Abstract-The study of atherogenesis in humans has been restricted by the limited availability and brief in vitro life span of plaque smooth muscle cells (SMCs). We describe plaque SMC lines with extended life spans generated by the expression of the human papillomavirus (HPV)-16 E6 and E7 genes, which has been shown to extend the life span of normal adult human aortic SMCs. Resulting cell lines (pdSMC1A and 2) demonstrated at least 10-fold increases in life span; pdSMC1A became immortal. The SMC identity of both pdSMC lines was confirmed by SM22 mRNA expression. pdSMC2 were generally diploid but with various structural and numerical alterations; pdSMC1A demonstrated several chromosomal abnormalities, most commonly ϪY, ϩ7, Ϫ13, anomalies previously reported in both primary pdSMCs and atherosclerotic tissue. Confluent pdSMC2 appeared grossly similar to HPV-16 E6/E7-expressing normal adult aortic SMCs (AASMCs), exhibiting typical SMC morphology/growth patterns; pdSMC1A displayed irregular cell shape/ organization with numerous mitotic figures. Dedifferentiation to a synthetic/proliferative phenotype has been hypothesized as a critical step in atherogenesis, because rat neonatal SMCs and adult intimal SMCs exhibit similar gene expression patterns. To confirm that our pdSMC lines likewise express this apparent plaque phenotype, osteopontin, platelet-derived growth factor B, and elastin mRNA levels were determined in pdSMC1A, pdSMC2, and AASMCs. However, no significant increases in osteopontin or platelet-derived growth factor B expression levels were observed in either pdSMC compared with AASMCs. pdSMC2 alone expressed high levels of elastin mRNA. Key Words: atherosclerosis Ⅲ smooth muscle Ⅲ plaque Ⅲ platelet-derived growth factor B Ⅲ osteopontin V ascular remodeling is a critical yet successful adaptive feature for the maintenance of blood flow in vessels with thickened intimas. However, additional neointimal expansion may surpass the adaptive capabilities of a vessel, leading to lumenal narrowing (for review, see Schwartz et al 1 ). Plaque rupture, vasospasm, and/or thrombus formation are common sequelae in the functionally compromised, diseased vessel. Smooth muscle cell (SMC) proliferation and migration from the arterial media into the intima have been described in the development of atherosclerotic disease in both human and animal models. 2,3 In addition, these neointimal SMCs are believed to promote key processes of plaque formation including the accumulation of extracellular matrix and deposition of calcium. 4 -6 Several initiating mechanisms responsible for these events have been postulated including the response-to-injury theory (for review, see Ross 7 ) and the theory of viral atherogenesis. 8 -10 The monoclonal nature of SMCs comprising the plaque supports the role of viral transformation in atherogenesis. [11][12][13] Whether this altered SMC population is the progeny of a single activated/ injured cell or represents the expansion of a developmentally unique population within the vessel wall is unknown...

Tissue factor (TF), a transmembrane glycoprotein, initiates the extrinsic coagulation cascade. TF is known to play a major role in mediating thrombosis and thrombotic episodes associated with the progression of atherosclerosis.