Abstract 691: Mir-146a as a Modulator and Pathomechanistic Target of Vascular Calcification

Abstract

Background: Arterial stiffness, which may develop due to vascular calcification, is a significant pathophysiological factor associated with arterial aging or diseases such as type-2 diabetes or end stage renal disease. With no effective therapy clinically available to date, molecular and epigenetic mechanisms of ectopic calcification in conduit arteries are receiving increasing attention to identify targets for therapeutical interference. Here we show that miR-146a may serve as a therapeutic candidate to counteract vascular calcification. Methods: Ectopic calcification was assessed in human aortic smooth muscle cells (AoSMCs) using Alizarin red and Von kossa stainings. The total calcium content in hydroxyapatite crystals was assessed using QuantiChrom TM calcium assay kit. The mRNA expression levels of BMP2, MSX2 and SORT1 were assessed by TaqMan real-time PCR. Results: The endogenous expression of miR-146a was significantly decreased and simultaneously ectopic calcium deposition was significantly increased in AoSMCs exposed to osteogenic stimulation. However, overexpression of miR-146a in AoSMCs cultured in vitro reduced the ectopic calcium deposits. Simultaneously, mRNA expression levels of osteogenic markers and drivers of calcification, such as BMP2, MSX2 and SORT1 - all predicted miR-146a target genes - were significantly reduced. Conversely, significantly increased calcium deposits were observed when miR-146a was inhibited in these cells in similar culture conditions with upregulated BMP2, MSX2 and SORT1 mRNA expression levels. Conclusion: The results suggest that miR-146a may serve as a modulator of AoSMC calcification and miR-146a supplementation may qualify as a therapeutic intervention to counteract vascular calcification due to aging, type-2 diabetes or end stage renal disease.