Sensitivity of chondrocytes of growing cartilage to reactive oxygen species |
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Authors: | Emanuela Fragonas Piero Pollesello Vladimir Mlinárik Renato Toffanin Cristina Grando Cristiana Godeas Franco Vittur |
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Institution: | 1. Department of Biochemistry, Biophysics and Macromolecular Chemistry, University of Trieste, L. Giorgieri 1, I-34127 Trieste, Italy;2. Orion Corporation, Orion Pharma, Reseach and Development, Drug Design Unit, NMR-Laboratory, P.O. Box 65, FIN-02101 Espoo, Finland;3. Magnetic Resonance Unit, Derer Hospital, Limbová 5, Sk-83305 Bratislava, Slovakia;4. Poly-Biós Research Center, Area di Ricerca, Padriciano 99, I-34012 Trieste, Italy |
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Abstract: | Vascular invasion of calcified cartilage, during endochondral ossification, is initiated and sustained by invasive cells (endothelial cells and macrophages) which degrade the tissue by releasing lytic enzymes. Concurrently, reactive oxygen species (ROS) are also released by these cells and we hypothesize that ROS also contribute to the degradation of the tissue. As a preliminary approach to this problem, the antioxidant activities and the effect of ROS on hypertrophic cartilage and chondrocytes (HCs) were investigated. Compared to resting or articular chondrocytes, HCs exhibited higher catalase but lower SOD specific activities and lower PHGPx concentration, thus revealing a defence activity specific against H2O2. Moreover, dose-dependent depletion of ATP occurred after few minutes of exposure to ROS, and a long-term treatment (16 h incubation with ROS) promoted the release of LDH activity and a significant variation of the poly- to mono-unsaturated fatty acid ratio. Finally, the incubation of HCs with low ROS doses induced the release of sedimentable alkaline phosphatase activity (matrix vesicles). How the obtained results fit the in vivo occurring events is discussed. |
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Keywords: | Reactive oxygen species Hypertrophic chondrocyte Growing cartilage Matrix vesicle NMR ROS reactive oxygen species SOD superoxide dismutase PHGPx phospholipid hydroperoxide glutathione peroxidase LDH lactate dehydrogenase HCs RCs and ACs hypertrophic resting and articular chondrocytes MUFA and PUFA mono and polyunsaturated fatty acid chains HX hypoxanthine XO xanthine oxidase |
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