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The Role of Layer-Specific Residual Stresses in Arterial Mechanics: Analysis via a Novel Modelling Framework. Artery Res 2022. [DOI: 10.1007/s44200-022-00013-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
AbstractThe existence of residual stresses in unloaded arteries has long been known. However, their effect is often neglected in experimental studies. Using a recently developed modelling framework, we aimed to investigate the role of residual stresses in the mechanical behaviour of the tri-layered wall of the pig thoracic aorta. The mechanical behaviour of the intact wall and isolated layers of n = 3 pig thoracic aortas was investigated via uniaxial tensile testing. After modelling the layer-specific mechanical data using a hyperelastic strain energy function, the layer-specific deformations in the unloaded vessel were estimated so that the mechanical response of the computationally assembled tri-layered flat wall would match that measured experimentally. Physiological tension–inflation of the cylindrical tri-layered vessel was then simulated, analysing changes in the distribution of stresses in the three layers when neglecting residual stresses. In the tri-layered model with residual stresses, layers exhibited comparable stresses throughout the physiological range of pressure. At 100 mmHg, intimal, medial, and adventitial circumferential load bearings were 16 $$\pm$$
±
3%, 59 $$\pm$$
±
4%, and 25 $$\pm$$
±
2%, respectively. Adventitial stiffening at high pressures produced a shift in load bearing from the media to the adventitia. When neglecting residual stresses, in vivo stresses were highest at the intima and lowest at the adventitia. Consequently, the intimal and adventitial load bearings, 23 $$\pm$$
±
2% and 18 $$\pm$$
±
3% at 100 mmHg, were comparable at all pressures. Residual stresses play a crucial role in arterial mechanics guaranteeing a uniform distribution of stresses through the wall thickness. Neglecting these leads to incorrect interpretation of the layers’ role in arterial mechanics.
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Handorf AM, Zhou Y, Halanski MA, Li WJ. Tissue stiffness dictates development, homeostasis, and disease progression. Organogenesis 2016; 11:1-15. [PMID: 25915734 DOI: 10.1080/15476278.2015.1019687] [Citation(s) in RCA: 382] [Impact Index Per Article: 47.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Tissue development is orchestrated by the coordinated activities of both chemical and physical regulators. While much attention has been given to the role that chemical regulators play in driving development, researchers have recently begun to elucidate the important role that the mechanical properties of the extracellular environment play. For instance, the stiffness of the extracellular environment has a role in orienting cell division, maintaining tissue boundaries, directing cell migration, and driving differentiation. In addition, extracellular matrix stiffness is important for maintaining normal tissue homeostasis, and when matrix mechanics become imbalanced, disease progression may ensue. In this article, we will review the important role that matrix stiffness plays in dictating cell behavior during development, tissue homeostasis, and disease progression.
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Key Words
- ECM, Extracellular matrix
- EPC, Endothelial progenitor cell
- FA, Focal adhesion
- FAK, Focal adhesion kinase
- LOX, Lysyl oxidase
- MKL1, Megakaryoblastic leukemia factor-1
- MMP, Matrix metalloproteinase
- MSC, Mesenchymal stem cell
- ROCK, Rho-associated protein kinase
- VSMC, Vascular smooth muscle cell.
- cancer
- extracellular matrix
- fibrosis
- stiffness
- tissue development
- tissue homeostasis
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Affiliation(s)
- Andrew M Handorf
- a Department of Orthopedics and Rehabilitation; University of Wisconsin-Madison ; Madison , WI , USA
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Akhtar R, Cruickshank JK, Zhao X, Derby B, Weber T. A pilot study of scanning acoustic microscopy as a tool for measuring arterial stiffness in aortic biopsies. Artery Res 2015; 13:1-5. [PMID: 26985242 PMCID: PMC4774581 DOI: 10.1016/j.artres.2015.11.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
This study explores the use of scanning acoustic microscopy (SAM) as a potential tool for characterisation of arterial stiffness using aortic biopsies. SAM data is presented for human tissue collected during aortic bypass graft surgery for multi-vessel coronary artery disease. Acoustic wave speed as determined by SAM was compared to clinical data for the patients namely, pulse wave velocity (PWV), blood pressure, cholesterol and glucose levels. There was no obvious trend relating acoustic wave speed to PWV values, and an inverse relationship was found between systolic and diastolic blood pressure and acoustic wave speed. However, in patients with a higher cholesterol or glucose level, the acoustic wave speed increased. A more detailed investigation is needed to relate SAM data to clinical measurements. Scanning acoustic microscopy (SAM) is a potential tool for arterial stiffness. SAM provides a measure of the acoustic wave speed. In this pilot study, no clear trend was observed with pulse wave velocity. Blood pressure was inversely related with acoustic wave speed. Trends observed with other clinical markers such as glucose and total cholesterol.
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Affiliation(s)
- Riaz Akhtar
- Centre for Materials and Structures, School of Engineering, University of Liverpool, L69 3GH, UK
| | - J Kennedy Cruickshank
- Diabetes & Cardiovascular Medicine, Nutritional Sciences Division, King's College London, Franklin Wilkins Building, 150 Stamford Street, London SE1 9NH, UK
| | - Xuegen Zhao
- School of Materials, The University of Manchester, Manchester M13 9PL, UK
| | - Brian Derby
- School of Materials, The University of Manchester, Manchester M13 9PL, UK
| | - Thomas Weber
- Cardiology Department, Klinikum Wels-Grieskirchen, Grieskirchnerstrasse 42, 4600 Wels, Austria
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Beshtawi IM, Akhtar R, Hillarby MC, O’Donnell C, Zhao X, Brahma A, Carley F, Derby B, Radhakrishnan H. Biomechanical changes after repeated collagen cross-linking on human corneas assessed in vitro using scanning acoustic microscopy. Invest Ophthalmol Vis Sci 2014; 55:1549-54. [PMID: 24508795 PMCID: PMC4120094 DOI: 10.1167/iovs.13-13042] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To explore the biomechanical changes induced by repeated cross-linking using scanning acoustic microscopy (SAM). METHODS Thirty human corneas were divided into three groups. In group A, five corneas were cross-linked once. In group B, five corneas were cross-linked twice, 24 hours apart. In group C, five corneas were cross-linked three times, 24 hours apart. The contralateral controls in all groups had similar treatment but without UV-A. The speed of sound, which is directly proportional to the square root of the tissue's elastic modulus, was assessed using SAM. RESULTS In group A, the speed of sound of the treated corneas was 1677.38 ± 10.70 ms(-1) anteriorly and 1603.90 ± 9.82 ms(-1) posteriorly, while it was 1595.23 ± 9.66 ms(-1) anteriorly and 1577.13 ± 8.16 ms(-1) posteriorly in the controls. In group B, the speed of sound of the treated corneas was 1746.33 ± 23.37 ms(-1) anteriorly and 1631.60 ± 18.92 ms(-1) posteriorly, while it was 1637.57 ± 22.15 ms(-1) anteriorly and 1612.30 ± 22.23 ms(-1) posteriorly in the controls. In group C, the speed of sound of the treated corneas was 1717.97 ± 18.92 ms(-1) anteriorly and 1616.62 ± 17.58 ms(-1) posteriorly, while it was 1628.69 ± 9.37 ms(-1) anteriorly and 1597.68 ± 11.97 ms(-1) posteriorly in the controls. The speed of sound in the anterior (200 × 200 μm) region between the cross-linked and control corneas in groups A, B, and C was increased by a factor of 1.051 (P = 0.005), 1.066 (P = 0.010), and 1.055 (P = 0.005) respectively. However, there was no significant difference among the cross-linked corneas in all groups (P = 0.067). CONCLUSIONS A significant increase in speed of sound was found in all treated groups compared with the control group; however, the difference among the treated groups is not significant, suggesting no further cross-links are induced when collagen cross-linking treatment is repeated.
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Affiliation(s)
- Ithar M. Beshtawi
- Optometry Department, Faculty of Medicine and Health Sciences, An-Najah National University, Nablus, Palestine
| | - Riaz Akhtar
- Centre for Materials and Structures, School of Engineering, University of Liverpool, Liverpool, United Kingdom
| | - M. Chantal Hillarby
- Centre for Regenerative Medicine, Institute of Inflammation and Repair, The University of Manchester, Manchester, United Kingdom
| | | | - Xuegen Zhao
- Manchester Materials Science Centre, School of Materials, The University of Manchester, Manchester, United Kingdom
| | - Arun Brahma
- Manchester Royal Eye Hospital, Central Manchester University Hospitals NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester
| | - Fiona Carley
- Manchester Royal Eye Hospital, Central Manchester University Hospitals NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester
| | - Brian Derby
- Manchester Materials Science Centre, School of Materials, The University of Manchester, Manchester, United Kingdom
| | - Hema Radhakrishnan
- Faculty of Life Sciences, The University of Manchester, Manchester, United Kingdom
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Beshtawi IM, Akhtar R, Hillarby MC, O'Donnell C, Zhao X, Brahma A, Carley F, Derby B, Radhakrishnan H. Biomechanical properties of human corneas following low- and high-intensity collagen cross-linking determined with scanning acoustic microscopy. Invest Ophthalmol Vis Sci 2013; 54:5273-80. [PMID: 23847309 DOI: 10.1167/iovs.13-12576] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To assess and compare changes in the biomechanical properties of the cornea following different corneal collagen cross-linking protocols using scanning acoustic microscopy (SAM). METHODS Ten donor human corneal pairs were divided into two groups consisting of five corneal pairs in each group. In group A, five corneas were treated with low-fluence (370 nm, 3 mW/cm(2)) cross-linking (CXL) for 30 minutes. In group B, five corneas were treated with high-fluence (370 nm, 9 mW/cm(2)) CXL for 10 minutes. The contralateral control corneas in both groups had similar treatment but without ultraviolet A. The biomechanical properties of all corneas were tested using SAM. RESULTS In group A, the mean speed of sound in the treated corneas was 1677.38 ± 10.70 ms(-1) anteriorly and 1603.90 ± 9.82 ms(-1) posteriorly, while it was 1595.23 ± 9.66 ms(-1) anteriorly and 1577.13 ± 8.16 ms(-1) posteriorly in the control corneas. In group B, the mean speed of sound of the treated corneas was 1665.06 ± 9.54 ms(-1) anteriorly and 1589.89 ± 9.73 ms(-1) posteriorly, while it was 1583.55 ± 8.22 ms(-1) anteriorly and 1565.46 ± 8.13 ms(-1) posteriorly in the untreated control corneas. The increase in stiffness between the cross-linked and control corneas in both groups was by a factor of 1.051×. CONCLUSIONS SAM successfully detected changes in the corneal stiffness after application of collagen cross-linking. A higher speed-of-sound value was found in the treated corneas when compared with the controls. No significant difference was found in corneal stiffness between the corneas cross-linked with low- and high-intensity protocols.
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Localised micro-mechanical stiffening in the ageing aorta. Mech Ageing Dev 2011; 132:459-67. [PMID: 21777602 PMCID: PMC3192262 DOI: 10.1016/j.mad.2011.07.003] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2011] [Revised: 05/09/2011] [Accepted: 07/05/2011] [Indexed: 12/31/2022]
Abstract
Age-related loss of tissue elasticity is a common cause of human morbidity and arteriosclerosis (vascular stiffening) is associated with the development of both fatal strokes and heart failure. However, in the absence of appropriate micro-mechanical testing methodologies, multiple structural remodelling events have been proposed as the cause of arteriosclerosis. Therefore, using a model of ageing in female sheep aorta (young: <18 months, old: >8 years) we: (i) quantified age-related macro-mechanical stiffness, (ii) localised in situ micro-metre scale changes in acoustic wave speed (a measure of tissue stiffness) and (iii) characterised collagen and elastic fibre remodelling. With age, there was an increase in both macro-mechanical stiffness and mean microscopic wave speed (and hence stiffness; young wave speed: 1701 ± 1 m s−1, old wave speed: 1710 ± 1 m s−1, p < 0.001) which was localized to collagen fibril-rich regions located between large elastic lamellae. These micro-mechanical changes were associated with increases in both collagen and elastic fibre content (collagen tissue area, young: 31 ± 2%, old: 40 ± 4%, p < 0.05; elastic fibre tissue area, young: 55 ± 3%, old: 69 ± 4%, p < 0.001). Localised collagen fibrosis may therefore play a key role in mediating age-related arteriosclerosis. Furthermore, high frequency scanning acoustic microscopy is capable of co-localising micro-mechanical and micro-structural changes in ageing tissues.
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Akhtar R, Sherratt MJ, Cruickshank JK, Derby B. Characterizing the elastic properties of tissues. MATERIALS TODAY (KIDLINGTON, ENGLAND) 2011; 14:96-105. [PMID: 22723736 PMCID: PMC3378034 DOI: 10.1016/s1369-7021(11)70059-1] [Citation(s) in RCA: 178] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The quality of life of ageing populations is increasingly determined by age-related changes to the mechanical properties of numerous biological tissues. Degradation and mechanical failure of these tissues has a profound effect on human morbidity and mortality. Soft tissues have complex and intricate structures and, similar to engineering materials, their mechanical properties are controlled by their microstructure. Thus age-relate changes in mechanical behavior are determined by changes in the properties and relative quantities of microstructural tissue components. This review focuses on the cardiovascular system; it discusses the techniques used both in vivo and ex vivo to determine the age-related changes in the mechanical properties of arteries.
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Affiliation(s)
- Riaz Akhtar
- School of Materials, The University of Manchester, Grosvenor Street, Manchester, M1 7HS, UK
- Cardiovascular Sciences Research Group, Manchester Academic Health Science Centre, The University of Manchester, 46 Grafton Street, Manchester, M13 9NT, UK
| | - Michael J. Sherratt
- Regenerative Biomedicine, Manchester Academic Health Science Centre, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - J. Kennedy Cruickshank
- Cardiovascular Sciences Research Group, Manchester Academic Health Science Centre, The University of Manchester, 46 Grafton Street, Manchester, M13 9NT, UK
| | - Brian Derby
- School of Materials, The University of Manchester, Grosvenor Street, Manchester, M1 7HS, UK
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Cox TR, Erler JT. Remodeling and homeostasis of the extracellular matrix: implications for fibrotic diseases and cancer. Dis Model Mech 2011; 4:165-78. [PMID: 21324931 PMCID: PMC3046088 DOI: 10.1242/dmm.004077] [Citation(s) in RCA: 1069] [Impact Index Per Article: 82.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Dynamic remodeling of the extracellular matrix (ECM) is essential for development, wound healing and normal organ homeostasis. Life-threatening pathological conditions arise when ECM remodeling becomes excessive or uncontrolled. In this Perspective, we focus on how ECM remodeling contributes to fibrotic diseases and cancer, which both present challenging obstacles with respect to clinical treatment, to illustrate the importance and complexity of cell-ECM interactions in the pathogenesis of these conditions. Fibrotic diseases, which include pulmonary fibrosis, systemic sclerosis, liver cirrhosis and cardiovascular disease, account for over 45% of deaths in the developed world. ECM remodeling is also crucial for tumor malignancy and metastatic progression, which ultimately cause over 90% of deaths from cancer. Here, we discuss current methodologies and models for understanding and quantifying the impact of environmental cues provided by the ECM on disease progression, and how improving our understanding of ECM remodeling in these pathological conditions is crucial for uncovering novel therapeutic targets and treatment strategies. This can only be achieved through the use of appropriate in vitro and in vivo models to mimic disease, and with technologies that enable accurate monitoring, imaging and quantification of the ECM.
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Affiliation(s)
- Thomas R. Cox
- Cancer Research UK Tumour Cell Signalling Unit, Section of Cell and Molecular Biology, The Institute of Cancer Research, 237 Fulham Road, London SW3 6JB, UK
| | - Janine T. Erler
- Cancer Research UK Tumour Cell Signalling Unit, Section of Cell and Molecular Biology, The Institute of Cancer Research, 237 Fulham Road, London SW3 6JB, UK
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Zhao X, Wilkinson S, Akhtar R, Sherratt MJ, Watson REB, Derby B. Quantifying Micro-mechanical Properties of Soft Biological Tissues with Scanning Acoustic Microscopy. MATERIALS RESEARCH SOCIETY SYMPOSIA PROCEEDINGS. MATERIALS RESEARCH SOCIETY 2011; 1301:mrsf10-1301-oo13-08. [PMID: 22723722 PMCID: PMC3378028 DOI: 10.1557/opl.2011.572] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
In this study we have established a new approach to more accurately map acoustic wave speed (which is a measure of stiffness) within soft biological tissues at micrometer length scales using scanning acoustic microscopy. By using thin (5 μm thick) histological sections of human skin and porcine cartilage, this method exploits the phase information preserved in the interference between acoustic waves reflected from the substrate surface as well as internal reflections from the acoustic lens. A stack of images were taken with the focus point of acoustic lens positioned at or above the substrate surface, and processed pixel by pixel using custom software developed with LABVIEW and IMAQ (National Instruments) to extract phase information. Scanning parameters, such as acoustic wave frequency and gate position were optimized to get reasonable phase and lateral resolution. The contribution from substrate inclination or uneven scanning surface was removed prior to further processing. The wave attenuation was also obtained from these images.
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Affiliation(s)
- Xuegen Zhao
- School of Materials, the University of Manchester, Manchester, M1 7HS, United Kingdom
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Graham HK, Hodson NW, Hoyland JA, Millward-Sadler SJ, Garrod D, Scothern A, Griffiths CEM, Watson REB, Cox TR, Erler JT, Trafford AW, Sherratt MJ. Tissue section AFM: In situ ultrastructural imaging of native biomolecules. Matrix Biol 2010; 29:254-60. [PMID: 20144712 PMCID: PMC2877882 DOI: 10.1016/j.matbio.2010.01.008] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2009] [Revised: 01/29/2010] [Accepted: 01/29/2010] [Indexed: 11/12/2022]
Abstract
Conventional approaches for ultrastructural high-resolution imaging of biological specimens induce profound changes in bio-molecular structures. By combining tissue cryo-sectioning with non-destructive atomic force microscopy (AFM) imaging we have developed a methodology that may be applied by the non-specialist to both preserve and visualize bio-molecular structures (in particular extracellular matrix assemblies) in situ. This tissue section AFM technique is capable of: i) resolving nm–µm scale features of intra- and extracellular structures in tissue cryo-sections; ii) imaging the same tissue region before and after experimental interventions; iii) combining ultrastructural imaging with complimentary microscopical and micromechanical methods. Here, we employ this technique to: i) visualize the macro-molecular structures of unstained and unfixed fibrillar collagens (in skin, cartilage and intervertebral disc), elastic fibres (in aorta and lung), desmosomes (in nasal epithelium) and mitochondria (in heart); ii) quantify the ultrastructural effects of sequential collagenase digestion on a single elastic fibre; iii) correlate optical (auto fluorescent) with ultrastructural (AFM) images of aortic elastic lamellae.
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Affiliation(s)
- Helen K Graham
- Unit of Cardiac Physiology, School of Biomedicine, The University of Manchester, Manchester Academic Health Science Centre, Manchester, M13 9PT, UK
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