Microscopic characterization of local strain field in healing tissue in the central third defect of mouse patellar tendon at early-phase of healing

Tendons exhibit a hierarchical collagen structure, wherein higher-level components, such as collagen fibres and fascicles, are elongated, slid, and rotated during macroscopic stretching. These mechanical behaviours of collagen fibres play important roles in stimulating tenocytes, imposing stretching, compression, and shear deformation. It was hypothesised that a lack of local fibre behaviours in healing tendon tissue may result in a limited application of mechanical stimuli to cells within the tissue, leading to incomplete recovery of tissue structure and functions in regenerated tendons. Therefore, the present study aimed to measure the microscopic strain field in the healing tendon tissue. A central third defect was created in the patellar tendon of mice, and the regenerated tissue in the defect was examined by tensile testing, collagen fibre analysis, and local strain measurement using confocal microscopy at 3 and 6 weeks after surgery. Healing tissue at 3 weeks exhibited a significantly lower strength and disorganised collagen fibre structure compared with the normal tendon. These characteristics at 6 weeks remained significantly different from those of the normal tendon. Moreover, the magnitude of local shear strain in the healing tissue under 4% tissue strain was significantly smaller than that in the normal tendon. Differences in the local strain field may be reflected in the cell nuclear shape and possibly the amount of mechanical stimuli applied to the cells during tendon deformation. Accordingly, restoration of a normal local mechanical environment in the healing tissue may be key to a better healing outcome of tendon injury.

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Microscopic characterisation of local strain field in healing tissue in the central third defect of mouse patellar tendon at early-phase of healing

Journal of the Mechanical Behavior of Biomedical Materials ◽

10.1016/j.jmbbm.2021.104702 ◽

2021 ◽

pp. 104702

Author(s):

Maeda Eijiro ◽

Kaname Kuroyanagi ◽

Takeo Matsumoto

Keyword(s):

Patellar Tendon ◽

Strain Field ◽

Early Phase ◽

Local Strain ◽

Healing Tissue

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Strain analysis with nanometer resolution using a conventional transmission electron microsopy technique: electron diffraction contrast imaging revisited

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100137215 ◽

1995 ◽

Vol 53 ◽

pp. 168-169

Author(s):

Koenraad G F Janssens ◽

Omer Van der Biest ◽

Jan Vanhellemont ◽

Herman E Maes ◽

Robert Hull

Keyword(s):

Electron Diffraction ◽

Strain Field ◽

Elastic Strain ◽

Strain Analysis ◽

Local Strain ◽

Contrast Imaging ◽

Strain Characterization ◽

Physical Mechanisms ◽

Diffraction Contrast ◽

Transmission Electron

There is a growing need for elastic strain characterization techniques with submicrometer resolution in several engineering technologies. In advanced material science and engineering the quantitative knowledge of elastic strain, e.g. at small particles or fibers in reinforced composite materials, can lead to a better understanding of the underlying physical mechanisms and thus to an optimization of material production processes. In advanced semiconductor processing and technology, the current size of micro-electronic devices requires an increasing effort in the analysis and characterization of localized strain. More than 30 years have passed since electron diffraction contrast imaging (EDCI) was used for the first time to analyse the local strain field in and around small coherent precipitates1. In later stages the same technique was used to identify straight dislocations by simulating the EDCI contrast resulting from the strain field of a dislocation and comparing it with experimental observations. Since then the technique was developed further by a small number of researchers, most of whom programmed their own dedicated algorithms to solve the problem of EDCI image simulation for the particular problem they were studying at the time.

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Intramuscular Injection of Botox Induces Tendon Atrophy and Senescence of Tendon-Derived Stem Cells

10.21203/rs.3.rs-70180/v1 ◽

2020 ◽

Author(s):

Peilin Chen ◽

Ziming Chen ◽

Christopher Mitchell ◽

Junjie Gao ◽

Lianzhi Chen ◽

...

Keyword(s):

Stem Cells ◽

Mechanical Loading ◽

Patellar Tendon ◽

Intramuscular Injection ◽

Vastus Lateralis ◽

Collagen Fibre ◽

Differentiation Capacity ◽

Botox Injection

Abstract Background: Botulinum toxin (Botox) injection is in widespread clinical use for the treatment of muscle spasms and tendinopathy but the mechanism of action is poorly understood. Hypothesis: We hypothesised that the reduction of patellar-tendon mechanical-loading following intra-muscular injection of Botox results in tendon atrophy that is at least in part mediated by the induction of senescence of tendon-derived stem cells (TDSCs). Study Design: Controlled laboratory study Methods: A total of 36 mice were randomly divided in 2 groups (18 Botox-injected and 18 vehicle-only control). Mice were injected into to right vastus lateralis of quadriceps muscles either with Botox to induce mechanical stress deprivation of the patellar tendon or with normal saline as control. At 2 weeks post-injection, animals were euthanized prior to tissues harvest for either evaluation of tendon morphology or in vitro studies. TDSCs were isolated by cell-sorting prior to determination of viability, differentiation capacity and senescence markers, as well as assessing their response to mechanical loading in a bioreactor. Finally, to examine the mechanism of tendon atrophy in vitro, key proteins in the PTEN/AKT pathway were evaluated in TDSCs in both groups. Results: Two weeks after Botox injection, patellar tendons displayed atrophic features including tissue volume reduction and collagen fibre misalignment and increased degradation. The colony formation assay revealed the significantly reduced colony units of TDSCs in Botox injected group compared to controls. Multipotent differentiation capacity of TDSCs has also diminished after Botox injection. To examine if mechanical deprived TDSC is capable of forming tendon tissue, we used an isolated bioreactor system to culture 3D TDSCs constructs. The result showed that TDSCs from the Botox-treated group failed to restore tenogenic differentiation after appropriate mechanical loading. Examination of PTEN/AKT signalling pathway revealed that injection of Botox into quadriceps muscle causes PTEN/AKT mediated cell senescence of TDSCs. Conclusion: Intramuscular injection of Botox interferes with tendon homeostasis by inducing tendon atrophy and senescence of TDSCs. Botox injection may have long-term adverse consequences for the treatment of tendinopathy. Clinical relevance: Intramuscular Botox injection for tendinopathy and tendon injury could cause adverse effects in human tendons and re-evaluation of its long-term efficacy is warranted.

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Photobleaching as a tool to measure the local strain field in fibrous membranes of connective tissues

Acta Biomaterialia ◽

10.1016/j.actbio.2014.02.031 ◽

2014 ◽

Vol 10 (6) ◽

pp. 2591-2601 ◽

Cited By ~ 14

Author(s):

C. Jayyosi ◽

G. Fargier ◽

M. Coret ◽

K. Bruyère-Garnier

Keyword(s):

Strain Field ◽

Local Strain ◽

Connective Tissues ◽

Fibrous Membranes

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Study on Local Strain Field Intensity Approach for Prediction Fatigue Life of Crankshaft Based on Mechanical Mechanics

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.644.251 ◽

2013 ◽

Vol 644 ◽

pp. 251-255 ◽

Cited By ~ 1

Author(s):

Ke Bao ◽

Qiu Fang Wang ◽

Shu Lin Liu ◽

Zhong Liang Wei

Keyword(s):

Field Intensity ◽

Strain Field ◽

Local Strain ◽

Fatigue Tests ◽

Bending Moments ◽

Test Results ◽

Life Test ◽

Test Load ◽

Bending Fatigue ◽

Crack Initiation Life

The bending fatigue limit moment and crack initiation life of 4105 crankishaft in five groups of bending moments are obtained by resonant bending fatigue tests first. Then, the static finite element calculation using sub-model is performed to get the strain distributions in every test load. The results show that in the region where stress concentrate, the strain field could be seen as plane strain state. So two dimensional strain field intensity model is selected. In order to remove the influences of size and surface conditions, the radius of strain field is determined with the strain distribution under the low-life test load. After that, the local strain field intensities under each test load are calculated with the radius of strain field. Finally, the strain-life curve of material is modified by the fatigue intensity limit of crankshaft, and the predicted life agree with the test results.

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Constitutive modelling of arteries considering fibre recruitment and three-dimensional fibre distribution

Journal of The Royal Society Interface ◽

10.1098/rsif.2015.0111 ◽

2015 ◽

Vol 12 (105) ◽

pp. 20150111 ◽

Cited By ~ 26

Author(s):

Hannah Weisbecker ◽

Michael J. Unterberger ◽

Gerhard A. Holzapfel

Keyword(s):

Experimental Data ◽

Matrix Material ◽

Three Dimensional ◽

Collagen Fibre ◽

Multiscale Model ◽

Orientation Distribution ◽

Constitutive Modelling ◽

Collagen Fibres ◽

Proposed Model ◽

The Matrix

Structurally motivated material models may provide increased insights into the underlying mechanics and physics of arteries under physiological loading conditions. We propose a multiscale model for arterial tissue capturing three different scales (i) a single collagen fibre; (ii) bundle of collagen fibres; and (iii) collagen network within the tissue. The waviness of collagen fibres is introduced by a probability density function for the recruitment stretch at which the fibre starts to bear load. The three-dimensional distribution of the collagen fibres is described by an orientation distribution function using the bivariate von Mises distribution, and fitted to experimental data. The strain energy for the tissue is decomposed additively into a part related to the matrix material and a part for the collagen fibres. Volume fractions account for the matrix/fibre constituents. The proposed model only uses two parameters namely a shear modulus of the matrix material and a (stiffness) parameter related to a single collagen fibre. A fit of the multiscale model to representative experimental data obtained from the individual layers of a human thoracic aorta shows that the proposed model is able to adequately capture the nonlinear and anisotropic behaviour of the aortic layers.

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Axial Strain Measurements in Skeletal Muscle at Various Strain Rates

Journal of Biomechanical Engineering ◽

10.1115/1.2794179 ◽

1995 ◽

Vol 117 (3) ◽

pp. 262-265 ◽

Cited By ~ 33

Author(s):

T. M. Best ◽

J. H. McElhaney ◽

W. E. Garrett ◽

B. S. Myers

Keyword(s):

Skeletal Muscle ◽

Strain Field ◽

High Speed ◽

Soft Tissues ◽

Axial Strain ◽

Local Strain ◽

Optical Systems ◽

Rate Dependent ◽

Strain Formulation ◽

Tissue Deformations

A noncontact optical system using high speed image analysis to measure local tissue deformations and axial strains along skeletal muscle is described. The spatial resolution of the system was 20 pixels/cm and the accuracy was ±0.125mm. In order to minimize the error associated with discrete data used to characterize a continuous strain field, the displacement data were fitted with a third order polynomial and the fitted data differentiated to measure surface strains using a Lagrangian finite strain formulation. The distribution of axial strain along the muscle-tendon unit was nonuniform and rate dependent. Despite a variation in local strain distribution with strain rate, the maximum axial strain, Exx = 0.614 ± 0.045 mm/mm, was rate insensitive and occurred at the failure site for all tests. The frequency response of the video system (1000 Hz) and the measurement of a continuous strain field along the entire length of the structure improve upon previous noncontact optical systems for measurement of surface strains in soft tissues.

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The mechanical properties of fin whale arteries are explained by novel connective tissue designs.

Journal of Experimental Biology ◽

10.1242/jeb.199.4.985 ◽

1996 ◽

Vol 199 (4) ◽

pp. 985-997 ◽

Cited By ~ 1

Author(s):

J M Gosline ◽

R E Shadwick

Keyword(s):

Mechanical Properties ◽

Elastic Modulus ◽

Aortic Arch ◽

Thoracic Aorta ◽

Collagen Fibre ◽

External Diameter ◽

Collagen Fibres ◽

Descending Aorta ◽

Fin Whale ◽

Terrestrial Mammals

The aortic arch and the descending aorta in the fin whale (Balaenoptera physalus) are structurally and mechanically very different from comparable vessels in other mammals. Although the external diameter of the whale's descending thoracic aorta (approximately 12 cm) is similar to that predicted by scaling relationships for terrestrial mammals, the wall thickness:diameter ratio in the whale (0.015) is much smaller than the characteristic value for other mammals (0.05). In addition, the elastic modulus of the thoracic aorta (12 MPa at 13 kPa blood pressure) is about 30 times higher than in other mammals. In contrast, the whale's aortic arch has a wall thickness/diameter ratio (0.055) and an elastic modulus (0.4 MPa) that are essentially identical to those for other mammals. However, the aortic arch is unusual in that it can be deformed biaxially to very large strains without entering a region of high stiffness caused by the recruitment of fully extended collagen fibres. Chemical composition studies indicate that the elastin:collagen ratio is high in the aortic arch (approximately 2:1) and that this ratio falls in the thoracic (approximately 1:2) and abdominal (approximately 1:3) aortas, but the magnitude of the change in composition does not account for the dramatic difference in mechanical properties. This suggests that there are differences in the elastin and collagen fibre architecture of these vessels. The descending aorta contains dense bands of tendon-like, wavy collagen fibres that run in the plane of the arterial wall, forming a fibre-lattice that runs in parallel to the elastin lamellae and reinforces the wall, making it very stiff. The aortic arch contains a very different collagen fibre-lattice in which fibres appear to have a component of orientation that runs through the thickness of the artery wall. This suggests that the collagen fibres may be arranged in series with elastin-containing elements, a difference in tissue architecture that could account for both the lower stiffness and the extreme extensibility of the whale's aortic arch. Thus, both the structure and the mechanical behaviour of the lamellar units in the aortic arch and aorta of the whale have presumably been modified to produce the unusual mechanical and haemodynamic properties of the whale circulation.

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Development of a Collagen Fibre Remodelling Rupture Risk Metric for Potentially Vulnerable Carotid Artery Atherosclerotic Plaques

Frontiers in Physiology ◽

10.3389/fphys.2021.718470 ◽

2021 ◽

Vol 12 ◽

Author(s):

Milad Ghasemi ◽

Robert D. Johnston ◽

Caitríona Lally

Keyword(s):

Carotid Artery ◽

Atherosclerotic Plaque ◽

Mechanical Response ◽

Plaque Rupture ◽

Collagen Fibre ◽

Local Stress ◽

Patient Specific ◽

Collagen Fibres ◽

Magnetic Resonance Imaging Mri ◽

Risk Metric

Atherosclerotic plaque rupture in carotid arteries can lead to stroke which is one of the leading causes of death or disability worldwide. The accumulation of atherosclerotic plaque in an artery changes the mechanical properties of the vessel. Whilst healthy arteries can continuously adapt to mechanical loads by remodelling their internal structure, particularly the load-bearing collagen fibres, diseased vessels may have limited remodelling capabilities. In this study, a local stress modulated remodelling algorithm is proposed to explore the mechanical response of arterial tissue to the remodelling of collagen fibres. This stress driven remodelling algorithm is used to predict the optimum distribution of fibres in healthy and diseased human carotid bifurcations obtained using Magnetic Resonance Imaging (MRI). In the models, healthy geometries were segmented into two layers: media and adventitia and diseased into four components: adventitia, media, plaque atheroma and lipid pool (when present in the MRI images). A novel meshing technique for hexahedral meshing of these geometries is also demonstrated. Using the remodelling algorithm, the optimum fibre patterns in various patient specific plaques are identified and the role that deviations from these fibre configurations in plaque vulnerability is shown. This study provides critical insights into the collagen fibre patterns required in carotid artery and plaque tissue to maintain plaque stability.

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