Formation of multinucleated variant endothelial cells with altered mitochondrial function in cultured coronary endothelium under simulated diabetes

Coronary endothelial dysfunction is associated with atherosclerosis and myocardial infarction in subjects with type 2 diabetes mellitus (T2DM). Vascular endothelial cells are referred to as small and polygonal mononuclear cells. However, multi-nucleated and large endothelial cells (named as multinucleated variant endothelial cells [MVECs]) have been reported in the aorta, wherein their abundance correlates with atherosclerosis severity. The role of MVECs in coronary endothelium remains obscure. We hypothesized that simulated diabetic conditions increase the number of MVECs and affect their mitochondrial structure/function in cultured coronary endothelium. The in vitro model of diabetes consisted in the treatment of bovine coronary artery endothelial cells (BCAECs) with high-insulin (100 nmol/L, HI) for three days followed by high-glucose (20 mmol/L, HG) and HI for nine additional days. Simulated diabetic conditions increased the abundance of MVECs compared to normal glucose (NG, 5.5 mM). MVECs had a higher nucleic acid content (7.2-Fold), cell diameter (2.2-Fold), and cell area (11.4-Fold) than mononuclear cells. Immunodetection of von-Willebrand factor (endothelial cell marker) in MVECs was positive. The mitochondrial mass was reduced, and mitochondrial membrane potential increased in mononuclear cells cultured in HG+HI compared to mononuclear cells grown in NG. However, the opposite mitochondrial findings were noted in MVECs compared to mononuclear cells. Mass spectrometry-based quantitative proteomic and gene ontology analysis suggested augmented mitochondrial autophagy, apoptosis, and inflammation suppression in cells cultured under HG+HI compared to NG conditions. These findings show that simulated diabetes increases the abundance of MVECs, and that mitochondrial structure and function are differentially affected between MVECs and mononuclear cells.