Accumulation of low density lipoprotein associated cholesterol in calcifying vesicle fractions correlates with intimal thickening in thoracic aortas of juvenile rabbits fed a supplemental cholesterol diet

BACKGROUND:It has been shown that calcifying vesicles play an important role in aortic calcification and that cholesterol content in the isolated vesicle fraction is increased when rabbits are fed supplemental cholesterol diets. Whether lipoprotein-associated cholesterols and other lipids are also increased in the vesicle fraction and whether the increase correlates with atherosclerosis remain unknown.RESULTS:Fourteen juvenile male rabbits fed an atherogenic diet containing 0.5% cholesterol and 2% peanut oil for 3 months developed varying degrees of hypercholesterolemia and intimal thickening in the ascending thoracic aorta. The correlation between these two parameters was insignificant, and likely attributable to the use of small numbers of rabbits in this study. Despite this lack of correlation, we demonstrate that the accumulation of cholesterol in calcifying vesicle fractions obtained from the collagenase-digested aorta fragments correlates well with intimal thickening (r2 = 0.98, p < 0.0001). To a smaller degree, the correlation was also significant between intimal thickening and the cholesterol accumulation in the microsomal and post-vesicle fractions. The cholesterol supplemental diet increased the low density lipoprotein-cholesterol (LDL-C) content in calcifying vesicle fractions by 3-fold but did not affect the triglyceride content. High density lipoprotein-cholesterol (HDL-C) and very low-density lipoprotein cholesterol (VLD-C) were absent in calcifying vesicle fractions.CONCLUSION:When limited numbers of rabbits are used, LDL-C accumulation in calcifying vesicle fractions is a better biomarker for atherosclerosis than LDL-C levels in the serum. The close association of LDL-C with calcifying vesicles may play an important role in atherosclerosis and calcification.