Zonal Poisson Effect on the Chondron Deformation in Articular Cartilage under Compression

2007 ◽  
Vol 342-343 ◽  
pp. 133-136
Author(s):  
Jae Bong Choi
Keyword(s):  
Extracellular Matrix ◽  
Articular Cartilage ◽  
Mechanical Response ◽  
Three Dimensional ◽  
Pericellular Matrix ◽  
Poisson Effect ◽  
Type Vi Collagen ◽  
Confocal Images ◽  
Three Dimensional Models

The objective of this study was to quantify the zonal difference of the in situ chondron’s Poisson effect under different magnitudes of compression. Fluorescence immunolabeling for type VI collagen was used to identify the pericellular matrix (PCM) and chondron, and a series of fluorescent confocal images were recorded and reconstructed to form quantitative three-dimensional models. The zonal variations in the mechanical response of the chondron do not appear to be due to zonal differences in PCM properties, but rather seem to result from significant inhomogeneities in relative stiffnesses of the extracellular matrix (ECM) and PCM with depth.

Determination of In Situ Articular Cartilage Pericellular Matrix Properties via Inverse BEM Analysis of Chondron Deformation

2010 ◽  
Author(s):  
Eunjung Kim ◽  
Farshid Guilak ◽  
Mansoor A. Haider
Keyword(s):  
Articular Cartilage ◽  
Compressive Strain ◽  
Critical Role ◽  
Three Dimensional ◽  
Cartilage Explants ◽  
Pericellular Matrix ◽  
Type Vi Collagen ◽  
Microscopy Technique

The pericellular matrix (PCM) of articular cartilage is the narrow tissue region surrounding all chondrocytes. Together, the chondrocyte and its surrounding PCM have been termed the chondron. In normal cartilage, the presence of type VI collagen is exclusive to the PCM, and the PCM is believed to play a critical role in regulating biomechanical cell-matrix interactions. Since the PCM is stiffer than the chondrocyte, it has been hypothesized to play a critical role in protecting the cell while, simultaneously, facilitating the transmission of mechanical signals to the cell. Previous studies that represent the cell, PCM and extracellular matrix (ECM) as linear biphasic materials have supported this hypothesized role for the PCM [1–4]. Previous in vitro micropipette studies of isolated chondrons [5–7] have shown that the PCM Young’s modulus ranges between 25–70kPa in middle and deep zone cartilage, separating it by an order of magnitude from both the chondrocyte stiffness (∼1kPa) and ECM stiffness (∼1MPa). In recent years, Choi et al. [8] measured changes in the three-dimensional morphology of the chondron, in situ within the ECM, under equilibrium unconfined compression of porcine cartilage explants subjected to 10–50% compressive strain (Fig. 1). Their study employed a novel 3D confocal microscopy technique, based on immunolabeling of type VI collagen, that yielded ellipsoidal approximations of undeformed and deformed chondron shapes in the superficial, middle and deep zones of the explant. In this study, an efficient computational model, based on the boundary element method (BEM), was developed and used to estimate cartilage PCM linear elastic properties based on the data reported in Choi et al. [8] for the case of middle zone cartilage under 10% compressive strain.

scholarly journals An Axisymmetric Boundary Element Model for Determination of Articular Cartilage Pericellular Matrix Properties In Situ via Inverse Analysis of Chondron Deformation

2010 ◽  
Vol 132 (3) ◽  
Author(s):  
Eunjung Kim ◽  
Farshid Guilak ◽  
Mansoor A. Haider
Keyword(s):  
Experimental Data ◽  
Articular Cartilage ◽  
Boundary Element ◽  
Elastic Properties ◽  
Inverse Analysis ◽  
Three Dimensional ◽  
Pericellular Matrix ◽  
Unconfined Compression ◽  
Linear Elastic

The pericellular matrix (PCM) is the narrow tissue region surrounding all chondrocytes in articular cartilage and, together, the chondrocyte(s) and surrounding PCM have been termed the chondron. Previous theoretical and experimental studies suggest that the structure and properties of the PCM significantly influence the biomechanical environment at the microscopic scale of the chondrocytes within cartilage. In the present study, an axisymmetric boundary element method (BEM) was developed for linear elastic domains with internal interfaces. The new BEM was employed in a multiscale continuum model to determine linear elastic properties of the PCM in situ, via inverse analysis of previously reported experimental data for the three-dimensional morphological changes of chondrons within a cartilage explant in equilibrium unconfined compression (Choi, et al., 2007, “Zonal Changes in the Three-Dimensional Morphology of the Chondron Under Compression: The Relationship Among Cellular, Pericellular, and Extracellular Deformation in Articular Cartilage,” J. Biomech., 40, pp. 2596–2603). The microscale geometry of the chondron (cell and PCM) within the cartilage extracellular matrix (ECM) was represented as a three-zone equilibrated biphasic region comprised of an ellipsoidal chondrocyte with encapsulating PCM that was embedded within a spherical ECM subjected to boundary conditions for unconfined compression at its outer boundary. Accuracy of the three-zone BEM model was evaluated and compared with analytical finite element solutions. The model was then integrated with a nonlinear optimization technique (Nelder–Mead) to determine PCM elastic properties within the cartilage explant by solving an inverse problem associated with the in situ experimental data for chondron deformation. Depending on the assumed material properties of the ECM and the choice of cost function in the optimization, estimates of the PCM Young's modulus ranged from ∼24 kPa to 59 kPa, consistent with previous measurements of PCM properties on extracted chondrons using micropipette aspiration. Taken together with previous experimental and theoretical studies of cell-matrix interactions in cartilage, these findings suggest an important role for the PCM in modulating the mechanical environment of the chondrocyte.

Chondrons from articular cartilage. V. Immunohistochemical evaluation of type VI collagen organisation in isolated chondrons by light, confocal and electron microscopy

1992 ◽  
Vol 103 (4) ◽  
pp. 1101-1110 ◽  
Author(s):  
C.A. Poole ◽  
S. Ayad ◽  
R.T. Gilbert
Keyword(s):  
Electron Microscopy ◽  
Extracellular Matrix ◽  
Articular Cartilage ◽  
Specific Cell ◽  
Potential Contribution ◽  
Collagen Network ◽  
Tail Region ◽  
Type Vi Collagen ◽  
Surface Receptors ◽  
Basal Pole

The pericellular microenvironment around articular cartilage chondrocytes must play a key role in regulating the interaction between the cell and its extracellular matrix. The potential contribution of type VI collagen to this interaction was investigated in this study using isolated canine tibial chondrons embedded in agarose monolayers. The immunohistochemical distribution of an anti-type VI collagen antibody was assessed in these preparations using fluorescence, peroxidase and gold particle probes in combination with light, confocal and transmission electron microscopy. Light and confocal microscopy both showed type VI collagen concentrated in the pericellular capsule and matrix around the chondrocyte with reduced staining in the tail region and the interconnecting segments between adjacent chondrons. Minimal staining was recorded in the territorial and interterritorial matrices. At higher resolution, type VI collagen appeared both as microfibrils and as amorphous deposits that accumulated at the junction of intersecting capsular fibres and microfibrils. Electron microscopy also showed type VI collagen anchored to the chondrocyte membrane at the articular pole of the pericellular capsule and tethered to the radial collagen network through the tail at the basal pole of the capsule. We suggest that type VI collagen plays a dual role in the maintenance of chondron integrity. First, it could bind to the radial collagen network and stabilise the collagens, proteoglycans and glycoproteins of the pericellular microenvironment. Secondly, specific cell surface receptors exist, which could mediate the interaction between the chondrocyte and type VI collagen, providing firm anchorage and signalling potentials between the pericellular matrix and the cell nucleus. In this way type VI collagen could provide a close functional interrelationship between the chondrocyte, its pericellular microenvironment and the load bearing extracellular matrix of adult articular cartilage.

Constitutive Modeling of Corneal Tissue: Influence of Three-Dimensional Collagen Fiber Microstructure

2020 ◽  
Vol 143 (3) ◽  
Author(s):  
Shuolun Wang ◽  
Hamed Hatami-Marbini
Keyword(s):  
Extracellular Matrix ◽  
Constitutive Modeling ◽  
Mechanical Response ◽  
Thickness Distribution ◽  
Three Dimensional ◽  
Vital Role ◽  
Collagen Fibrils ◽  
Model Parameters ◽  
Corneal Tissue ◽  
Numerical Predictions

Abstract The cornea, the transparent tissue in the front of the eye, along with the sclera, plays a vital role in protecting the inner structures of the eyeball. The precise shape and mechanical strength of this tissue are mostly determined by the unique microstructure of its extracellular matrix. A clear picture of the 3D arrangement of collagen fibrils within the corneal extracellular matrix has recently been obtained from the secondary harmonic generation images. However, this important information about the through-thickness distribution of collagen fibrils was seldom taken into account in the constitutive modeling of the corneal behavior. This work creates a generalized structure tensor (GST) model to investigate the mechanical influence of collagen fibril through-thickness distribution. It then uses numerical simulations of the corneal mechanical response in inflation experiments to assess the efficacy of the proposed model. A parametric study is also done to investigate the influence of model parameters on numerical predictions. Finally, a brief comparison between the performance of this new constitutive model and a recent angular integration (AI) model from the literature is given.

In Situ Hierarchical Strain Transfer From the Articular Cartilage Surface to the Chondrocyte Nucleus

2012 ◽  
Author(s):  
Jonathan T. Henderson ◽  
Corey P. Neu
Keyword(s):  
Extracellular Matrix ◽  
Articular Cartilage ◽  
Cartilage Surface ◽  
Strain Transfer ◽  
Nuclear Mechanics ◽  
Articular Cartilage Surface ◽  
Matrix Interactions ◽  
Wear And Tear ◽  
Extracellular Matrix Interactions

Osteoarthritis (OA) is a disabling disease, commonly thought of as the “wear and tear” of articular cartilage, afflicting 27 million Americans [1]. Multiple (e.g. biomechanical and biochemical) factors [2] contribute to maintenance of healthy joints through chondrocyte and extracellular matrix interactions. Interestingly, volumetric contractions of nuclei exhibit a zonal dependence [3], suggesting that nuclear mechanics may play a key role in the maintenance of healthy tissue by mechanically-mediated pathways.

scholarly journals Microstructural deformation observed by Mueller polarimetry during traction assay on myocardium samples

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Nicole Tueni ◽  
Jérémy Vizet ◽  
Martin Genet ◽  
Angelo Pierangelo ◽  
Jean-Marc Allain
Keyword(s):  
Mechanical Response ◽  
Three Dimensional ◽  
Full Field ◽  
Tissue Scattering ◽  
Traction Device ◽  
First Time ◽  
Heart Wall ◽  
Mechanical Traction ◽  
Collagen Layer

AbstractDespite recent advances, the myocardial microstructure remains imperfectly understood. In particular, bundles of cardiomyocytes have been observed but their three-dimensional organisation remains debated and the associated mechanical consequences unknown. One of the major challenges remains to perform multiscale observations of the mechanical response of the heart wall. For this purpose, in this study, a full-field Mueller polarimetric imager (MPI) was combined, for the first time, with an in-situ traction device. The full-field MPI enables to obtain a macroscopic image of the explored tissue, while providing detailed information about its structure on a microscopic scale. Specifically it exploits the polarization of the light to determine various biophysical quantities related to the tissue scattering or anisotropy properties. Combined with a mechanical traction device, the full-field MPI allows to measure the evolution of such biophysical quantities during tissue stretch. We observe separation lines on the tissue, which are associated with a fast variation of the fiber orientation, and have the size of cardiomyocyte bundles. Thus, we hypothesize that these lines are the perimysium, the collagen layer surrounding these bundles. During the mechanical traction, we observe two mechanisms simultaneously. On one hand, the azimuth shows an affine behavior, meaning the orientation changes according to the tissue deformation, and showing coherence in the tissue. On the other hand, the separation lines appear to be resistant in shear and compression but weak against traction, with a forming of gaps in the tissue.

Importance of Collagen Orientation and Depth-Dependent Fixed Charge Densities of Cartilage on Mechanical Behavior of Chondrocytes

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Rami K. Korhonen ◽  
Petro Julkunen ◽  
Wouter Wilson ◽  
Walter Herzog
Keyword(s):  
Extracellular Matrix ◽  
Articular Cartilage ◽  
Current Model ◽  
Fixed Charge ◽  
Solid Matrix ◽  
Pericellular Matrix ◽  
Collagen Network ◽  
Mechanical Environment ◽  
Collagen Orientation ◽  
Charge Densities

The collagen network and proteoglycan matrix of articular cartilage are thought to play an important role in controlling the stresses and strains in and around chondrocytes, in regulating the biosynthesis of the solid matrix, and consequently in maintaining the health of diarthrodial joints. Understanding the detailed effects of the mechanical environment of chondrocytes on cell behavior is therefore essential for the study of the development, adaptation, and degeneration of articular cartilage. Recent progress in macroscopic models has improved our understanding of depth-dependent properties of cartilage. However, none of the previous works considered the effect of realistic collagen orientation or depth-dependent negative charges in microscopic models of chondrocyte mechanics. The aim of this study was to investigate the effects of the collagen network and fixed charge densities of cartilage on the mechanical environment of the chondrocytes in a depth-dependent manner. We developed an anisotropic, inhomogeneous, microstructural fibril-reinforced finite element model of articular cartilage for application in unconfined compression. The model consisted of the extracellular matrix and chondrocytes located in the superficial, middle, and deep zones. Chondrocytes were surrounded by a pericellular matrix and were assumed spherical prior to tissue swelling and load application. Material properties of the chondrocytes, pericellular matrix, and extracellular matrix were obtained from the literature. The loading protocol included a free swelling step followed by a stress-relaxation step. Results from traditional isotropic and transversely isotropic biphasic models were used for comparison with predictions from the current model. In the superficial zone, cell shapes changed from rounded to elliptic after free swelling. The stresses and strains as well as fluid flow in cells were greatly affected by the modulus of the collagen network. The fixed charge density of the chondrocytes, pericellular matrix, and extracellular matrix primarily affected the aspect ratios (height/width) and the solid matrix stresses of cells. The mechanical responses of the cells were strongly location and time dependent. The current model highlights that the collagen orientation and the depth-dependent negative fixed charge densities of articular cartilage have a great effect in modulating the mechanical environment in the vicinity of chondrocytes, and it provides an important improvement over earlier models in describing the possible pathways from loading of articular cartilage to the mechanical and biological responses of chondrocytes.

scholarly journals Nonlinear mechanics of lamin filaments and the meshwork topology build an emergent nuclear lamina

2019 ◽  
Author(s):  
K. Tanuj Sapra ◽  
Zhao Qin ◽  
Anna Dubrovsky-Gaupp ◽  
Ueli Aebi ◽  
Daniel J. Müller ◽  
...  
Keyword(s):  
Mechanical Response ◽  
Mechanical Stability ◽  
Electron Tomography ◽  
Three Dimensional ◽  
Small World ◽  
Nuclear Lamina ◽  
Integrative Approach ◽  
Graph Theory Analysis ◽  
Dynamics Simulations

AbstractThe nuclear lamina – a meshwork of intermediate filaments termed lamins – functions as a mechanotransduction interface between the extracellular matrix and the nucleus via the cytoskeleton. Although lamins are primarily responsible for the mechanical stability of the nucleus in multicellular organisms, in situ characterization of lamin filaments under tension has remained elusive. Here, we apply an integrative approach combining atomic force microscopy, cryo-electron tomography, network analysis, and molecular dynamics simulations to directly measure the mechanical response of single lamin filaments in its three-dimensional meshwork. Endogenous lamin filaments portray non-Hookean behavior – they deform reversibly under a force of a few hundred picoNewtons and stiffen at nanoNewton forces. The filaments are extensible, strong and tough, similar to natural silk and superior to the synthetic polymer Kevlar®. Graph theory analysis shows that the lamin meshwork is not a random arrangement of filaments but the meshwork topology follows ‘small world’ properties. Our results suggest that the lamin filaments arrange to form a robust, emergent meshwork that dictates the mechanical properties of individual lamin filaments. The combined approach provides quantitative insights into the structure-function organization of lamins in situ, and implies a role of meshwork topology in laminopathies.

In situ implantable three-dimensional extracellular matrix bioactive composite scaffold for postoperative skin cancer therapy

2020 ◽  
Vol 400 ◽  
pp. 125949
Author(s):  
Yutian Su ◽  
Xichen Zhang ◽  
Guohong Ren ◽  
Zhicheng Zhang ◽  
Ying Liang ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Skin Cancer ◽  
Cancer Therapy ◽  
Composite Scaffold ◽  
Three Dimensional
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