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International audience; Urothelium is a highly specialized epithelium covering the entire urinary excretory system. Tissue engineering of this urinary tract may allow to consider its reconstruction to perform in vitro studies or in vivo replacement. Therefore, the question of specific reconstruction of the urothelium arises in order to guarantee the neotissue’s ability to act as a barrier against highly cytotoxic urine. This literature review describes the different cell types and strategies available for this reconstruction. The non-reconstruction of urothelium relies on the colonization of a biomaterial by the adjacent healthy tissue but allows only incomplete reconstruction and fibrosis. The use of autologous urothelial cells requires preliminary surgery and has not been successful enough in humans. Research has therefore focused on the use of stem cells. Adipose Derived Stem Cells (ADSCs) and Bone Marrow Derived Stem Cells (BMSCs) allow the reconstruction of the smooth muscle layer, but have little effect on urothelium reconstruction. Urine Derived Stem Cells (UDSCs) and Bladder mesenchymal Stem Cells (BSCs) are very promising because they allow the achievement of a differentiated urothelium. Induced Pluripotent Stem Cells (IPSCs) and Embryonic Stem Cells (ESCs) can be differentiated towards urothelial phenotype but their use is restricted by ethics.

Objective The aim of this study is to investigate the changes of human dental pulp stem cell (hDPSC) viability, proliferation and osteogenic differentiation in high glucose condition. Design After 21 days of culture in low (5.5 mM) and high (20 mM) glucose medium, hDPSC viability and proliferation were assessed with respectively the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and Hoechst assays. To investigate the influence of glucose on osteogenic differentiation hDPSCs were cultured for 28 days in low or high glucose medium with osteoinductive cocktail. Mineralization was examined by alizarin red staining/quantification and the expression of osteogenic-related genes [Runt-related transcription factor 2 (RUNX2), Osteocalcin (OCN), Collagen 1A1 (COL1A1)] analyzed by RT-qPCR. Results We observed no significant difference (p > 0.05) on hDPSC proliferation or cell viability between low or high glucose groups. We did not highlight a significant difference after alizarin red staining and quantification between hDPSCs cultured with high or low glucose concentration in the culture medium. In the same manner, high glucose concentration did not appear to modify osteogenic gene expression: there was no significant difference in osteogenic-related gene expression between high or low glucose groups. Conclusion Proliferation, viability, and osteogenic differentiation of hDPSCs were not changed by high glucose environment.

International audience; Proteomics users enjoy the rapid development of LC-MS-based label-free relative quantification methods but in practice these remain restricted to mass spectrometers using electrospray ionization. Here, tools dedicated to ion chromatogram extraction, time alignment, signal normalization and statistical analysis were used to interpret label-free relative difference between primary human chondrocyte secretomes and dilutions thereof, analyzed successively by LC-MALDI. The analysis of secretomes diluted into culture medium demonstrated that abundant proteins could be relatively quantified within 1.5 20-fold changes with satisfactory statistics. In addition, comparison of multiple samples requires analyzing most samples in TOP mode only, saving considerable machine-time usage. The method allowed identification and quantification of most secreted proteins relevant to the chondrocyte phenotype and evidenced their up- or down regulations by TGF131 and patient-to-patient differential expression. Novel targets of TGFB1 were evidenced, such as pro-collagen C-proteinase enhancer protein 1, Metalloproteinase inhibitor 1, Fibulin-3, Tetranectin and Cartilage Intermediate Layer Protein 1, while others match previous findings. Several were verified by Western blot. This whole workflow is non-invasive, compatible with many cell culture protocols, technically straightforward and rapid, particularly regarding mass spectrometer time usage and could make label-free LC-MALDI analysis of low-complexity proteomes a major tool for routine cell culture characterization. Biological significance The present work presents the adaptation of label free relative protein quantification principles to LC-MALDI data to rapidly measure protein fold-changes between samples of relative complexity and its utility to characterize the secreted proteome of human primary chondrocytes. The method was employed to characterize the chondrocyte secretome regulation by TGF beta 1 and is proposed as a routine tool to assess the quality of biomaterials designed for cartilage repair and to quantitatively investigate the influence of environmental factors upon it. (C) 2014 The Authors. Published by Elsevier B.V.

Before studying the impact of 2-deoxy-2-[F-18]fluoro-d-glucose (FDG) imaging with a dual-head coincidence gamma camera (DHC) for the follow-up of animal tumor models, we wanted to optimize this technique. Three different animal tumor models (osteosarcoma, melanoma, and breast cancer) were studied after FDG injection. Dynamic and dual time point FDG/DHC imaging were studied from one hour to five hours postinjection. In vitro tumor cell FDG uptake was assessed in eight different tumor cell lines. In one model (osteosarcoma), tumor growth, lung metastasis emergence, and survival were assessed by classical clinical follow-up and compared to FDG imaging in a control group (n = 6) and in a group treated by endostatin liposome complexes (n = 6). Images obtained five hours after injection were more reliable for tumor growth follow-up than standard images (one hour). In vitro tumor cell FDG uptake confirmed in vivo imaging studies. In eight different tumor cell lines the FDG uptake was higher after five hours incubation than after one hour (p < 0.002). With FDG follow-up, we found that FDG uptake was strongly correlated with survival and that lung metastasis larger than 5 mm could be detected. Using the optimization proposed above, DHC/FDG functional imaging seems to be a powerful tool to study rat tumor models and to help develop novel cancer therapies.

Objective : to evaluate the ability of T2 mapping on an 8.5T imager to characterize morphologically and quantitatively spontaneous repair of rat patellar cartilage following full thickness defect. Methods : Patellar cartilage defects were created in 24 rats knees on D0. Eight rats per time-point were killed on D20, D40 and D60 after surgery. T2 maps of repair tissue in patellar defects were obtained from eight different axial spin echo images on an 8.5T imager. Global, superficial and deep T2 values were evaluated in spontaneous repair tissues (3×8 right patellae) vs the opposite patellae (3×8 left patellae) of the same animals. MR data were compared with macroscopic and histological studies. Results : T2 map was able to identify morphologically three types of repair tissue observed macroscopically and histologically: ‘ total ', ‘ partial ' and ‘ hypertrophic ' repair tissue. ‘ Total ' and ‘ partial ' repair tissues were characterized by global T2 values almost similar to controls, whereas ‘hypertrophic' repair tissues were characterized by T2 global values higher than controls. Zonal variation between superficial and deep T2 values observed in controls was not depicted in repair tissue before D60. Conclusion : T2 map is able to characterize quantitatively and qualitatively rat patellar cartilage repair, and thus can be promoted, as a non invasive technique, in clinical longitudinal studies of articular cartilage repair.

1- article; International audience; BACKGROUND: Biodegradable polymers used in tissue engineering applications, such as poly(ε-caprolactone) (PCL), are hydrophobic leading to a lack of favorable cell signalization and finally to a poor cell adhesion, proliferation and differentiation. To overcome this problem, scaffolds undergo generally a surface modification. OBJECTIVE: Our laboratory has demonstrated that the grafting of poly(sodium styrene sulfonate) (pNaSS) onto titanium or poly(ethylene terephthalate) surfaces, leads to a more specific protein adsorption and a better control of cell proliferation. The objective of this work is to develop, through a straightforward way, bioactive elastomeric PCL scaffolds by grafting pNaSS. METHODS: Porous elastomeric PCL scaffolds were developed using a particulate-leaching process. pNaSS was grafted into the scaffold by a "grafting from" technique. In vitro tests were carried out to assess cell adhesion and protein expression. RESULTS: pNaSS was grafted homogeneously onto PCL scaffolds without degrading the biodegradable polymer or the porous structure. The in vitro studies have shown that pNaSS grafted onto PCL improves the cell response with a better expression of collagen, fibronectin and integrin α1. CONCLUSIONS: The grafting of pNaSS onto biomaterial surfaces is a versatile method that can provide a new generation of biodegradable scaffolds which could be "biointegrable".

Aim. To determine whether viscosupplementation with intra-articular (i.a.) low- or high-molecular-weight hyaluronate (HA) injections influenced both chondral and synovial lesions in rats with surgically-induced OA knee. Methods. On D0, rats underwent anterior cruciate ligament transection (ACLX) and were divided in 4 groups: sham group, ACLX-saline control group, ACLX-hyaluronate group, ACLX-hylan group. IA injections were performed on D7, D14 and D21. Histological grading of chondral and synovial lesions were performed on D28. Concomitant immunostainings of Caspase3a and Hsp70 were also performed. Results. Articular damages were significantly reduced in both HAs-treated knee joints. In contrast, a significant increase of histological score of synovial inflammation was noted in both ACLX + HAs groups. Apoptotic events significantly decreased as anti-apoptotic Hsp70 expression increased significantly in both HAs groups. Conclusion. HAs may exert, independently of its molecular weight, ambivalent properties on articular structures, simultane- ously exerting chondroprotective properties and promoting long-term subacute synovitis.

The extracellular matrix (ECM) has long been viewed primarily as an organized network of solid-phase ligands for integrin receptors. During degenerative processes, such as osteoarthritis, the ECM undergoes deterioration, resulting in its remodeling and in the release of some of its components. Matrilin-3 (MATN3) is an almost cartilage specific, pericellular protein acting in the assembly of the ECM of chondrocytes. In the past, MATN3 was found required for cartilage homeostasis, but also involved in osteoarthritis-related pro-catabolic functions. Here, to better understand the pathological and physiological functions of MATN3, its concentration as a circulating protein in articular fluids of human osteoarthritic patients was determined and its functions as a recombinant protein produced in human cells were investigated with particular emphasis on the physical state under which it is presented to chondrocytes. MATN3 down-regulated cartilage extracellular matrix (ECM) synthesis and up-regulated catabolism when administered as a soluble protein. When artificially immobilized, however, MATN3 induced chondrocyte adhesion via a α5β1 integrin-dependent mechanism, AKT activation and favored survival and ECM synthesis. Furthermore, MATN3 bound directly to isolated α5β1 integrin in vitro. TGFβ1 stimulation of chondrocytes allowed integration of exogenous MATN3 into their ECM and ECM-integrated MATN3 induced AKT phosphorylation and improved ECM synthesis and accumulation. In conclusion, the integration of MATN3 to the pericellular matrix of chondrocytes critically determines the direction toward which MATN3 regulates cartilage metabolism. These data explain how MATN3 plays either beneficial or detrimental functions in cartilage and highlight the important role played by the physical state of ECM molecules.

International audience; Introduction: We have taken advantage of the large screening capacity of a multiplex immunoassay to better define the respective contribution of articular versus systemic cytokines in experimental arthritis.Methods: We performed a follow up (from 7 hours to 14 days) multiplex analysis of 24 cytokines in synovial fluid and sera of rats developing Antigen-Induced Arthritis (AIA) and confronted their protein level changes with molecular, biochemical, histological and clinical events occurring in the course of the disease.Results: The time-scheduled findings in arthritic joints correlated with time-dependent changes of cytokine amounts in joint effusions but not with their blood levels. From seven hours after sensitization, high levels of chemokines (MCP-1, MIP1α, GRO/KC, RANTES, eotaxin) were found in synovial fluid of arthritic knees whereas perivascular infiltration occurred in the synovium; local release of inflammatory cytokines (IFNγ, IL-1β, IL-6) preceded the spreading of inflammation and resulted in progressive degradation of cartilage and bone. Finally a local overexpression of several cytokines/adipocytokines poorly described in arthritis (IL-13, IL-18, leptin) was observed.Conclusions: Distinct panels of cytokines were found in arthritic fluid during AIA, and the expected effect of mediators correlated well with changes occurring in joint tissues. Moreover, multiplex analysis could be helpful to identify new pathogenic mediators and to elucidate the mechanisms supporting the efficacy of putative targeted therapies.

Tumor necrosis factor-α (TNF-α), a proinflammatory cytokine, plays a key role in the pathogenesis of many inflammatory diseases, including arthritis. Neutralization of this cytokine by anti-TNF-α antibodies has shown its efficacy in rheumatoid arthritis (RA) and is now widely used. Nevertheless, some patients currently treated with anti-TNF-α remain refractory or become nonresponder to these treatments. In this context, there is a need for new or complementary therapeutic strategies. In this study, we investigated in vitro and in vivo anti-inflammatory potentialities of an anti-TNF-α triplex-forming oligonucleotide (TFO), as judged from effects on two rat arthritis models. The inhibitory activity of this TFO on articular cells (synoviocytes and chondrocytes) was verified and compared to that of small interfering RNA (siRNA) in vitro. The use of the anti-TNF-α TFO as a preventive and local treatment in both acute and chronic arthritis models significantly reduced disease development. Furthermore, the TFO efficiently blocked synovitis and cartilage and bone destruction in the joints. The results presented here provide the first evidence that gene targeting by anti-TNF-α TFO modulates arthritis in vivo, thus providing proof-of-concept that it could be used as therapeutic tool for TNF-α-dependent inflammatory disorders.

World Congress of the Osteoarthritis-Research-Society-International (OARSI), Paris, FRANCE, APR 24-27, 2014; International audience; no abstract

The aim of this study is to evaluate the toxicity of nanoparticles of poly(D,L-lactic acid) (PLA) or poly(D,L-lactic-co-glycolic acid) (PLGA) covered by chemically esterified amphiphilic hyaluronate (HA) which will be used for intra-articular injection as a drug carrier for the treatment of arthritis (RA) and/or osteoarthritis (OA). PLA and PLGA are FDA approved polymers that are already used for the preparation of nano or microparticles. HA is a natural polysaccharide already present in the articulations known to interact with the CD44 receptors of the cells (especially chondrocytes). Therefore, we can envisage that the HA covering can improve the interactions between the cells and the nanoparticles, leading to better targeting or biodistribution. The knee of healthy male rats was injected one to two times weekly, with various concentrations of nanoparticles encapsulating Dextran-FITC. The synovial membranes and the patellae were collected aseptically and histologically analyzed to assess the effects and localization of the nanocapsules in the knee joint. We did not observe significant modifications in the synovial membranes (weak hyperplasia) or patellae integrity after local administration of nanodevices into the rats. While we found some nanoparticles in the synovial membrane, none were detected in the patellae. Moreover, the histological observations for patellae were confirmed by radiosulfate intake, which depicted no decrease in proteoglycans biosynthesis in nanoparticles treated animals. Concerning the safety towards synovial membranes, we also had a look at the inflammatory response after injections of nanoparticles covered by amphiphilic HA or polyvinyl alcohol (PVA) by monitoring the mRNA expression levels of some specific early cytokines (IL-1β and TNF-α). Once again, no differences were observed between the control rats and the rats treated with nanoparticles. Considering these preliminary results obtained in healthy rats, we can establish that neither the amphiphilic HA-covered PLGA nanoparticles nor their degradation products induce major modifications of articular tissues functions, while injected into the knee of healthy rats. These results should be confirmed in OA or RA rat models, in order to confirm that nanoparticles do not worsen already altered (degenerative or inflamed) articular tissues. Once confirmed, such tuneable nanoparticles could be proposed as a safe drug delivery system for the treatment of articular disease, allowing a wide range of encapsulating molecules.

AIM Assessing the activity of synovitis, which is characterized by an increase in cell metabolism, is important for the prediction of future articular destruction in clinical and preclinical studies. To evaluate the correlation between ¹⁸F-FDG accumulation and arthritis pathology during its establishment, we used microPET to evaluted ¹⁸F-FDG accumulation in vivo during rat Mycobacterium wall-induced knee arthritis. METHODS ¹⁸F-FDG PET images of arthritic rats were acquired on days 1, 2, 3 and 7 after arthritis induction. The subjects (n=2/time) were subsequently subjected to macro-autoradiography, and ¹⁸F-FDG accumulation was compared with histological findings. RESULTS ¹⁸F-FDG PET images depicted swollen joints, and ¹⁸F-FDG accumulation increased with the progression of arthritis. Histologically, increased ¹⁸F-FDG accumulation correlated with the pannus rather than the infiltration of inflammatory cells around the joints. CONCLUSION ¹⁸F-FDG accumulation in arthritis reflects proliferating pannus and inflammatory activity enhanced by inflammatory cytokines. ¹⁸F-FDG microPET should be effective for quantifying the inflammatory activity of arthritis and/or its therapeutic response.

International audience

AIM to determine if chondrocytic Hsp70 induction, via intra-articular injections of a reversible proteasome inhibitor (MG132), can protect articular chondrocytes from cellular death in experimental rat OA knee induced surgically by anterior cruciate ligament transection (ACLT). MATERIALS AND METHODS ACLT was performed on D0. Histological lesions in naive (sham) controls (ACLT+saline) and treated (ACLT+MG132) rats were assessed according to Mankin's score. Repeated intra-articular injections (1.5 muM MG132 or saline were performed on D1, D7, D14 and D21. Rats were sacrificed sequentially on D7, D14 and D28. Detection of active caspase-3 and protein expression of Hsp70 was also determined on D7, D14 and D28 by immunostaining methods. RESULTS MG132 significantly reduced OA lesions on D28 in the MG132 treated group. The expression of Hsp70 increased 11-fold in the MG132-treated group versus 2-3-fold in ACLT-control rats on D28. Concomitantly, cells expressing caspase-3 increased 4-fold in ACLT model and decreased 2-fold with MG132 treatment. CONCLUSIONS Intra-articular induction of Hsp70 by MG132 could be a safe and interesting tool in chondrocytes protection from cellular injuries and thus might be a novel chondroprotective modality in rat OA.

Aim: To evaluate the efficiency of 3 short hairpin RNA (shRNA) interfering with the herpes simplex virus type 1 (HSV-1) gene coding glycoprotein D (gD) for inhibiting the gD expression and virus replication in vitro . Methods: Vero cells were selected for an in vitro model of infection. Three shRNA sequences (shRNA-gD1, -gD2, and -gD3) targeting specifically the gD gene of HSV-1 were selected for evaluating the antiviral effects. The antiviral effects of shRNA in the cells infected with HSV-1 were evaluated by cytopathic effect (CPE) observations and plaque assays. The transcription level of viral RNA and the gD expression were studied by RT-PCR, Western blotting, and flow cytometry. Results: With the 3 shRNA at a final concentration of 120 nmol/L, a significant inhibition of CPE in the HSV-1-infected cells was observed. The ED50 of shRNA-gD1, gD2, and gD3 were 48.74±2.57, 57.13±3.24, and 114.64±5.12 nmol/L, respectively. The gD gene decreased significantly after viral infection in the Vero cells pretreated with shRNA compared to the virus group. The expressions of the gD protein, determined by Western blotting and flow cytometry, were also drastically decreased in shRNA-transfected cells. Conclusion: Exogenous shRNA molecules can suppress the HSV-1 gD expression. They are inhibitors of HSV replication during infection in Vero cells.

Hyaluronic acid (HA) has a high affinity for the CD44 receptor present at the surface of articular cells, particularly of chondrocytes. HA-covered polylactide nanoparticles containing bioactive compounds such as HA and chondroitin sulfate (CS) were thus prepared in order to achieve a controlled delivery targeted to cartilage cells after injection near articular alterations/erosions. Such nanoparticles (diameter = 700 nm) were prepared by double emulsion/solvent evaporation, using amphiphilic derivatives of HA, as stabilizer of the secondary emulsion. These nanoparticles were incubated with articular cells, and several tests were carried out. First, they proved that the nanospheres provoked no decrease in cell viability, even after 72 h of contact. Second, a confocal microscopy analysis on fluorescent HA-covered particles showed that they were captured by articular cells, while with those covered with poly(vinyl alcohol), the uptake was far lower. Third, a scattering electron microscopy analysis proved that the HA-coated nanoparticles were localized in the cell intracytoplasmic area.

This study evaluated the in vitro behaviour of bovine chondrocytes seeded in collagen gels, promising recently reported scaffolds for the treatment of full-thickness cartilage defects. To determine how chondrocytes respond to a collagen gel environment, 2 x 10(6) chondrocytes isolated from fetal, calf and adult bovine cartilage were seeded within type I collagen gels and grown for 12 days in both attached and floating (detached from the culture dish after polymerisation) conditions. Monolayer cultures were performed in parallel. All chondrocytes contracted floating gels to 55% of the initial size, by day 12. Contraction was dependent on initial cell density and inhibited by the presence of dihydrocytochalasin B as previously observed with fibroblasts. Gene expression was determined using conventional and real-time PCR. The chondrocyte phenotype was better maintained in floating gels compared to attached gels and monolayers. This was demonstrated by comparing the ratio of COL2A1/ COL1A2 mRNA and also of alpha10/alpha11 integrin mRNA. A strong up-regulation of MMP13 expression was measured at day 12 in floating gels. The composition of cartilage-like tissue obtained by growing chondrocytes in a collagen gel varied depending on the floating or attached conditions and initial cell density. It is thus important to consider these parameters when using this culture system in order to prepare a well-defined implant for cartilage repair.This study evaluated the in vitro behaviour of bovine chondrocytes seeded in collagen gels, promising recently reported scaffolds for the treatment of full-thickness cartilage defects. To determine how chondrocytes respond to a collagen gel environment, 2 x 10(6) chondrocytes isolated from fetal, calf and adult bovine cartilage were seeded within type I collagen gels and grown for 12 days in both attached and floating (detached from the culture dish after polymerisation) conditions. Monolayer cultures were performed in parallel. All chondrocytes contracted floating gels to 55% of the initial size, by day 12. Contraction was dependent on initial cell density and inhibited by the presence of dihydrocytochalasin B as previously observed with fibroblasts. Gene expression was determined using conventional and real-time PCR. The chondrocyte phenotype was better maintained in floating gels compared to attached gels and monolayers. This was demonstrated by comparing the ratio of COL2A1/ COL1A2 mRNA and also of alpha10/alpha11 integrin mRNA. A strong up-regulation of MMP13 expression was measured at day 12 in floating gels. The composition of cartilage-like tissue obtained by growing chondrocytes in a collagen gel varied depending on the floating or attached conditions and initial cell density. It is thus important to consider these parameters when using this culture system in order to prepare a well-defined implant for cartilage repair.

To evaluate experimentally the sensitivity of T2 mapping with magnetic resonance (MR) imaging at 8.5 T in depicting variations in proteoglycan content and concurrent extracellular matrix of rat patellar cartilage.The study was performed in 36 immature (age, 5 weeks) and 36 mature (age, 10 weeks) Wistar rats. Maintenance and care of the rats were conducted in accordance with National Institutes of Health guidelines. Fifty-six rats underwent T2 mapping in 28 right patellae degraded with hyaluronidase for 1 and 6 hours and in 28 undegraded age-matched patellae that served as controls. After MR mapping, the rats were sacrificed, and the patellae were studied histologically to evaluate proteoglycan and collagen content and collagen network organization in cartilage. Biochemical analysis was performed in 88 patellae to quantify sulfated glycosaminoglycan and hydroxyproline content. Effects of age and/or degree of degradation were evaluated after rank transformation of continuous data by using rank analysis of variance (ANOVA). Associations between continuous variables were assessed with the Spearman rank correlation coefficient.Results of histologic analysis showed proteoglycan loss after hyaluronidase degradation without alteration of collagen network. No significant variation in hydroxyproline sulfate content was observed with depletion of proteoglycan. Proteoglycan losses of 19% and 13%, found after 1-hour degradation in immature and mature groups, respectively, were associated with significantly increased global T2 values (ANOVA, P.001). Six-hour degradation resulted in more severe proteoglycan losses of 45% and 53% in immature and mature groups, respectively, inducing significant increases in global T2 values in immature and mature groups (ANOVA, P.001). Variations in T2 values between superficial and deep cartilage zones were not affected by proteoglycan depletion.In rat patellar cartilage, T2 mapping permits detection of slight or severe proteoglycan depletion and concurrent changes of extracellular matrix when age-matched samples are compared.

Cartilage engineering consists of re-constructing functional cartilage by seeding chondrocytes in suitable biomaterials in vitro. The characteristics of neocartilage differ upon the type of biomaterial chosen. This study aims at determining the appropriate scaffold material for articular cartilage reconstruction using non articular chondrocytes harvested from rat sternum. For this purpose, the use of polysaccharide hydrogels such as alginate (AA) and hyaluronic acid (HA) was investigated. Several ratios of AA/HA were used as well as three derivatives obtained by chemical modification of HA (HA-C18, HA-C12(2.3), HA-C12(2.5)-TEG0.5). Sternal chondrocytes were successfully cultured in 3D alginate and alginate/HA scaffolds. HA retention in alginate beads was found to be higher in beads seeded with cells than in beads without cells. HA-C18 improved HA retention in beads but inhibited the chondrocyte synthesis process. Cell proliferation and metabolism were enhanced in all biomaterials when beads were mechanically agitated. Preliminary results have shown that the chondrocyte neo-synthesised matrix had acquired articular characteristics after 21 days culture.

The aim of this work was to determine whether Hsp70 overexpression via proteasome inhibitor MG132 was able to protect chondrocytes towards mono-iodoacetate (MIA) cytotoxicity both in vitro and in vivo. In vitro, overexpression of Hsp70 via MG132 was significantly able to protect chondrocytes from MIA toxicity (MTT/LDH analyses). Hsp70 essentially mediated this chondroprotective effect as demonstrated by antisense strategy. In vivo, chondrocytic overexpression of Hsp70, after a preventive intra-articular injection of MG132 in rat knee, was sufficient to decrease the severity of OA-induced MIA lesions, as demonstrated histologically and biochemically. In conclusion, intracellular overexpression of Hsp70, through proteasome inhibition, could be an interesting tool in protecting chondrocytes from cellular injuries, either necrotic or apoptotic in nature, and thus might be a novel chondroprotective modality in rat experimental OA.

To evaluate the ability of MR T2 mapping (8.5 T) to characterize ex vivo longitudinally, morphologically and quantitatively, alginate-based tissue engineering in a rat model of patellar cartilage chondral focal defect. Calibrated rat patellar cartilage defects (1.3 mm) were created at day 0 (D0) and alginate sponge with (Sp/C+) or without (Sp/C−) autologous chondrocytes were implanted. Animals were sacrificed sequentially at D20, D40 and D60 after surgery and dissected patellae underwent MRI exploration (8.5 T). T2 values were calculated from eight SE images by using nonlinear least-squares curve fitting on a pixel-by-pixel basis (constant repetition time of 1.5 s, eight different echo times: 5.5, 7.5, 10.5, 12.5, 15.0, 20.0, 25.0 and 30.0 ms). On the T2 map, acquired in a transversal plane through the repair zone, global T2 values and zonal variation of T2 values of repair tissue were evaluated versus control group and compared with macroscopic score and histological studies (toluidine blue, sirius red and hematoxylin-eosin). “Partial”, “total” and “hypertrophic” repair patterns were identified. At D40 and D60, Sp/C+ group was characterized by a higher proportion of “total” repair in comparison to Sp/C− group. At D60, the proportion of “hypertrophic” repair was two fold in Sp/C− group versus Sp/C+ group. As confirmed morphologically and histologically, the T2 map also permitted the distinction of three types of repair tissue: “total”, “partial” and “hypertrophic”. “Total” repair tissue was characterized by high T2 values versus normal cartilage (p

Objective To investigate the influence of a calibrated exercise on the progression of structural lesions in an experimental model of osteoarthritis (OA) in the rat, and to explore the effect of exercise on the level of chondrocyte caspase-dependent apoptosis and of Hsp70. Methods The OA model was induced by anterior cruciate ligament transection (ACLT). Rats were placed in 4 experimental groups: operated (ACLT) free moving rats, and 3 exercise groups (slight, moderate and intense) subjected to running training. Rats were killed 14 and 28 days after surgery. Results On D14 histological assessment demonstrated a beneficial influence of a slight and a moderate exercise vs control ACLT group. Hsp70 increased significantly in the moderate group vs controls. On D28, histological lesions strongly decreased in the slight and moderate exercise groups vs ACLT group, while an intense effort abolished this beneficial trend. Interestingly, the concomitant course of apoptotic events (caspase 3-positive cells) and the co-expression of Hsp70 in the various groups varied, when significant, in an inverse manner. In the intense group this overexpression was not noted, as a "burn out" appeared, thus leading to a loss of this protective effect. Conclusion This study shows that a calibrated slight or moderate exercise exerts a beneficial influence on the severity of chondral lesions in ACLT rats. Conversely, a strong effort abolishes this chondroprotective effect. This effect could be related to a reduced level of chondrocyte apoptosis through anti-apoptotic capacities of stress-induced Hsp70 overexpression.

To establish a system for efficient direct in vivo gene targeting into rat joint, we have evaluated a strategy of gene transfer by means of the delivery of external electric pulses (EP) to the knee after intra-articular injection of a reporter gene (GFP). Rats were killed at various times after the electro gene-therapy to analyze GFP gene expression by immunohistochemistry. GFP staining was detected in the superficial, middle, and deep zones of the patellar cartilage at days 2 and 9, and thereafter only in the deep zone (months 1 and 2). The average percentage of GFP-positive cells was estimated at 30% both one and 2 months after the gene transfer. Moreover, no pathologic change caused by the EP was detected in the cartilage. The level and stability of the long-term GFP expression found in this study demonstrate the feasibility of a treatment of joint disorders (inflammatory or degenerative, focal or diffuse) using electric gene transfer.

The MR aspect of articular cartilage, that reflects the interactions between protons and macromolecular constituents, is affected by the intrinsic tissue structure (water content, the content of matrix constituents, collagen network organization), imager characteristics, and acquisition parameters. On the T1-weighted sequences, the bovine articular cartilage appears as an homogeneous tissue in high signal intensity, whatever the age of animals considered, whereas on the T2-weighted sequences, the articular bovine cartilage presents variations of its imaging pattern (laminar appearance) well correlated to the variations of its histological and biochemical structure. The T2 relaxation time measurement (T2 mapping), which reflects quantitatively the signal intensity variations observed on T2 weighted sequences, is a way to evaluate more precisely the modifications of cartilage structure during the aging and maturation processes (rat's study). This technique so far confined to experimental micro-imagers is now developed on clinical imagers. Consequently, it may permit to depict the early stages of osteoarthritic disease (OA) or to evaluate the chondroprotective effect of drugs.

Objective The present study aims at evaluating, in a rat model of cartilage defect, the potential of various polymers as filling and repair biomaterials. The macroscopic and histological observations are compared to biochemical parameters in order to appreciate the pertinence of the latter as suitable criteria in tissue engineering. Methods A hydrogel, consisting of hyaluronic acid (HA), covalently substituted by hydrophobic alkyl chains (HA12, HA18) and an alginate sponge, alone (Asp) or combined with HA (AHAsp) or combined with HA and chondrocytes (HYBsp) were evaluated. Cartilage lesions were drilled in femoral trochlea of rats. The analyses were performed on trochlea as well as on patella and condyles. Results Repairs achieved with hydrogels had a similar macroscopic appearance than those afforded by AHAsp and HYBsp. Best macroscopic and histological scores were obtained with HA18 and HYBsp in comparison with alginate group (P< 0.01 and P< 0.02 respectively). Biochemical evaluations confirmed the presence of similar amounts of proteoglycans in the repaired zones and in the controls, though with different ΔdiC4S/ΔdiC6S ratios and enhanced HA levels. Conclusions Hydrogels or sponges proved to be colonized by cells synthesizing a matrix with a high HA content. The matrix obtained eventually turns hyaline and takes over the scaffold. The addition of HA and/or chondrocytes to Asp significantly improves the macroscopic and histological scores (P< 0.05 and P< 0.02 respectively). However, biochemical parameters are significantly different of those evaluated in native cartilage. The present study shows that only biochemical parameters allow to discriminate between various biomaterials in tissue engineering and are essential informations which should be taken into account in addition to macroscopic and histological observations. Copyright 2003 OsteoArthritis Research Society International. Published by Elsevier Science Ltd. All rights reserved.

One of the major issues with treatment of osteoarticular diseases is reaching cells or tissue inside the joint. Administration of an active compound by intravenous or per os requires elevated amount to be effective, and can initiate systemic and negative side effects. In this work we have evaluated a drug delivery system for hydrophilic molecule, which can be used for articular tissues. Polymeric nanoparticles of poly lactic-co-glycolic acid, labelled with a fluorescent dye were evaluated both in vitro and in vivo. These nanoparticles are covered with hyaluronic acid to favor particles-cells interaction. We demonstrated here that such particles are internalized after 8 hours of exposure in synoviocytes, chondrocytes and mesenchymal stem cells. Evaluation of cytotoxicity and inflammation revealed the neutrality of these particles for articular cell types. Finally, intraarticular injections of particles were performed in healthy rat joint and in pathological models. Histological analyses of extracellular matrix integrity and inflammatory status do not demonstrate any side-effect following particles injections. These healthy nano-device target primarily synovial cells, and their degradation inside cells does not provoke deleterious effects. This PLGA based drug delivery system would be used to safely deliver active molecules to the joint. The combination of these particles with various hydrophilic molecules (as nucleic acid, drugs,…) may allow their direct distribution in the joint, and lead to new therapeutics perspectives.; Un des écueils du traitement des pathologies ostéoarticulaires est l’adressage de molécules aux cellules et tissus qui constituent l’articulation. L’administration de principes actifs par voie sanguine ou orale nécessite l’apport de quantités importantes et peut causer des effets indésirables. Dans ces travaux, nous avons évalué un système d’adressage de molécules hydrophiles. Des particules de polymère d’acide lactique et glycolique, marquées par un traceur fluorescent ont été évaluées in vitro puis in vivo. Ces particules possèdent un recouvrement en acide hyaluronique pour améliorer les interactions avec les cellules. Les études réalisées ont permis de mettre en évidence l’internalisation des particules dans les synoviocytes, chondrocytes, et cellules souches mésenchymateuses après 8 heures d’exposition. Parallèlement, l’évaluation in vitro de différents paramètres de cytotoxicité et d’inflammation a permis de souligner la compatibilité de ces vecteurs avec les cellules articulaires. Enfin, les effets de l’injection intra-articulaire de particules ont été évalués chez le rat sain et différents modèles pathologiques. L’analyse histologique des articulations a démontré l’absence de dégradation de la matrice cartilagineuse et de réaction inflammatoire suite à l’injection de particules. Il a été également constaté un ciblage majoritaire des particules vers la membrane synoviale. Ces travaux permettent de valider l’utilisation de ce type de vecteur pour le ciblage de l’articulation et l’apport de principes actifs. L’association de ces particules à des molécules hydrophiles (acides nucléiques, médicaments,…), pourra permettre leur apport direct dans l’articulation et ouvrir de nouvelles perspectives thérapeutiques.

One of the major issues with treatment of osteoarticular diseases is reaching cells or tissue inside the joint. Administration of an active compound by intravenous or per os requires elevated amount to be effective, and can initiate systemic and negative side effects. In this work we have evaluated a drug delivery system for hydrophilic molecule, which can be used for articular tissues. Polymeric nanoparticles of poly lactic-co-glycolic acid, labelled with a fluorescent dye were evaluated both in vitro and in vivo. These nanoparticles are covered with hyaluronic acid to favor particles-cells interaction. We demonstrated here that such particles are internalized after 8 hours of exposure in synoviocytes, chondrocytes and mesenchymal stem cells. Evaluation of cytotoxicity and inflammation revealed the neutrality of these particles for articular cell types. Finally, intraarticular injections of particles were performed in healthy rat joint and in pathological models. Histological analyses of extracellular matrix integrity and inflammatory status do not demonstrate any side-effect following particles injections. These healthy nano-device target primarily synovial cells, and their degradation inside cells does not provoke deleterious effects. This PLGA based drug delivery system would be used to safely deliver active molecules to the joint. The combination of these particles with various hydrophilic molecules (as nucleic acid, drugs,…) may allow their direct distribution in the joint, and lead to new therapeutics perspectives., Un des écueils du traitement des pathologies ostéoarticulaires est l’adressage de molécules aux cellules et tissus qui constituent l’articulation. L’administration de principes actifs par voie sanguine ou orale nécessite l’apport de quantités importantes et peut causer des effets indésirables. Dans ces travaux, nous avons évalué un système d’adressage de molécules hydrophiles. Des particules de polymère d’acide lactique et glycolique, marquées par un traceur fluorescent ont été évaluées in vitro puis in vivo. Ces particules possèdent un recouvrement en acide hyaluronique pour améliorer les interactions avec les cellules. Les études réalisées ont permis de mettre en évidence l’internalisation des particules dans les synoviocytes, chondrocytes, et cellules souches mésenchymateuses après 8 heures d’exposition. Parallèlement, l’évaluation in vitro de différents paramètres de cytotoxicité et d’inflammation a permis de souligner la compatibilité de ces vecteurs avec les cellules articulaires. Enfin, les effets de l’injection intra-articulaire de particules ont été évalués chez le rat sain et différents modèles pathologiques. L’analyse histologique des articulations a démontré l’absence de dégradation de la matrice cartilagineuse et de réaction inflammatoire suite à l’injection de particules. Il a été également constaté un ciblage majoritaire des particules vers la membrane synoviale. Ces travaux permettent de valider l’utilisation de ce type de vecteur pour le ciblage de l’articulation et l’apport de principes actifs. L’association de ces particules à des molécules hydrophiles (acides nucléiques, médicaments,…), pourra permettre leur apport direct dans l’articulation et ouvrir de nouvelles perspectives thérapeutiques.