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Giudici A, Li Y, Yasmin, Cleary S, Connolly K, McEniery C, Wilkinson IB, Khir AW. Time-course of the human thoracic aorta ageing process assessed using uniaxial mechanical testing and constitutive modelling. J Mech Behav Biomed Mater 2022; 134:105339. [DOI: 10.1016/j.jmbbm.2022.105339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 06/18/2022] [Accepted: 06/25/2022] [Indexed: 10/17/2022]
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van Soldt BJ, Wang T, Filogonio R, Danielsen CC. The mechanical and morphological properties of systemic and pulmonary arteries differ in the earth boa, a snake without ventricular pressure separation. J Exp Biol 2022; 225:275580. [PMID: 35642934 DOI: 10.1242/jeb.244419] [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: 04/13/2022] [Accepted: 05/27/2022] [Indexed: 11/20/2022]
Abstract
The walls of the mammalian aorta and pulmonary artery are characterized by diverging morphologies and mechanical properties, which has been correlated with high systemic and low pulmonary blood pressures, as a result of intraventricular pressure separation. However, the relation between intraventricular pressure separation and diverging aortic and pulmonary artery wall morphologies and mechanical characteristics is not understood. The snake cardiovascular system poses a unique model for the study of this question, since representatives both with and without intraventricular pressure separation exist. In this study we perform uniaxial tensile testing on vessel samples taken from the aortas and pulmonary arteries of the earth boa, Acrantophis madagascariensis, a species without intraventricular pressure separation. We then compare these morphological and mechanical characteristics with samples from the ball python, Python regius, and the yellow anaconda, Eunectes notaeus, species with and without intraventricular pressure separation, respectively. Our data suggest that although the aortas and pulmonary arteries of A. madagascariensis respond similarly to the same intramural blood pressures, they diverge in morphology, and that this attribute extends to E. notaeus. In contrast, P. regius aortas and pulmonary arteries diverge both morphologically and in terms of their mechanical properties. Our data indicate that intraventricular pressure separation cannot fully explain diverging aortic and pulmonary artery morphologies. Following the Law of Laplace, we propose that pulmonary arteries of small luminal diameter represent a mechanism to protect the fragile pulmonary vasculature by reducing the blood volume that passes through, to which genetic factors may contribute more strongly than physiological parameters.
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Affiliation(s)
- Benjamin J van Soldt
- Gladstone Institute of Cardiovascular Disease, J. David Gladstone Institutes, 1650 Owns St, San Francisco, CA, 94158, USA
| | - Tobias Wang
- Aarhus Institute of Advanced Sciences (AIAS), Aarhus University, 8000 Aarhus C, Denmark
| | - Renato Filogonio
- Department of Physiological Sciences, Federal University of São Carlos, São Carlos, SP 13565-905, Brazil
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Logvinov SV, Naryzhnaya NV, Kurbatov BK, Gorbunov AS, Birulina YG, Maslov LL, Oeltgen PR. High carbohydrate high fat diet causes arterial hypertension and histological changes in the aortic wall in aged rats: The involvement of connective tissue growth factors and fibronectin. Exp Gerontol 2021; 154:111543. [PMID: 34455071 DOI: 10.1016/j.exger.2021.111543] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 08/23/2021] [Accepted: 08/23/2021] [Indexed: 10/20/2022]
Abstract
BACKGROUND Age and diabetes are risk factors for arterial hypertension. However, the relationship between age, connective tissue growth factors, vascular aging and arterial hypertension while on a the high-carbohydrate high-fat diet (HCHFD) remains poorly understood. PURPOSE To estimate the relationship between humoral factors, the morphological changes of aorta and impaired blood pressure regulation under the influence of age and a HCHFD. METHODS A study was carried out in male Wistar rats, which were divided into the following groups: 1st (n = 15) - naive young rats; 2nd (n = 15) - young rats, exposed to HCHFD; 3rd (n = 14) - naive old rats; 4th (n = 12) - old rats exposed to HCHFD. The age of old rats was 540 days, and young rats 150 days at the end of the diet. HCHFD contained proteins 16%, fats 21%, carbohydrates 46%, including 17% fructose, 0.125% cholesterol, 90 days. Blood pressure and body weight were measured weekly, carbohydrate metabolism, histological signs of changes in the aorta, serum transforming growth factor-β (TGF-β), connective tissue growth factor (CTGF), fibronectin, and endothelin-1 levels were determined one week after the onset of diet. RESULTS The severity of arterial hypertension and its histological signs in the aortic wall was found to be most pronounced in elderly rats kept on a HCHFD. In young rats kept on a HCHFD, arterial hypertension was transient. An increase in systolic blood pressure has a positive correlation with the degree of obesity, serum fibronectin, and endothelin-1 content, and impaired carbohydrate metabolism. The rise in diastolic blood pressure has a positive correlation with the serum CTGF, endothelin-1, fibronectin levels and aortic wall thickness, and impaired carbohydrate metabolism. A rise in the serum concentration of fibronectin was also associated with increased endothelin-1, TGFβ and CTGF serum levels. CONCLUSION This study indicated that an increase in blood pressure in old rats with a high-carbohydrate high-fat diet is due to a disturbance of a structure of the vascular wall, the release of fibronectin, which can occur under the influence of carbohydrate metabolism disorders, endothelin-1, TGFβ and CTGF.
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Affiliation(s)
- Sergey V Logvinov
- Cardiology Research Institute, Tomsk National Research Medical Center, The Russian Academy of Sciences, 634012 Tomsk, Russia; Siberian State Medical University, Tomsk, Russia
| | - Natalia V Naryzhnaya
- Cardiology Research Institute, Tomsk National Research Medical Center, The Russian Academy of Sciences, 634012 Tomsk, Russia.
| | - Boris K Kurbatov
- Cardiology Research Institute, Tomsk National Research Medical Center, The Russian Academy of Sciences, 634012 Tomsk, Russia
| | - Alexander S Gorbunov
- Cardiology Research Institute, Tomsk National Research Medical Center, The Russian Academy of Sciences, 634012 Tomsk, Russia
| | | | - Leonid L Maslov
- Cardiology Research Institute, Tomsk National Research Medical Center, The Russian Academy of Sciences, 634012 Tomsk, Russia
| | - Peter R Oeltgen
- Department of Pathology, University of Kentucky College of Medicine, Lexington, KY, USA
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Giudici A, Wilkinson IB, Khir AW. Review of the Techniques Used for Investigating the Role Elastin and Collagen Play in Arterial Wall Mechanics. IEEE Rev Biomed Eng 2021; 14:256-269. [PMID: 32746366 DOI: 10.1109/rbme.2020.3005448] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The arterial wall is characterised by a complex microstructure that impacts the mechanical properties of the vascular tissue. The main components consist of collagen and elastin fibres, proteoglycans, Vascular Smooth Muscle Cells (VSMCs) and ground matrix. While VSMCs play a key role in the active mechanical response of arteries, collagen and elastin determine the passive mechanics. Several experimental methods have been designed to investigate the role of these structural proteins in determining the passive mechanics of the arterial wall. Microscopy imaging of load-free or fixed samples provides useful information on the structure-function coupling of the vascular tissue, and mechanical testing provides information on the mechanical role of collagen and elastin networks. However, when these techniques are used separately, they fail to provide a full picture of the arterial micromechanics. More recently, advances in imaging techniques have allowed combining both methods, thus dynamically imaging the sample while loaded in a pseudo-physiological way, and overcoming the limitation of using either of the two methods separately. The present review aims at describing the techniques currently available to researchers for the investigation of the arterial wall micromechanics. This review also aims to elucidate the current understanding of arterial mechanics and identify some research gaps.
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Berquand A, Wahart A, Henry A, Gorisse L, Maurice P, Blaise S, Romier-Crouzet B, Pietrement C, Bennasroune A, Sartelet H, Jaisson S, Gillery P, Martiny L, Touré F, Duca L, Molinari M. Revealing the elasticity of an individual aortic fiber during ageing at nanoscale by in situ atomic force microscopy. NANOSCALE 2021; 13:1124-1133. [PMID: 33399602 DOI: 10.1039/d0nr06753a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Arterial stiffness is a complex process affecting the aortic tree that significantly contributes to cardiovascular diseases (systolic hypertension, coronary artery disease, heart failure or stroke). This process involves a large extracellular matrix remodeling mainly associated with elastin content decrease and collagen content increase. Additionally, various chemical modifications that accumulate with ageing have been shown to affect long-lived assemblies, such as elastic fibers, that could affect their elasticity. To precisely characterize the fiber changes and the evolution of its elasticity with ageing, high resolution and multimodal techniques are needed for precise insight into the behavior of a single fiber and its surrounding medium. In this study, the latest developments in atomic force microscopy and the related nanomechanical modes are used to investigate the evolution and in a near-physiological environment, the morphology and elasticity of aorta cross sections obtained from mice of different ages with an unprecedented resolution. In correlation with more classical approaches such as pulse wave velocity and fluorescence imaging, we demonstrate that the relative Young's moduli of elastic fibers, as well as those of the surrounding areas, significantly increase with ageing. This nanoscale characterization presents a new view on the stiffness process, showing that, besides the elastin and collagen content changes, elasticity is impaired at the molecular level, allowing a deeper understanding of the ageing process. Such nanomechanical AFM measurements of mouse tissue could easily be applied to studies of diseases in which elastic fibers suffer pathologies such as atherosclerosis and diabetes, where the precise quantification of fiber elasticity could better follow the fiber remodeling and predict plaque rupture.
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Affiliation(s)
- Alexandre Berquand
- Laboratoire de Recherche en Nanosciences, LRN EA4682, University of Reims Champagne-Ardenne, 51685 Reims, France
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6
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Sherratt MJ, Hopkinson L, Naven M, Hibbert SA, Ozols M, Eckersley A, Newton VL, Bell M, Meng QJ. Circadian rhythms in skin and other elastic tissues. Matrix Biol 2019; 84:97-110. [PMID: 31422155 DOI: 10.1016/j.matbio.2019.08.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 07/19/2019] [Accepted: 08/13/2019] [Indexed: 12/15/2022]
Abstract
Circadian rhythms are daily oscillations that, in mammals, are driven by both a master clock, located in the brain, and peripheral clocks in cells and tissues. Approximately 10% of the transcriptome, including extracellular matrix components, is estimated to be under circadian control. Whilst it has been established that certain collagens and extracellular matrix proteases are diurnally regulated (for example in tendon, cartilage and intervertebral disc) the role played by circadian rhythms in mediating elastic fiber homeostasis is poorly understood. Skin, arteries and lungs are dynamic, resilient, elastic fiber-rich organs and tissues. In skin, circadian rhythms influence cell migration and proliferation, wound healing and susceptibility of the tissues to damage (from protease activity, oxidative stress and ultraviolet radiation). In the cardiovascular system, blood pressure and heart rate also follow age-dependent circadian rhythms whilst the lungs exhibit diurnal variations in immune response. In order to better understand these processes it will be necessary to characterise diurnal changes in extracellular matrix biology. In particular, given the sensitivity of peripheral clocks to external factors, the timed delivery of interventions (chronotherapy) has the potential to significantly improve the efficacy of treatments designed to repair and regenerate damaged cutaneous, vascular and pulmonary tissues.
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Affiliation(s)
- Michael J Sherratt
- Division of Cell Matrix Biology & Regenerative Medicine, The University of Manchester, UK.
| | - Louise Hopkinson
- Division of Cell Matrix Biology & Regenerative Medicine, The University of Manchester, UK; Centre for Doctoral Training in Regenerative Medicine, Faculty of Biology, Medicine and Health, The University of Manchester, UK; Wellcome Trust Centre for Cell-Matrix Research, UK
| | - Mark Naven
- Division of Cell Matrix Biology & Regenerative Medicine, The University of Manchester, UK; Wellcome Trust Centre for Cell-Matrix Research, UK
| | - Sarah A Hibbert
- Division of Cell Matrix Biology & Regenerative Medicine, The University of Manchester, UK
| | - Matiss Ozols
- Division of Cell Matrix Biology & Regenerative Medicine, The University of Manchester, UK
| | - Alexander Eckersley
- Division of Cell Matrix Biology & Regenerative Medicine, The University of Manchester, UK
| | | | - Mike Bell
- Walgreens Boots Alliance, Thane Rd, Nottingham, England, UK
| | - Qing-Jun Meng
- Division of Cell Matrix Biology & Regenerative Medicine, The University of Manchester, UK; Wellcome Trust Centre for Cell-Matrix Research, UK
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Streuli CH, Meng QJ. Influence of the extracellular matrix on cell-intrinsic circadian clocks. J Cell Sci 2019; 132:jcs207498. [PMID: 30709969 DOI: 10.1242/jcs.207498] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Cell-autonomous circadian clocks coordinate tissue homeostasis with a 24-hourly rhythm. The molecular circadian clock machinery controls tissue- and cell type-specific sets of rhythmic genes. Disruptions of clock mechanisms are linked to an increased risk of acquiring diseases, especially those associated with aging, metabolic dysfunction and cancer. Despite rapid advances in understanding the cyclic outputs of different tissue clocks, less is known about how the clocks adapt to their local niche within tissues. We have discovered that tissue stiffness regulates circadian clocks, and that this occurs in a cell-type-dependent manner. In this Review, we summarise new work linking the extracellular matrix with differential control of circadian clocks. We discuss how the changes in tissue structure and cellular microenvironment that occur throughout life may impact on the molecular control of circadian cycles. We also consider how altered clocks may have downstream impacts on the acquisition of diseases.
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Affiliation(s)
- Charles H Streuli
- Wellcome Centre for Cell-Matrix Research and Manchester Breast Centre, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PT, UK
| | - Qing-Jun Meng
- Wellcome Centre for Cell-Matrix Research and Manchester Breast Centre, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PT, UK
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8
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Chang Z, Paoletti P, Hansen ML, Beck HC, Chen PY, Rasmussen LM, Akhtar R. AFM Characterization of the Internal Mammary Artery as a Novel Target for Arterial Stiffening. SCANNING 2018; 2018:6340425. [PMID: 30524642 PMCID: PMC6247466 DOI: 10.1155/2018/6340425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2018] [Accepted: 09/06/2018] [Indexed: 05/05/2023]
Abstract
Using the atomic force microscopy- (AFM-) PeakForce quantitative nanomechanical mapping (QNM) technique, we have previously shown that the adventitia of the human internal mammary artery (IMA), tested under dehydrated conditions, is altered in patients with a high degree of arterial stiffening. In this study, we explored the nanoscale elastic modulus of the tunica media of the IMA in hydrated and dehydrated conditions from the patients with low and high arterial stiffening, as assessed in vivo by carotid-femoral pulse wave velocity (PWV). In both hydrated and dehydrated conditions, the medial layer was significantly stiffer in the high PWV group. The elastic modulus of the hydrated and dehydrated tunica media was significantly correlated with PWV. In the hydrated condition, the expression activity of certain small leucine-rich repeat proteoglycans (SLRPs), which are associated with arterial stiffening, were found to be negatively correlated to the medial elastic modulus. We also compared the data with our previous work on the IMA adventitia. We found that the hydrated media and dehydrated adventitia are both suitable for reflecting the development of arterial stiffening and SLRP expression. This comprehensive study of the nanomechanical properties integrated with the proteomic analysis in the IMAs demonstrates the possibility of linking structural properties and function in small biological samples with novel AFM methods. The IMA is a suitable target for predicting arterial stiffening.
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Affiliation(s)
- Zhuo Chang
- Department of Mechanical, Materials and Aerospace Engineering, School of Engineering, University of Liverpool, L69 3GH, UK
- Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Paolo Paoletti
- Department of Mechanical, Materials and Aerospace Engineering, School of Engineering, University of Liverpool, L69 3GH, UK
| | - Maria Lyck Hansen
- Department of Clinical Biochemistry and Pharmacology, Center for Individualized Medicine in Arterial Diseases, Odense University Hospital, University of Southern Denmark, Denmark
| | - Hans Christian Beck
- Department of Clinical Biochemistry and Pharmacology, Center for Individualized Medicine in Arterial Diseases, Odense University Hospital, University of Southern Denmark, Denmark
| | - Po-Yu Chen
- Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Lars Melholt Rasmussen
- Department of Clinical Biochemistry and Pharmacology, Center for Individualized Medicine in Arterial Diseases, Odense University Hospital, University of Southern Denmark, Denmark
| | - Riaz Akhtar
- Department of Mechanical, Materials and Aerospace Engineering, School of Engineering, University of Liverpool, L69 3GH, UK
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9
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Keen AN, Fenna AJ, McConnell JC, Sherratt MJ, Gardner P, Shiels HA. Macro- and micromechanical remodelling in the fish atrium is associated with regulation of collagen 1 alpha 3 chain expression. Pflugers Arch 2018; 470:1205-1219. [PMID: 29594338 PMCID: PMC6060776 DOI: 10.1007/s00424-018-2140-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 02/16/2018] [Accepted: 03/12/2018] [Indexed: 12/19/2022]
Abstract
Numerous pathologies lead to remodelling of the mammalian ventricle, often associated with fibrosis. Recent work in fish has shown that fibrotic remodelling of the ventricle is 'reversible', changing seasonally as temperature-induced changes in blood viscosity alter haemodynamic load on the heart. The atrial response to varying haemodynamic load is less understood in mammals and completely unexplored in non-mammalian vertebrates. To investigate atrial remodelling, rainbow trout were chronically cooled (from 10 ± 1 to 5 ± 1 °C) and chronically warmed (from 10 ± 1 to 18 ± 1 °C) for a minimum of 8 weeks. We assessed the functional effects on compliance using ex vivo heart preparations and atomic force microscopy nano-indentation and found chronic cold increased passive stiffness of the whole atrium and micromechanical stiffness of tissue sections. We then performed histological, biochemical and molecular assays to probe the mechanisms underlying functional remodelling of the atrial tissue. We found cooling resulted in collagen deposition which was associated with an upregulation of collagen-promoting genes, including the fish-specific collagen I alpha 3 chain, and a reduction in gelatinase activity of collagen-degrading matrix metalloproteinases (MMPs). Finally, we found that cooling reduced mRNA expression of cardiac growth factors and hypertrophic markers. Following long-term warming, there was an opposing response to that seen with cooling; however, these changes were more moderate. Our findings suggest that chronic cooling causes atrial dilation and increased myocardial stiffness in trout atria analogous to pathological states defined by changes in preload or afterload of the mammalian atria. The reversal of this phenotype following chronic warming is particularly interesting as it suggests that typically pathological features of mammalian atrial remodelling may oscillate seasonally in the fish, revealing a more dynamic and plastic atrial remodelling response.
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Affiliation(s)
- Adam N Keen
- Division of Cardiovascular Sciences, Manchester Academic Health Sciences Centre, University of Manchester, Manchester, UK
| | - Andrew J Fenna
- Division of Cardiovascular Sciences, Manchester Academic Health Sciences Centre, University of Manchester, Manchester, UK
| | - James C McConnell
- Centre for Tissue Injury and Repair, Faculty of Biology, Medicine, and Health, University of Manchester, Manchester, UK
| | - Michael J Sherratt
- Centre for Tissue Injury and Repair, Faculty of Biology, Medicine, and Health, University of Manchester, Manchester, UK
| | - Peter Gardner
- School of Chemical Engineering and Analytical Science, Manchester Institute of Biotechnology, University of Manchester, Manchester, UK
| | - Holly A Shiels
- Division of Cardiovascular Sciences, Manchester Academic Health Sciences Centre, University of Manchester, Manchester, UK.
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10
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Kohn JC, Abdalrahman T, Sack KL, Reinhart-King CA, Franz T. Endothelial cells on an aged subendothelial matrix display heterogeneous strain profiles in silico. Biomech Model Mechanobiol 2018; 17:1405-1414. [PMID: 29802577 DOI: 10.1007/s10237-018-1034-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Accepted: 05/16/2018] [Indexed: 10/24/2022]
Abstract
Within the artery intima, endothelial cells respond to mechanical cues and changes in subendothelial matrix stiffness. Recently, we found that the aging subendothelial matrix stiffens heterogeneously and that stiffness heterogeneities are present on the scale of one cell length. However, the impacts of these complex mechanical micro-heterogeneities on endothelial cells have not been fully understood. Here, we simulate the effects of matrices that mimic young and aged vessels on single- and multi-cell endothelial cell models and examine the resulting cell basal strain profiles. Although there are limitations to the model which prohibit the prediction of intracellular strain distributions in alive cells, this model does introduce mechanical complexities to the subendothelial matrix material. More heterogeneous basal strain distributions are present in the single- and multi-cell models on the matrix mimicking an aged artery over those exhibited on the young artery. Overall, our data indicate that increased heterogeneous strain profiles in endothelial cells are displayed in silico when there is an increased presence of microscale arterial mechanical heterogeneities in the matrix.
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Affiliation(s)
- J C Kohn
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, College of Engineering, Cornell University, Ithaca, NY, USA.,Division of Biomedical Engineering, Department of Human Biology, University of Cape Town, Observatory, South Africa
| | - T Abdalrahman
- Division of Biomedical Engineering, Department of Human Biology, University of Cape Town, Observatory, South Africa
| | - K L Sack
- Division of Biomedical Engineering, Department of Human Biology, University of Cape Town, Observatory, South Africa
| | - C A Reinhart-King
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, College of Engineering, Cornell University, Ithaca, NY, USA.,Department of Biomedical Engineering, School of Engineering, Vanderbilt University, Nashville, TN, USA
| | - T Franz
- Division of Biomedical Engineering, Department of Human Biology, University of Cape Town, Observatory, South Africa. .,Bioengineering Science Research Group, Engineering Sciences, Faculty of Engineering and the Environment, University of Southampton, Southampton, UK.
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11
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Disney CM, Lee PD, Hoyland JA, Sherratt MJ, Bay BK. A review of techniques for visualising soft tissue microstructure deformation and quantifying strain Ex Vivo. J Microsc 2018; 272:165-179. [PMID: 29655273 DOI: 10.1111/jmi.12701] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Revised: 03/08/2018] [Accepted: 03/16/2018] [Indexed: 12/16/2022]
Abstract
Many biological tissues have a complex hierarchical structure allowing them to function under demanding physiological loading conditions. Structural changes caused by ageing or disease can lead to loss of mechanical function. Therefore, it is necessary to characterise tissue structure to understand normal tissue function and the progression of disease. Ideally intact native tissues should be imaged in 3D and under physiological loading conditions. The current published in situ imaging methodologies demonstrate a compromise between imaging limitations and maintaining the samples native mechanical function. This review gives an overview of in situ imaging techniques used to visualise microstructural deformation of soft tissue, including three case studies of different tissues (tendon, intervertebral disc and artery). Some of the imaging techniques restricted analysis to observational mechanics or discrete strain measurement from invasive markers. Full-field local surface strain measurement has been achieved using digital image correlation. Volumetric strain fields have successfully been quantified from in situ X-ray microtomography (micro-CT) studies of bone using digital volume correlation but not in soft tissue due to low X-ray transmission contrast. With the latest developments in micro-CT showing in-line phase contrast capability to resolve native soft tissue microstructure, there is potential for future soft tissue mechanics research where 3D local strain can be quantified. These methods will provide information on the local 3D micromechanical environment experienced by cells in healthy, aged and diseased tissues. It is hoped that future applications of in situ imaging techniques will impact positively on the design and testing of potential tissue replacements or regenerative therapies. LAY DESCRIPTION: The soft tissues in our bodies, such as tendons, intervertebral discs and arteries, have evolved to have complicated structures which deform and bear load during normal function. Small changes in these structures can occur with age and disease which then leads to loss of function. Therefore, it is important to image tissue microstructure in 3D and under functional conditions. This paper gives an overview of imaging techniques used to record the deformation of soft tissue microstructures. Commonly there are compromises between obtaining the best imaging result and retaining the samples native structure and function. For example, invasive markers and dissecting samples damages the tissues natural structure, and staining or clearing (making the tissue more transparent) can distort tissue structure. Structural deformation has been quantified from 2D imaging techniques (digital image correlation) to create surface strain maps which help identify local tissue mechanics. When extended to 3D (digital volume correlation), deformation measurement has been limited to bone samples using X-ray micro-CT. Recently it has been possible to image the 3D structure of soft tissue using X-ray micro-CT meaning that there is potential for internal soft tissue mechanics to be mapped in 3D. Future application of micro-CT and digital volume correlation will be important for soft tissue mechanics studies particularly to understand normal function, progression of disease and in the design of tissue replacements.
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Affiliation(s)
- C M Disney
- Centre for Doctoral Training in Regenerative Medicine, University of Manchester, Manchester, U.K.,Division of Cell Matrix Biology and Regenerative Medicine, University of Manchester, Manchester, U.K
| | - P D Lee
- School of Materials, University of Manchester, Manchester, U.K
| | - J A Hoyland
- Division of Cell Matrix Biology and Regenerative Medicine, University of Manchester, Manchester, U.K.,NIHR Manchester Biomedical Research Centre, Manchester Academic Health Science Centre, Central Manchester University Hospitals NHS Foundation Trust, Manchester, U.K
| | - M J Sherratt
- Division of Cell Matrix Biology and Regenerative Medicine, University of Manchester, Manchester, U.K
| | - B K Bay
- School of Mechanical, Industrial and Manufacturing Engineering, Oregon State University, Corvallis, Oregon, U.S.A
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12
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Wijesinghe P, Johansen NJ, Curatolo A, Sampson DD, Ganss R, Kennedy BF. Ultrahigh-Resolution Optical Coherence Elastography Images Cellular-Scale Stiffness of Mouse Aorta. Biophys J 2018; 113:2540-2551. [PMID: 29212007 DOI: 10.1016/j.bpj.2017.09.022] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 08/22/2017] [Accepted: 09/19/2017] [Indexed: 01/08/2023] Open
Abstract
Cellular-scale imaging of the mechanical properties of tissue has helped to reveal the origins of disease; however, cellular-scale resolution is not readily achievable in intact tissue volumes. Here, we demonstrate volumetric imaging of Young's modulus using ultrahigh-resolution optical coherence elastography, and apply it to characterizing the stiffness of mouse aortas. We achieve isotropic resolution of better than 15 μm over a 1-mm lateral field of view through the entire depth of an intact aortic wall. We employ a method of quasi-static compression elastography that measures volumetric axial strain and uses a compliant, transparent layer to measure surface axial stress. This combination is used to estimate Young's modulus throughout the volume. We demonstrate differentiation by stiffness of individual elastic lamellae and vascular smooth muscle. We observe stiffening of the aorta in regulator of G protein signaling 5-deficient mice, a model that is linked to vascular remodeling and fibrosis. We observe increased stiffness with proximity to the heart, as well as regions with micro-structural and micro-mechanical signatures characteristic of fibrous and lipid-rich tissue. High-resolution imaging of Young's modulus with optical coherence elastography may become an important tool in vascular biology and in other fields concerned with understanding the role of mechanics within the complex three-dimensional architecture of tissue.
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Affiliation(s)
- Philip Wijesinghe
- BRITElab, Harry Perkins Institute of Medical Research, QEII Medical Centre, Nedlands and Centre for Medical Research, The University of Western Australia, Perth, Western Australia, Australia; Optical+Biomedical Engineering Laboratory, School of Electrical, Electronic and Computer Engineering, The University of Western Australia, Perth, Western Australia, Australia.
| | - Niloufer J Johansen
- Centre for Medical Research, The University of Western Australia, Perth, Western Australia, Australia; Research Department, St John of God Subiaco Hospital, Subiaco, Western Australia, Australia
| | - Andrea Curatolo
- BRITElab, Harry Perkins Institute of Medical Research, QEII Medical Centre, Nedlands and Centre for Medical Research, The University of Western Australia, Perth, Western Australia, Australia; School of Electrical, Electronic and Computer Engineering, The University of Western Australia, Perth, Western Australia, Australia
| | - David D Sampson
- Optical+Biomedical Engineering Laboratory, School of Electrical, Electronic and Computer Engineering, The University of Western Australia, Perth, Western Australia, Australia; Centre for Microscopy, Characterisation and Analysis, The University of Western Australia, Perth, Western Australia, Australia
| | - Ruth Ganss
- Vascular Biology and Stromal Targeting, Harry Perkins Institute of Medical Research, QEII Medical Centre, Nedlands and Centre for Medical Research, The University of Western Australia, Perth, Western Australia, Australia
| | - Brendan F Kennedy
- BRITElab, Harry Perkins Institute of Medical Research, QEII Medical Centre, Nedlands and Centre for Medical Research, The University of Western Australia, Perth, Western Australia, Australia; School of Electrical, Electronic and Computer Engineering, The University of Western Australia, Perth, Western Australia, Australia
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Serralheiro P, Soares A, Costa Almeida CM, Verde I. TGF-β1 in Vascular Wall Pathology: Unraveling Chronic Venous Insufficiency Pathophysiology. Int J Mol Sci 2017; 18:E2534. [PMID: 29186866 PMCID: PMC5751137 DOI: 10.3390/ijms18122534] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2017] [Revised: 11/21/2017] [Accepted: 11/22/2017] [Indexed: 12/21/2022] Open
Abstract
Chronic venous insufficiency and varicose veins occur commonly in affluent countries and are a socioeconomic burden. However, there remains a relative lack of knowledge about venous pathophysiology. Various theories have been suggested, yet the molecular sequence of events is poorly understood. Transforming growth factor-beta one (TGF-β1) is a highly complex polypeptide with multifunctional properties that has an active role during embryonic development, in adult organ physiology and in the pathophysiology of major diseases, including cancer and various autoimmune, fibrotic and cardiovascular diseases. Therefore, an emphasis on understanding its signaling pathways (and possible disruptions) will be an essential requirement for a better comprehension and management of specific diseases. This review aims at shedding more light on venous pathophysiology by describing the TGF-β1 structure, function, activation and signaling, and providing an overview of how this growth factor and disturbances in its signaling pathway may contribute to specific pathological processes concerning the vessel wall which, in turn, may have a role in chronic venous insufficiency.
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Affiliation(s)
- Pedro Serralheiro
- Norfolk and Norwich University Hospital, Colney Ln, Norwich NR47UY, UK.
- Faculty of Health Sciences, CICS-UBI-Health Sciences Research Centre, University of Beira Interior, Av. Infante D. Henrique, 6201-506 Covilhã, Portugal.
| | - Andreia Soares
- Norfolk and Norwich University Hospital, Colney Ln, Norwich NR47UY, UK.
| | - Carlos M Costa Almeida
- Department of General Surgery (C), Coimbra University Hospital Centre, Portugal; Faculty of Medicine, University of Coimbra, Praceta Prof. Mota Pinto, 3000-075 Coimbra, Portugal.
| | - Ignacio Verde
- Faculty of Health Sciences, CICS-UBI-Health Sciences Research Centre, University of Beira Interior, Av. Infante D. Henrique, 6201-506 Covilhã, Portugal.
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14
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Hayashi K, Hirayama E. Age-related changes of wall composition and collagen cross-linking in the rat carotid artery – In relation with arterial mechanics. J Mech Behav Biomed Mater 2017; 65:881-889. [DOI: 10.1016/j.jmbbm.2016.10.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Revised: 10/12/2016] [Accepted: 10/17/2016] [Indexed: 01/20/2023]
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15
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16
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Moronkeji K, Todd S, Dawidowska I, Barrett SD, Akhtar R. The role of subcutaneous tissue stiffness on microneedle performance in a representative in vitro model of skin. J Control Release 2016; 265:102-112. [PMID: 27838272 DOI: 10.1016/j.jconrel.2016.11.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Revised: 10/14/2016] [Accepted: 11/08/2016] [Indexed: 12/28/2022]
Abstract
There has been growing interest in the mechanical behaviour of skin due to the rapid development of microneedle devices for drug delivery applications into skin. However, most in vitro experimentation studies that are used to evaluate microneedle performance do not consider the biomechanical properties of skin or that of the subcutaneous layers. In this study, a representative experimental model of skin was developed which was comprised of subcutaneous and muscle mimics. Neonatal porcine skin from the abdominal and back regions was used, with gelatine gels of differing water content (67, 80, 88 and 96%) to represent the subcutaneous tissue, and a type of ballistic gelatine, Perma-Gel®, as a muscle mimic. Dynamic nanoindentation was used to characterize the mechanical properties of each of these layers. A custom-developed impact test rig was used to apply dense polymethylmethacrylate (PMMA) microneedles to the skin models in a controlled and repeatable way with quantification of the insertion force and velocity. Image analysis methods were used to measure penetration depth and area of the breach caused by microneedle penetration following staining and optical imaging. The nanoindentation tests demonstrated that the tissue mimics matched expected values for subcutaneous and muscle tissue, and that the compliance of the subcutaneous mimics increased linearly with water content. The abdominal skin was thinner and less stiff as compared to back skin. The maximum force decreased with gel water content in the abdominal skin but not in the back skin. Overall, larger and deeper perforations were found in the skin models with increasing water content. These data demonstrate the importance of subcutaneous tissue on microneedle performance and the need for representative skin models in microneedle technology development.
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Affiliation(s)
- K Moronkeji
- Centre for Materials and Structures, School of Engineering, University of Liverpool, L69 3GH, United Kingdom
| | - S Todd
- Renephra Ltd., MedTech Centre, Manchester Science Park, Pencroft Way, M15 6JJ, United Kingdom
| | - I Dawidowska
- Renephra Ltd., MedTech Centre, Manchester Science Park, Pencroft Way, M15 6JJ, United Kingdom
| | - S D Barrett
- Department of Physics, University of Liverpool, L69 7ZE, United Kingdom
| | - R Akhtar
- Centre for Materials and Structures, School of Engineering, University of Liverpool, L69 3GH, United Kingdom.
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17
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Frequency-modulated atomic force microscopy localises viscoelastic remodelling in the ageing sheep aorta. J Mech Behav Biomed Mater 2016; 64:10-7. [PMID: 27479890 PMCID: PMC5020410 DOI: 10.1016/j.jmbbm.2016.07.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 07/08/2016] [Accepted: 07/14/2016] [Indexed: 12/23/2022]
Abstract
Age-related aortic stiffening is associated with cardiovascular diseases such as heart failure. The mechanical functions of the main structural components of the aorta, such as collagen and elastin, are determined in part by their organisation at the micrometer length scale. With age and disease both components undergo aberrant remodelling, hence, there is a need for accurate characterisation of the biomechanical properties at this length scale. In this study we used a frequency-modulated atomic force microscopy (FM-AFM) technique on a model of ageing in female sheep aorta (young: ~18 months, old: >8 years) to measure the micromechanical properties of the medial layer of the ascending aorta. The novelty of our FM-AFM method, operated at 30 kHz, is that it is non-contact and can be performed on a conventional AFM using the ׳cantilever tune’ mode, with a spatial (areal) resolution of around 1.6 μm2. We found significant changes in the elastic and viscoelastic properties within the medial lamellar unit (elastic lamellae and adjacent inter-lamellar space) with age. In particular, there was an increase in elastic modulus (Young; geometric mean (geometric SD)=42.9 (2.26) kPa, Old=113.9 (2.57) kPa, P<0.0001), G′ and G″ (storage and loss modulus respectively) (Young; G′=14.3 (2.26) kPa, Old G′=38.0 (2.57) kPa, P<0.0001; Young; G″=14.5 (2.56) kPa, Old G″=32.8 (2.52) kPa, P<0.0001). The trends observed in the elastic properties with FM-AFM matched those we have previously found using scanning acoustic microscopy (SAM). The utility of the FM-AFM method is that it does not require custom AFM hardware and can be used to simultaneously determine the elastic and viscoelastic behaviour of a biological sample.
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18
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Keen AN, Shiels HA, Crossley DA. Cardiovascular function, compliance, and connective tissue remodeling in the turtle, Trachemys scripta, following thermal acclimation. Am J Physiol Regul Integr Comp Physiol 2016; 311:R133-43. [PMID: 27101300 PMCID: PMC4967230 DOI: 10.1152/ajpregu.00510.2015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 04/07/2016] [Indexed: 01/12/2023]
Abstract
Low temperature directly alters cardiovascular physiology in freshwater turtles, causing bradycardia, arterial hypotension, and a reduction in systemic blood pressure. At the same time, blood viscosity and systemic resistance increase, as does sensitivity to cardiac preload (e.g., via the Frank-Starling response). However, the long-term effects of these seasonal responses on the cardiovascular system are unclear. We acclimated red-eared slider turtles to a control temperature (25°C) or to chronic cold (5°C). To differentiate the direct effects of temperature from a cold-induced remodeling response, all measurements were conducted at the control temperature (25°C). In anesthetized turtles, cold acclimation reduced systemic resistance by 1.8-fold and increased systemic blood flow by 1.4-fold, resulting in a 2.3-fold higher right to left (R-L; net systemic) cardiac shunt flow and a 1.8-fold greater shunt fraction. Following a volume load by bolus injection of saline (calculated to increase stroke volume by 5-fold, ∼2.2% of total blood volume), systemic resistance was reduced while pulmonary blood flow and systemic pressure increased. An increased systemic blood flow meant the R-L cardiac shunt was further pronounced. In the isolated ventricle, passive stiffness was increased following cold acclimation with 4.2-fold greater collagen deposition in the myocardium. Histological sections of the major outflow arteries revealed a 1.4-fold higher elastin content in cold-acclimated animals. These results suggest that cold acclimation alters cardiac shunting patterns with an increased R-L shunt flow, achieved through reducing systemic resistance and increasing systemic blood flow. Furthermore, our data suggests that cold-induced cardiac remodeling may reduce the stress of high cardiac preload by increasing compliance of the vasculature and decreasing compliance of the ventricle. Together, these responses could compensate for reduced systolic function at low temperatures in the slider turtle.
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Affiliation(s)
- Adam N Keen
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom; and
| | - Holly A Shiels
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom; and
| | - Dane A Crossley
- Department of Biological Sciences, University of North Texas, Denton, Texas
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19
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Keen AN, Fenna AJ, McConnell JC, Sherratt MJ, Gardner P, Shiels HA. The Dynamic Nature of Hypertrophic and Fibrotic Remodeling of the Fish Ventricle. Front Physiol 2016; 6:427. [PMID: 26834645 PMCID: PMC4720793 DOI: 10.3389/fphys.2015.00427] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 12/27/2015] [Indexed: 11/13/2022] Open
Abstract
Chronic pressure or volume overload can cause the vertebrate heart to remodel. The hearts of fish remodel in response to seasonal temperature change. Here we focus on the passive properties of the fish heart. Building upon our previous work on thermal-remodeling of the rainbow trout ventricle, we hypothesized that chronic cooling would initiate fibrotic cardiac remodeling, with increased myocardial stiffness, similar to that seen with pathological hypertrophy in mammals. We hypothesized that, in contrast to pathological hypertrophy in mammals, the remodeling response in fish would be plastic and the opposite response would occur following chronic warming. Rainbow trout held at 10°C (control group) were chronically (>8 weeks) exposed to cooling (5°C) or warming (18°C). Chronic cold induced hypertrophy in the highly trabeculated inner layer of the fish heart, with a 41% increase in myocyte bundle cross-sectional area, and an up-regulation of hypertrophic marker genes. Cold acclimation also increased collagen deposition by 1.7-fold and caused an up-regulation of collagen promoting genes. In contrast, chronic warming reduced myocyte bundle cross-sectional area, expression of hypertrophic markers and collagen deposition. Functionally, the cold-induced fibrosis and hypertrophy were associated with increased passive stiffness of the whole ventricle and with increased micromechanical stiffness of tissue sections. The opposite occurred with chronic warming. These findings suggest chronic cooling in the trout heart invokes a hypertrophic phenotype with increased cardiac stiffness and fibrosis that are associated with pathological hypertrophy in the mammalian heart. The loss of collagen and increased compliance following warming is particularly interesting as it suggests fibrosis may oscillate seasonally in the fish heart, revealing a more dynamic nature than the fibrosis associated with dysfunction in mammals.
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Affiliation(s)
- Adam N Keen
- Faculty of Life Sciences, University of Manchester Manchester, UK
| | - Andrew J Fenna
- Faculty of Life Sciences, University of Manchester Manchester, UK
| | - James C McConnell
- Faculty of Medical and Human Sciences, Centre for Tissue Injury and Repair, University of Manchester Manchester, UK
| | - Michael J Sherratt
- Faculty of Medical and Human Sciences, Centre for Tissue Injury and Repair, University of Manchester Manchester, UK
| | - Peter Gardner
- School of Chemical Engineering and Analytical Science, Manchester Institute of Biotechnology, University of Manchester Manchester, UK
| | - Holly A Shiels
- Faculty of Life Sciences, University of Manchester Manchester, UK
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20
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McConnell JC, O'Connell OV, Brennan K, Weiping L, Howe M, Joseph L, Knight D, O'Cualain R, Lim Y, Leek A, Waddington R, Rogan J, Astley SM, Gandhi A, Kirwan CC, Sherratt MJ, Streuli CH. Increased peri-ductal collagen micro-organization may contribute to raised mammographic density. Breast Cancer Res 2016; 18:5. [PMID: 26747277 PMCID: PMC4706673 DOI: 10.1186/s13058-015-0664-2] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Accepted: 12/15/2015] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND High mammographic density is a therapeutically modifiable risk factor for breast cancer. Although mammographic density is correlated with the relative abundance of collagen-rich fibroglandular tissue, the causative mechanisms, associated structural remodelling and mechanical consequences remain poorly defined. In this study we have developed a new collaborative bedside-to-bench workflow to determine the relationship between mammographic density, collagen abundance and alignment, tissue stiffness and the expression of extracellular matrix organising proteins. METHODS Mammographic density was assessed in 22 post-menopausal women (aged 54-66 y). A radiologist and a pathologist identified and excised regions of elevated non-cancerous X-ray density prior to laboratory characterization. Collagen abundance was determined by both Masson's trichrome and Picrosirius red staining (which enhances collagen birefringence when viewed under polarised light). The structural specificity of these collagen visualisation methods was determined by comparing the relative birefringence and ultrastructure (visualised by atomic force microscopy) of unaligned collagen I fibrils in reconstituted gels with the highly aligned collagen fibrils in rat tail tendon. Localised collagen fibril organisation and stiffness was also evaluated in tissue sections by atomic force microscopy/spectroscopy and the abundance of key extracellular proteins was assessed using mass spectrometry. RESULTS Mammographic density was positively correlated with the abundance of aligned periductal fibrils rather than with the abundance of amorphous collagen. Compared with matched tissue resected from the breasts of low mammographic density patients, the highly birefringent tissue in mammographically dense breasts was both significantly stiffer and characterised by large (>80 μm long) fibrillar collagen bundles. Subsequent proteomic analyses not only confirmed the absence of collagen fibrosis in high mammographic density tissue, but additionally identified the up-regulation of periostin and collagen XVI (regulators of collagen fibril structure and architecture) as potential mediators of localised mechanical stiffness. CONCLUSIONS These preliminary data suggest that remodelling, and hence stiffening, of the existing stromal collagen microarchitecture promotes high mammographic density within the breast. In turn, this aberrant mechanical environment may trigger neoplasia-associated mechanotransduction pathways within the epithelial cell population.
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Affiliation(s)
- James C McConnell
- Centre for Tissue Injury & Repair, Faculty of Medical and Human Sciences, University of Manchester, Manchester, UK.
| | - Oliver V O'Connell
- Wellcome Trust Centre for Cell-Matrix Research and Manchester Breast Centre, Faculty of Life Sciences, University of Manchester, Manchester, UK.
| | - Keith Brennan
- Wellcome Trust Centre for Cell-Matrix Research and Manchester Breast Centre, Faculty of Life Sciences, University of Manchester, Manchester, UK.
| | - Lisa Weiping
- Wellcome Trust Centre for Cell-Matrix Research and Manchester Breast Centre, Faculty of Life Sciences, University of Manchester, Manchester, UK.
| | - Miles Howe
- University Hospital of South Manchester, Manchester, UK.
| | - Leena Joseph
- University Hospital of South Manchester, Manchester, UK.
| | - David Knight
- Wellcome Trust Centre for Cell-Matrix Research and Manchester Breast Centre, Faculty of Life Sciences, University of Manchester, Manchester, UK.
| | - Ronan O'Cualain
- Wellcome Trust Centre for Cell-Matrix Research and Manchester Breast Centre, Faculty of Life Sciences, University of Manchester, Manchester, UK. ronan.o'
| | - Yit Lim
- University Hospital of South Manchester, Manchester, UK.
| | - Angela Leek
- Manchester Cancer Research Centre Tissue Biobank, University of Manchester, Manchester, UK.
| | - Rachael Waddington
- Manchester Cancer Research Centre Tissue Biobank, University of Manchester, Manchester, UK.
| | - Jane Rogan
- Manchester Cancer Research Centre Tissue Biobank, University of Manchester, Manchester, UK.
| | - Susan M Astley
- Centre for Imaging Sciences, Institute of Population Health, Faculty of Medical and Human Sciences, University of Manchester, Manchester, UK.
| | - Ashu Gandhi
- University Hospital of South Manchester, Manchester, UK.
| | - Cliona C Kirwan
- Institute of Cancer Sciences, Manchester Academic Health Sciences Centre, University Hospital of South Manchester, University of Manchester, Manchester, UK.
| | - Michael J Sherratt
- Centre for Tissue Injury & Repair, Faculty of Medical and Human Sciences, University of Manchester, Manchester, UK.
| | - Charles H Streuli
- Wellcome Trust Centre for Cell-Matrix Research and Manchester Breast Centre, Faculty of Life Sciences, University of Manchester, Manchester, UK.
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21
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22
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Walton LA, Bradley RS, Withers PJ, Newton VL, Watson REB, Austin C, Sherratt MJ. Morphological Characterisation of Unstained and Intact Tissue Micro-architecture by X-ray Computed Micro- and Nano-Tomography. Sci Rep 2015; 5:10074. [PMID: 25975937 PMCID: PMC4650804 DOI: 10.1038/srep10074] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Accepted: 03/27/2015] [Indexed: 02/08/2023] Open
Abstract
Characterisation and quantification of tissue structures is limited by sectioning-induced artefacts and by the difficulties of visualising and segmenting 3D volumes. Here we demonstrate that, even in the absence of X-ray contrast agents, X-ray computed microtomography (microCT) and nanotomography (nanoCT) can circumvent these problems by rapidly resolving compositionally discrete 3D tissue regions (such as the collagen-rich adventitia and elastin-rich lamellae in intact rat arteries) which in turn can be segmented due to their different X-ray opacities and morphologies. We then establish, using X-ray tomograms of both unpressurised and pressurised arteries that intra-luminal pressure not only increases lumen cross-sectional area and straightens medial elastic lamellae but also induces profound remodelling of the adventitial layer. Finally we apply microCT to another human organ (skin) to visualise the cell-rich epidermis and extracellular matrix-rich dermis and to show that conventional histological and immunohistochemical staining protocols are compatible with prior X-ray exposure. As a consequence we suggest that microCT could be combined with optical microscopy to characterise the 3D structure and composition of archival paraffin embedded biological materials and of mechanically stressed dynamic tissues such as the heart, lungs and tendons.
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Affiliation(s)
| | | | | | - Victoria L. Newton
- Institute of Inflammation and Repair, University of Manchester, Manchester, United Kingdom
| | - Rachel E. B. Watson
- Institute of Inflammation and Repair, University of Manchester, Manchester, United Kingdom
| | - Clare Austin
- Institute of Cardiovascular Sciences
- Faculty of Health and Social Care, Edge Hill University, Ormskirk, United Kingdom
| | - Michael J. Sherratt
- Institute of Inflammation and Repair, University of Manchester, Manchester, United Kingdom
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23
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Babaei B, Davarian A, Pryse KM, Elson EL, Genin GM. Efficient and optimized identification of generalized Maxwell viscoelastic relaxation spectra. J Mech Behav Biomed Mater 2015; 55:32-41. [PMID: 26523785 PMCID: PMC5668653 DOI: 10.1016/j.jmbbm.2015.10.008] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2015] [Revised: 10/09/2015] [Accepted: 10/12/2015] [Indexed: 12/19/2022]
Abstract
Viscoelastic relaxation spectra are essential for predicting and interpreting the mechanical responses of materials and structures. For biological tissues, these spectra must usually be estimated from viscoelastic relaxation tests. Interpreting viscoelastic relaxation tests is challenging because the inverse problem is expensive computationally. We present here an efficient algorithm that enables rapid identification of viscoelastic relaxation spectra. The algorithm was tested against trial data to characterize its robustness and identify its limitations and strengths. The algorithm was then applied to identify the viscoelastic response of reconstituted collagen, revealing an extensive distribution of viscoelastic time constants.
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Affiliation(s)
- Behzad Babaei
- Department of Mechanical Engineering & Materials Science, Washington University in St. Louis, St. Louis, MO, USA.
| | - Ali Davarian
- Department of Biochemistry & Molecular Biophysics, School of Medicine, Washington University in St. Louis, St. Louis, MO, USA; Ischemic Disorders Research Center, Golestan University of Medical Sciences, Gorgan, Iran.
| | - Kenneth M Pryse
- Department of Biochemistry & Molecular Biophysics, School of Medicine, Washington University in St. Louis, St. Louis, MO, USA.
| | - Elliot L Elson
- Department of Biochemistry & Molecular Biophysics, School of Medicine, Washington University in St. Louis, St. Louis, MO, USA.
| | - Guy M Genin
- Department of Mechanical Engineering & Materials Science, Washington University in St. Louis, St. Louis, MO, USA.
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24
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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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25
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Localized micro- and nano-scale remodelling in the diabetic aorta. Acta Biomater 2014; 10:4843-4851. [PMID: 25014552 PMCID: PMC4199142 DOI: 10.1016/j.actbio.2014.07.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Revised: 05/22/2014] [Accepted: 07/01/2014] [Indexed: 11/20/2022]
Abstract
Diabetes is strongly associated with cardiovascular disease, but the mechanisms, structural and biomechanical consequences of aberrant blood vessel remodelling remain poorly defined. Using an experimental (streptozotocin, STZ) rat model of diabetes, we hypothesized that diabetes enhances extracellular protease activity in the aorta and induces morphological, compositional and localized micromechanical tissue remodelling. We found that the medial aortic layer underwent significant thickening in diabetic animals but without significant changes in collagen or elastin (abundance). Scanning acoustic microscopy demonstrated that such tissue remodelling was associated with a significant decrease in acoustic wave speed (an indicator of reduced material stiffness) in the inter-lamellar spaces of the vessel wall. This index of decreased stiffness was also linked to increased extracellular protease activity (assessed by semi-quantitative in situ gelatin zymography). Such a proteolytically active environment may affect the macromolecular structure of long-lived extracellular matrix molecules. To test this hypothesis, we also characterized the effects of diabetes on the ultrastructure of an important elastic fibre component: the fibrillin microfibril. Using size exclusion chromatography and atomic force microscopy, we isolated and imaged microfibrils from both healthy and diabetic aortas. Microfibrils derived from diabetic tissues were fragmented, morphologically disrupted and weakened (as assessed following molecular combing). These structural and functional abnormalities were not replicated by in vitro glycation. Our data suggest that proteolysis may be a key driver of localized mechanical change in the inter-lamellar space of diabetic rat aortas and that structural proteins (such as fibrillin microfbrils) may be biomarkers of diabetes induced damage.
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26
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Ohanian J, Liao A, Forman SP, Ohanian V. Age-related remodeling of small arteries is accompanied by increased sphingomyelinase activity and accumulation of long-chain ceramides. Physiol Rep 2014; 2:2/5/e12015. [PMID: 24872355 PMCID: PMC4098743 DOI: 10.14814/phy2.12015] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The structure and function of large arteries alters with age leading to increased risk of cardiovascular disease. Age‐related large artery remodeling and arteriosclerosis is associated with increased collagen deposition, inflammation, and endothelial dysfunction. Bioactive sphingolipids are known to regulate these processes, and are also involved in aging and cellular senescence. However, less is known about age‐associated alterations in small artery morphology and function or whether changes in arterial sphingolipids occur in aging. We show that mesenteric small arteries from old sheep have increased lumen diameter and media thickness without a change in media to lumen ratio, indicative of outward hypertrophic remodeling. This remodeling occurred without overt changes in blood pressure or pulse pressure indicating it was a consequence of aging per se. There was no age‐associated change in mechanical properties of the arteries despite an increase in total collagen content and deposition of collagen in a thickened intima layer in arteries from old animals. Analysis of the sphingolipid profile showed an increase in long‐chain ceramide (C14–C20), but no change in the levels of sphingosine or sphingosine‐1‐phosphate in arteries from old compared to young animals. This was accompanied by a parallel increase in acid and neutral sphingomyelinase activity in old arteries compared to young. This study demonstrates remodeling of small arteries during aging that is accompanied by accumulation of long‐chain ceramides. This suggests that sphingolipids may be important mediators of vascular aging. In this study, we have investigated remodeling of small arteries in a large animal model of aging, the sheep. We show that there is age‐related formation of neointima and increased collagen deposition that is accompanied by changes in sphingolipid metabolism resulting in ceramide accumulation in the tissues. These are the first data implicating sphingolipids as important mediators of vascular aging in small arteries. Given that aging is a major risk factor for cardiovascular disease, our study opens a new area for further research into the mechanisms that underlie vascular remodeling in aging.
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Affiliation(s)
- Jacqueline Ohanian
- Institute of Cardiovascular Sciences, Manchester Academic Health Sciences Centre, University of Manchester, Manchester, UK
| | - Aiyin Liao
- Institute of Cardiovascular Sciences, Manchester Academic Health Sciences Centre, University of Manchester, Manchester, UK
| | - Simon P Forman
- Institute of Cardiovascular Sciences, Manchester Academic Health Sciences Centre, University of Manchester, Manchester, UK
| | - Vasken Ohanian
- Institute of Cardiovascular Sciences, Manchester Academic Health Sciences Centre, University of Manchester, Manchester, UK
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27
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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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Clarke LE, McConnell JC, Sherratt MJ, Derby B, Richardson SM, Hoyland JA. Growth differentiation factor 6 and transforming growth factor-beta differentially mediate mesenchymal stem cell differentiation, composition, and micromechanical properties of nucleus pulposus constructs. Arthritis Res Ther 2014; 16:R67. [PMID: 24618041 PMCID: PMC4060243 DOI: 10.1186/ar4505] [Citation(s) in RCA: 108] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Accepted: 02/25/2014] [Indexed: 02/08/2023] Open
Abstract
INTRODUCTION Currently, there is huge research focus on the development of novel cell-based regeneration and tissue-engineering therapies for the treatment of intervertebral disc degeneration and the associated back pain. Both bone marrow-derived (BM) mesenchymal stem cells (MSCs) and adipose-derived MSCs (AD-MSCs) are proposed as suitable cells for such therapies. However, currently no consensus exists as to the optimum growth factor needed to drive differentiation to a nucleus pulposus (NP)-like phenotype. The aim of this study was to investigate the effect of growth differentiation factor-6 (GDF6), compared with other transforming growth factor (TGF) superfamily members, on discogenic differentiation of MSCs, the matrix composition, and micromechanics of engineered NP tissue constructs. METHODS Patient-matched human AD-MSCs and BM-MSCs were seeded into type I collagen hydrogels and cultured in differentiating media supplemented with TGF-β3, GDF5, or GDF6. After 14 days, quantitative polymerase chain reaction analysis of chondrogenic and novel NP marker genes and sulfated glycosaminoglycan (sGAG) content of the construct and media components were measured. Additionally, construct micromechanics were analyzed by using scanning acoustic microscopy (SAM). RESULTS GDF6 stimulation of BM-MSCs and AD-MSCs resulted in a significant increase in expression of novel NP marker genes, a higher aggrecan-to-type II collagen gene expression ratio, and higher sGAG production compared with TGF-β or GDF5 stimulation. These effects were greater in AD-MSCs than in BM-MSCs. Furthermore, the acoustic-wave speed measured by using SAM, and therefore tissue stiffness, was lowest in GDF6-stiumlated AD-MSC constructs. CONCLUSIONS The data suggest that GDF6 stimulation of AD-MSCs induces differentiation to an NP-like phenotype and results in a more proteoglycan-rich matrix. Micromechanical analysis shows that the GDF6-treated AD-MSCs have a less-stiff matrix composition, suggesting that the growth factor is inducing a matrix that is more akin to the native NP-like tissue. Thus, this cell and growth-factor combination may be the ideal choice for cell-based intervertebral disc (IVD)-regeneration therapies.
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Akhtar R. In vitro characterisation of arterial stiffening: From the macro- to the nano-scale. Artery Res 2014. [DOI: 10.1016/j.artres.2014.01.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
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Busnadiego O, González-Santamaría J, Lagares D, Guinea-Viniegra J, Pichol-Thievend C, Muller L, Rodríguez-Pascual F. LOXL4 is induced by transforming growth factor β1 through Smad and JunB/Fra2 and contributes to vascular matrix remodeling. Mol Cell Biol 2013; 33:2388-401. [PMID: 23572561 PMCID: PMC3700097 DOI: 10.1128/mcb.00036-13] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Accepted: 04/01/2013] [Indexed: 12/29/2022] Open
Abstract
Transforming growth factor β1 (TGF-β1) is a pleiotropic factor involved in the regulation of extracellular matrix (ECM) synthesis and remodeling. In search for novel genes mediating the action of TGF-β1 on vascular ECM, we identified the member of the lysyl oxidase family of matrix-remodeling enzymes, lysyl oxidase-like 4 (LOXL4), as a direct target of TGF-β1 in aortic endothelial cells, and we dissected the molecular mechanism of its induction. Deletion mapping and mutagenesis analysis of the LOXL4 promoter demonstrated the absolute requirement of a distal enhancer containing an activator protein 1 (AP-1) site and a Smad binding element for TGF-β1 to induce LOXL4 expression. Functional cooperation between Smad proteins and the AP-1 complex composed of JunB/Fra2 accounted for the action of TGF-β1, which involved the extracellular signal-regulated kinase (ERK)-dependent phosphorylation of Fra2. We furthermore provide evidence that LOXL4 was extracellularly secreted and significantly contributed to ECM deposition and assembly. These results suggest that TGF-β1-dependent expression of LOXL4 plays a role in vascular ECM homeostasis, contributing to vascular processes associated with ECM remodeling and fibrosis.
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Affiliation(s)
- Oscar Busnadiego
- Centro de Biología Molecular Severo Ochoa and Laboratorio Mixto Consejo Superior de Investigaciones Científicas/Fundación Renal Iñigo Alvarez de Toledo, Madrid, Spain
| | - José González-Santamaría
- Centro de Biología Molecular Severo Ochoa and Laboratorio Mixto Consejo Superior de Investigaciones Científicas/Fundación Renal Iñigo Alvarez de Toledo, Madrid, Spain
| | - David Lagares
- Fundación Banco Bilbao Vizcaya-CNIO Cancer Cell Biology Program, Centro Nacional de Investigaciones Oncológicas, Madrid, Spain
| | - Juan Guinea-Viniegra
- College de France, Center for Interdisciplinary Research in Biology, Paris, France
| | | | - Laurent Muller
- Centro de Biología Molecular Severo Ochoa and Laboratorio Mixto Consejo Superior de Investigaciones Científicas/Fundación Renal Iñigo Alvarez de Toledo, Madrid, Spain
| | - Fernando Rodríguez-Pascual
- Centro de Biología Molecular Severo Ochoa and Laboratorio Mixto Consejo Superior de Investigaciones Científicas/Fundación Renal Iñigo Alvarez de Toledo, Madrid, Spain
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Tonge TK, Atlan LS, Voo LM, Nguyen TD. Full-field bulge test for planar anisotropic tissues: part I--experimental methods applied to human skin tissue. Acta Biomater 2013; 9:5913-25. [PMID: 23261928 DOI: 10.1016/j.actbio.2012.11.035] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Revised: 10/27/2012] [Accepted: 11/29/2012] [Indexed: 10/27/2022]
Abstract
The nonlinear anisotropic properties of human skin tissue were investigated using bulge testing. Full-field displacement data were obtained during testing of human skin tissues procured from the lower back of post-mortem human subjects using 3-D digital image correlation. To measure anisotropy, the dominant fiber direction of the tissue was determined from the deformed geometry of the specimen. Local strains and stress resultants were calculated along both the dominant fiber direction and the perpendicular direction. Variation in anisotropy and stiffness was observed between specimens. The use of stress resultants rather than the membrane stress approximation accounted for bending effects, which are significant for a thick nonlinear tissue. Of the six specimens tested, it was observed that specimens from older donors exhibited a stiffer and more isotropic response than those from younger donors. It was seen that the mechanical response of the tissue was negligibly impacted by preconditioning or the ambient humidity. The methods presented in this work for skin tissue are sufficiently general to be applied to other planar tissues, such as pericardium, gastrointestinal tissue, and fetal membranes. The stress resultant-stretch relations will be used in a companion paper to obtain material parameters for a nonlinear anisotropic hyperelastic model.
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Beshtawi IM, Akhtar R, Hillarby MC, O'Donnell C, Zhao X, Brahma A, Carley F, Derby B, Radhakrishnan H. Scanning acoustic microscopy for mapping the microelastic properties of human corneal tissue. Curr Eye Res 2013; 38:437-44. [PMID: 23402595 DOI: 10.3109/02713683.2012.753094] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
PURPOSE To assess the feasibility of applying scanning acoustic microscopy (SAM) on UV cross-linked corneal tissue for mapping and analyzing its biomechanical properties. MATERIALS AND METHODS Five corneal pairs (10 corneas) were used. In each pair, one cornea was cross-linked (epithelium removed, riboflavin application for 45 min and UVA irradiation for 30 min) and the contralateral control cornea was epithelial debrided and treated only with riboflavin for 45 min. Histological sections were prepared and their mechanical properties were examined using SAM. A line profile technique and 2D analysis was used to analyze the mechanical properties of the corneas. Then the corneal paraformaldehyde and unfixed sections were examined histologically using hematoxylin and eosin (H&E) staining. RESULTS In the frozen fresh corneal tissue, the speed of sound of the treated corneas was 1672.5 ± 36.9 ms(-1), while it was 1584.2 ± 25.9 ms(-1) in the untreated corneas. In the paraformaldehyde fixed corneal tissue, the speed of sound of the treated corneas was 1863.0 ± 12.7 ms(-1), while it was 1739.5 ± 30.4 ms(-1) in the untreated corneas. The images obtained from the SAM technique corresponded well with the histological images obtained with H&E staining. CONCLUSION SAM is a novel tool for examining corneal tissue with a high spatial resolution, providing both histological and mechanical data.
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Affiliation(s)
- Ithar M Beshtawi
- Carys Bannister Building, Faculty of Life Sciences, The University of Manchester, Manchester, UK
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Sherratt MJ. Age-Related Tissue Stiffening: Cause and Effect. Adv Wound Care (New Rochelle) 2013; 2:11-17. [PMID: 24527318 DOI: 10.1089/wound.2011.0328] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2011] [Indexed: 11/12/2022] Open
Abstract
SIGNIFICANCE Tissue elasticity is severely compromised in aging skin, lungs, and blood vessels. In the vascular and pulmonary systems, respectively, loss of mechanical function is linked to hypertension, which in turn is a risk factor for heart and renal failure, stroke, and aortic aneurysms, and to an increased risk of mortality as a result of acute lung infections. RECENT ADVANCES Although cellular mechanisms were thought to play an important role in mediating tissue aging, the reason for the apparent sensitivity of elastic fibers to age-related degradation remained unclear. We have recently demonstrated that compared with type I collagen, a key component of the elastic fiber system, the cysteine-rich fibrillin microfibril is highly susceptible to direct UV exposure in a cell-free environment. We hypothesized therefore that, as a consequence of both their remarkable longevity and cysteine-rich composition, many elastic fiber-associated components will be susceptible to the accumulation of damage by both direct UV radiation and reactive oxygen species-mediated oxidation. CRITICAL ISSUES Although elastic fiber remodeling is a common feature of aging dynamic tissues, the inaccessibility of most human tissues has hampered attempts to define the molecular causes. CLINICAL CARE RELEVANCE Although, currently, the localized repair of damaged elastic fibers may be effected by the topical application of retinoids and some cosmetic products, future studies may extend the application of systemic transforming growth factor β antagonists, which can prevent cardiovascular remodeling in murine Marfan syndrome, to aging humans. Acellular mechanisms may be key mediators of elastic fiber remodeling and hence age-related tissue stiffening.
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Affiliation(s)
- Michael J. Sherratt
- Manchester Academic Health Sciences Centre and School of Regenerative Biomedicine, Faculty of Medical and Human Sciences, The University of Manchester, Manchester, United Kingdom
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Hausman N, Martin J, Taggart MJ, Austin C. Age-related changes in the contractile and passive arterial properties of murine mesenteric small arteries are altered by caveolin-1 knockout. J Cell Mol Med 2012; 16:1720-30. [PMID: 21973085 PMCID: PMC3822685 DOI: 10.1111/j.1582-4934.2011.01457.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2011] [Accepted: 09/05/2011] [Indexed: 01/19/2023] Open
Abstract
Caveolin-1, an integral protein of caveolae, is associated with multiple cardiovascular signalling pathways. Caveolin-1 knockout (KO) mice have a reduced lifespan. As changes in artery structure and function are associated with ageing we have investigated the role of caveolin-1 ablation on age-related changes of small artery contractility and passive mechanical properties. Mesenteric small arteries isolated from 3 and 12-month wild-type (WT) and caveolin-1 KO mice were mounted on a pressure myograph and changes in passive and functional arterial properties were continuously monitored. In WT mice ageing was associated with a reduction in arterial contractility to noradrenaline which was reversed by inhibition of nitric oxide synthase with L-NNA. Similarly, in 3-month-old mice, caveolin-1 KO reduced contractility to noradrenaline by an L-NNA-sensitive mechanism. However, ageing in caveolin-1 KO mice was not associated with any further change in contractility. In WT mice ageing was associated with an increased passive arterial diameter and cross-sectional area (CSA), consistent with outward remodelling of the arterial wall, and a reduced arterial distensibility. Caveolin-1 ablation at 3 months of age resulted in similar changes in passive arterial properties to those observed with ageing in WT animals. However, ageing in caveolin-1 KO mice resulted in a reduced arterial CSA indicating different effects on passive structural characteristics from that observed in WT mice. Thus, caveolin-1 mice show abnormalities of small mesenteric artery function and passive mechanical characteristics indicative of premature vascular ageing. Moreover, caveolin-1 ablation modulates the age-related changes usually observed in mesenteric arteries of WT mice.
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Affiliation(s)
- Natasha Hausman
- Cardiovascular Research Group, University of ManchesterManchester, UK
| | - Julie Martin
- Institute of Cellular Medicine, Newcastle UniversityNewcastle-upon-Tyne, UK
| | - Michael J Taggart
- Institute of Cellular Medicine, Newcastle UniversityNewcastle-upon-Tyne, UK
| | - Clare Austin
- Cardiovascular Research Group, University of ManchesterManchester, UK
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López-Andrés N, Rousseau A, Akhtar R, Calvier L, Iñigo C, Labat C, Zhao X, Cruickshank K, Díez J, Zannad F, Lacolley P, Rossignol P. Cardiotrophin 1 is involved in cardiac, vascular, and renal fibrosis and dysfunction. Hypertension 2012; 60:563-73. [PMID: 22733458 DOI: 10.1161/hypertensionaha.112.194407] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Cardiotrophin 1 (CT-1), a cytokine belonging to the interleukin 6 family, is increased in hypertension and in heart failure. We aimed to study the precise role of CT-1 on cardiac, vascular, and renal function; morphology; and remodeling in early stages without hypertension. CT-1 (20 μg/kg per day) or vehicle was administrated to Wistar rats for 6 weeks. Cardiac and vascular functions were analyzed in vivo using M-mode echocardiography, Doppler, and echo tracking device and ex vivo using a scanning acoustic microscopy method. Cardiovascular and renal histomorphology were measured by immunohistochemistry, RT-PCR, and Western blot. Kidney functional properties were assessed by serum creatinine and neutrophile gelatinase-associated lipocalin and microalbuminuria/creatininuria ratio. Without alterations in blood pressure levels, CT-1 treatment increased left ventricular volumes, reduced fractional shortening and ejection fraction, and induced myocardial dilatation and myocardial fibrosis. In the carotid artery of CT-1-treated rats, the circumferential wall stress-incremental elastic modulus curve was shifted leftward, and the acoustic speed of sound in the aorta was augmented, indicating increased arterial stiffness. Vascular media thickness, collagen, and fibronectin content were increased by CT-1 treatment. CT-1-treated rats presented unaltered serum creatinine concentrations but increased urinary and serum neutrophile gelatinase-associated lipocalin and microalbuminuria/creatininuria ratio. This paralleled a glomerular and tubulointerstitial fibrosis accompanied by renal epithelial-mesenchymal transition. CT-1 is a new potent fibrotic agent in heart, vessels, and kidney able to induce cardiovascular-renal dysfunction independent from blood pressure. Thus, CT-1 could be a new target simultaneously integrating alterations of heart, vessels, and kidney in early stages of heart failure.
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Affiliation(s)
- Natalia López-Andrés
- Institut National de la Santé et de la Recherche Médicale U961, Faculty of Medicine, Vandoeuvre-lès-Nancy, France.
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Zhao X, Akhtar R, Nijenhuis N, Wilkinson SJ, Murphy L, Ballestrem C, Sherratt MJ, Watson RE, Derby B. Multi-layer phase analysis: quantifying the elastic properties of soft tissues and live cells with ultra-high-frequency scanning acoustic microscopy. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2012; 59:610-20. [PMID: 22547273 PMCID: PMC3492756 DOI: 10.1109/tuffc.2012.2240] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Scanning acoustic microscopy is potentially a powerful tool for characterizing the elastic properties of soft biological tissues and cells. In this paper, we present a method, multi-layer phase analysis (MLPA), which can be used to extract local speed of sound values, for both thin tissue sections mounted on glass slides and cultured cells grown on cell culture plastic, with a resolution close to 1 μm. The method exploits the phase information that is preserved in the interference between the acoustic wave reflected from the substrate surface and internal reflections from the acoustic lens. In practice, a stack of acoustic images are captured beginning with the acoustic focal point 4 μm above the substrate surface and moving down in 0.1-μm increments. Scanning parameters, such as acoustic wave frequency and gate position, were adjusted to obtain optimal phase and lateral resolution. The data were processed offline to extract the phase information with the contribution of any inclination in the substrate removed before the calculation of sound speed. Here, we apply this approach to both skin sections and fibroblast cells, and compare our data with the V(f) (voltage versus frequency) method that has previously been used for characterization of soft tissues and cells. Compared with the V(f) method, the MPLA method not only reduces signal noise but can be implemented without making a priori assumptions with regards to tissue or cell parameters.
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Affiliation(s)
- Xuegen Zhao
- School of Materials, The University of Manchester UK ()
| | - Riaz Akhtar
- School of Materials and Cardiovascular Sciences Research Group (Manchester Academic Health Science Centre), The University of Manchester UK
| | - Nadja Nijenhuis
- Faculty of Life Sciences, Michael Smith Building, Oxford Road,Manchester,M13 9PT, The University of Manchester UK ()
| | | | - Lilli Murphy
- School of Materials, The University of Manchester UK ()
| | - Christoph Ballestrem
- Faculty of Life Sciences, Michael Smith Building, Oxford Road,Manchester,M13 9PT, The University of Manchester UK ()
| | - Michael. J. Sherratt
- Faculty of Medical & Human Sciences, Manchester Academic Health Science Centre, The University of Manchester UK ()
| | - Rachel E.B. Watson
- Faculty of Medical & Human Sciences, Manchester Academic Health Science Centre,, The University of Manchester UK ()
| | - Brian Derby
- School of Materials, The University of Manchester, UK ()
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Hemmasizadeh A, Darvish K, Autieri M. Characterization of changes to the mechanical properties of arteries due to cold storage using nanoindentation tests. Ann Biomed Eng 2012; 40:1434-42. [PMID: 22230967 DOI: 10.1007/s10439-011-0506-z] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2011] [Accepted: 12/28/2011] [Indexed: 11/24/2022]
Abstract
Understanding the effect of cold storage on arterial tissues is essential in various clinical and experimental practices. Cold storage techniques could significantly affect the post-cryosurgical or post-cryopreservation mechanical behavior of arteries. Previously, arteries were considered homogenous and elastic and the changes in material properties due to cold storage were inconclusive. In this study, using a custom-made nanoindentation device, changes to the local viscoelastic properties of porcine thoracic aorta wall due to three common storage temperatures (+4, -20, and -80 °C) within 24 h, 48 h, 1 week, and 3 weeks were characterized. The changes to both elastic and relaxation behaviors were investigated considering the multilayer, heterogeneous nature of the aortic wall. The results showed that the average instantaneous Young's modulus (E) of +4 °C storage samples decreased while their permanent average relaxation amplitude (G (∞)) increased and after 48 h these changes became significant (10 and 13% for E and G (∞), respectively). Generally, in freezer storage, E increased and G (∞) showed no significant change. In prolonged preservation (>1 week), the results of -20 °C showed significant increase in E (20% after 3 weeks) while this increase for -80 °C was not significant, making it a better choice for tissue cold storage applications.
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Affiliation(s)
- Ali Hemmasizadeh
- Department of Mechanical Engineering, College of Engineering, Temple University, 1947 N. 12th Street, Philadelphia, PA 19122, USA
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