Fluidity Promotes Epithelial Wound Healing. NATURE PHYSICS 2019; 15:1195-1203. [PMID: 31700525 PMCID: PMC6837871 DOI: 10.1038/s41567-019-0618-1] [Citation(s) in RCA: 95] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The collective behaviour of cells in epithelial tissues is dependent on their mechanical properties. However, the contribution of tissue mechanics to wound healing in vivo remains poorly understood. Here we investigate the relationship between tissue mechanics and wound healing in live Drosophila wing imaginal discs and show that by tuning epithelial cell junctional tension, we can systematically alter the rate of wound healing. Coincident with the contraction of an actomyosin purse string, we observe cells flowing past each other at the wound edge by intercalating, reminiscent of molecules in a fluid, resulting in seamless wound closure. Using a cell-based physical model, we predict that a reduction in junctional tension fluidises the tissue through an increase in intercalation rate and corresponding reduction in bulk viscosity, in the manner of an unjamming transition. The resultant fluidisation of the tissue accelerates wound healing. Accordingly, when we experimentally reduce tissue tension in wing discs, intercalation rate increases and wounds repair in less time.
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Affiliation(s)
- Robert J. Tetley
- MRC Laboratory for Molecular Cell Biology, University College
London, Gower Street, London WC1E 6BT, United Kingdom
- Institute for the Physics of Living Systems, University College
London, London, United Kingdom
| | - Michael F. Staddon
- Institute for the Physics of Living Systems, University College
London, London, United Kingdom
- Department of Physics & Astronomy, University College London,
London, United Kingdom
| | - Davide Heller
- Institute of Molecular Life Sciences, University of Zurich,
Winterthurerstrasse 190, Zurich, 8057, Switzerland
- SIB Swiss Institute of Bioinformatics, Quartier Sorge, Batiment
Genopode, Lausanne, 1015, Switzerland
| | - Andreas Hoppe
- Faculty of Science, Engineering and Computing, Kingston University,
Kingston-upon-Thames, United Kingdom
| | - Shiladitya Banerjee
- Institute for the Physics of Living Systems, University College
London, London, United Kingdom
- Department of Physics & Astronomy, University College London,
London, United Kingdom
| | - Yanlan Mao
- MRC Laboratory for Molecular Cell Biology, University College
London, Gower Street, London WC1E 6BT, United Kingdom
- Institute for the Physics of Living Systems, University College
London, London, United Kingdom
- College of Information and Control, Nanjing University of
Information Science and Technology, Nanjing, Jiangsu 210044, China
- Correspondence:
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Rothenberg KE, Fernandez-Gonzalez R. Forceful closure: cytoskeletal networks in embryonic wound repair. Mol Biol Cell 2019; 30:1353-1358. [PMID: 31145669 PMCID: PMC6724689 DOI: 10.1091/mbc.e18-04-0248] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 03/26/2019] [Accepted: 04/02/2019] [Indexed: 12/12/2022] Open
Abstract
Embryonic tissues heal wounds rapidly and without scarring, in a process conserved across species and driven by collective cell movements. The mechanisms of coordinated cell movement during embryonic wound closure also drive tissue development and cancer metastasis; therefore, embryonic wound repair has received considerable attention as a model of collective cell migration. During wound closure, a supracellular actomyosin cable at the wound edge coordinates cells, while actin-based protrusions contribute to cell crawling and seamless wound healing. Other cytoskeletal networks are reorganized during wound repair: microtubules extend into protrusions and along cell-cell boundaries as cells stretch into damaged regions, septins accumulate at the wound margin, and intermediate filaments become polarized in the cells adjacent to the wound. Thus, diverse cytoskeletal networks work in concert to maintain tissue structure, while also driving and organizing cell movements to promote rapid repair. Understanding the signals that coordinate the dynamics of different cytoskeletal networks, and how adhesions between cells or with the extracellular matrix integrate forces across cells, will be important to elucidate the mechanisms of efficient embryonic wound healing and may have far-reaching implications for developmental and cancer cell biology.
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Affiliation(s)
- Katheryn E. Rothenberg
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON M5S 3G9, Canada
- Ted Rogers Centre for Heart Research, University of Toronto, Toronto, ON M5G 1M1, Canada
| | - Rodrigo Fernandez-Gonzalez
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON M5S 3G9, Canada
- Ted Rogers Centre for Heart Research, University of Toronto, Toronto, ON M5G 1M1, Canada
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada
- Developmental and Stem Cell Biology Program, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada
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Oltean A, Taber LA. Apoptosis generates mechanical forces that close the lens vesicle in the chick embryo. Phys Biol 2018; 15:025001. [PMID: 28914615 DOI: 10.1088/1478-3975/aa8d0e] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
During the initial stages of eye development, optic vesicles grow laterally outward from both sides of the forebrain and come into contact with the surrounding surface ectoderm (SE). Within the region of contact, these layers then thicken locally to create placodes and invaginate to form the optic cup (primitive retina) and lens vesicle (LV), respectively. This paper examines the biophysical mechanisms involved in LV formation, which consists of three phases: (1) lens placode formation; (2) invagination to create the lens pit (LP); and (3) closure to form a complete ellipsoidally shaped LV. Previous studies have suggested that extracellular matrix deposited between the SE and optic vesicle causes the lens placode to form by locally constraining expansion of the SE as it grows, while actomyosin contraction causes this structure to invaginate. Here, using computational modeling and experiments on chick embryos, we confirm that these mechanisms for Phases 1 and 2 are physically plausible. Our results also suggest, however, that they are not sufficient to close the LP during Phase 3. We postulate that apoptosis provides an additional mechanism by removing cells near the LP opening, thereby decreasing its circumference and generating tension that closes the LP. This hypothesis is supported by staining that shows a ring of cell death located around the LP opening during closure. Inhibiting apoptosis in cultured embryos using caspase inhibitors significantly reduced LP closure, and results from a finite-element model indicate that closure driven by cell death is plausible. Taken together, our results suggest an important mechanical role for apoptosis in lens development.
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Affiliation(s)
- Alina Oltean
- Department of Biomedical Engineering, Washington University, St Louis, MO 63130, United States of America
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Barnes LA, Marshall CD, Leavitt T, Hu MS, Moore AL, Gonzalez JG, Longaker MT, Gurtner GC. Mechanical Forces in Cutaneous Wound Healing: Emerging Therapies to Minimize Scar Formation. Adv Wound Care (New Rochelle) 2018; 7:47-56. [PMID: 29392093 DOI: 10.1089/wound.2016.0709] [Citation(s) in RCA: 118] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2016] [Accepted: 12/15/2016] [Indexed: 12/25/2022] Open
Abstract
Significance: Excessive scarring is major clinical and financial burden in the United States. Improved therapies are necessary to reduce scarring, especially in patients affected by hypertrophic and keloid scars. Recent Advances: Advances in our understanding of mechanical forces in the wound environment enable us to target mechanical forces to minimize scar formation. Fetal wounds experience much lower resting stress when compared with adult wounds, and they heal without scars. Therapies that modulate mechanical forces in the wound environment are able to reduce scar size. Critical Issues: Increased mechanical stresses in the wound environment induce hypertrophic scarring via activation of mechanotransduction pathways. Mechanical stimulation modulates integrin, Wingless-type, protein kinase B, and focal adhesion kinase, resulting in cell proliferation and, ultimately, fibrosis. Therefore, the development of therapies that reduce mechanical forces in the wound environment would decrease the risk of developing excessive scars. Future Directions: The development of novel mechanotherapies is necessary to minimize scar formation and advance adult wound healing toward the scarless ideal. Mechanotransduction pathways are potential targets to reduce excessive scar formation, and thus, continued studies on therapies that utilize mechanical offloading and mechanomodulation are needed.
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Affiliation(s)
- Leandra A. Barnes
- Division of Plastic and Reconstructive Surgery, Department of Surgery, Stanford University School of Medicine, Stanford, California
| | - Clement D. Marshall
- Division of Plastic and Reconstructive Surgery, Department of Surgery, Stanford University School of Medicine, Stanford, California
| | - Tripp Leavitt
- Division of Plastic and Reconstructive Surgery, Department of Surgery, Stanford University School of Medicine, Stanford, California
| | - Michael S. Hu
- Division of Plastic and Reconstructive Surgery, Department of Surgery, Stanford University School of Medicine, Stanford, California
- Department of Surgery, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii
| | | | - Jennifer G. Gonzalez
- Division of Plastic and Reconstructive Surgery, Department of Surgery, Stanford University School of Medicine, Stanford, California
| | - Michael T. Longaker
- Division of Plastic and Reconstructive Surgery, Department of Surgery, Stanford University School of Medicine, Stanford, California
| | - Geoffrey C. Gurtner
- Division of Plastic and Reconstructive Surgery, Department of Surgery, Stanford University School of Medicine, Stanford, California
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Thompson MS, Bajuri MN, Khayyeri H, Isaksson H. Mechanobiological modelling of tendons: Review and future opportunities. Proc Inst Mech Eng H 2017; 231:369-377. [DOI: 10.1177/0954411917692010] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Tendons are adapted to carry large, repeated loads and are clinically important for the maintenance of musculoskeletal health in an increasing, actively ageing population, as well as in elite athletes. Tendons are known to adapt to mechanical loading. Also, their healing and disease processes are highly sensitive to mechanical load. Computational modelling approaches developed to capture this mechanobiological adaptation in tendons and other tissues have successfully addressed many important scientific and clinical issues. The aim of this review is to identify techniques and approaches that could be further developed to address tendon-related problems. Biomechanical models are identified that capture the multi-level aspects of tendon mechanics. Continuum whole tendon models, both phenomenological and microstructurally motivated, are important to estimate forces during locomotion activities. Fibril-level microstructural models are documented that can use these estimated forces to detail local mechanical parameters relevant to cell mechanotransduction. Cell-level models able to predict the response to such parameters are also described. A selection of updatable mechanobiological models is presented. These use mechanical signals, often continuum tissue level, along with rules for tissue change and have been applied successfully in many tissues to predict in vivo and in vitro outcomes. Signals may include scalars derived from the stress or strain tensors, or in poroelasticity also fluid velocity, while adaptation may be represented by changes to elastic modulus, permeability, fibril density or orientation. So far, only simple analytical approaches have been applied to tendon mechanobiology. With the development of sophisticated computational mechanobiological models in parallel with reporting more quantitative data from in vivo or clinical mechanobiological studies, for example, appropriate imaging, biochemical and histological data, this field offers huge potential for future development towards clinical applications.
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Affiliation(s)
- Mark S Thompson
- Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Oxford, UK
| | - M Nazri Bajuri
- Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Oxford, UK
- Faculty of Biosciences & Medical Engineering, Universiti Teknologi Malaysia, Johor Bahru, Malaysia
| | - Hanifeh Khayyeri
- Department of Biomedical Engineering, Lund University, Lund, Sweden
| | - Hanna Isaksson
- Department of Biomedical Engineering, Lund University, Lund, Sweden
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Begnaud S, Chen T, Delacour D, Mège RM, Ladoux B. Mechanics of epithelial tissues during gap closure. Curr Opin Cell Biol 2016; 42:52-62. [PMID: 27131272 DOI: 10.1016/j.ceb.2016.04.006] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Revised: 04/06/2016] [Accepted: 04/08/2016] [Indexed: 12/15/2022]
Abstract
The closure of gaps is crucial to maintaining epithelium integrity during developmental and repair processes such as dorsal closure and wound healing. Depending on biochemical as well as physical properties of the microenvironment, gap closure occurs through assembly of multicellular actin-based contractile cables and/or protrusive activity of cells lining the gap. This review discusses the relative contributions of 'purse-string' and cell crawling mechanisms regulated by cell-substrate and cell-cell interactions, cellular mechanics and physical constraints from the environment.
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Affiliation(s)
- Simon Begnaud
- Institut Jacques Monod (IJM), CNRS UMR 7592 & University Paris Diderot, Paris, France
| | - Tianchi Chen
- Mechanobiology Institute (MBI), National University of Singapore, Singapore
| | - Delphine Delacour
- Institut Jacques Monod (IJM), CNRS UMR 7592 & University Paris Diderot, Paris, France
| | - René-Marc Mège
- Institut Jacques Monod (IJM), CNRS UMR 7592 & University Paris Diderot, Paris, France.
| | - Benoît Ladoux
- Institut Jacques Monod (IJM), CNRS UMR 7592 & University Paris Diderot, Paris, France; Mechanobiology Institute (MBI), National University of Singapore, Singapore.
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9
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A morphoelastic model for dermal wound closure. Biomech Model Mechanobiol 2015; 15:663-81. [DOI: 10.1007/s10237-015-0716-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Accepted: 08/01/2015] [Indexed: 02/08/2023]
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10
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Boyle JJ, Kume M, Wyczalkowski MA, Taber LA, Pless RB, Xia Y, Genin GM, Thomopoulos S. Simple and accurate methods for quantifying deformation, disruption, and development in biological tissues. J R Soc Interface 2015; 11:20140685. [PMID: 25165601 DOI: 10.1098/rsif.2014.0685] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
When mechanical factors underlie growth, development, disease or healing, they often function through local regions of tissue where deformation is highly concentrated. Current optical techniques to estimate deformation can lack precision and accuracy in such regions due to challenges in distinguishing a region of concentrated deformation from an error in displacement tracking. Here, we present a simple and general technique for improving the accuracy and precision of strain estimation and an associated technique for distinguishing a concentrated deformation from a tracking error. The strain estimation technique improves accuracy relative to other state-of-the-art algorithms by directly estimating strain fields without first estimating displacements, resulting in a very simple method and low computational cost. The technique for identifying local elevation of strain enables for the first time the successful identification of the onset and consequences of local strain concentrating features such as cracks and tears in a highly strained tissue. We apply these new techniques to demonstrate a novel hypothesis in prenatal wound healing. More generally, the analytical methods we have developed provide a simple tool for quantifying the appearance and magnitude of localized deformation from a series of digital images across a broad range of disciplines.
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Affiliation(s)
- John J Boyle
- Department of Orthopaedic Surgery, Washington University, St Louis, MO 63130, USA Department of Biomedical Engineering, Washington University, St Louis, MO 63130, USA
| | - Maiko Kume
- Department of Biomedical Engineering, Washington University, St Louis, MO 63130, USA
| | | | - Larry A Taber
- Department of Biomedical Engineering, Washington University, St Louis, MO 63130, USA
| | - Robert B Pless
- Department of Computer Science and Engineering, Washington University, St Louis, MO 63130, USA
| | - Younan Xia
- The Wallace H. Coulter Department of Biomedical Engineering, School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Guy M Genin
- Department of Mechanical Engineering and Materials Science, Washington University, St Louis, MO 63130, USA
| | - Stavros Thomopoulos
- Department of Orthopaedic Surgery, Washington University, St Louis, MO 63130, USA Department of Mechanical Engineering and Materials Science, Washington University, St Louis, MO 63130, USA Department of Biomedical Engineering, Washington University, St Louis, MO 63130, USA
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Buganza Tepole A, Kuhl E. Computational modeling of chemo-bio-mechanical coupling: a systems-biology approach toward wound healing. Comput Methods Biomech Biomed Engin 2014; 19:13-30. [DOI: 10.1080/10255842.2014.980821] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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12
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Growth and remodelling for profound circular wounds in skin. Biomech Model Mechanobiol 2014; 14:357-70. [PMID: 25183422 PMCID: PMC4349964 DOI: 10.1007/s10237-014-0609-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Accepted: 08/01/2014] [Indexed: 12/22/2022]
Abstract
Wound healing studies both in vitro and in vivo have received a lot of attention recently. In vivo wound healing is a multi-step process involving physiological factors such as fibrinogen forming the clot, the infiltrated inflammatory cells, the recruited fibroblasts and the differentiated myofibroblasts as well as deposited collagens. All these actors play their roles at different times, aided by a cascade of morphogenetic agents and the result for the repair is approximatively successful but the imperfection is remained for large scars with fibrosis. Here, we want to study wound healing from the viewpoint of skin biomechanics, integrating the particular layered geometry of the skin, and the role of the neighbouring wound epidermis. After 2 days post-injury, it migrates towards the wound centre to cover the hole, the migration being coupled to proliferation at the wound border. Such a process is dominated by the skin properties which varies with ages, locations, pathologies, radiations, etc. It is also controlled by passive (actin, collagen) and active (myo-fibroblasts) fibres. We explore a growth model in finite elasticity of a bilayer surrounding a circular wound, only the interior one being proliferative and contractile. We discuss the occurrence of an irregular wound geometry generated by stresses and show quantitatively that it results from the combined effects of the stiffness, the size of the wound, eventually weakened by actin cables. Comparison of our findings is made with known observations or experiments in vivo.
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