Solute Transport in Porous Medium Under External Loads

Volume 4 ◽  
2004 ◽  
Author(s):  
Yiling Lu ◽  
Wen Wang
Keyword(s):  
Extracellular Matrix ◽  
Solute Transport ◽  
Soft Tissues ◽  
Extracellular Fluid ◽  
Solute Concentration ◽  
Dynamic Loads ◽  
Solute Diffusion ◽  
Cyclic Loads ◽  
Study Results ◽  
The Matrix

Dynamic compression of soft tissues affects tissue mechanical properties and metabolic activities. The effect is attributed, in part, to the movement of water and solutes in extracellular matrix, which alters the mechanical (e.g. fluid shear stress) and chemical (e.g. growth factors, cytokines and hormones) microenvironments for cells in the tissue. To quantify contributions of external dynamic loads on solute transport in extracellular matrix, we have applied a poroelastic theory to calculate the deformation of the matrix and the movement of the fluid. In the simplified two-dimensional model, the solid phase represented the matrix of collagens and proteoglycans and the liquid phase represented the interstitial fluid. Deformable matrix embedded with cells was immersed in a solution inside a well with rigid, impermeable walls. On top of the matrix, solution with known solute concentration existed. Solute moved into the matrix and was consumed by cells. Mechanical cyclic loads were applied over a central area on the top surface of the matrix, causing its deformation and extracellular fluid movement. Resulting cell density in the matrix changed with the time during the loading cycle and it varied with the location in the matrix as well. Movement of the extracellular fluid coupled with solute diffusion contributed to the overall solute transport in the matrix. Effects of different loading frequencies and amplitudes were investigated. Different sized molecules were also considered in the study. Results from the model confirmed experimental findings that cyclic loads facilitated solute transport in soft tissues. The effect was more significant for large sized molecules. Special attention was given to regions of the matrix where cells would initially remain metabolically inactive due to lower than the critical value of the solute concentration. Quantitative analysis of solute concentration distribution in the matrix made it possible to predict regions where cells became activated by the improved solute supply. The fact that more cells in tissues became metabolically active under dynamic loads exemplified most directly the effect of external dynamic loads on solute transport in soft tissues.

scholarly journals Binding and degradation of platelet thrombospondin by cultured fibroblasts.

1984 ◽  
Vol 98 (1) ◽  
pp. 22-28 ◽  
Author(s):  
P J McKeown-Longo ◽  
R Hanning ◽  
D F Mosher
Keyword(s):  
Extracellular Matrix ◽  
Cell Layer ◽  
Extracellular Fluid ◽  
Human Platelets ◽  
Lung Fibroblasts ◽  
Human Embryonic Lung ◽  
Cultured Fibroblasts ◽  
The Matrix ◽  
Specific Receptors ◽  
Or Organization

Thrombospondin was purified from human platelets and labeled with 125I, and its metabolism was quantified in cell cultures of human embryonic lung fibroblasts. 125I-Thrombospondin bound to the cell layer. The binding reached an apparent steady state within 45 min. Trichloroacetic acid-soluble radioactivity was detected in the medium after 30 min of incubation; the rate of degradation of 125I-thrombospondin was linear for several hours thereafter. Degradation of 125I-thrombospondin was saturable. The apparent Km and Vmax for degradation at 37 degrees C were 6 X 10(-8) M and 1.4 X 10(5) molecules per cell per minute, respectively. Degradation was inhibited by chloroquine or by lowering the temperature to 4 degrees C. Experiments in which cultures were incubated with thrombospondin for 45 min and then incubated in medium containing no thrombospondin revealed two fractions of bound thrombospondin. One fraction was localized by indirect immunofluorescence to punctate structures; these structures were lost coincident with the rapid degradation of 50-80% of bound 125I-thrombospondin. The second fraction was localized to a trypsin-sensitive, fibrillar, extracellular matrix. 125I-Thrombospondin in the matrix was slowly degraded over a period of hours. Binding of 125I-thrombospondin to the extracellular matrix was not saturable and indeed was enhanced at thrombospondin concentrations greater than 3 X 10(-8) M. The ability of 125I-thrombospondin to bind to extracellular matrix was diminished tenfold by limited proteolytic cleavage with trypsin. Degradation of trypsinized 125I-thrombospondin was also diminished, although to a lesser extent than matrix binding. Heparin inhibited both degradation and matrix binding. These results suggest that thrombospondin may play a transitory role in matrix formation and/or organization and that specific receptors on the cell surface are responsible for the selective removal of thrombospondin from the extracellular fluid and matrix.

Solute Transport in the Bone Lacunar-Canalicular System is Size and Shape Dependent

2008 ◽  
Author(s):  
Wen Li ◽  
Jun Pan ◽  
Liyun Wang
Keyword(s):  
Solute Transport ◽  
Solute Diffusion ◽  
Sodium Fluorescein ◽  
Size And Shape ◽  
Molecular Weights ◽  
Fluorescence Dye ◽  
The Matrix ◽  
Solute Movement ◽  
And Function

Solute transport through the bone lacunar-canalicular system is believed to be essential for osteocyte survival and function. We have developed an approach that permits direct measurement of real-time solute movement in intact bones by using fluorescence recovery after phtobleaching (FRAP) technology [1]. The movement of vitally injected fluorescence dye (sodium fluorescein) among individual osteocytic lacunae was visualized in situ and the transport was analyzed by using a two-compartment mathematical model of solute diffusion. Our previous studies [1] suggested that the matrix surrounding osteocytes is similar to the glycocalyx of endothelial cells as first proposed by Weinbaum et al. (1994) [2]. In the present study, we investigated diffusive transport of five fluorescent tracers of different molecular weights and shapes in the bone lacunar-canalicular system (LCS). Our hypothesis is that the solute transport in lacunar-canalicular system is size and shape dependent, due to the molecular sieving of the pericellular matrix.

Extracellular matrix: the gatekeeper of tumor angiogenesis

2019 ◽  
Vol 47 (5) ◽  
pp. 1543-1555 ◽  
Author(s):  
Maurizio Mongiat ◽  
Simone Buraschi ◽  
Eva Andreuzzi ◽  
Thomas Neill ◽  
Renato V. Iozzo
Keyword(s):  
Extracellular Matrix ◽  
Tumor Angiogenesis ◽  
Signaling Cascades ◽  
Cancer Growth ◽  
Cell Behavior ◽  
Metastatic Progression ◽  
Surface Receptors ◽  
The Matrix ◽  
Multiple Signaling

Abstract The extracellular matrix is a network of secreted macromolecules that provides a harmonious meshwork for the growth and homeostatic development of organisms. It conveys multiple signaling cascades affecting specific surface receptors that impact cell behavior. During cancer growth, this bioactive meshwork is remodeled and enriched in newly formed blood vessels, which provide nutrients and oxygen to the growing tumor cells. Remodeling of the tumor microenvironment leads to the formation of bioactive fragments that may have a distinct function from their parent molecules, and the balance among these factors directly influence cell viability and metastatic progression. Indeed, the matrix acts as a gatekeeper by regulating the access of cancer cells to nutrients. Here, we will critically evaluate the role of selected matrix constituents in regulating tumor angiogenesis and provide up-to-date information concerning their primary mechanisms of action.

scholarly journals von Willebrand factor released from Weibel-Palade bodies binds more avidly to extracellular matrix than that secreted constitutively

Blood ◽  
1987 ◽  
Vol 69 (5) ◽  
pp. 1531-1534 ◽  
Author(s):  
LA Sporn ◽  
VJ Marder ◽  
DD Wagner
Keyword(s):  
Extracellular Matrix ◽  
Endothelial Cells ◽  
Von Willebrand Factor ◽  
Immunofluorescent Staining ◽  
Cultured Endothelial Cells ◽  
Human Foreskin Fibroblasts ◽  
Platelet Binding ◽  
The Matrix ◽  
Von Willebrand ◽  
Willebrand Factor

Abstract Large multimers of von Willebrand factor (vWf) are released from the Weibel-Palade bodies of cultured endothelial cells following treatment with a secretagogue (Sporn et al, Cell 46:185, 1986). These multimers were shown by immunofluorescent staining to bind more extensively to the extracellular matrix of human foreskin fibroblasts than constitutively secreted vWf, which is composed predominantly of dimeric molecules. Increased binding of A23187-released vWf was not due to another component present in the releasate, since releasate from which vWf was adsorbed, when added together with constitutively secreted vWf, did not promote binding. When iodinated plasma vWf was overlaid onto the fibroblasts, the large forms bound preferentially to the matrix. These results indicated that the enhanced binding of the vWf released from the Weibel-Palade bodies was likely due to its large multimeric size. It appears that multivalency is an important component of vWf interaction with the extracellular matrix, just as has been shown for vWf interaction with platelets. The pool of vWf contained within the Weibel-Palade bodies, therefore, is not only especially suited for platelet binding, but also for interaction with the extracellular matrix.

A Multiscale Approach to Modeling the Passive Mechanical Contribution of Cells in Tissues

2013 ◽  
Author(s):  
Victor K. Lai ◽  
Mohammad F. Hadi ◽  
Robert T. Tranquillo ◽  
Victor H. Barocas
Keyword(s):  
Extracellular Matrix ◽  
Soft Tissues ◽  
Multiscale Model ◽  
Tissue Mechanics ◽  
Multiscale Approach ◽  
Cellular Solids ◽  
Comprehensive Model ◽  
Modeling Framework ◽  
Tissue Biomechanics ◽  
Tensegrity Model

In addition to their obvious biological roles in tissue function, cells often play a significant mechanical role through a combination of passive and active behaviors. Phenomenological and continuum modeling approaches to understand tissue biomechanics have included improved constitutive laws that incorporate anisotropy in the extracellular matrix (ECM) and/or cellular phenomenon, e.g, [1]. The lack of microstructural detail in these models, however, limits their ability to explore the respective contributions and interactions between different components within a tissue. In contrast, structural approaches attempt to understand tissue biomechanics by incorporating microstructural details directly into the model, e.g., the tensegrity model [2], cellular solids models [3], or biopolymer models [4]. Research in our group focuses on developing a comprehensive model to predict the mechanical behavior of soft tissues via a multiscale approach, a technique that allows integration of the microstructural details of different components into the modeling framework. A significant gap in our previous models, however, is the absence of cells. The current work represents an improvement of the multiscale model via the addition of cells, and investigates the passive mechanical contribution of cells to overall tissue mechanics.

scholarly journals Proteolytic Events of Wound-Healing — Coordinated Interactions Among Matrix Metalloproteinases (MMPs), Integrins, and Extracellular Matrix Molecules

2001 ◽  
Vol 12 (5) ◽  
pp. 373-398 ◽  
Author(s):  
Bjorn Steffensen ◽  
Lari Häkkinen ◽  
Hannu Larjava
Keyword(s):  
Extracellular Matrix ◽  
Wound Healing ◽  
Matrix Metalloproteinases ◽  
Wound Repair ◽  
Enzyme Activation ◽  
Processing Enzymes ◽  
The Matrix ◽  
Signaling Receptors ◽  
State Of Rest ◽  
And Function

During wound-healing, cells are required to migrate rapidly into the wound site via a proteolytically generated pathway in the provisional matrix, to produce new extracellular matrix, and, subsequently, to remodel the newly formed tissue matrix during the maturation phase. Two classes of molecules cooperate closely to achieve this goal, namely, the matrix adhesion and signaling receptors, the integrins, and matrix-degrading and -processing enzymes, the matrix metalloproteinases (MMPs). There is now substantial experimental evidence that blocking key molecules of either group will prevent or seriously delay wound-healing. It has been known for some time now that cell adhesion by means of the integrins regulates the expression of MMPs. In addition, certain MMPs can bind to integrins or other receptors on the cell surface involved in enzyme activation, thereby providing a mechanism for localized matrix degradation. By proteolytically modifying the existing matrix molecules, the MMPs can then induce changes in cell behavior and function from a state of rest to migration. During wound repair, the expression of integrins and MMPs is simultaneously up-regulated. This review will focus on those aspects of the extensive knowledge of fibroblast and keratinocyte MMPs and integrins in biological processes that relate to wound-healing.

Extracellular regulation of BMP signaling: welcome to the matrix

2017 ◽  
Vol 45 (1) ◽  
pp. 173-181 ◽  
Author(s):  
Georg Sedlmeier ◽  
Jonathan P. Sleeman
Keyword(s):  
Extracellular Matrix ◽  
Physical Properties ◽  
Bone Morphogenetic Protein ◽  
Bmp Signaling ◽  
Intracellular Level ◽  
Morphogenetic Protein ◽  
The Matrix ◽  
Mechanical Barrier

Given its importance in development and homeostasis, bone morphogenetic protein (BMP) signaling is tightly regulated at the extra- and intracellular level. The extracellular matrix (ECM) was initially thought to act as a passive mechanical barrier that sequesters BMPs. However, a new understanding about how the ECM plays an instructive role in regulating BMP signaling is emerging. In this mini-review, we discuss various ways in which the biochemical and physical properties of the ECM regulate BMP signaling.

The distribution of fibronectin, laminin and entactin in the neurulating rat embryo studied by indirect immunofluorescence

Development ◽  
1986 ◽  
Vol 94 (1) ◽  
pp. 95-112
Author(s):  
Fiona Tuckett ◽  
Gillian M. Morriss-Kay
Keyword(s):  
Extracellular Matrix ◽  
Indirect Immunofluorescence ◽  
Active Sites ◽  
Polyclonal Antibodies ◽  
Tube Formation ◽  
Basement Membranes ◽  
General Distribution ◽  
Rat Embryo ◽  
Structural Element ◽  
The Matrix

This paper forms part of our study of the extracellular matrix and its role in the morphogenesis of the brain during the period of neurulation in the rat embryo. Using indirect immunofluorescence with polyclonal antibodies, we present here a descriptive study of the distribution of the matrix glycoproteins fibronectin, laminin and entactin. The observed distribution of the fibronectin matrix implicates it in providing a structural element in several morphologically active sites; in addition our observations support the previously suggested involvement of fibronectin in the migration of neural crest cells. Entactin was present only in the basement membranes in conjunction with laminin which was not itself confined to these regions. Laminin was also identified within the mesenchymal extracellular matrix, and its general distribution confirms the previously documented role of laminin in maintaining epithelial structure and organization. No patterning in the distribution of these three glycoproteins could be correlated with the change in shape of the neural epithelium associated with either tube formation or neuromere morphogenesis.

A NUMERICAL PROOF THAT CERTAIN CELLS FOLLOW THE TRAILS OF THE DIFFUSIONS OF SOME CHEMICALS IN THE EXTRACELLULAR MATRIX

2021 ◽  
pp. 2150027
Author(s):  
İREM ÇAY ◽  
SERDAL PAMUK
Keyword(s):  
Mathematical Model ◽  
Extracellular Matrix ◽  
Tumor Angiogenesis ◽  
Numerical Solutions ◽  
Extra Cellular Matrix ◽  
The Matrix ◽  
Good Agreement ◽  
Cellular Matrix

In this work, we obtain the numerical solutions of a 2D mathematical model of tumor angiogenesis originally presented in [Pamuk S, ÇAY İ, Sazci A, A 2D mathematical model for tumor angiogenesis: The roles of certain cells in the extra cellular matrix, Math Biosci 306:32–48, 2018] to numerically prove that the certain cells, the endothelials (EC), pericytes (PC) and macrophages (MC) follow the trails of the diffusions of some chemicals in the extracellular matrix (ECM) which is, in fact, inhomogeneous. This leads to branching, the sprouting of a new neovessel from an existing vessel. Therefore, anastomosis occurs between these sprouts. In our figures we do see these branching and anastomosis, which show the fact that the cells diffuse according to the structure of the ECM. As a result, one sees that our results are in good agreement with the biological facts about the movements of certain cells in the Matrix.

Latent TGF-beta binding protein LTBP-1 contains three potential extracellular matrix interacting domains

2001 ◽  
Vol 114 (1) ◽  
pp. 187-197 ◽  
Author(s):  
C. Unsold ◽  
M. Hyytiainen ◽  
L. Bruckner-Tuderman ◽  
J. Keski-Oja
Keyword(s):  
Extracellular Matrix ◽  
Expression System ◽  
Covalent Binding ◽  
Sodium Deoxycholate ◽  
Current Data ◽  
Lung Fibroblasts ◽  
Tgf Beta ◽  
Mammalian Expression ◽  
The Matrix ◽  
Recombinant Fragments

Latent TGF-beta binding proteins (LTBPs) are components of the extracellular matrix (ECM). They belong to the fibrillin/LTBP-superfamily, and are high molecular weight glycoproteins characterized by EGF-like repeats and 8-Cys repeats. Most LTBPs associate with the small latent forms of TGF-beta. Their roles include to facilitate the secretion of latent TGF-beta and to target it to the ECM. In order to identify new matrix-binding domains of LTBP-1 and to characterize their association with the extracellular matrix, we have produced (in a mammalian expression system) partly overlapping recombinant fragments of its shorter form, LTBP-1S, and analyzed the binding of the purified fusion proteins to extracellular matrices of cultured human dermal and lung fibroblasts. Recombinant fragments from three different regions of the N- and C-termini showed affinity to the matrix. These interacting regions contain either the first (hybrid), second or fourth 8-Cys domains of the LTBP-1S molecule. They bound independently to the matrix. Each of them had an ability to inhibit the association of native exogenous LTBP-1 with fibroblast extracellular matrix. The interactions of the LTBP-1 fragments with the extracellular matrix resisted treatment with sodium deoxycholate, suggesting strong, possibly covalent binding. The binding occurred in a time- and dose-dependent fashion. The N-terminal fragments bound more readily to the matrices. With all fragments the binding took place both with intact fibroblast matrices and with matrices isolated by sodium deoxycholate. When using CHO cell layers, which form sparse matrices, only the N-terminal fragment of LTBP-1 was efficiently incorporated. The association of the binding fragments with isolated matrices was enhanced by soluble, cell-derived factors. The current data suggest that LTBP-1 contains three different domains with an ability to associate with the extracellular matrix.

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