Abstract P156: Intimal And Medial Calcification Underlie Differential Molecular Mechanisms

Abstract

Introduction: Vascular calcification (VC) is a significant risk factor for cardiovascular morbidity and mortality. Based on the mineral deposition site in the arterial wall, VC classifies into intimal and medial calcification. We hypothesize that distinct in vitro mineralization methods promote specific intracellular signalling pathways in vascular smooth muscle cells (SMC), reflecting both VC types. Methods and Results: Human coronary artery SMCs were cultured in osteogenic medium (OM) or high calcium-phosphate medium (CaP) to induce calcification. OM resembles SMCs differentiation in intimal calcification - a key process in atherosclerotic plaque remodeling. CaP is associated with chronic kidney disease - a risk factor for medial calcification. Transcriptomics revealed a distinct gene expression profile of OM and CaP-calcifying SMCs, that share 6.9% and 11.3% of their genes, respectively. The 109 shared dysregulated genes between OM and CaP-calcifying SMCs highlighted enriched pathways related to SMC contraction and metabolism. Real-time extracellular efflux analysis demonstrated a different metabolic profile in OM and CaP-calcifying SMCs. We observed decreased mitochondrial respiration and glycolysis (-57,3% p=0.029) by CaP and increased mitochondrial respiration without altered glycolysis by OM. Subsequent kinome and in silico drug repurposing analysis (Connectivity Map) revealed a distinct role of protein kinase C (PKC). Validation using prostratin, a specific PKC activator, demonstrated differential effects on matrix mineralization that was decreased by OM (-69,3%, p<0.001) and increased by CaP (+69,6%, p=0.044). Conclusions: In conclusion, OM and CaP-induced SMC calcification underlies differential mechanisms in vitro. Therefore, research should distinguish between the two aspects of VC and increased knowledge about the underlying pathophysiological mechanisms may open the possibility for preventing intimal and medial calcification.