Characterisation of Calcium Phosphate Crystals on Calcified Human Aortic Vascular Smooth Muscle Cells and Potential Role of Magnesium |
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| Authors: | Lo?c Louvet Dominique Bazin Janine Büchel Sonja Steppan Jutta Passlick-Deetjen Ziad A Massy |
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| Institution: | 1. INSERM U-1088, Amiens, France.; 2. University of Picardie Jules Verne, Amiens, France.; 3. Université Pierre et Marie Curie, Collège de France, Paris, France.; 4. Fresenius Medical Care Deutschland GmbH, Bad Homburg, Germany.; 5. Department of Nephrology, University of Dusseldorf, Dusseldorf, Germany.; 6. Paris Ile de France Ouest (UVSQ) University, Paris, France.; Brigham and Women’s Hospital, Harvard Medical School, UNITED STATES, |
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| Abstract: | BackgroundCardiovascular disease including vascular calcification (VC) remains the leading cause of death in patients suffering from chronic kidney disease (CKD). The process of VC seems likely to be a tightly regulated process where vascular smooth muscle cells are playing a key role rather than just a mere passive precipitation of calcium phosphate. Characterisation of the chemical and crystalline structure of VC was mainly led in patients or animal models with CKD. Likewise, Mg2+ was found to be protective in living cells although a potential role for Mg2+ could not be excluded on crystal formation and precipitation. In this study, the crystal formation and the role of Mg2+ were investigated in an in vitro model of primary human aortic vascular smooth muscle cells (HAVSMC) with physical techniques.Methodology/Principal FindingsIn HAVSMC incubated with increased Ca x Pi medium, only calcium phosphate apatite crystals (CPA) were detected by Micro-Fourier Transform InfraRed spectroscopy (µFTIR) and Field Effect Scanning Electron Microscope (FE — SEM) and Energy Dispersive X-ray spectrometry (EDX) at the cell layer level. Supplementation with Mg2+ did not alter the crystal composition or structure. The crystal deposition was preferentially positioned near or directly on cells as pictured by FE — SEM observations and EDX measurements. Large µFTIR maps revealed spots of CPA crystals that were associated to the cellular layout. This qualitative analysis suggests a potential beneficial effect of Mg2+ at 5 mM in noticeably reducing the number and intensities of CPA µFTIR spots.Conclusions/SignificanceFor the first time in a model of HAVSMC, induced calcification led to the formation of the sole CPA crystals. Our data seems to exclude a physicochemical role of Mg2+ in altering the CPA crystal growth, composition or structure. Furthermore, Mg2+ beneficial role in attenuating VC should be linked to an active cellular role. |
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