In Vitro Chronic Hyperinsulinemia Induces Remodelling of Vascular Smooth Muscle Cells from Young Men and Women in a Sex Hormone Independent Manner

Abstract

Elevated circulating insulin levels between 80 and 100 µU/mL characterize hyperinsulinemia, which often leads to metabolic disorders such as obesity, insulin resistance, and type 2 diabetes (T2D). Elevated circulating insulin levels can directly affect vascular function and contribute to the pathophysiology of the cardiovascular system, including secondary arterial hypertension (SAH) and atherosclerosis. It is well known that hyperinsulinemia induced remodeling of the heart. However, there is no information on whether intrinsic differences exist between human vascular smooth muscle cells (VSMCs) and if in vitro mimicking hyperinsulinemia induces human VSMCs morphological and intracellular homeostasis remodeling in a sex- and sex hormones-dependent manner. Our in vitro cultured human VSMCs, coupled with quantitative 3D confocal imaging results, show that intrinsic differences exist between VSMCs from young men and women. Chronic hyperinsulinemia (80 µU/mL, 48 h treatment) increases cell and nuclear volumes associated with increased intracellular calcium (Ca2+) and ROS and decreased glutathione. In the absence of hyperinsulinemia, pretreatment with testosterone in VSMCs from men and oestradiol in VSMCs from women had no effect. Both sex hormones partially but not completely prevented hyperinsulinemia-induced remodeling of VSMCs from young men and women. The increase in VSMC volume may increase the thickness of the tunica media, leading to a decrease in the lumen of the blood vessel, which promotes the development of SAH and atherosclerosis in a sex-dependent manner.

Keywords

• human vascular smooth muscle cells
• insulin
• hyperinsulinemia
• sex dependency
• sex hormones
• calcium overload