[The phenotypes of arterial smooth-muscle cells during ontogeny and in atherosclerotic plaques].

Smooth-muscle cell (SMC) myosin expression, SMC alpha-actin, h-caldesmon and calponin expression were studied in developing SMC of embryonic aorta as well as in adult human aorta and coronary arteries. It was found that ontogenesis is associated with SMC phenotypic modulations. In 8-23-week embryos SMC express SMC myosin and alpha-actin. In adult humans arterial SMC express all the markers studied. Normal subendothelium contains a heterogeneous SMC population. SMC heterogeneity is most marked in atherosclerotic plaques in the form of clusters of homogeneous cells different by expression of contractile system proteins. It is suggested that SMC heterogeneous population in atherosclerotic plaques may arise due to proliferation of phenotypically different precursors cells.