Comparison of rat and mouse pulmonary tissue  mechanical properties and histology

The present study compares the dynamic mechanical properties and the contents of collagen and elastic fibers (oxytalan + elaunin + fully developed elastic fibers) of mice and rat lung strips. Resistance, elastance (E), and hysteresivity (η) were obtained during sinusoidal oscillations. The relative amounts of blood vessel, bronchial, and alveolar walls, as well as the mean alveolar diameter were determined. In both species, resistance had a negative and E a positive dependence on frequency, whereas η remained unchanged. Mice showed higher E and lower η than rats. Although collagen and elastic fiber contents were similar in both groups, mice had more oxytalan and less elaunin and fully developed elastic fibers than rats. Rats showed less alveolar and more blood vessel walls and higher mean alveolar diameter than mice. In conclusion, mice and rats present distinct tissue mechanical properties, which are accompanied by specific extracellular fiber composition.

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Lung tissue mechanics and extracellular matrix composition in a murine model of silicosis

Journal of Applied Physiology ◽

10.1152/jappl.2001.90.4.1400 ◽

2001 ◽

Vol 90 (4) ◽

pp. 1400-1406 ◽

Cited By ~ 47

Author(s):

Débora S. Faffe ◽

Gabriela H. Silva ◽

Pedro M. P. Kurtz ◽

Elnara M. Negri ◽

Vera L. Capelozzi ◽

...

Keyword(s):

Mechanical Properties ◽

Extracellular Matrix ◽

Lung Tissue ◽

Elastic System ◽

Elastic Fiber ◽

Dynamic Mechanical Properties ◽

Tissue Mechanics ◽

Matrix Composition ◽

Elastic Fibers ◽

Oxytalan Fibers

The dynamic mechanical properties of lung tissue and its contents of collagen and elastic fibers were studied in strips prepared from mice instilled intratracheally with saline (C) or silica [15 (S15) and 30 days (S30) after instillation]. Resistance, elastance, and hysteresivity were studied during oscillations at different frequencies on S15 and S30. Elastance increased from C to silica groups but was similar between S15 and S30. Resistance was augmented from C to S15 and S30 and was greater in S30 than in S15 at higher frequencies. Hysteresivity was higher in S30 than in C and S15. Silica groups presented a greater amount of collagen than did C. Elastic fiber content increased progressively along time. This increment was related to the higher amount of oxytalan fibers at 15 and 30 days, whereas elaunin and fully developed elastic fibers were augmented only at 30 days. Silicosis led not only to pulmonary fibrosis but also to fibroelastosis, thus assigning a major role to the elastic system in the silicotic lung.

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Functionally Distinct Tendons From Elastin Haploinsufficient Mice Exhibit Mild Stiffening and Tendon-Specific Structural Alteration

Journal of Biomechanical Engineering ◽

10.1115/1.4037932 ◽

2017 ◽

Vol 139 (11) ◽

Cited By ~ 14

Author(s):

Jeremy D. Eekhoff ◽

Fei Fang ◽

Lindsey G. Kahan ◽

Gabriela Espinosa ◽

Austin J. Cocciolone ◽

...

Keyword(s):

Mechanical Properties ◽

Elastic Fiber ◽

Mechanical Effect ◽

Elastic Fibers ◽

Minor Role ◽

Tendon Mechanics ◽

Different Types ◽

A Minor ◽

Collagen Alignment

Elastic fibers are present in low quantities in tendon, where they are located both within fascicles near tenocytes and more broadly in the interfascicular matrix (IFM). While elastic fibers have long been known to be significant in the mechanics of elastin-rich tissue (i.e., vasculature, skin, lungs), recent studies have suggested a mechanical role for elastic fibers in tendons that is dependent on specific tendon function. However, the exact contribution of elastin to properties of different types of tendons (e.g., positional, energy-storing) remains unknown. Therefore, this study purposed to evaluate the role of elastin in the mechanical properties and collagen alignment of functionally distinct supraspinatus tendons (SSTs) and Achilles tendons (ATs) from elastin haploinsufficient (HET) and wild type (WT) mice. Despite the significant decrease in elastin in HET tendons, a slight increase in linear stiffness of both tendons was the only significant mechanical effect of elastin haploinsufficiency. Additionally, there were significant changes in collagen nanostructure and subtle alteration to collagen alignment in the AT but not the SST. Hence, elastin may play only a minor role in tendon mechanical properties. Alternatively, larger changes to tendon mechanics may have been mitigated by developmental compensation of HET tendons and/or the role of elastic fibers may be less prominent in smaller mouse tendons compared to the larger bovine and human tendons evaluated in previous studies. Further research will be necessary to fully elucidate the influence of various elastic fiber components on structure–function relationships in functionally distinct tendons.

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An increase of elastic tissue fibers in blood vessel walls of placental stem villi and differences in the thickness of blood vessel walls in third trimester pre-eclampsia pregnancies

Open Medicine ◽

10.2478/s11536-009-0025-6 ◽

2010 ◽

Vol 5 (2) ◽

pp. 227-234 ◽

Cited By ~ 1

Author(s):

Özlem Baran ◽

Mehmet Tuncer ◽

Yusuf Nergiz ◽

Murat Akkuş ◽

Mahmut Erdemoğlu ◽

...

Keyword(s):

Blood Vessel ◽

Blood Vessels ◽

Elastic Fiber ◽

Elastic Fibers ◽

Elastic Tissue ◽

Fiber System ◽

Tissue Samples ◽

Terminal Villi ◽

Vessel Walls ◽

Stem Villi

AbstractThis study has goals of examining whether pre-eclampsia may lead to an increase of elastic tissue fibers in blood vessel walls of placental stem villi or whether there are differences in the thickness of blood vessel walls within these villi when compared to normotensive pregnant women. Non-infarcted placental tissue samples from 28 participants with uncomplicated pregnancies and 26 patients with pre-eclampsia were obtained. After routine histological procedures, the sections were processed either for conventional Verhoeff staining for the demonstration of elastic fiber system. Paraffine sections from placenta biopsies prepared for light microscopic examination were gathered. In uncomplicated pregnancies, terminal villi blood vessels were observed with no stained elastic tissue fibers in most areas. In the pre-eclampsia pregnancy of human placenta, the elastic fibers significiantly increased in terminal villi blood vessel walls which were dark in color, using Verhoeff’s tissue stain, when comparing with the uncomplicated pregnancy group. Our results indicate that an increase of elastic tissue fibers in blood vessels of placental stem villus and terminal villi, and also an increase of wall thickness during pre-eclampsia.

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IUGR decreases elastin mRNA expression in the developing rat lung and alters elastin content and lung compliance in the mature rat lung

Physiological Genomics ◽

10.1152/physiolgenomics.00183.2010 ◽

2011 ◽

Vol 43 (9) ◽

pp. 499-505 ◽

Cited By ~ 32

Author(s):

Lisa A. Joss-Moore ◽

Yan Wang ◽

Xing Yu ◽

Michael S. Campbell ◽

Christopher W. Callaway ◽

...

Keyword(s):

Elastic Fiber ◽

Lung Compliance ◽

Fiber Formation ◽

Elastic Fibers ◽

Mrna Levels ◽

Rat Lung ◽

Mrna Transcript ◽

Transcript Levels ◽

Alveolar Development ◽

Fiber Deposition

Complications of intrauterine growth restriction (IUGR) include increased pulmonary morbidities and impaired alveolar development. Normal alveolar development depends upon elastin expression and processing, as well as the formation and deposition of elastic fibers. This is true of the human and rat. In this study, we hypothesized that uteroplacental insufficiency (UPI)-induced IUGR decreases mRNA levels of elastin and genes required for elastin fiber synthesis and assembly, at birth (prealveolarization) and postnatal day 7 (midalveolarization) in the rat. We further hypothesized that this would be accompanied by reduced elastic fiber deposition and increased static compliance at postnatal day 21 (mature lung). We used a well characterized rat model of IUGR to test these hypotheses. IUGR decreases mRNA transcript levels of genes essential for elastic fiber formation, including elastin, at birth and day 7. In the day 21 lung, IUGR decreases elastic fiber deposition and increases static lung compliance. We conclude that IUGR decreases mRNA transcript levels of elastic fiber synthesis genes, before and during alveolarization leading to a reduced elastic fiber density and increased static lung compliance in the mature lung. We speculate that the mechanism by which IUGR predisposes to pulmonary disease may be via decreased lung elastic fiber deposition.

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Nanoindentation of histological specimens: Mapping the elastic properties of soft tissues

Journal of Materials Research ◽

10.1557/jmr.2009.0130 ◽

2009 ◽

Vol 24 (3) ◽

pp. 638-646 ◽

Cited By ~ 59

Author(s):

R. Akhtar ◽

N. Schwarzer ◽

M.J. Sherratt ◽

R.E.B. Watson ◽

H.K. Graham ◽

...

Keyword(s):

Mechanical Properties ◽

Extracellular Matrix ◽

Elastic Modulus ◽

Soft Tissues ◽

Elastic Fiber ◽

Vena Cava ◽

Elastic Fibers ◽

Fiber Density ◽

Tissue Microstructure ◽

Micromechanical Properties

Although alterations in the gross mechanical properties of dynamic and compliant tissues have a major impact on human health and morbidity, there are no well-established techniques to characterize the micromechanical properties of tissues such as blood vessels and lungs. We have used nanoindentation to spatially map the micromechanical properties of 5-μm-thick sections of ferret aorta and vena cava and to relate these mechanical properties to the histological distribution of fluorescent elastic fibers. To decouple the effect of the glass substrate on our analysis of the nanoindentation data, we have used the extended Oliver and Pharr method. The elastic modulus of the aorta decreased progressively from 35 MPa in the adventitial (outermost) layer to 8 MPa at the intimal (innermost) layer. In contrast, the vena cava was relatively stiff, with an elastic modulus >30 MPa in both the extracellular matrix-rich adventitial and intimal regions of the vessel. The central, highly cellularized, medial layer of the vena cava, however, had an invariant elastic modulus of ∼20 MPa. In extracellular matrix-rich regions of the tissue, the elastic modulus, as determined by nanoindentation, was inversely correlated with elastic fiber density. Thus, we show it is possible to distinguish and spatially resolve differences in the micromechanical properties of large arteries and veins, which are related to the tissue microstructure.

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The role of caveolin-1 in pulmonary matrix remodeling and mechanical properties

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.90207.2008 ◽

2008 ◽

Vol 295 (6) ◽

pp. L1007-L1017 ◽

Cited By ~ 37

Author(s):

O. Le Saux ◽

K. Teeters ◽

S. Miyasato ◽

J. Choi ◽

G. Nakamatsu ◽

...

Keyword(s):

Mechanical Properties ◽

Signal Transduction ◽

Airway Resistance ◽

Transforming Growth Factor ◽

Interstitial Fibrosis ◽

Elastic Fiber ◽

Elastic Fibers ◽

Matrix Remodeling ◽

Caveolin 1 ◽

Fiber Deposition

Caveolin-1 (cav1) is a 22-kDa membrane protein essential to the formation of small invaginations in the plasma membrane, called caveolae. The cav1 gene is expressed primarily in adherent cells such as endothelial and smooth muscle cells and fibroblasts. Caveolae contain a variety of signaling receptors, and cav1 notably downregulates transforming growth factor (TGF)-β signal transduction. In pulmonary pathologies such as interstitial fibrosis or emphysema, altered mechanical properties of the lungs are often associated with abnormal ECM deposition. In this study, we examined the physiological functions and the deposition of ECM in cav1−/− mice at various ages (1–12 mo). Cav1−/− mice lack caveolae and by 3 mo of age have significant reduced lung compliance and increased elastance and airway resistance. Pulmonary extravasation of fluid, as part of the cav1−/− mouse phenotype, probably contributed to the alteration of compliance, which was compounded by a progressive increase in deposition of collagen fibrils in airways and parenchyma. We also found that the increased elastance was caused by abundant elastic fiber deposition primarily around airways in cav1−/− mice at least 3 mo old. These observed changes in the ECM composition probably also contribute to the increased airway resistance. The higher deposition of collagen and elastic fibers was associated with increased tropoelastin and col1α2 and col3α1 gene expression in lung tissues, which correlated tightly with increased TGF-β/Smad signal transduction. Our study illustrates that perturbation of cav1 function may contribute to several pulmonary pathologies as the result of the important role played by cav1, as part of the TGF-β signaling pathway, in the regulation of the pulmonary ECM.

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Carbamylation of elastic fibers is a molecular substratum of aortic stiffness

Scientific Reports ◽

10.1038/s41598-021-97293-5 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Manon Doué ◽

Anaïs Okwieka ◽

Alexandre Berquand ◽

Laëtitia Gorisse ◽

Pascal Maurice ◽

...

Keyword(s):

Mechanical Properties ◽

Cardiovascular Diseases ◽

Aortic Stiffness ◽

Molecular Mechanisms ◽

Elastic Fiber ◽

Plasma Concentrations ◽

Vascular Wall ◽

Elastic Fibers ◽

Fiber Morphology

AbstractBecause of their long lifespan, matrix proteins of the vascular wall, such as elastin, are subjected to molecular aging characterized by non-enzymatic post-translational modifications, like carbamylation which results from the binding of cyanate (mainly derived from the dissociation of urea) to protein amino groups. While several studies have demonstrated a relationship between increased plasma concentrations of carbamylated proteins and the development of cardiovascular diseases, molecular mechanisms explaining the involvement of protein carbamylation in these pathological contexts remain to be fully elucidated. The aim of this work was to determine whether vascular elastic fibers could be carbamylated, and if so, what impact this phenomenon would have on the mechanical properties of the vascular wall. Our experiments showed that vascular elastin was carbamylated in vivo. Fiber morphology was unchanged after in vitro carbamylation, as well as its sensitivity to elastase degradation. In mice fed with cyanate-supplemented water in order to increase protein carbamylation within the aortic wall, an increased stiffness in elastic fibers was evidenced by atomic force microscopy, whereas no fragmentation of elastic fiber was observed. In addition, this increased stiffness was also associated with an increase in aortic pulse wave velocity in ApoE−/− mice. These results provide evidence for the carbamylation of elastic fibers which results in an increase in their stiffness at the molecular level. These alterations of vessel wall mechanical properties may contribute to aortic stiffness, suggesting a new role for carbamylation in cardiovascular diseases.

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