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A. Hari Reddi - One of the best experts on this subject based on the ideXlab platform.
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Modulation of Superficial Zone Protein/Lubricin/PRG4 by Kartogenin and Transforming Growth Factor-β1 in Surface Zone Chondrocytes in Bovine Articular Cartilage.
Cartilage, 2016Co-Authors: Kazumasa Miyatake, Sean M. Mcnary, Gordon Peng, Kenjiro Iwasa, A. Hari ReddiAbstract:ObjectiveSuperficial zone protein (SZP)/lubricin/PRG4 functions as a Boundary Lubricant in articular cartilage to decrease friction and wear. As articular cartilage lubrication is critical for normal joint function, the accumulation of SZP at the surface of cartilage is important for joint homeostasis. Recently, a heterocyclic compound called kartogenin (KGN) was found to induce chondrogenic differentiation and enhance mRNA expression of lubricin. The objective of this study was to determine whether KGN can stimulate synthesis of SZP in superficial zone, articular chondrocytes.DesignWe investigated the effects of KGN and transforming growth factor-β1 (TGF-β1) on articular cartilage and synovium of the bovine knee joint by evaluating SZP secretion by enzyme-linked immunosorbent assay analysis. Monolayer, micromass, and explant cultures of articular cartilage, and monolayer culture of synoviocytes, were treated with KGN. SZP accumulation in the medium was evaluated and mRNA expression was measured through q...
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Induction of chondrogenesis and expression of superficial zone protein in synovial explants with TGF-β1 and BMP-7.
Tissue Engineering Part A, 2013Co-Authors: Takashi Iwakura, Ryosuke Sakata, A. Hari ReddiAbstract:Superficial zone protein (SZP) functions as a Boundary Lubricant in articular cartilage and decreases the coefficient of friction. As lubrication of articular cartilage is critical for normal joint function, the ability to secrete SZP at the surface of tissue-engineered cartilage is a prerequisite for optimal lubrication. Synovium-derived mesenchymal stem cells (MSCs) are thought to be an attractive cell source for cartilage regeneration. However, optimization of a three-dimensional environment is necessary for tissue engineering. In this study, we investigated whether synovial explants, which would preserve the physiologic microenvironment for MSCs therein, have the potential of SZP secretion after chondrogenic differentiation by treatment with transforming growth factor-β1 (TGF-β1) and bone morphogenetic protein-7 (BMP-7). Immunostaining and enzyme-linked immunosorbent assay analysis demonstrated that synovial explants can synthesize and secrete SZP following chondrogenic differentiation in response to ...
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Regulation of lubricin/superficial zone protein by Wnt signalling in bovine synoviocytes.
Journal of Tissue Engineering and Regenerative Medicine, 2013Co-Authors: Atsuyuki Inui, Takashi Iwakura, A. Hari ReddiAbstract:Lubricin, homologous to superficial zone protein (SZP), functions as a Boundary Lubricant in articular cartilage and plays an essential role in the maintenance of joint function and homeostasis. Wnt signalling plays a key role in joint development, including synovial joint formation, and several Wnt proteins are expressed in the synovium and articular cartilage in arthritis. The aim of this study was to determine the role of Wnt signalling on SZP accumulation in synoviocytes. Isolated synoviocytes from bovine knee joints were cultured with Wnt proteins (Wnt-3a and Wnt-5a) and antagonists or agonists of the Wnt–β-catenin pathway or Wnt–Ca2+ pathway in serum-free chemically defined medium. SZP accumulation in the culture medium was determined by enzyme-linked immunosorbent assay. Wnt-3a suppressed SZP accumulation via a Wnt–β-catenin-dependent pathway. In contrast, Wnt-5a stimulated SZP accumulation via a β-catenin independent pathway. The present investigation provides novel insights into the role of the Wnt signalling pathways in SZP accumulation in synoviocytes and their roles in the homeostasis of normal joints. Copyright © 2013 John Wiley & Sons, Ltd.
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Tribological altruism: A sacrificial layer mechanism of synovial joint lubrication in articular cartilage
Journal of Biomechanics, 2012Co-Authors: S M T Chan, Kyriakos Komvopoulos, Grayson D. Duraine, A. Hari ReddiAbstract:Boundary lubrication is characterized by sliding surfaces separated by a molecularly thin film that reduces friction and wear of the underlying substrate when fluid lubrication cannot be established. In this study, the wear and replenishment rates of articular cartilage were examined in the context of friction coefficient changes, protein loss, and direct imaging of the surface ultrastructure, to determine the efficiency of the Boundary Lubricant (BL) layer. Depletion of cartilage lubricity occurred with the concomitant loss of surface proteoglycans. Restoration of lubrication by incubation with synovial fluid was much faster than incubation with culture media and isolated superficial zone protein. The replenishment action of the BL layer in articular cartilage was rapid, with the rate of formation exceeding the rate of depletion of the BL layer to effectively protect the tissue from mechanical wear. The obtained results indicate that Boundary lubrication in articular cartilage depends in part on a sacrificial layer mechanism. The present study provides insight into the natural mechanisms that minimize wear and resist tissue degeneration over the lifetime of an organism.
Hari A Reddi - One of the best experts on this subject based on the ideXlab platform.
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modulation of superficial zone protein lubricin prg4 by kartogenin and transforming growth factor β1 in surface zone chondrocytes in bovine articular cartilage
Cartilage, 2016Co-Authors: Kazumasa Miyatake, Sean M. Mcnary, Gordon Peng, Kenjiro Iwasa, Hari A ReddiAbstract:ObjectiveSuperficial zone protein (SZP)/lubricin/PRG4 functions as a Boundary Lubricant in articular cartilage to decrease friction and wear. As articular cartilage lubrication is critical for normal joint function, the accumulation of SZP at the surface of cartilage is important for joint homeostasis. Recently, a heterocyclic compound called kartogenin (KGN) was found to induce chondrogenic differentiation and enhance mRNA expression of lubricin. The objective of this study was to determine whether KGN can stimulate synthesis of SZP in superficial zone, articular chondrocytes.DesignWe investigated the effects of KGN and transforming growth factor-β1 (TGF-β1) on articular cartilage and synovium of the bovine knee joint by evaluating SZP secretion by enzyme-linked immunosorbent assay analysis. Monolayer, micromass, and explant cultures of articular cartilage, and monolayer culture of synoviocytes, were treated with KGN. SZP accumulation in the medium was evaluated and mRNA expression was measured through q...
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regulation of lubricin superficial zone protein by wnt signalling in bovine synoviocytes
Journal of Tissue Engineering and Regenerative Medicine, 2016Co-Authors: Atsuyuki Inui, Takashi Iwakura, Hari A ReddiAbstract:Lubricin, homologous to superficial zone protein (SZP), functions as a Boundary Lubricant in articular cartilage and plays an essential role in the maintenance of joint function and homeostasis. Wnt signalling plays a key role in joint development, including synovial joint formation, and several Wnt proteins are expressed in the synovium and articular cartilage in arthritis. The aim of this study was to determine the role of Wnt signalling on SZP accumulation in synoviocytes. Isolated synoviocytes from bovine knee joints were cultured with Wnt proteins (Wnt-3a and Wnt-5a) and antagonists or agonists of the Wnt–β-catenin pathway or Wnt–Ca2+ pathway in serum-free chemically defined medium. SZP accumulation in the culture medium was determined by enzyme-linked immunosorbent assay. Wnt-3a suppressed SZP accumulation via a Wnt–β-catenin-dependent pathway. In contrast, Wnt-5a stimulated SZP accumulation via a β-catenin independent pathway. The present investigation provides novel insights into the role of the Wnt signalling pathways in SZP accumulation in synoviocytes and their roles in the homeostasis of normal joints. Copyright © 2013 John Wiley & Sons, Ltd.
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stimulation of the superficial zone protein and lubrication in the articular cartilage by human platelet rich plasma
American Journal of Sports Medicine, 2015Co-Authors: Ryosuke Sakata, Kazumasa Miyatake, Sean M. Mcnary, James M Van Den Bogaerde, Richard A Marder, Hari A ReddiAbstract:Background:Platelet-rich plasma (PRP) contains high concentrations of autologous growth factors that originate from platelets. Intra-articular injections of PRP have the potential to ameliorate the symptoms of osteoarthritis in the knee. Superficial zone protein (SZP) is a Boundary Lubricant in articular cartilage and plays an important role in reducing friction and wear and therefore is critical in cartilage homeostasis.Purpose:To determine if PRP influences the production of SZP from human joint-derived cells and to evaluate the lubricating properties of PRP on normal bovine articular cartilage.Study Design:Controlled laboratory study.Methods:Cells were isolated from articular cartilage, synovium, and the anterior cruciate ligament (ACL) from 12 patients undergoing ACL reconstruction. The concentrations of SZP in PRP and culture media were measured by enzyme-linked immunosorbent assay. Cellular proliferation was quantified by determination of cell numbers. The lubrication properties of PRP from healthy ...
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mesenchymal progenitor cells derived from synovium and infrapatellar fat pad as a source for superficial zone cartilage tissue engineering analysis of superficial zone protein lubricin expression
Tissue Engineering Part A, 2010Co-Authors: Toshiyuki Nakagawa, Hari A ReddiAbstract:Superficial zone protein (SZP) is a Boundary Lubricant of articular cartilage in joints. As SZP at the surface of articular cartilage plays an important role in the normal function of synovial joints, the localization of SZP-secreting cells at the surface of tissue-engineered cartilage is prerequisite. The aim of this study was to identify suitable progenitor cell sources for tissue engineering of superficial zone cartilage. We investigated whether mesenchymal progenitor cells (MPCs) from synovium and infrapatellar fat pad (IFP) have the potential for secretion of SZP after chondrogenic differentiation in an aggregate pellet culture system. SZP was immunolocalized in pellets from synovium-MPCs and IFP-MPCs. The enzyme-linked immunosorbent assay analysis of SZP demonstrated that chondrogenically differentiated synovium-MPC and IFP-MPC pellets secreted SZP into media. Real-time polymerase chain reaction analysis showed significant upregulation of SZP mRNA in synovium-MPC and IFP-MPC pellets after chondrogen...
Takashi Iwakura - One of the best experts on this subject based on the ideXlab platform.
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regulation of lubricin superficial zone protein by wnt signalling in bovine synoviocytes
Journal of Tissue Engineering and Regenerative Medicine, 2016Co-Authors: Atsuyuki Inui, Takashi Iwakura, Hari A ReddiAbstract:Lubricin, homologous to superficial zone protein (SZP), functions as a Boundary Lubricant in articular cartilage and plays an essential role in the maintenance of joint function and homeostasis. Wnt signalling plays a key role in joint development, including synovial joint formation, and several Wnt proteins are expressed in the synovium and articular cartilage in arthritis. The aim of this study was to determine the role of Wnt signalling on SZP accumulation in synoviocytes. Isolated synoviocytes from bovine knee joints were cultured with Wnt proteins (Wnt-3a and Wnt-5a) and antagonists or agonists of the Wnt–β-catenin pathway or Wnt–Ca2+ pathway in serum-free chemically defined medium. SZP accumulation in the culture medium was determined by enzyme-linked immunosorbent assay. Wnt-3a suppressed SZP accumulation via a Wnt–β-catenin-dependent pathway. In contrast, Wnt-5a stimulated SZP accumulation via a β-catenin independent pathway. The present investigation provides novel insights into the role of the Wnt signalling pathways in SZP accumulation in synoviocytes and their roles in the homeostasis of normal joints. Copyright © 2013 John Wiley & Sons, Ltd.
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Induction of chondrogenesis and expression of superficial zone protein in synovial explants with TGF-β1 and BMP-7.
Tissue Engineering Part A, 2013Co-Authors: Takashi Iwakura, Ryosuke Sakata, A. Hari ReddiAbstract:Superficial zone protein (SZP) functions as a Boundary Lubricant in articular cartilage and decreases the coefficient of friction. As lubrication of articular cartilage is critical for normal joint function, the ability to secrete SZP at the surface of tissue-engineered cartilage is a prerequisite for optimal lubrication. Synovium-derived mesenchymal stem cells (MSCs) are thought to be an attractive cell source for cartilage regeneration. However, optimization of a three-dimensional environment is necessary for tissue engineering. In this study, we investigated whether synovial explants, which would preserve the physiologic microenvironment for MSCs therein, have the potential of SZP secretion after chondrogenic differentiation by treatment with transforming growth factor-β1 (TGF-β1) and bone morphogenetic protein-7 (BMP-7). Immunostaining and enzyme-linked immunosorbent assay analysis demonstrated that synovial explants can synthesize and secrete SZP following chondrogenic differentiation in response to ...
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Regulation of lubricin/superficial zone protein by Wnt signalling in bovine synoviocytes.
Journal of Tissue Engineering and Regenerative Medicine, 2013Co-Authors: Atsuyuki Inui, Takashi Iwakura, A. Hari ReddiAbstract:Lubricin, homologous to superficial zone protein (SZP), functions as a Boundary Lubricant in articular cartilage and plays an essential role in the maintenance of joint function and homeostasis. Wnt signalling plays a key role in joint development, including synovial joint formation, and several Wnt proteins are expressed in the synovium and articular cartilage in arthritis. The aim of this study was to determine the role of Wnt signalling on SZP accumulation in synoviocytes. Isolated synoviocytes from bovine knee joints were cultured with Wnt proteins (Wnt-3a and Wnt-5a) and antagonists or agonists of the Wnt–β-catenin pathway or Wnt–Ca2+ pathway in serum-free chemically defined medium. SZP accumulation in the culture medium was determined by enzyme-linked immunosorbent assay. Wnt-3a suppressed SZP accumulation via a Wnt–β-catenin-dependent pathway. In contrast, Wnt-5a stimulated SZP accumulation via a β-catenin independent pathway. The present investigation provides novel insights into the role of the Wnt signalling pathways in SZP accumulation in synoviocytes and their roles in the homeostasis of normal joints. Copyright © 2013 John Wiley & Sons, Ltd.
Carlos Drummond - One of the best experts on this subject based on the ideXlab platform.
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Experimental Study and Modeling of Boundary Lubricant Polyelectrolyte Films
Macromolecules, 2015Co-Authors: Anne-sophie Bouchet, Colette Cazeneuve, Nawel Baghdadli, Gustavo S. Luengo, Carlos DrummondAbstract:Strongly adsorbed polyelectrolytes are central in the conditioning properties of many personal care products. Whereas the mechanism of polymer adsorption is rather well understood, less is known about the actual mechanism of polyelectrolyte lubrication. We investigated the adsorption on mica and the Lubricant properties of a strong polyelectrolyte, poly- (diallyldimethylammonium chloride), polyDADMAC, in aqueous solutions of different salt concentrations. We found that the adsorption of the polymer was enhanced and the morphology of the adsorbed layer modified by increasing salt concentration. The Lubricant properties of the adsorbed polyelectrolyte layer were good at low compressions but rapidly deteriorated at larger applied pressure. A complex velocity dependence of the friction was observed, with a maximum value at intermediate velocities and hysteresis in an acceleration/ deceleration cycle. A progressive increase in separation between the rubbing surfaces with velocity was also observed. We developed a model that describes the complex behavior of friction observed, taking into account the hysteretic elastic deformation of the polymer layer under shear and the dilatency due to the elastohydrodynamic effects resulting from its low elastic modulus. Our results can help to explain the significant lasting of the lubricating properties when polyDADMAC is used in conditioners, where polymer-lubricated hair-hair contacts exhibit low shear forces.
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experimental study and modeling of Boundary Lubricant polyelectrolyte films
Macromolecules, 2015Co-Authors: Anne-sophie Bouchet, Colette Cazeneuve, Nawel Baghdadli, Gustavo S. Luengo, Carlos DrummondAbstract:Strongly adsorbed polyelectrolytes are central in the conditioning properties of many personal care products. Whereas the mechanism of polymer adsorption is rather well understood, less is known about the actual mechanism of polyelectrolyte lubrication. We investigated the adsorption on mica and the Lubricant properties of a strong polyelectrolyte, poly(diallyldimethylammonium chloride), polyDADMAC, in aqueous solutions of different salt concentrations. We found that the adsorption of the polymer was enhanced and the morphology of the adsorbed layer modified by increasing salt concentration. The Lubricant properties of the adsorbed polyelectrolyte layer were good at low compressions but rapidly deteriorated at larger applied pressure. A complex velocity dependence of the friction was observed, with a maximum value at intermediate velocities and hysteresis in an acceleration/deceleration cycle. A progressive increase in separation between the rubbing surfaces with velocity was also observed. We developed a...
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Boundary Lubricant polymer films effect of cross linking
Langmuir, 2013Co-Authors: Suzanne Giasson, Jeannemarie Lagleize, Juan Rodriguezhernandez, Carlos DrummondAbstract:We have studied the adsorption and Lubricant properties of a multifunctional triblock copolymer poly(l-lysine)-b-poly(acrylic acid)-b-poly(l-lysine). In particular, we investigated the nature of the layer adsorbed under different conditions of polymer and salt concentration and the Lubricant properties of the polymer layer before and after its chemical cross-linking by bridging the poly(acrylic acid) blocks. We found that the amount of polymer adsorbed is controlled by the ionic strength and the polymer concentration in the solution. In all cases, the self-assembled polymer layer is a poor Lubricant before cross-linking, but the cohesion and load-carrying ability of the layer are substantially improved by this reaction. However, the chemically cross-linked coating has a limited deformation capacity as a consequence of its permanent network nature, and irreversible damage is observed after excessive strain of the film.
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delamination and renovation of a molecular surfactant polymer Boundary Lubricant film
Langmuir, 2009Co-Authors: J M Lagleize, P Richetti, Carlos DrummondAbstract:We have studied the behavior under compression and shear of two molecularly smooth mica surfaces immersed in aqueous solutions of a dimeric cationic surfactant and an oppositely charged polyelectrolyte-neutral diblock copolymer by using a surface force apparatus-nanotribometer, SFA-N. The surfactant and copolymer coadsorb as a mix molecular Boundary Lubricant film on the negatively charged mica surfaces leading to low friction in a sliding mechanical contact. However, under fritting conditions, shearing can induce different dynamic transitions of the confined films. Transitions from the initial low friction steady state to new steady states of low or high friction can be induced when the sliding velocity is increased above certain values. These dynamical transitions occur together with thickness reduction of the confined film. A reverse transition to the low friction steady state accompanied by the renovation of the film can be triggered by reintroducing some matter in the contact, via increasing the amplitude of the fritting cycles.
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Boundary Lubricant films under shear: effect of roughness and adhesion
Journal of Chemical Physics, 2007Co-Authors: Carlos Drummond, Juan Rodriguez-hernandez, Sébastien Lecommandoux, Philippe RichettiAbstract:The normal interaction and the behavior under shear of mica surfaces covered by two different triblock copolymers of polylysine-polydimethysiloxane-polylysine were studied by combining the capabilities of the surface forces apparatus and the atomic force microscopy. At low pH values these copolymers spontaneously adsorb on the negatively charged mica surfaces from aqueous solutions as a consequence of the positive charge of the polylysine moieties. The morphology of the adsorbed layer is determined by the molecular structure of the particular copolymer investigated. This morphology plays a fundamental role on the behavior of the adsorbed layers under shear and compression. While nonadhesive smooth layers oppose an extremely small resistance to sliding, the presence of asperities even at the nanometric scale originates a frictional resistance to the motion. The behavior of uniform nonadhesive nanorough surfaces under shear can be quantitatively understood in terms of a simple multistable thermally activated junction model. The electric charge of the adsorbed copolymer molecules and hence the adhesion energy between the coated surfaces can be modified by varying the pH of the surrounding media. In the presence of an adhesive interaction between the surfaces the behavior under shear is strongly modified. Time-dependent mechanisms of energy dissipation have to be evoked in order to explain the changes observed
Atsuyuki Inui - One of the best experts on this subject based on the ideXlab platform.
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regulation of lubricin superficial zone protein by wnt signalling in bovine synoviocytes
Journal of Tissue Engineering and Regenerative Medicine, 2016Co-Authors: Atsuyuki Inui, Takashi Iwakura, Hari A ReddiAbstract:Lubricin, homologous to superficial zone protein (SZP), functions as a Boundary Lubricant in articular cartilage and plays an essential role in the maintenance of joint function and homeostasis. Wnt signalling plays a key role in joint development, including synovial joint formation, and several Wnt proteins are expressed in the synovium and articular cartilage in arthritis. The aim of this study was to determine the role of Wnt signalling on SZP accumulation in synoviocytes. Isolated synoviocytes from bovine knee joints were cultured with Wnt proteins (Wnt-3a and Wnt-5a) and antagonists or agonists of the Wnt–β-catenin pathway or Wnt–Ca2+ pathway in serum-free chemically defined medium. SZP accumulation in the culture medium was determined by enzyme-linked immunosorbent assay. Wnt-3a suppressed SZP accumulation via a Wnt–β-catenin-dependent pathway. In contrast, Wnt-5a stimulated SZP accumulation via a β-catenin independent pathway. The present investigation provides novel insights into the role of the Wnt signalling pathways in SZP accumulation in synoviocytes and their roles in the homeostasis of normal joints. Copyright © 2013 John Wiley & Sons, Ltd.
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Regulation of lubricin/superficial zone protein by Wnt signalling in bovine synoviocytes.
Journal of Tissue Engineering and Regenerative Medicine, 2013Co-Authors: Atsuyuki Inui, Takashi Iwakura, A. Hari ReddiAbstract:Lubricin, homologous to superficial zone protein (SZP), functions as a Boundary Lubricant in articular cartilage and plays an essential role in the maintenance of joint function and homeostasis. Wnt signalling plays a key role in joint development, including synovial joint formation, and several Wnt proteins are expressed in the synovium and articular cartilage in arthritis. The aim of this study was to determine the role of Wnt signalling on SZP accumulation in synoviocytes. Isolated synoviocytes from bovine knee joints were cultured with Wnt proteins (Wnt-3a and Wnt-5a) and antagonists or agonists of the Wnt–β-catenin pathway or Wnt–Ca2+ pathway in serum-free chemically defined medium. SZP accumulation in the culture medium was determined by enzyme-linked immunosorbent assay. Wnt-3a suppressed SZP accumulation via a Wnt–β-catenin-dependent pathway. In contrast, Wnt-5a stimulated SZP accumulation via a β-catenin independent pathway. The present investigation provides novel insights into the role of the Wnt signalling pathways in SZP accumulation in synoviocytes and their roles in the homeostasis of normal joints. Copyright © 2013 John Wiley & Sons, Ltd.