Effect of insulin and heparin on glucose-induced vascular damage in cell culture

Effect of insulin and heparin on glucose-induced vascular damage in cell culture.BackgroundClinical trials have shown that tight glycemic control reduces the risk of diabetic microvascular complications, namely retinopathy, nephropathy, and neuropathy. The mechanism of these microvascular complications is not yet fully elucidated. The present study describes the effect of different concentrations of glucose on vascular endothelial cells (ECs) and vascular smooth muscle cells (VSMCs) in cell culture. Our objective was to shed some light through this biological study on the mechanism and prevention of diabetic microvascular complications.MethodsECs and VSMCs were treated with 5 mmol/L (90 mg/dL) or 30 mmol/L (540 mg/dL) D-glucose or D-glucose plus insulin or D-glucose plus insulin and heparin in culture. ECs were studied with light microscopy (LM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) for surface changes. The cultured ECs were treated with vimentin antibodies and VSMCs with actin antibodies for immunoflourescence microscopy (IFM) study. Endothelin-1 (ET-1) assay was done on ECs culture medium using enzyme-linked immunosorbent assay (ELISA).ResultsLM, SEM, and TEM of ECs treated with a physiological concentration (90 mg/dL) of D-glucose appeared the same as control. However, LM and SEM of ECs treated with a high concentration of D-glucose (540 mg/dL) showed pronounced intercellular gaps. This finding was further confirmed by TEM study. These gaps were minimally or not at all discernible when insulin, heparin, or a combination of both was added to the culture medium. IFM showed increased vimentin expression with a high concentration of D-glucose. Vimentin expression was attenuated with the addition of insulin or heparin in the medium and more markedly with combined insulin and heparin. Significant correlations were obtained between glucose levels, vimentin expression, and ET-1 levels. The higher the glucose level, the higher is the ET-1 production and the greater vimentin expression in ECs. Cultured VSMCs treated with a high concentration of D-glucose showed enhanced actin expression. Actin expression was blunted with the addition of insulin or heparin in the culture medium.ConclusionsThese biological findings indicate the salutary effect of insulin or insulin and heparin in the mitigation of vascular disorganization caused by a high concentration of D-glucose