Liang “Charles” Guo Recent Publications
Iron is an essential element for life. While it plays fundamental roles in processes such as oxygen transport, DNA synthesis, and electron transport, it can also be toxic. As such its homeostasis is tightly controlled. Disorders of iron metabolism are well recognized as a cause of disease in humans. Yet the role of iron in the context of atherosclerosis and coronary artery disease (CAD) remains uncertain, despite iron having been known to be present in atherosclerotic lesions for decades. Sullivan proposed iron as a cardiovascular risk factor, suggesting modest increases in levels of stored iron, promote cardiovascular disease while relative iron deficiency might protect against it. The “iron hypothesis” was initially presented as an explanation for sex-based differences in cardiovascular disease with an increase in women after menopause. The more basic idea was that free iron released from tissues might accelerate lipid peroxidation and inflammation through production of hydroxyl radicals via the Fenton reaction.
Coronary artery disease remains an important cause of morbidity and mortality. Previous work, including ours, has focused on the role of intraplaque hemorrhage, particularly from immature microvessel angiogenesis, as an important contributor to plaque progression via increases in vascular permeability leading to further intraplaque hemorrhage, which increases red cell membrane-derived free cholesterol in plaque content and inflammatory cell recruitment. Evans Blue Dye (EBD) assay is widely used as a standard assay for vasculature permeability. However, the method has not been established in fresh human coronary artery autopsy samples to evaluate intraplaque microvessel permeability and angiogenesis. In this protocol, we describe a method to evaluate human coronary samples for microvascular permeability, including procedures to perfuse coronary arteries, collection of artery samples for histological analysis and immunostaining as well as the use of appropriate methodology to analyze the images. An optional procedure is also provided for the use of FITC-dextran in mouse model to evaluate vascular permeability. These Evans Blue Dye procedures may be useful in providing functional measure of the endothelium integrity and permeability in both human samples and animal models in various pathological conditions.