Background: Calcification of the media of arteries is common in patients with end-stage renal disease (ESRD) undergoing haemodialysis and is a major cause of arteriosclerosis. The aim of this study was to clarify the role of glycoxidative modification of elastin in the calcification of aortic media in this group of patients.
Methods: Samples of tunica media were obtained from non-atherosclerotic areas of the aortas of cadavers of seven non-diabetic patients with ESRD (age 65.5 +/- 10.6 years) and 10 age-matched controls (age 61.1 +/- 10.3 years). The localization of pentosidine, a major glycoxidation product, and calcium deposits in the media were examined using immunohistochemical and von Kossa staining, followed by orcein staining for elastin fibres. Tissue levels of pentosidine and calcium were measured in elastase-digested media using reversed high-performance liquid chromatography and atomic absorption spectrophotometry, respectively.
Results: In aortic media, but not intima, immunostained pentosidine was observed along elastin fibres or in the extracellular spaces between them. Early calcification was manifest as small punctate calcified deposits along elastin fibres in the media. Advanced calcification was found as large, confluent calcified deposits in extracellular spaces between elastin fibres. Double staining showed co-localization of pentosidine and calcified deposits in the media. Both the staining density of pentosidine and calcification were more prominent in ESRD patients than in controls. The mean medial contents of both elastin-associated pentosidine and calcium were significantly higher in ESRD patients than in controls. In ESRD patients, the level of calcium in elastase-digested media correlated significantly with pentosidine levels, which increased in parallel with the duration of haemodialysis.
Conclusions: Our results indicate that glycoxidative modification of elastin in aortic media may be involved in the enhancement of medial calcification in ESRD patients on haemodialysis.