Cytogenetic aspects of cell proliferation in atherosclerotic plaques

Fluorescence in situ hybridization (FISH) using chromosome specific alpha-satellite DNA probes for chromosome 7, was performed on paraffin-embedded sections of 21 cases of human "unstable" atherosclerotic plaques, in order to determine whether trisomy 7, found by some Authors with conventional cytogenetics, is a biological characteristic of the atherosclerotic plaque. In 15 cases (71%) the FISH method showed smooth muscle cells with three or more spots. In particular the trisomy 7 was the most significant and constant result. The presence of an extra chromosome 7 is strictly correlated with an overexpression of the gene for chain A of the platelet-derived growth factor (PDGF), which was mapped at pter-7q22 region. Therefore trisomy 7 seems to correspond to an increase in PDGF synthesis and consequently to an increase in proliferative activity of smooth muscle cells.