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PLoS One. 2015 Jan 21;10(1):e0115342. doi: 10.1371/journal.pone.0115342. eCollection 2015.

Characterisation of calcium phosphate crystals on calcified human aortic vascular smooth muscle cells and potential role of magnesium.

Author information

1
INSERM U-1088, Amiens, France; University of Picardie Jules Verne, Amiens, France.
2
Université Pierre et Marie Curie, Collège de France, Paris, France.
3
Fresenius Medical Care Deutschland GmbH, Bad Homburg, Germany.
4
Fresenius Medical Care Deutschland GmbH, Bad Homburg, Germany; Department of Nephrology, University of Dusseldorf, Dusseldorf, Germany.
5
INSERM U-1088, Amiens, France; University of Picardie Jules Verne, Amiens, France; Paris Ile de France Ouest (UVSQ) University, Paris, France.

Abstract

BACKGROUND:

Cardiovascular 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 FINDINGS:

In 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/SIGNIFICANCE:

For 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.

PMID:
25607936
PMCID:
PMC4301909
DOI:
10.1371/journal.pone.0115342
[Indexed for MEDLINE]
Free PMC Article

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