Resistance to Arteriosclerosis in Pigs with von Willebrand's Disease

The aortas of 11 pigs (aged 1-3 yr) with homozygous von Willebrand's disease (vWd) were compared with those of 11 normal pigs of the same ages. Six of the controls exhibited multiple arteriosclerotic plaques with intimal thickening of 63-130 mum. In contrast, none of the pigs with vWd had multiple plaques, and only one had a lesion >2 mm in diameter. In a subsequent study, 3-mo-old pigs (11 controls and 7 with homozygous vWd) were placed on a 2% cholesterol diet for up to 6 mo. All of the controls developed arteriosclerotic plaques in the aorta, and in nine of the controls, at least 13% of the entire surface was involved. Intimal thickness ranged up to 390 mum. In contrast, four of the pigs with vWd did not develop such lesions, two developed arteriosclerotic lesions affecting 6 and 7% of the aortic surface, and the seventh had 13% of the aortic surface involved. Most of the pigs with vWd, however, developed flat fatty lesions in contrast to the normal pigs whether on the normal or the high cholesterol diet. There was blue staining of the flat fatty lesions when two pigs with vWd were injected with Evans blue dye antemortem. By electron microscopy, severe endothelial damage was apparent, but there was no intimal proliferation. The coincidence of the impaired platelet-arterial wall interaction and lack of arteriosclerosis in this bleeding disease is discussed.