BIOTIN-CONJUGATED OR DIGOXIGENIN-CONJUGATED NUCLEOTIDES BIND TO MATRIX VESICLES IN ATHEROSCLEROTIC PLAQUES

The present study analyzes the staining pattern of DNA in situ end-lab eling techniques of human and rabbit atherosclerotic plaques. Both the terminal deoxynucleotidyl transferase end-labeling and the in situ ni ck translation technique detected, besides apoptotic nuclei, numerous round vesicles with diameters front 0.5 to 5 mu m within the atheroscl erotic plaques. These vesicles did not contain DNA but contained calci um. A pretreatment with EDTA or citric acid abolished the labeling of the vesicles but did not influence the detection of apoptotic nuclei. Ultrastructurally, the vesicles were of variable diameter and density, and their aspect was compatible with matrix vesicles, which are well snows ht the epiphyses during bone formation. The larger vesicles cont ained cell organelles, and the small vesicles were very dense. X-ray m icroanalysis demonstrated high calcium and phosphorus levels within th e most dense vesicles, Different stages of the process were present in the plaques, rn this way we could demonstrate that cytoplasmic fragme ntation of smooth muscle cells and subsequent formation of matrix vesi cles are a frequent finding in atherosclerotic plaques. The associatio n of apoptotic cell death and formation of matrix vesicles could be an interesting pathway in explaining calcification of atherosclerotic pl aques. Both the terminal deoxynucleotidyl transferase end-labeling and the in situ nick translation technique detected simultaneously apopto tic nuclei and matrix vesicles if calcium is not removed from the sect ions.