SMOOTH-MUSCLE CELL-PROLIFERATION IN THE OCCLUDED RAT CAROTID-ARTERY - LACK OF REQUIREMENT FOR LUMINAL PLATELETS

  • 1 January 1979
    • journal article
    • research article
    • Vol. 94  (3) , 585-+
Abstract
The relationship of intimal smooth muscle cell proliferation in the permanently occluded rat carotid artery to the presence or absence of luminal platelets was studied. Blood was rinsed from the arterial lumen immediately after occlusion and was replaced by autologous, citrated platelet-rich plasma (PRP, 6-20 .times. 105 platelets/.mu.l) or filtered platelet-poor plasma (PPP, < 100 platelets/.mu.l). Occluded arteries were studied after 1-28 days by EM and light microscopy. Events occurring within the first 2 days included fibrin clot formation, endothelial degeneration and denudation, transmural migration of polymorphonuclear leukocytes and monocytes, and, in PRP-filled arteries, degranulation and disappearance of platelets. By 7 days a neointima was formed by macrophages and undifferentiated cells. The latter cells had some features of vascular smooth muscle cells and were apparently derived from medial cells which traversed the internal elastic lamina. After 14 days, identifiable smooth muscle cells emerged as the predominant cell type in a rapidly growing intimal plaque. No differences could be discerned between arteries originally filled with PRP or PPP. This experimental model is similar to atherosclerosis in dimensions of avascular area and in coexistence of degenerative, inflammatory and proliferative processes. Cell proliferation deep within an atherosclerotic plaque could be initiated by factors other than platelets, perhaps by products of inflammatory cells.