Mechanism of dystrophic calcification in rabbit aortas: temporal and spatial distributions of calcifying vesicles and calcification-related structural proteins.

INTRODUCTION: We have previously demonstrated the accumulation of calcifying vesicles in the thoracic aorta undergoing dystrophic calcification. Whether the distributions of other structural proteins related to calcification such as collagen and elastin fibers undergo coordinated modifications has not been established.
METHODS: Young rabbits with various degrees of aortic calcification induced by cholesterol dietary interventions were used as an animal model to study the correlations.
RESULTS: Rabbits fed a diet enriched in cholesterol for 3 months accumulated calcifying vesicles in the ascending thoracic aortas but did not develop histologically identifiable calcification. There were concomitant marked thickenings of the intima with focal deposition of collagen and disruption of the internal elastic fibers at this stage. By the 6th month, calcification was predominantly present in the intimal area adjacent to the media. At this calcified stage, calcifying activity of vesicles was higher than earlier stages. Concomitantly, collagen deposition in the lesions was intensified and the internal elastic fibers were completely disintegrated. These changes were found to be more profound in the proximal than in the distal portion of the aortas.
CONCLUSION: The coordinated changes in the accumulation of collagen, disintegration of internal elastic fibers, and the appearance of calcifying vesicles in the lesions before calcification may set the stage for aortic calcification.