scholarly journals Stimulation of corneal differentiation by interaction between cell surface and extracellular matrix. I. Morphometric analysis of transfilter "induction".

1975 ◽  
Vol 66 (2) ◽  
pp. 275-291 ◽  
Author(s):  
L Meier ◽  
E D Hay
Keyword(s):  
Extracellular Matrix ◽  
Electron Microscope ◽  
Cell Surface ◽  
Pore Size ◽  
Collagen Synthesis ◽  
Lens Capsule ◽  
Physical Contact ◽  
Corneal Epithelial ◽  
Cell Processes

The present study was undertaken to determine whether or not physical contact with the substratum is essential for the stimulatory effect of extracellular matrix (ECM) on corneal epithelial collagen synthesis. Previous studies showed that collagenous substrata stimulate isolated epithelia to produce three times as much collagen as they produce on noncollagenous substrate; killed collagenous substrata (e.g., lens capsule) are just as effective as living substrata (e.g., living lens) in promoting the production of new corneal stroma in vitro. In the experiments to be reported here, corneal epithelia were placed on one side of Nucleopore filters of different pore sizes and killed lens capsule on the other, with the expectation that contact of the reacting cells with the lens ECM should be limited by the number and size of the cell processes that can tranverse the pores. Transfilter cultures were grown for 24 h in [3H]proline-containing median and incorporation of isotope into hot trichloroacetic acid-soluble protein was used to measure corneal epithelial collagen production. Epithelial collagen synthesis increases directly as the size of the pores in the interposed filter increases and decreases as the thickness of the filter layer increases. Cell processes within Nucleopore filters were identified with the transmission electron microscope with difficulty; with the scanning electron microscope, however, the processes could easily be seen emerging from the undersurface of even 0.1-mum pore size filters. Morphometric techniques were used to show that cell surface area thus exposed to the underlying ECM is linearly correlated with enhancement of collagen synthesis. Epithelial cell processes did not pass through ultrathin (25-mum thick) 0.45-mum pore size Millipore filters nor did "induction" occur across them. The results are discussed in relation to current theories of embryonic tissue interaction.

scholarly journals Enhanced Piezoelectric Fibered Extracellular Matrix to Promote Cardiomyocyte Maturation and Tissue Formation: A 3D Computational Model

Biology ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 135
Author(s):  
Pau Urdeitx ◽  
Mohamed H. Doweidar
Keyword(s):  
Extracellular Matrix ◽  
Cell Migration ◽  
Computational Models ◽  
Cell Junctions ◽  
Tissue Formation ◽  
Cardiac Muscle Cells ◽  
Cell Processes ◽  
Electrical Stimuli ◽  
Cell Cell

Mechanical and electrical stimuli play a key role in tissue formation, guiding cell processes such as cell migration, differentiation, maturation, and apoptosis. Monitoring and controlling these stimuli on in vitro experiments is not straightforward due to the coupling of these different stimuli. In addition, active and reciprocal cell–cell and cell–extracellular matrix interactions are essential to be considered during formation of complex tissue such as myocardial tissue. In this sense, computational models can offer new perspectives and key information on the cell microenvironment. Thus, we present a new computational 3D model, based on the Finite Element Method, where a complex extracellular matrix with piezoelectric properties interacts with cardiac muscle cells during the first steps of tissue formation. This model includes collective behavior and cell processes such as cell migration, maturation, differentiation, proliferation, and apoptosis. The model has employed to study the initial stages of in vitro cardiac aggregate formation, considering cell–cell junctions, under different extracellular matrix configurations. Three different cases have been purposed to evaluate cell behavior in fibered, mechanically stimulated fibered, and mechanically stimulated piezoelectric fibered extra-cellular matrix. In this last case, the cells are guided by the coupling of mechanical and electrical stimuli. Accordingly, the obtained results show the formation of more elongated groups and enhancement in cell proliferation.

Developmental aspects of secondary palate formation

Development ◽  
1976 ◽  
Vol 36 (2) ◽  
pp. 225-245
Author(s):  
Robert M. Greene ◽  
Robert M. Pratt
Keyword(s):  
Extracellular Matrix ◽  
Cell Death ◽  
Epithelial Cells ◽  
Cell Surface ◽  
Hydrolytic Enzymes ◽  
Cellular Adhesion ◽  
Control Mechanisms ◽  
Adhesive Interaction ◽  
Secondary Palate

Research on development of the secondary palate has, in the past, dealt primarily with morphological aspects of shelf elevation and fusion. The many factors thought to be involved in palatal elevation, such as fetal neuromuscular activity and growth of the cranial base and mandible, as well as production of extracellular matrix and contractile elements in the palate, are mostly based on gross, light microscopic, morphometric or histochemical observations. Recently, more biochemical procedures have been utilized to describe palatal shelf elevation. Although these studies strongly suggest that palatal extracellular matrix plays a major role in shelf movement, interpretation of these data remains difficult owing to the complexity of tissue interactions involved in craniofacial development. Shelf elevation does not appear to involve a single motive factor, but rather a coordinated interaction of all of the abovementioned developmental events. Further analysis of mechanisms of shelf elevation requires development of new, and refinement of existing, in vitro procedures. A system that enables one to examine shelf elevation in vitro would allow more meaningful analysis of the relative importance of the various components in shelf movement. Much more is known about fusion of the palatal shelves, owing in large part to in vitro studies. Fusion of the apposing shelves, both in vivo and in vitro, is dependent upon adhesion and cell death of the midline epithelial cells. Adhesion between apposing epithelial surfaces appears to involve epithelial cell surface macromolecules. Further analysis of palatal epithelial adhesion should be directed towards characterization of those cell surface components responsible for this adhesive interaction. Midline epithelial cells cease DNA synthesis 24–36 h before shelf elevation and contact, become active in the synthesis of cell surface glycoproteins, and subsequently manifest morphological signs of necrosis. Death of the midline epithelial cells is thought to involve a programmed, lysosomal-mediated autolysis. Information regarding the appearance, distribution and quantitation of epithelial hydrolytic enzymes is needed. The control mechanisms which regulate adhesiveness and cell death in the palatal epithelium are not fully understood. Although palatal epithelial-mesenchymal recombination experiments have demonstrated a close relationship between the underlying mesenchyme and the differentiating epithelium, the molecular mechanism of interaction remains unclear. Recently cyclic nucleotides have been implicated as possible mediators of palatal epithelial differentiation. The developing secondary palate therefore offers a system whereby one can probe a variety of developmental phenomena. Cellular adhesion, programmed cell death and epithelial- mesenchymal interactions are all amenable to both morphological as well as bio- chemical analysis. Although research in the field of secondary palate development has been extensive, there still remain many provocative questions relating to normal development of this structure.

scholarly journals MT1-MMP–dependent neovessel formation within the confines of the three-dimensional extracellular matrix

2004 ◽  
Vol 167 (4) ◽  
pp. 757-767 ◽  
Author(s):  
Tae-Hwa Chun ◽  
Farideh Sabeh ◽  
Ichiro Ota ◽  
Hedwig Murphy ◽  
Kevin T. McDonagh ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Endothelial Cells ◽  
Cell Surface ◽  
Type I Collagen ◽  
Ex Vivo ◽  
Three Dimensional ◽  
Collagenolytic Activity ◽  
Type I ◽  
Ex Vivo Model

During angiogenesis, endothelial cells initiate a tissue-invasive program within an interstitial matrix comprised largely of type I collagen. Extracellular matrix–degradative enzymes, including the matrix metalloproteinases (MMPs) MMP-2 and MMP-9, are thought to play key roles in angiogenesis by binding to docking sites on the cell surface after activation by plasmin- and/or membrane-type (MT) 1-MMP–dependent processes. To identify proteinases critical to neovessel formation, an ex vivo model of angiogenesis has been established wherein tissue explants from gene-targeted mice are embedded within a three-dimensional, type I collagen matrix. Unexpectedly, neither MMP-2, MMP-9, their cognate cell-surface receptors (i.e., β3 integrin and CD44), nor plasminogen are essential for collagenolytic activity, endothelial cell invasion, or neovessel formation. Instead, the membrane-anchored MMP, MT1-MMP, confers endothelial cells with the ability to express invasive and tubulogenic activity in a collagen-rich milieu, in vitro or in vivo, where it plays an indispensable role in driving neovessel formation.

scholarly journals Lectin binding to neural crest cells. Changes of the cell surface during differentiation in vitro.

1978 ◽  
Vol 76 (3) ◽  
pp. 628-638 ◽  
Author(s):  
M Sieber-Blum ◽  
A M Cohen
Keyword(s):  
Cell Surface ◽  
Neural Crest ◽  
Lectin Binding ◽  
Neural Crest Cells ◽  
Nerve Fibers ◽  
Con A ◽  
Contact Points ◽  
Cell Processes ◽  
Surface Carbohydrates

To examine possible changes in cell surface carbohydrates, fluorescent lectins were applied at various times during differentiation of neural crest cells in vitro. The pattern and intensity of binding of several lectins changed as the crest cells developed into melanocytes and adrenergic cells. Considerable amounts of concanavalin A (Con A) and wheat germ agglutinin (WGA) bound to all unpigmented cells throughout the culture period. Melanocytes, however, bound much less of these lectins. Soy bean agglutinin (SBA), unlike Con A and WGA, only bound later in development to unpigmented cells at about the time when catecholamines were detected histochemically. Binding of SBA could be induced in younger cultures by pretreating the cells with neuraminidase. Melanocytes, however, did not bind detectable amounts of SBA even if treated with neuraminidase. The SBA-binding sites were often concentrated on cytoplasmic extensions and on contact points between neighboring cells, even when receptor mobility was restricted by prefixation of the cells or adsorption of lectin at 0 degrees C. All three lectins bound to cell processes resembling nerve fibers in particularly high amounts.

Transfilter studies on the mechanism of epitheliomesenchymal interaction leading to chondrogenic differentiation of neural crest cells

Development ◽  
1983 ◽  
Vol 75 (1) ◽  
pp. 165-188
Author(s):  
Linda Smith ◽  
Peter Thorogood
Keyword(s):  
Neural Crest ◽  
Pore Size ◽  
Direct Contact ◽  
Chondrogenic Differentiation ◽  
Causal Mechanism ◽  
Pigmented Epithelium ◽  
Cell Processes ◽  
Scanning Electron

Interaction with an epithelium is a prerequisite for avian cranial neural crest (NC) cells to differentiate into cartilage and bone (Bee & Thorogood, 1980). In order to investigate the causal mechanism we have selected one such interaction - that between mesencephalic NC and retinal pigmented epithelium (RPE) for further study. Premigratory NC cells were grown transfilter to RPE explants of different developmental ages and on Nuclepore filters of different pore size which either allowed or prevented penetration by cell processes. Initial scanning electron microscopy (SEM) observations established that pores of 0·8 μm allowed the passage of cell processes through the filter whereas 0·2 μm pores did not. The transfilter experiments demonstrated that chondrogenic differentiation of NC cells will occur only if the Nuclepore filters have a pore size large enough to permit the passage of cell processes. Furthermore SEM observations established that cell processes do traverse the Nuclepore filter when NC and RPE are grown in transfilter combination. The results indicate that the mechanism is not mediated by diffusable factors but rather is mediated either by direct contact between NC cells and non-diffusable matrix closely associated with RPE or by direct plasmalemmal contact between RPE and NC cells through discontinuities in the basement membrane. The results of these experiments also demonstrate that younger (stage 17) RPE is more effective at eliciting chondrogenesis from premigratory NC cells than older (stage 24) RPE and that the interaction between RPE and NC cells is a prolonged one, taking place over days rather than within hours. Both of these in vitro observations are compatible with the timing of events leading to scleral cartilage formation in vivo.

Ectoderm and mesoderm interactions in the limb bud of the chick embryo studied by transfilter cultures: cartilage differentiation and ultrastructural observations

Development ◽  
1980 ◽  
Vol 59 (1) ◽  
pp. 157-173
Author(s):  
Madeleine Gumpel-Pinot
Keyword(s):  
Chick Embryo ◽  
Pore Size ◽  
Limb Bud ◽  
Mesoderm Cell ◽  
Cartilage Differentiation ◽  
Cell Processes ◽  
Upper Face ◽  
Wing Bud

The wing mesoderm of the chick embryo cultured in vitro without ectoderm is able to differentiate into cartilage from stage 17 (Hamburger & Hamilton, 1951). But before this stage the presence of ectoderm is necessary. In transfilter cultures of wing-bud ectoderm and mesoderm, the mesodermal response as measured by chondrogenesis was directly related to the pore size (0·2–1 μm) of the filter. Filters of 0·2 μm pore size and 10 μm thickness gave no increase in chondrogenesis over that of mesoderm cultures alone. The lower face of filters on the upper face of which mesoderm or ectoderm had been cultured was observed by scanning electron microscopy. With ectoderm, no cell processes crossed the filter. In contrast, with mesoderm, cell processes crossed the filter and this was also related to pore size. A good correlation was observed between the mass and density of processes crossing the filter and the mesodermal response. It is concluded that induction of cartilage in limb mesoderm cannot be classified as a ‘long-range transmission’ system. It requires ectoderm and mesoderm to be separated by a very narrow gap and this condition can be brought about in vitro by extension of mesodermal processes through the filter close to the ectoderm. The results are discussed in relation to a possible role of the basement membrane and associated extracellular matrix in limb cartilage induction.

scholarly journals Ligand-mediated autophosphorylation activity of the epidermal growth factor receptor during internalization.

1989 ◽  
Vol 109 (6) ◽  
pp. 2751-2760 ◽  
Author(s):  
W H Lai ◽  
P H Cameron ◽  
J J Doherty ◽  
B I Posner ◽  
J J Bergeron
Keyword(s):  
Electron Microscope ◽  
Cell Surface ◽  
Egf Receptor ◽  
Growth Factor Receptor ◽  
Receptor Complexes ◽  
Diminished Capacity ◽  
Epidermal Growth ◽  
Polyethylene Glycol Precipitation

The association of EGF with its receptor in endosomes isolated from rat liver homogenates was assessed biochemically by polyethylene glycol precipitation and morphologically by electron microscope radioautography. The proportion of receptor-bound ligand in endosomes at 15 min after the injection of doses of 0.1 and 1 microgram EGF/100 g body weight was 57%. This value increased to 77% for the dose of 10 micrograms EGF injected. Quantitative electron microscope radioautography carried out on endosomes isolated at 15 min after the injection of 10 micrograms 125I-EGF demonstrated that most radiolabel was over the endosomal periphery thereby indicating that ligand-receptor complexes were in the bounding membrane but not in intraluminal vesicles of the content. EGF receptor autophosphorylation activity during internalization was evaluated in plasmalemma and endosome fractions. This activity was markedly but transiently reduced on the cell surface shortly after the administration of saturating doses of EGF. The same activity, however, was augmented and prolonged in endosomes for up to 30 min after EGF injection. The transient desensitization of cell surface activity was not due to prior in vivo phosphorylation since receptor dephosphorylation in vitro failed to restore autophosphorylation activity. Transient desensitization of cell surface autophosphorylation activity coincided with a diminished capacity for endocytosis of 125I-EGF with endocytosis returning to normal after the restoration of cell surface autophosphorylation activity. The inhibition of cell surface autophosphorylation activity and the activation of endosomal autophosphorylation activity coincident with downregulation suggest that EGF receptor traffic is governed by ligand-regulated phosphorylation activity.

scholarly journals Comparison of the effects of triamcinolone acetonide or platelet-rich plasma on expression of extracellular matrix-related genes in equine healthy chondrocytes in vitro

2019 ◽  
Vol 49 (7) ◽  
Author(s):  
Heloisa Einloft Palma ◽  
Miguel Gallio ◽  
Gabriele Biavaschi da Silva ◽  
Camila Cantarelli ◽  
Kalyne Bertolin ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Collagen Synthesis ◽  
Platelet Rich Plasma ◽  
Joint Damage ◽  
Type Ii Collagen ◽  
Control Group ◽  
Type Ii ◽  
Healthy Cartilage ◽  
Pro Inflammatory Cytokines

ABSTRACT: In healthy cartilage, chondrocytes maintain an expression of collagens and proteoglycans and are sensitive to growth factors and cytokines that either enhance or reduce type II collagen synthesis. In osteoarthritis, pro-inflammatory cytokines, such as IL-6, induce overexpression of metalloproteinases (MMP) and decreasing synthesis of aggrecan. Use of chondroprotectors agents, such as Platelet-Rich Plasma (PRP) and triamcinolone (TA) are alternatives to reduce the progression of joint damage. In this study, we used chondrocytes extracted from metacarpophalangeal joints of healthy horses as the experimental model. Cells were treated in vitro with PRP or TA. No differences were observed between these treatments in comparison to the control group when the expressions of MMP9, MMP13, IL-6 and ACAN genes were evaluated (P<0.05). With these results, we can suggest that the treatments were not deleterious to equine cultured chondrocyte, once they did not stimulate MMPs and IL-6 synthesis or caused changes in ACAN.

Oxidative stress regulates collagen synthesis and matrix metalloproteinase activity in cardiac fibroblasts

2001 ◽  
Vol 280 (1) ◽  
pp. C53-C60 ◽  
Author(s):  
Deborah A. Siwik ◽  
Patrick J. Pagano ◽  
Wilson S. Colucci
Keyword(s):  
Oxidative Stress ◽  
Extracellular Matrix ◽  
Collagen Synthesis ◽  
Cardiac Fibroblasts ◽  
Antioxidant Systems ◽  
Leucine Incorporation ◽  
Gelatinase Activity ◽  
Adult Rat ◽  
Endogenous Antioxidant

Oxidative stress has been implicated in the pathophysiology of myocardial failure. We tested the hypothesis that oxidative stress can regulate extracellular matrix in cardiac fibroblasts. Neonatal and adult rat cardiac fibroblasts in vitro were exposed to H2O2 (0.05–5 μM) or the superoxide-generating system xanthine (500 μM) plus xanthine oxidase (0.001–0.1 mU/ml) (XXO) for 24 h. In-gel zymography demonstrated that H2O2 and XXO each increased gelatinase activity corresponding to matrix metalloproteinases (MMP) MMP-13, MMP-2, and MMP-9. H2O2 and XXO decreased collagen synthesis (collagenase-sensitive [3H]proline incorporation) without affecting total protein synthesis ([3H]leucine incorporation). H2O2 and XXO decreased the expression of procollagen α1(I), α2(I), and α1(III) mRNA but increased the expression of fibronectin mRNA, suggesting a selective transcriptional effect on collagen synthesis. H2O2, but not XXO, also decreased the expression of nonfibrillar procollagen α1(IV) and α2(IV) mRNA. To determine the role of endogenous antioxidant systems, cells were treated with the superoxide dismutase (SOD) inhibitor diethyldithiocarbamic acid (DDC, 100 μM) to increase intracellular superoxide or with the glucose-6-phosphate dehydrogenase inhibitor dehydroisoandrosterone 3-acetate (DHEA; 10 μM) to increase intracellular H2O2. DDC and DHEA decreased collagen synthesis and increased MMP activity, and both effects were inhibited by an SOD/catalase mimetic. Thus increased oxidative stress activates MMPs and decreases fibrillar collagen synthesis in cardiac fibroblasts. Oxidative stress may play a role in the pathogenesis of myocardial remodeling by regulating the quantity and quality of extracellular matrix.

scholarly journals Spatial and Temporal Distribution of Arabinogalactan Proteins during Larix decidua Mill. Male Gametophyte and Ovule Interaction

2021 ◽  
Vol 22 (9) ◽  
pp. 4298
Author(s):  
Katarzyna Rafińska ◽  
Katarzyna Niedojadło ◽  
Michał Świdziński ◽  
Janusz Niedojadło ◽  
Elżbieta Bednarska-Kozakiewicz
Keyword(s):  
Extracellular Matrix ◽  
Pollen Tube ◽  
Male Gametophyte ◽  
Temporal Distribution ◽  
Arabinogalactan Proteins ◽  
Larix Decidua ◽  
Pollen Grain ◽  
Physical Contact ◽  
Germination Of Pollen

The role of ArabinoGalactan Proteins (AGPs) in the sexual reproduction of gymnosperms is not as well documented as that of angiosperms. In earlier studies, we demonstrated that AGPs play important roles during ovule differentiation in Larix decidua Mill. The presented results encouraged us to carry out further studies focused on the functions of these unique glycoproteins during pollen/pollen tube and ovule interactions in Larix. We identified and analyzed the localization of AGPs epitopes by JIM4, JIM8, JIM13 and LM2 antibodies (Abs) in male gametophytes and ovule tissue during pollination, the progamic phase, and after fertilization and in vitro growing pollen tubes. Our results indicated that (1) AGPs recognized by JIM4 Abs play an essential role in the interaction of male gametophytes and ovules because their appearance in ovule cells is induced by physical contact between reproductive partners; (2) after pollination, AGPs are secreted from the pollen cytoplasm into the pollen wall and contact the extracellular matrix of stigmatic tip cells followed by micropylar canal cells; (3) AGPs synthesized in nucellus cells before pollen grain germination are secreted during pollen tube growth into the extracellular matrix, where they can directly interact with male gametophytes; (4) in vitro cultured pollen tube AGPs labeled with LM2 Abs participate in the germination of pollen grain, while AGPs recognized by JIM8 Abs are essential for pollen tube tip growth.

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