Understanding the molecular mechanisms underlying diabetic endothelial dysfunction is necessary in order to improve the cardiovascular health of diabetic patients. Previously, we described an in vivo, murine model of insulin resistance induced by feeding a high-fat diet (HFD) whereby the endothelium may be isolated by fluorescence-activated cell sorting (FACS) based on Tie2-GFP expression and cell-surface staining. Here, we apply this model to two new strains of mice, ScN/Tie2-GFP and ApoE(？/？)/Tie2-GFP, and describe their metabolic responses and endothelial isolation. ScN/Tie2-GFP mice, which lack a functional toll-like receptor 4 (TLR4), display lower fasting glucose and insulin levels and improved glucose tolerance compared to Tie2-GFP mice, suggesting that TLR4 deficiency decreases susceptibility to the development of insulin resistance. ApoE(？/？)/Tie2-GFP mice display elevated glucose and cholesterol levels versus Tie2-GFP mice. Endothelial isolation by FACS achieves a pure population of endothelial cells that retain GFP fluorescence and endothelial functions. Transcriptional analysis of the aortic and muscle endothelium isolated from ApoE(？/？)/Tie2-GFP mice reveals a reduced endothelial response to HFD compared to Tie2-GFP mice, perhaps resulting from preexisting endothelial dysfunction in the hypercholesterolemic state. These mouse models and endothelial isolation techniques are valuable for assessing diabetic endothelial dysfunction and vascular responses in vivo. 1. Introduction Vascular complications are the main causes of morbidity and mortality associated with diabetes. Diabetics have a 2–4-fold increased risk for developing cardiovascular disease [1]. Progressive degeneration of microvascular beds is a major contributing factor to many complications of diabetes including retinopathy, nephropathy, and neuropathy. Macrovascular complications associated with diabetes include coronary heart disease, stroke, and peripheral vascular disease. The relationship between diabetes and vascular complications emphasizes the importance of understanding the mechanisms underlying this association. The increased risk of cardiovascular disease observed in diabetes is primarily due to a damaged or dysfunctional endothelium. In the diabetic state, numerous inflammatory, hormonal, and metabolic influences impinge upon the endothelium and alter its function. Elevated glucose and fatty acids lead to endothelial nitric oxide synthase (eNOS) uncoupling [2]. This in turn leads to reduced nitric oxide bioavailability and generation of reactive nitrogen and oxygen
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