Effect of hyperglycaemia and the antidiabetic drug “metformin" on heart valve endothelial cells

Abstract

Valve endothelial cells (VECs) are key effectors in the protection, homeostasis, and pathogenesis of the heart valve. Diabetes is one of the risk factors for heart valve diseases. This project focused on the effects of hyperglycemia on human VECs (hVECs) function, and effects of the antidiabetic drug metformin in restoring the function of hVECS under hyperglycemic conditions. hVECs were isolated from human aortic valves using collagenase digestion. Cells were treated with media containing normal(5.5mM) or high(25mM) glucose concentrations for 72hr and cell functions were studied in absence and presence of metformin (10, 25 and 50 µm). Cell proliferation was tested by AlamarBlueTM assay and cell counts of DAPI stained nuclei. Cytotoxicity was estimated by lactate-dehydrogenase-cytotoxicity assay. Expression of adhesion molecules was estimated by fluorescent-immunocytochemistry staining. Hyperglycemia reduced hVECs metabolic activity and counts, and this reduction was not linked to cytotoxic effects on the cells, where cytotoxicity percent was <10% for all treatments. Treatments with metformin for 72hr had no significant effect on hVECs proliferation and cytotoxicity. The expression of adhesion molecules (VCAM-1 and e-selectin) was induced in high glucose treated cells, and treatments with metformin attenuated this effect. Our findings suggest a reduction in hVECs proliferation and an upregulation of adhesion molecules in response to chronic hyperglycemia. These molecules are known to be upregulated in activated valve endothelial cells during early stages of calcific aortic disease, suggesting their involvement in heart valve disease in diabetics.  

QNRF-Fund# UREP24-036-3-013 & PDRA4-0129-18003.