Early changes in coronary artery wall structure detected by microcomputed tomography in experimental hypercholesterolemia

Early changes in coronary artery wall structure detected by microcomputed tomography in experimental hypercholesterolemia. Am J Physiol Heart Circ Physiol 293: H1997-H2003, 2007. First published June 15, 2007; doi:10.1152/ajpheart.00362.2007.-Changes in the structure of the artery wall commence shortly after exposure to cardiovascular risk factors, such as hypercholesterolemia ( HC), but may be difficult to detect. The ability to study vascular wall structure could be helpful in evaluation of the factors that instigate atherosclerosis and its pathomechanisms. The present study tested the hypothesis that early morphological changes in coronary arteries of hypercholesterolemic ( HC) pigs can be detected using the novel X-ray contrast agent OsO4 and three-dimensional micro-computed tomography ( CT). Two groups of pigs were studied after they were fed a normal or an HC ( 2% cholesterol) diet for 12 wk. Hearts were harvested, coronary arteries were injected with 1% OsO4 solution, and cardiac samples ( 6-mu m-thick) were scanned by micro-CT. Layers of the epicardial coronary artery wall, early lesions, and perivascular OsO4 accumulation were determined. Leakage of OsO4 from myocardial microvessels was used to assess vascular permeability, which was correlated with immunoreactivity of vascular endothelial growth factor in corresponding histological cross sections. OsO4 enhanced the visualization of coronary artery wall layers and facilitated detection of early lesions in HC in longitudinal tomographic sections of vascular segments. Increased density of perivascular OsO4 in HC was correlated with increased vascular endothelial growth factor expression and suggested increased microvascular permeability. The use of OsO4 as a contrast agent in micro-CT allows three- dimensional visualization of coronary artery wall structure, early lesion formation, and changes in vascular permeability. Therefore, this technique can be a useful tool in atherosclerosis research.