Stenosis of medium-sized arteries, such as the coronaries, is the most common and threatening complication of atherosclerosis. When stenosis is established, it tends to progress. The mechanism of this progression is not well understood; presumably it represents the combination of physical factors (related to flow) and biological responses of the arterial lining. We plan a combined biophysical and biological approach to this problem: (1) Stenosis of the rat aorta will be induced with U-shaped clips, restricting the lumen by 10, 25, 50, or 80%. The short and long-term effects will be studied morphologically, searching for evidence not only of endothelial damage, but also of endothelial stimulation (""""""""activation"""""""" - especially as expressed by attachment of white blood cells and increased production of visible large molecules). In parallel, a team of biophysicists will build scaled-up models of the stenotic aortas. Disturbances of flow detected in these models will be correlated with morphologic findings on the rat aortas. (2) Stenosis and arterial fat deposits. Until now it has not been possible to induce an atherosclerotic lesion at a given site at will. Previous work has shown that if rats are fed a high cholesterol diet, fat deposits form just above and just below a stenosis. These deposits represent early atherosclerotic lesions. We therefore plan to use them to study the genesis, regression, and response to therapy of atherosclerotic lesions. (3) Lipoprotein uptake by the arterial wall. It is possible to label the plasma lipoprotein particles with ultramicroscopic particles of gold, visible by electron microscopy. We will therefore study the uptake and fate of these particles in the arterial lining and their role in the genesis of atherosclerotic lesions. To do this we will induce stenosis in the aorta of hypercholesterolemic rats, then (later) isolate the vessel and perfuse it with a fluid containing gold-labeled lipoproteins. (4) Studies on cultured endothelium. Certain events related to stenosis can be studied in tissue cultures of endothelium, because - in a mildly stenotic artery - the increased shear stress induces an activation of the endothelial cells, and a similar activation can be induced in tissue cultures by chemical means. We will therefore analyze, in endothelial cultures, two events (related to cell activation) that occur in stenosis, namely white blood cell attachment and contraction of the endothelial cells.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL025973-11
Application #
3338403
Study Section
Pathology A Study Section (PTHA)
Project Start
1982-07-01
Project End
1992-11-30
Budget Start
1990-12-15
Budget End
1992-11-30
Support Year
11
Fiscal Year
1991
Total Cost
Indirect Cost
Name
University of Massachusetts Medical School Worcester
Department
Type
Schools of Medicine
DUNS #
660735098
City
Worcester
State
MA
Country
United States
Zip Code
01655
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MacWilliams, B A; Hoffman, A H; Savilonis, B J (1998) Variation of arterial compliance within the cardiac pressure pulse. J Biomech 31:867-71
Majno, G (1992) Maude Abbott Lecture--1991. The capillary then and now: an overview of capillary pathology. Mod Pathol 5:9-22
Boswell, C A; Majno, G; Joris, I et al. (1992) Acute endothelial cell contraction in vitro: a comparison with vascular smooth muscle cells and fibroblasts. Microvasc Res 43:178-91
Boswell, C A; Joris, I; Majno, G (1992) The concept of cellular tone: reflections on the endothelium, fibroblasts, and smooth muscle cells. Perspect Biol Med 36:79-86
Zand, T; Majno, G; Nunnari, J J et al. (1991) Lipid deposition and intimal stress and strain. A study in rats with aortic stenosis. Am J Pathol 139:101-13
Joris, I; Cuenoud, H F; Doern, G V et al. (1990) Capillary leakage in inflammation. A study by vascular labeling. Am J Pathol 137:1353-63
Desemone, J; Majno, G; Joris, I et al. (1990) Morphological and physiological characteristics of pancreas-specific venular permeability induced by Monastral blue B. Exp Mol Pathol 52:141-53
Zand, T; Nunnari, J J; Hoffman, A H et al. (1988) Endothelial adaptations in aortic stenosis. Correlation with flow parameters. Am J Pathol 133:407-18
Moyer, C F; Dennis, P A; Majno, G et al. (1988) Venular endothelium in vitro: isolation and characterization. In Vitro Cell Dev Biol 24:359-68

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