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Bio-medical materials and engineering 02/2008; 18(4-5):213-20. · 1.23 Impact Factor
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ABSTRACT: To investigate whether the chondrocytes-alginate construct properties, such as cell seeding density and alginate concentration might affect the redifferentiation, dedifferentiated rat articular chondrocytes were encapsulated at low density (LD: 3 x 10(6) cells/ml) or high density (HD: 10 x 10(6) cells/ml) in two different concentrations of alginate gel (1.2% or 2%, w/v) to induce redifferentiation. Cell viability and cell proliferation of LD culture was higher than those of HD culture. The increase in alginate gel concentration did not make an obvious difference in cell viability, but reduced cell proliferation rate accompanied with the decrease of cell population in S phase and G2/M phase. Scan electron microscopy observation revealed that chondrocytes maintained round in shape and several direct cell-cell contacts were noted in HD culture. In addition, more extracellular matrix was observed in the pericellular region of chondrocytes in 2% alginate culture than those in 1.2% alginate culture. The same tendency was found for the synthesis of collagen type II. No noticeable expression of collagen type I was detected in all constructs at the end of 28-day cultures. These results suggested that construct properties play an important role in the process of chondrocytes' redifferentiation and should be considered for creating of an appropriate engineered articular cartilage.
Biorheology 02/2008; 45(3-4):527-38. · 1.93 Impact Factor
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ABSTRACT: Osteoarthritis (OA) is a progressive joint disease which represents a combination of several disorders leading to cartilage degradation. The production of nitric oxide (NO) by iNOS, which is stimulated by proinflammatory mediators, is involved in cartilage catabolism and should therefore be considered a potential target for therapeutic interventions. Diacerein is a slow-acting drug that may slow down the breakdown of cartilage and relieve pain and swelling. Diacerhein, in contrast to an NSAID, is a potent inhibitor of IL-1beta induced NO production by chondrocytes and cartilage. This effect appeared to result from iNOS transcriptional and/or post-transcriptional events, maybe by the inhibition of the NF-kappaB transcription factor. This paper presents results on the influence of Diacerein on NO production.
Bio-medical materials and engineering 02/2008; 18(1 Suppl):S99-104. · 1.23 Impact Factor
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ABSTRACT: Tissue engineering requires the response of the cells to different stimuli inducing the synthesis of the extracellular matrix (ECM). It was been shown that mechanical and biochemical stimuli acted on the synthesis of ECM, particularly type I and III collagens. Growth factors implied in transduction pathways are multiple, but the main is TGF-beta. Member of the transforming growth factor-beta (TGF-beta) family bind to type II and type I serine/threonine kinase receptors, which initiate intracellular signals through activation of SMADs proteins. Nevertheless, the effects of mechanical stress of this pathway remain unknown. The aim of this work was to study the pathway of TGF-beta via the SMADs proteins under mechanical (stretching) and biochemical (TGF-beta) stimulations. Endogenous SMADs expression and its modulation by biochemical and mechanical stimulations were evaluated by both flow cytometry and confocal microscopy. Our results demonstrate that 10 ng of TGF-beta and stretching (5%, 1 Hz) applied during 15 min induced a negative feed back loop which blocks the signalling pathway to control TGF-beta activity. This inhibition effect was raised after 1 h of stimulation. Nevertheless, these preliminary studies should be continued by study of expression and localization of inhibitory SMADs (SMAD7).
Bio-medical materials and engineering 02/2008; 18(1 Suppl):S77-86. · 1.23 Impact Factor
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ABSTRACT: Vascular endothelial cells form a monocellular layer on blood vessel walls with an estimated mass of 1.5 kg. One of the roles of endothelial cells is to control the hemodynamics through various metabolic activities affecting homeostasis, vascular tonus, blood fluidity, coagulating properties and blood cell adhesion. In other respects thousands of studies have underlined the crucial role of local blood flow conditions on their properties. However, the hemodynamic forces are different according to the anatomical site and to the type of blood vessels (arteries, veins, venules, ...). In microcirculation, the endothelial cells in the venules are particularly active and constitute the physiological site of liquid exchange (permeability) and above all cellular transit. During critical ischemia, the post-capillary venules are deeply involved. In other respects the properties of endothelial cells may be impaired in many diseases as atherosclerosis, hypertension, inflammation and metabolic diseases.
Clinical hemorheology and microcirculation 02/2007; 37(1-2):5-8. · 3.40 Impact Factor
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ABSTRACT: The cartilage is a hydrated connective tissue in joints that withstands and distributes mechanical forces. The chondrocytes utilize mechanical signals to regulate their metabolic activity through complex biological and biophysical interactions with the extracellular matrix (ECM). The aim of this work was to study the influence of mechanical stress on cells behavior cultured in 3D biosystems (alginate and alginate supplemented with hyaluronate). After mechanical stimulation, cell viability and cell death process were the main studied parameters. Our results indicated that viability and cell cycle progression were inhibited under mechanical stimulation, as far as the extracellular matrix was not yet synthesized. In contrast, on day 21, the mechanical stimulation had positive effect on these parameters.
Biorheology 02/2006; 43(3-4):371-5. · 1.93 Impact Factor
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Biorheology 02/2006; 43(3-4):171-80. · 1.93 Impact Factor
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ABSTRACT: Several factors are known to be involved in the destruction of the articular cartilage. Interleukin-1 (IL-1) plays an important role in the pathogenesis of osteoarthritis (OA) either directly or through the stimulation of catabolic factors. The action of IL-1 on articular cartilage is multifaceted and it most likely plays an important role in the mechanism of cartilage destruction. IL-1 suppresses the synthesis of the cartilage matrix components and promotes the degradation of cartilage matrix macromolecules. Diacerein is an anthraquinone molecule that has been shown to reduce the severity of OA, both in man and in animal models. The present study was designed to evaluate in vitro effects of diacerein on IL-1beta expression in LPS or IL-1alpha stimulated chondrocytes. Intracellular IL-1beta production was analysed in articular chondrocytes cultured in monolayer or in alginate 3D-biosystems in the presence of lipopolysaccharide (LPS) or IL-1alpha, with or without diacerein. The results show that LPS and IL-1alpha increase intracellular IL-1beta and Diacerein inhibited LPS-induced and IL-1alpha induced IL-1beta production by articular chondrocytes. Moreover, the effect of mechanical stimulation was analysed. An inhibitory effect of DAR at therapeutic concentrations on IL-1beta production in articular chondrocytes is suggested.
Biorheology 02/2006; 43(3-4):595-601. · 1.93 Impact Factor
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ABSTRACT: The surface modification using thin polyelectrolyte multilayered films was proposed as a new scaffold material for different cell lines. In this study, we evaluated the possible use of polyelectrolyte multilayers as surface modification for the development of endothelial cells. In order to control the behaviour of endothelial cells, cell viability by MTT assay was studied. Moreover, the endothelial cell phenotype was checked and the expression of a leukocyte adhesion molecule (ICAM-1) was quantified. The behaviour of the cells on two polyelectrolyte multilayers was compared to cells on polystyrene, and two polyelectrolyte monolayers (terminating the multilayer architectures). The results have shown a better cell viability on the polyelectrolyte multilayers, inducing a higher cell number compared to polyelectrolyte monolayers after 1 and 3 days of culture. Moreover, the cells showed a normal morphology of cytoskeleton. The phenotype of the endothelial cells was kept and a low level of leukocyte adhesion molecules was observed. In conclusion, the polyelectrolyte multilayers can be considered as a potential surface modification procedure to enhance the development of endothelial cells on hydrophobic substrate and which can be applied to vascular tissue engineering.
Clinical hemorheology and microcirculation 02/2005; 33(3):269-75. · 3.40 Impact Factor
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ABSTRACT: The aim of this work was to study the influences of Ca2+ (medium free calcium, with BAPTA, with 100 mM Ca2+, 100 mM Ca2++10 microM ionomycin) on the expression of caveolin-1 (structural protein of caveolae) of endothelial cells (ECs) submitted to mechanical forces (shear stress) or biochemical stimulation (TNF-alpha). We found that shear stress enhanced the caveolin-1 expression. Simultaneously, the caveolin-1 expression is dependant on [Ca2+]i: [Ca2+]free medium+100 microM BAPTA<[Ca2+]free medium<[Ca2+]100 mM<[Ca2+]100 mM+10 microM ionomycin. In contrast, TNF-alpha induced a decrease of caveolin-1 in the cells, whatever the [Ca2+]i. These results suggest that there could be a synergistic effect between shear stress and Ca2+ on caveolin-1 expression but an inflammatory stimulation (TNF-alpha) induces a down regulation of caveolin-1 expression.
Clinical hemorheology and microcirculation 01/2005; 33(3):253-61. · 3.40 Impact Factor
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ABSTRACT: We studied the effect of mechanical forces (shear stress) on the kinetics of internalization of native LDL and ox-LDL in endothelial cell line ECV304. This study was performed by using Confocal microscopy and FRET with two carbocyanine dyes, 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiO) as the donor and 3,3'-dioctadecyloxacarbocyanine perchlorate (DiI) as the receptor. The cells were incubated with a culture medium containing either 10 microg/ml DiI-LDL or DiO-LDL in static conditions or subjected to a laminar flow under a Confocal Laser Scanning Microscope (SP2 Leica, Germany). The results showed: (1) the possibility to evaluate the kinetics of LDL endocytosis in living cells, (2) shear stress in comparison with control group more effectively enhanced LDL uptake, (3) ox-LDL (>50 microg/ml) >4 hours incubation was found to affect the cells as reflected by their detachment at low shear stress.
Clinical hemorheology and microcirculation 01/2005; 33(3):243-51. · 3.40 Impact Factor
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S Muller,
V Labrador,
N Da Isla,
D Dumas,
R Sun,
X Wang,
L Wei,
S Fawzi-Grancher,
W Yang,
M Traore,
C Boura,
D Bensoussan,
A Eljaafari,
J-F Stoltz
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ABSTRACT: Almost all of the cells of the human body are subjected to mechanical stresses. In endothelial cells, mechanical stresses can vary from some milli-Pascal (shear stress) to one ore more Pascal (hydrostatic pressure). Now it is know that mechanical stresses have a decisive part cellular physiology. However, if the main biological effects of mechanical stress are well related, the mechanisms allowed the relation between mechanical stress to physiological phenomenon remain nearly unknown (mechanotransduction phenomenon). In this work, through personal results and published works, the authors considers all the effects of mechanical stresses and the possible hypothesis.
Clinical hemorheology and microcirculation 02/2004; 30(3-4):185-200. · 3.40 Impact Factor
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ABSTRACT: The firm adhesion of activated polymorphonuclear neutrophils to endothelial cells in blood vessels is achieved through binding of the integrin intercellular adhesion molecule. To contribute to the better understanding of this adhesion step, our investigation is aimed at the relationship between integrin expression and the strength of neutrophil binding to endothelial cells. Flow cytometry and 3D scanning microscopy are used to study integrin expression and distribution, respectively. It is found that CD11b/CD18 integrin expression is localized in clusters distributed irregularly over the neutrophil surface. After cell activation, the cluster distribution polarizes, increasing the local CD11b/CD18 density concurrently with nearly doubled integrin expression. The neutrophil adhesion efficiency is measured in a flow chamber coated successively by various substrates, including endothelial cells in an activated state. Analysis of the flow dependence of the number of attached cells reveals the prevailing number of neutrophils with stronger binding to the endothelium when both cells are in the activated state in comparison with non-activated cells.
European Biophysics Journal 01/2004; 32(8):684-8. · 2.14 Impact Factor
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ABSTRACT: Endothelial cell seeding constitutes an appreciated method to improve blood compatibility of small-diameter vascular grafts. In this study, we report the development of a simple innovative technique based on multilayered polyelectrolyte films as cell adhesive substrates. Polyelectrolyte multilayered films ending by poly(sodium-4-styrenesulfonate)/poly(allylamine hydrochloride) (PSS/PAH) or poly(L-glutamic acid)/poly(D-lysine) (PGA/PDL) could enhance cell adhesion by modification of the physico-chemical properties of the surface. The biological responses of human umbilical vein endothelial cells seeded on the polyelectrolyte multilayer films, on PDL or PAH monolayers, and on control surfaces, were evaluated in terms of initial attachment, growth, cellular metabolic activity, endothelial phenotype, and adhesion. The results showed that polyelectrolyte multilayers neither induce cytotoxic effects nor alter the phenotype of the endothelial cells. The polyelectrolyte multilayered films enhanced initial cell attachment as compared to the polyelectrolyte monolayer. Cell growth observed on the films was similar to that on TCPS. Among the different coating tested, the film ending by PSS/PAH exhibited an excellent cellular biocompatibility and appeared to be the most interesting surface in terms of cellular adhesion and growth. Such films could be used to cover hydrophobic (cell resistant) substrates in order to promote cell colonization, thereby constituting an excellent material for endothelial cell seeding.
Biomaterials 10/2003; 24(20):3521-30. · 7.40 Impact Factor
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ABSTRACT: The cardiovascular effects of hemoglobin-based oxygen carriers (HBOCs) are mainly related to their nitric oxide (NO) scavenging properties but other effects such as the impact of these hemoglobins on the endothelial cell (EC) biology are not well understood. We hypothesized that HBOCs could modify EC functions by altering gene expression, in particular the endothelial NO synthase (NOS3) and/or by activating EC. Cultured human aortic endothelial cells (HAEC) were incubated for 3 hours with purified cell-free Hb, Dex-BTC-Hb or alpha alpha-Hb (16 g/L). Expression of NOS3 mRNA and protein were assessed by semi-quantitative RT-PCR and Western blot respectively immediately after and 24 hours after incubation. The expression and localization of the adhesion molecule ICAM-1 were detected by fluorescence microscopy. None of the solutions tested modified NOS3 mRNA and protein expression despite adequate controls that up- or down-regulate NOS3 expression. The expression and the localization of ICAM-1 on the cell membrane were modified after 3 hours of incubation with all the hemoglobin solutions tested in a manner similar to tumor necrosis factor-alpha. In conclusion, HAEC incubation with clinically relevant concentrations of HBOCs induced changes in the pattern of ICAM-1 expression consistent with cell activation/cell signaling mechanisms. However, HBOCs did not alter NOS3 gene expression.
Life Sciences 02/2003; 72(10):1143-57. · 2.53 Impact Factor
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ABSTRACT: The role of clustered of L-selectin receptors on the leukocyte surface is discussed in connection with the postulated velocity-dependent formation of selectin-ligand tether bonds to interpret the mechanism of leukocyte tethering to, and rolling along, the vascular endothelium. The distinct feature of this step-wise process is a weak dependence of leukocyte rolling velocity on the hydrodynamic forces of ambient flow due to the increased number of selectin bonds with increasing flow shear rate and also their clustering. The contact zones on the leukocyte surface are separated by distances with distribution which corresponds to the distribution of distances of the observed L-selectin clusters. It suggests that the localization of L-selectin receptors to clusters and the way of their approach to the ligand molecules creates such conditions for binding of L-selectin and ligand molecules that resulting number of bonds stabilizes rolling velocity.
Biorheology 02/2003; 40(1-3):161-6. · 1.93 Impact Factor
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ABSTRACT: Caveolin-1 is a principal component of caveolae and is involved in signaling transduction in a number of cells. A hypothesis was proposed in this work that mechanical forces due to flow induce caveolin-1 translocation. So the changes of caveolin-1 expression and distribution in cultured endothelial cells (HUVECs) exposed to a steady laminar flow were studied. For comparing with the influence of cytokine, caveolin-1 in the cells stimulated by TNF-alpha was also investigated. Indirect immunofluorescence and double fluorescence labeling showed that in control cells, caveolin-1 was primarily localized on the cell surface, which corresponded to the peripheral distribution of F-actin, and presented some local concentrations. In the cells exposed to a laminar flow (1.0 Pa), caveolin-1 distribution showed a time-dependent variation. After 24 h of shear, the local concentration of caveolin-1 was found, in the most cells, at upstream side of cell body. Also more caveolin-1 molecules were observed in the cells. In contrast, TNF-alpha induced a decrease of caveolin-1 in cells. The redistribution of caveolin-1 seems to be correlated to F-actin organization.
Biorheology 02/2003; 40(1-3):31-9. · 1.93 Impact Factor
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ABSTRACT: Considering that vascular endothelial caveolae could be flow sensors converting mechanical stimuli into chemical signals transmitted into the cell, this work studied, in vitro, the change of caveolin-1 expression and distribution of cultured endothelial cells exposed to laminar flows. Experimental results showed that, in control cells, caveolin-1 were primarily localized on the cell surface, and presented some local concentrations. In cells exposed to laminar flows, caveolin-1 distribution showed a time-dependent variation. After 24 h of shear (1.0 Pa), the expression of caveolin-1 increased and a local caveolin-1 concentration was found, in most cells, at the upstream side of the cell body where the hydrostatic pressure and the spatial gradient of shear stress were at a maximum. As a comparison, tumor necrosis factor-a induced a decrease of caveolin-1 in the cells.
European Biophysics Journal 03/2002; 30(8):605-11. · 2.14 Impact Factor
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ABSTRACT: The purpose of the present study was to investigate the intracellular IL-1beta production and beta1 integrins (alpha4/beta1 and alpha5/beta1) expression on chondrocytes. Chondroytes monolayer (human chondrosarcoma cell line HEM-C55) were incubated for 12, 24 and 48 hours in the presence of Tumor Necrosis Factor-alpha (TNF-alpha, Sigma, France) or recombinant human IL-1alpha (rh-IL1alpha, Becton Dickinson, France). After direct immunolabelling, cells were either analyzed on FACScan flow cytometer (Becton Dickinson, France), or observed under an epi-fluorescence inverted microscope equipped with the CellScan EPR optical scanning acquisition system (IPLab-Scanalytics, USA). We found that the IL-1beta mean fluorescence intensity in flow cytometry and in 3D microscopy was increased in the presence of TNF-alpha or rh-IL-1alpha, and alpha4/beta1 or alpha5/beta1 expression was higher on stimulated cells than on control cells. On the other hand, we have evaluated the in vitro effects of rhein (10(-5) M, Negma, France), an active metabolite of diacerein, on the intracellular IL-1beta and beta1 integrins expressed by stimulated or no-stimulated chondrocytes. The results indicated that rhein leads to a reduction of IL-1beta synthesis whereas a weak decrease of beta1 integrins receptors expression is observed. From this study, it seems that rhein partially reduce cytokine-induced intracellular IL-1beta production, and it has a weak action on alpha4/beta1 or alpha5/beta1 receptors.
Biorheology 02/2002; 39(1-2):277-85. · 1.93 Impact Factor
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ABSTRACT: Hb-based oxygen carriers (HbOCs) have vasoactive effects that are still poorly understood. Factors known to have vasoactive effects, such as plasma, whole-blood viscosity, and the rheologic behavior of RBCs, are modulated by HbOCs in vitro, but few in vivo studies have been performed.
Rabbits were phlebotomized (30%) and resuscitated with unmodified stroma-free Hb (SFHb), dextran-tetracarboxylate-Hb (Dex-BTC-Hb), O-raffinose-polymerized Hb (OrpHb), HSA, or hydroxyethyl starch 200 (HES). Plasma viscosity was assessed with a capillary viscometer and whole-blood viscosity with a rotational viscosimeter. RBC aggregation kinetics were determined by analysis of back-scattered light in a rotating device.
As compared to that in the control RBC suspension, resuscitation with SFHb, OrpHb, or HSA decreased plasma and whole-blood viscosity as well as RBC aggregation; resuscitation with Dex-BTC-Hb increased whole-blood viscosity at low shear rates as well as RBC aggregation, whereas that with HES decreased whole-blood viscosity but increased RBC aggregation.
HbOCs have different rheologic effects in vitro and in vivo. There are marked differences among the Hb solutions in their in vivo effects on viscosity and RBC rheologic behavior (especially at low shear rates encountered in the venous circulation and the microcirculation), which may be related to the chemical modifications applied to hemoprotein. These results could contribute to an understanding of the vasoactive effects of HbOCs.
Transfusion 10/2000; 40(9):1095-103. · 3.22 Impact Factor
