© 1997 American Heart Association, Inc.
Articles |
Antifibrinolytic Properties of the Vascular Wall
Dependence on the History of Smooth Muscle Cell Doublings In Vitro and In Vivo
From the Departments of Cardiology (G.C., G.M., K.H.), Vascular Biology and Thrombosis Research (G.C., P.H., C.K., J.W., B.R.B.), and Cardiothoracic Surgery (G.L.), University of Vienna, Austria.
Correspondence to Günter Christ, MD, Department of Vascular Biology and Thrombosis Research, University of Vienna, Schwarzspanierstr17, A-1090 Vienna, Austria.
Abstract Increased expression of plasminogen activator inhibitor-1 (PAI-1) mRNA in atherosclerotic human arteries suggests a linkage between PAI-1 gene expression and cellular proliferation, the fundamental feature of atherosclerosis. To investigate whether smooth muscle cell (SMC) proliferation influences overall fibrinolytic properties of the vascular wall, we examined the effect of serial in vitro passaging of human SMCs on tissue plasminogen activator (TPA) and PAI-1 synthesis levels as well as the ability to modulate TPA and PAI-1 synthesis of human umbilical vein endothelial cells (HUVECs). As in vivo correlates for such late-passage cells in culture, SMCs derived from human atherosclerotic plaques were used, because they are thought to have already undergone numerous cell doublings. We observed an increase of PAI-1 secretion (from 591±106 to 2952±290 ng PAI-1·105 cells-1·24 h-1) with a concomitant fourfold to fivefold increase of PAI-1 mRNA levels, as well as a decrease of TPA secretion (from 118±34 to 8±1.3 ng TPA·105 cells-1·24 h-1) and a twofold to threefold decrease of TPA mRNA levels with increasing in vitro passage number (from passage 3 to 11) of normal pulmonary artery smooth muscle cells (PASMCs) (P<.05). SMCs derived from atherosclerotic plaques of coronary arteries (CASMCs) displayed higher levels of PAI-1 antigen synthesis (3093±507 ng PAI-1·105 cells-1·24 h-1) with an approximately twofold increase of PAI-1 mRNA levels, as well as decreased levels of TPA antigen synthesis (10±1.6 ng TPA·105 cells-1·24 h-1) with an 
1.5- to 2-fold decrease of TPA mRNA levels in passage 1, compared with their counterparts derived from normal-appearing arterial tissue of the same vessel (1794±525 ng PAI-1·105 cells-1·24 h-1; 17±5 ng TPA·105 cells-1·24 h-1) (P<.001; P<.01). Incubation of HUVEC cultures with the 24-hour conditioned media (CM) of early-passage PASMCs decreased endothelial PAI-1 antigen synthesis by 42% (P<.001) and endothelial PAI-1 mRNA levels about twofold to threefold (P<.001), whereas by incubation with the 24-hour CM of late-passage PASMCs, endothelial PAI-1 antigen synthesis was upregulated by 68% (P=.001), with a concomitant twofold increase of endothelial PAI-1 mRNA levels (P<.001). The apparent MW of this heat- and acid-stable PAI-1 upregulating factor appears to be between 50 and 100 kD, as judged by ultrafiltration. Incubation of HUVEC cultures with the 24-hour CM of early-passage CASMCs derived from normal-appearing arterial tissue showed no significant influence on endothelial PAI-1 synthesis, whereas incubation with late-passage normal CASMCs, as well as early-passage atherosclerotic CASMCs from the same vessel, increased endothelial PAI-1 antigen secretion by 45% and 48% (P<.001), with a concomitant 1.5-fold to 2-fold increase of endothelial PAI-1 mRNA levels (P<.05). No significant change in endothelial TPA synthesis was observed by incubation with CM of either PASMCs (early or late passage) or CASMCs (atherosclerotic or normal). These data suggest that SMC proliferation is associated with (1) increased SMC PAI-1 synthesis as well as decreased TPA synthesis and (2) upregulation of endothelial PAI-1 synthesis by SMC CM. This phenomenon is observed with either late passages of normal PASMCs and CASMCs or early passages of atherosclerotic plaque CASMCs. This suggests that proliferating SMCs are a major regulator of the fibrinolytic potential within the vessel wall, thereby contributing to the thrombotic risk associated with the development of atherosclerosis.
Key Words: plasminogen activator inhibitor-1 • smooth muscle • endothelial cells • atherosclerosis
This article has been cited by other articles:
 |
|
 |
|
  L. T. Vaszar, T. Nishimura, J. D. Storey, G. Zhao, D. Qiu, J. L. Faul, R. G. Pearl, and P. N. Kao Longitudinal transcriptional analysis of developing neointimal vascular occlusion and pulmonary hypertension in rats Physiol Genomics, April 13, 2004; 17(2): 150 - 156. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 N. Kobayashi, S. Nakano, S.-i. Mita, T. Kobayashi, T. Honda, Y. Tsubokou, and H. Matsuoka Involvement of Rho-Kinase Pathway for Angiotensin II-Induced Plasminogen Activator Inhibitor-1 Gene Expression and Cardiovascular Remodeling in Hypertensive Rats J. Pharmacol. Exp. Ther., May 1, 2002; 301(2): 459 - 466. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 B. R. Binder, G. Christ, F. Gruber, N. Grubic, P. Hufnagl, M. Krebs, J. Mihaly, and G. W. Prager Plasminogen Activator Inhibitor 1: Physiological and Pathophysiological Roles Physiology, April 1, 2002; 17(2): 56 - 61. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 L. Sironi, A. M. Calvio, L. Arnaboldi, A. Corsini, A. Parolari, M. de Gasparo, E. Tremoli, and L. Mussoni Effect of Valsartan on Angiotensin II-Induced Plasminogen Activator Inhibitor-1 Biosynthesis in Arterial Smooth Muscle Cells Hypertension, March 1, 2001; 37(3): 961 - 966. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 W. Dichtl, A. Stiko, P. Eriksson, I. Goncalves, F. Calara, C. Banfi, M. P. S. Ares, A. Hamsten, and J. Nilsson Oxidized LDL and Lysophosphatidylcholine Stimulate Plasminogen Activator Inhibitor-1 Expression in Vascular Smooth Muscle Cells Arterioscler Thromb Vasc Biol, December 1, 1999; 19(12): 3025 - 3032. [Abstract] [Full Text] [PDF]
|
|