RGD-dependent integrins are mechanotransducers in dynamically compressed tissue-engineered cartilage constructs |
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| Authors: | Linda M Kock Ronny M Schulz Corrinus C van Donkelaar Christian B Thümmler Augustinus Bader Keita Ito |
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| Institution: | 1. Department of Biomedical Engineering, Eindhoven University of Technology, The Netherlands;2. Department of Cell Techniques and Applied Stem Cell Biology, Center of Biotechnology and Biomedicine, University of Leipzig, Germany;1. European Institute for Molecular Imaging – EIMI, University of Münster, Münster, Germany;2. Department of Nuclear Medicine, University Hospital Münster, Münster, Germany;3. DFG Cluster of Excellence EXC 1003 ‘CiM – Cells in Motion’, Münster, Germany;2. Comparative Orthopaedic Research Laboratory, Département de sciences cliniques, Faculté de Médecine Vétérinaire, Université de Montréal, 3200 Rue Sicotte, St-Hyacinthe, QC J2S 2M2, Canada;3. Département de Pathologie et Microbiologie Vétérinaires, Faculté de Médecine Vétérinaire, Université de Montréal, 3200 Rue Sicotte, St-Hyacinthe, QC J2S 2M2, Canada;1. Dept. of Mechanical Engineering, University of Melbourne, Parkville, Victoria 3010, Australia;2. Dept. of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, IL 61801, USA;3. St Vincent?s Institute of Medical Research and Department of Medicine at St Vincent?s Hospital, University of Melbourne, Parkville, Victoria 3010, Australia;4. Dept. of Surgery, University of Melbourne, Parkville, Victoria 3010, Australia;5. Dept. of Surgery, Epworth Healthcare, Melbourne, Victoria 3010, Australia;1. Yale Cardiovascular Research Center, Section of Cardiovascular Medicine, Department of Internal Medicine, United States;2. Department of Cell Biology, United States |
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| Abstract: | Recent studies have shown that integrins act as mechanoreceptors in articular cartilage. In this study, we examined the effect of blocking RGD-dependent integrins on both ECM gene expression and ECM protein synthesis.Chondrocytes were isolated from full-depth porcine articular cartilage and seeded in 3% agarose constructs. These constructs were loaded in compression with 15% strain at 0.33 and 1 Hz for 12 h, in the presence or absence of GRGDSP, which blocks RGD-dependent integrin receptors. The levels of mRNA for aggrecan, collagen II and MMP-3 were determined by semi-quantitative PCR at several time points up to 24 h post-stimulation. DNA and sGAG content were determined at several time points up to 28 days post-stimulation.At 0.33 Hz, the mRNA levels for aggrecan and MMP-3 were increased after loading, but the mRNA levels for collagen II remained unchanged. Incubation with GRGDSP counteracted these effects. Loading at 1 Hz led to increased mRNA levels for all three molecules directly after loading and these effects were counteracted by incubation with GRGDSP. The constructs that were loaded at 0.33 Hz showed a lower amount of sGAG, compared to the unstrained control. In contrast, loading at 1 Hz caused an increase in sGAG deposition over the culture period. Blocking integrins had only a counteracting effect on the long-term biosynthetic response of constructs that were compressed at 1 Hz.The results confirmed the role of RGD-dependent integrins as mechanotransducers in the regulation of both ECM gene expression and matrix biosynthesis for chondrocytes seeded in agarose under the applied loading regime. Interestingly, this role seems to be dependent on the applied loading frequency. |
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