Free DNA precipitates calcium phosphate apatite crystals in the arterial wall in vivo. (April 2017)

• Record Type: Journal Article
• Authors: Coscas, Raphaël; Bensussan, Marie; Jacob, Marie-Paule; Louedec, Liliane; Massy, Ziad; Sadoine, Jeremy; Daudon, Michel; Chaussain, Catherine; Bazin, Dominique; Michel, Jean-Baptiste
• Is Part Of: Atherosclerosis. Volume 259(2017)
• Page Start: 60
• Page End: 67
• Publication Date: 2017-04
• Subjects: Free DNA -- Calcium score -- Smooth muscle cell -- Calcification -- Aneurysm -- Human atherosclerosis; Arteriosclerosis -- Periodicals; Electronic journals; 616.136
• DOI: 10.1016/j.atherosclerosis.2017.03.005
• Languages: English
• ISSNs: 0021-9150

Abstract

Abstract: Background and aims: The arterial wall calcium score and circulating free DNA levels are now used in clinical practice as biomarkers of cardiovascular risk. Calcium phosphate apatite retention in the arterial wall necessitates precipitation on an anionic platform. Here, we explore the role of tissue-free DNA as such a platform. Methods: The first step consisted of histological observation of samples from human and rat calcified arteries. Various stains were used to evaluate colocalization of free DNA with calcified tissue (alizarin red, fluorescent Hoechst, DNA immunostaining and TUNEL assay). Sections were treated by EDTA to reveal calcification background. Secondly, a rat model of vascular calcifications induced by intra-aortic infusions of free DNA and elastase + free DNA was developed. Rat aortas underwent a micro-CT for calcium score calculation at 3 weeks. Rat and human calcifications were qualitatively characterized using μFourier Transform Infrared Spectroscopy (μFTIR) and Field Emission-Scanning Electron Microscopy (FE-SEM). Results: Our histological study shows colocalization of calcified arterial plaques with free DNA. In the intra-aortic infusion model, free DNA was able to penetrate into the arterial wall and induce calcifications whereas no microscopic calcification was seen in control aortas. The calcification score in the elastase + free DNA group was significantly higher than in the control groups. Qualitative evaluation with μFTIR and FE-SEM demonstrated typical calcium phosphate retention in human and rat arterial specimens. Conclusions: This translational study demonstrates that free DNA could be involved in arterial calcification formation by precipitating calcium phosphate apatite crystals in the vessel wall. Graphical abstract: Highlights: Free DNA colocalizes with calcifications in human and rat arteries. EDTA calcium chelation allowed to identify free DNA as background of calcification. A calcification model based on intra-aortic free DNA infusion is presented. Free DNA may serve as an anionic platform precipitating calcium phosphate.