Atherosclerotic plaques and restenoses in carotid arteries after endarterectomy. Phenotypic characteristics of smooth muscle cells

Indirect immunofluorescence was used for the study of phenotypes of smooth muscle cells (SMCs) in normal intima with age related diffuse thickening, media and atherosclerotic plaques from carotid arteries of adult humans. Phenotypes of SMCs from restenotic areas after carotid endarterectomy were also investigated. The following immunohistochemical markers were used in the study: SMCs myosin, vimentin, desmin, h-caldesmon, calponin, cytokeratin-8, and fibronectin with ED-A sequence. Phenotypes of SMCs in diffuse intimal thickenings, primary atherosclerotic plaques as well as in areas of myointimal hyperplasia and atherosclerotic lesions of endarterectomy sites were similar and differed from the medial SMCs. Unlike SMCs in the media in subendothelium from intimal thickenings and atherosclerotic lesions all SMCs expressed fibronectin with ED-A sequence, many SMCs contained cytokeratin-8, and there were clusters of h-caldesmon and calponin deficient SMCs. While stem cells present in endothelium prior to development of atherosclerotic lesions have been assumed to be the precursors of SMCs in primary atherosclerotic plaques, SMCs in areas of myointimal hyperplasia apparently originate from congener cells which have invaded subendothelium during formation of diffuse thickening of the intima whereas population of SMC in atherosclerotic lesions of restenotic sites presumable develop from precursor cells localized in regions of myointimal hyperplasia.