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Medina-Lombardero S, Bain C, Charlton L, Pellicoro A, Rocliffe H, Cash J, Reuben R, Crichton ML. The biomechanics of wounds at physiologically relevant levels: Understanding skin's stress-shielding effect for the quantitative assessment of healing. Mater Today Bio 2024; 25:100963. [PMID: 38312802 PMCID: PMC10835282 DOI: 10.1016/j.mtbio.2024.100963] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Revised: 12/15/2023] [Accepted: 01/15/2024] [Indexed: 02/06/2024] Open
Abstract
Wounds are responsible for the decrease in quality of life of billions of people around the world. Their assessment relies on subjective parameters which often delays optimal treatments and results in increased healthcare costs. In this work, we sought to understand and quantify how wounds at different healing stages (days 1, 3, 7 and 14 post wounding) change the mechanical properties of the tissues that contain them, and how these could be measured at clinically relevant strain levels, as a step towards quantitative wound tracking technologies. To achieve this, we used digital image correlation and mechanical testing on a mouse model of wound healing to map the global and local tissue strains. We found no significant differences in the elastic and viscoelastic properties of wounded vs unwounded skin when samples were measured in bulk, presumably as these were masked by the protective mechanisms of skin, which redistributes the applied loads to mitigate high stresses and reduce tissue damage. By measuring local strain values and observing the distinct patterns they formed, it was possible to establish a connection between the healing phase of the tissue (determined by the time post-injury and the observed histological features) and the overall mechanical behaviour. Importantly, these parameters were measured from the surface of the tissue, using physiologically relevant strains without increasing the tissue's damage. Adaptations of these approaches for clinical use have the potential to aid in the identification of skin healing problems, such as excessive inflammation or lack of mechanical progression over time. An increase, decrease, or lack of change in the elasticity and viscoelasticity parameters, can be indicative of wound state, thus ultimately leading to improved diagnostic outcomes.
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Affiliation(s)
- Sara Medina-Lombardero
- School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, United Kingdom
| | - Connor Bain
- School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, United Kingdom
| | - Laura Charlton
- School of Engineering, University of Edinburgh, Edinburgh, EH9 3RF, United Kingdom
| | - Antonella Pellicoro
- Centre for Inflammation Research, University of Edinburgh, Edinburgh, EH16 4TJ, United Kingdom
| | - Holly Rocliffe
- Centre for Inflammation Research, University of Edinburgh, Edinburgh, EH16 4TJ, United Kingdom
| | - Jenna Cash
- Centre for Inflammation Research, University of Edinburgh, Edinburgh, EH16 4TJ, United Kingdom
| | - Robert Reuben
- School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, United Kingdom
| | - Michael L. Crichton
- School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, United Kingdom
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Elouneg A, Chambert J, Lejeune A, Lucot Q, Jacquet E, Bordas SPA. Anisotropic mechanical characterization of human skin by in vivo multi-axial ring suction test. J Mech Behav Biomed Mater 2023; 141:105779. [PMID: 36940583 DOI: 10.1016/j.jmbbm.2023.105779] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 02/10/2023] [Accepted: 03/12/2023] [Indexed: 03/17/2023]
Abstract
Human skin is a soft tissue behaving as an anisotropic material. The anisotropy emerges from the alignment of collagen fibers in the dermis, which causes the skin to exhibit greater stiffness in a certain direction, known as Langer's line. The importance of determining this anisotropy axis lies in assisting surgeons in making incisions that do not produce undesirable scars. In this paper, we introduce an open-source numerical framework, MARSAC (Multi-Axial Ring Suction for Anisotropy Characterization: https://github.com/aflahelouneg/MARSAC), adapted to a commercial device CutiScan CS 100® that applies a suction load on an annular section, causing a multi-axial stretch in the central zone, where in-plane displacements are captured by a camera. The presented framework receives inputs from a video file and converts them into displacement fields through Digital Image Correlation (DIC) technique. From the latter and based on an analytical model, the method assesses the anisotropic material parameters of human skin: Langer's line ϕ, and the elastic moduli E1 and E2 along the principal axes, providing that the Poisson's ratio is fixed. The pipeline was applied to a public data repository, https://search-data.ubfc.fr/femto/FR-18008901306731-2021-08-25_In-vivo-skin-anisotropy-dataset-for-a-young-man.html, containing 30 test series performed on a forearm of a Caucasian subject. As a result, the identified parameter averages, ϕˆ=40.9±8.2∘ and the anisotropy ratio E1ˆ/E2ˆ=3.14±1.60, were in accordance with the literature. The intra-subject analysis showed a reliable assessment of ϕ and E2. As skin anisotropy varies from site to site and from subject to subject, the novelty of the method consists in (i) an optimal utilization of CutiScan CS 100® probe to measure the Langer's line accurately and rapidly on small areas with a minimum diameter of 14mm, (ii) validation of an analytical model based on deformation ellipticity.
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Affiliation(s)
- A Elouneg
- Université de Franche-Comté, CNRS, institut FEMTO-ST, F-25000 Besançon, France; Institute of Computational Engineering and Sciences, Department of Engineering, Université du Luxembourg, Esch-sur-Alzette, Luxembourg
| | - J Chambert
- Université de Franche-Comté, CNRS, institut FEMTO-ST, F-25000 Besançon, France
| | - A Lejeune
- Université de Franche-Comté, CNRS, institut FEMTO-ST, F-25000 Besançon, France
| | - Q Lucot
- Université de Franche-Comté, CNRS, institut FEMTO-ST, F-25000 Besançon, France
| | - E Jacquet
- Université de Franche-Comté, CNRS, institut FEMTO-ST, F-25000 Besançon, France
| | - S P A Bordas
- Université de Franche-Comté, CNRS, institut FEMTO-ST, F-25000 Besançon, France; Institute of Computational Engineering and Sciences, Department of Engineering, Université du Luxembourg, Esch-sur-Alzette, Luxembourg.
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Dwivedi KK, Lakhani P, Sihota P, Tikoo K, Kumar S, Kumar N. The multiscale characterization and constitutive modeling of healthy and type 2 diabetes mellitus Sprague Dawley rat skin. Acta Biomater 2023; 158:324-346. [PMID: 36565785 DOI: 10.1016/j.actbio.2022.12.037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 11/26/2022] [Accepted: 12/15/2022] [Indexed: 12/24/2022]
Abstract
In type 2 diabetes mellitus (T2DM), elevated glucose level impairs the biochemistry of the skin which may result in alteration of its mechanical and structural properties. The several aspects of structural and mechanical changes in skin due to T2DM remain poorly understood. To fill these research gaps, we developed a non-obese T2DM rat (Sprague Dawley (SD)) model for investigating the effect of T2DM on the in vivo strain stress state, mechanical and structural properties of skin. In vivo strain and mechanical anisotropy of healthy and T2DM skin were measured using the digital imaging correlation (DIC) technique and DIC coupled bulge experiment, respectively. Fluorescence microscopy and histology were used to assess the collagen and elastin fibers microstructure whereas nanoscale structure was captured through atomic force microscopy (AFM). Based on the microstructural observations, skin was modeled as a multilayer membrane where in and out of plane distribution of collagen fibers and planar distribution of elastin fibers were cast in constitutive model. Further, the state of in vivo stresses of healthy and T2DM were measured using model parameters and in vivo strain in the constitutive model. The results showed that T2DM causes significant loss in in vivo stresses (p < 0.01) and increase in anisotropy (p < 0.001) of skin. These changes were found in good correlation with T2DM associated alteration in skin microstructure. Statistical analysis emphasized that increase in blood glucose concentration (HbA1c) was the main cause of impaired biomechanical properties of skin. The presented data in this study can help to understand the skin pathology and to simulate the skin related clinical procedures. STATEMENT OF SIGNIFICANCE: Our study is significant as it presents findings related to the effect of T2DM on the physiologic stress strain, structural and mechanical response of SD rat skin. In this study, we developed a non-obese T2DM SD rat model which mimics the phenotype of Asian type 2 diabetics (non-obese). Several structural and mechanical characterization techniques were explored for multiscale characterization of healthy and T2DM skin. Further, based on microstructural information, we presented the constitutive models that incorporate the real microstructure of skin. The presented results can be helpful to simulate the realistic mechanical response of skin during various clinical trials.
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Affiliation(s)
- Krashn Kr Dwivedi
- Department of Biomedical Engineering, Indian institute of Technology Ropar, India
| | - Piyush Lakhani
- Department of Mechanical Engineering, Indian institute of Technology Ropar, India
| | - Praveer Sihota
- Department of Mechanical Engineering, Indian institute of Technology Ropar, India
| | - Kulbhushan Tikoo
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research, Mohali, India
| | - Sachin Kumar
- Department of Mechanical Engineering, Indian institute of Technology Ropar, India.
| | - Navin Kumar
- Department of Biomedical Engineering, Indian institute of Technology Ropar, India; Department of Mechanical Engineering, Indian institute of Technology Ropar, India.
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Tihăuan BM, Pircalabioru GG, Axinie (Bucos) M, Marinaș IC, Nicoară AC, Măruțescu L, Oprea O, Matei E, Maier SS. Crosslinked Collagenic Scaffold Behavior Evaluation by Physico-Chemical, Mechanical and Biological Assessments in an In Vitro Microenvironment. Polymers (Basel) 2022; 14:polym14122430. [PMID: 35746006 PMCID: PMC9227487 DOI: 10.3390/polym14122430] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Revised: 05/31/2022] [Accepted: 06/08/2022] [Indexed: 12/15/2022] Open
Abstract
Wound healing-associated difficulties continue to drive biotechnological creativeness into complex grounds. The sophisticated architecture of skin wound sites and the intricate processes involved in the response to the use of regenerative devices play a critical role in successful skin regeneration approaches and their possible outcomes. Due to a plethora of complications involved in wound healing processes as well as the coordination of various cellular mechanisms, biomimetic approaches seems to be the most promising starting ground. This study evaluates the behavior of a crosslinked, porous collagen scaffold obtained by lyophilization and dehydrothermal reticulation (DHT). We address the key physio-chemical and mechanical factors, such as swelling, density and porosity, mechano-dynamic properties, SEM and TG-DSC, as well as important biological outcomes regarding scaffold biocompatibility and cellular metabolic activity, cytokine expression in inflammation, apoptosis and necrosis, as well as hemocompatibility and biodegradation. The mechanical and visco-elastic behavior are correlated, with the samples found to present similar thermal behavior and increased rigidity after DHT treatment. High biocompatibility rates were obtained, with no inflammatory stimulation and a reduction in necrotic cells. Higher percentages of cellular early apoptosis were observed. The hemocompatibility rate was under 2%, coagulation effects expressed after 4 min, and the DHT scaffold was more resistant to the biodegradation of collagenase compared with the untreated sample.
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Affiliation(s)
- Bianca-Maria Tihăuan
- Research & Development for Advanced Biotechnologies and Medical Devices, SC Sanimed International Impex SRL, 087040 Călugăreni, Romania; (B.-M.T.); (M.A.); (I.C.M.); (S.S.M.)
- Research Institute of the University of Bucharest—ICUB, 91-95 Spl. Independentei, 50567 Bucharest, Romania;
| | - Gratiela Gradisteanu Pircalabioru
- Research & Development for Advanced Biotechnologies and Medical Devices, SC Sanimed International Impex SRL, 087040 Călugăreni, Romania; (B.-M.T.); (M.A.); (I.C.M.); (S.S.M.)
- Research Institute of the University of Bucharest—ICUB, 91-95 Spl. Independentei, 50567 Bucharest, Romania;
- Academy of Romanian Scientists, Ilfov Street 3, 050054 Bucharest, Romania;
- Correspondence:
| | - Mădălina Axinie (Bucos)
- Research & Development for Advanced Biotechnologies and Medical Devices, SC Sanimed International Impex SRL, 087040 Călugăreni, Romania; (B.-M.T.); (M.A.); (I.C.M.); (S.S.M.)
- Department of Science and Engineering of Oxide Materials and Nanomaterials, Faculty of Applied Chemistry and Materials Science, University Politehnica of Bucharest, 1-7 Gh. Polizu Street, 011061 Bucharest, Romania
| | - Ioana Cristina Marinaș
- Research & Development for Advanced Biotechnologies and Medical Devices, SC Sanimed International Impex SRL, 087040 Călugăreni, Romania; (B.-M.T.); (M.A.); (I.C.M.); (S.S.M.)
- Research Institute of the University of Bucharest—ICUB, 91-95 Spl. Independentei, 50567 Bucharest, Romania;
| | - Anca-Cecilia Nicoară
- Faculty of Pharmacy, University of Medicine and Pharmacy “Carol Davila”, 020021 Bucharest, Romania;
| | - Luminița Măruțescu
- Research Institute of the University of Bucharest—ICUB, 91-95 Spl. Independentei, 50567 Bucharest, Romania;
| | - Ovidiu Oprea
- Academy of Romanian Scientists, Ilfov Street 3, 050054 Bucharest, Romania;
- Faculty of Chemical Engineering and Biotechnologies, University of Politehnica Bucharest, Gh. Polizu Street 1-7, 011061 Bucharest, Romania
| | - Elena Matei
- National Institute of Materials Physics–Magurele, 405A Atomistilor Street, 077125 Magurele, Romania;
| | - Stelian Sergiu Maier
- Research & Development for Advanced Biotechnologies and Medical Devices, SC Sanimed International Impex SRL, 087040 Călugăreni, Romania; (B.-M.T.); (M.A.); (I.C.M.); (S.S.M.)
- Department of Chemical Engineering in Textiles and Leather, Faculty of Industrial Design and Business Management, “Gheorghe Asachi” Technical University of Iasi, 700050 Iași, Romania
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Dwivedi KK, Lakhani P, Kumar S, Kumar N. Effect of collagen fibre orientation on the Poisson's ratio and stress relaxation of skin: an ex vivo and in vivo study. ROYAL SOCIETY OPEN SCIENCE 2022; 9:211301. [PMID: 35345435 PMCID: PMC8941416 DOI: 10.1098/rsos.211301] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/05/2021] [Accepted: 01/31/2022] [Indexed: 06/14/2023]
Abstract
During surgical treatment skin undergoes extensive deformation, hence it must be able to withstand large mechanical stresses without damage. Therefore, understanding the mechanical properties of skin becomes important. A detailed investigation on the relationship between the three-dimensional deformation response of skin and its microstructure is conducted in the current study. This study also discloses the underlying science of skin viscoelasticity. Deformation response of skin is captured using digital image correlation, whereas micro-CT, scanning electron microscopy and atomic force microscopy are used for microstructure analysis. Skin shows a large lateral contraction and expansion (auxeticity) when stretched parallel and perpendicular to the skin tension lines, respectively. Large lateral contraction is a result of fluid exudation from the tissue, while large rotation of the stiff collagen fibres in the loading direction explains the skin auxeticity. During stress relaxation, lateral contraction and fluid effluxion from skin reveal that tissue volume loss is the intrinsic science of skin viscoelasticity. Furthermore, the results obtained from in vivo study on human skin show the relevance of the ex vivo study to physiological conditions and stretching of the skin during its treatments.
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Affiliation(s)
- Krashn Kumar Dwivedi
- Department of Biomedical Engineering, Indian Institute of Technology, Ropar, India
| | - Piyush Lakhani
- Department of Mechanical Engineering, Indian Institute of Technology, Ropar, India
| | - Sachin Kumar
- Department of Mechanical Engineering, Indian Institute of Technology, Ropar, India
| | - Navin Kumar
- Department of Biomedical Engineering, Indian Institute of Technology, Ropar, India
- Department of Mechanical Engineering, Indian Institute of Technology, Ropar, India
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