Isolation of a morphologically and functionally distinct smooth muscle cell type from the intimal aspect of the normal rat aorta. Evidence for smooth muscle cell heterogeneity |
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Authors: | Sergio Villaschi Roberto F Nicosia Marion R Smith |
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Institution: | (1) Present address: Department of Surgery, University of Rome “Tor Vergata”, Rome, Italy;(2) Department of Pathology, Medical College of Pennsylvania, 3300 Henry Avenue, 19129 Philadelphia, Pennsylvania |
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Abstract: | Summary Recent studies indicate that the neointima of injured rat arteries is composed of a subpopulation of smooth muscle cells (SMCs)
distinct from medial smooth muscle cells. However, SMC diversity in normal adult aorta has remained elusive. This study characterizes
two morphologically and functionally distinct SMC types isolated from different anatomic regions of the normal rat aorta.
Rat aortic medial smooth muscle cells (MSMCs) were isolated from the media after removal of the intimal and adventitial cells.
Rat aortic intimal smooth muscle cells (ISMCs) were isolated from the intimal aspect of everted rat aortas. The two cell types
were characterized morphologically and immunohistochemically and were compared for their capacity to contract collagen gels
in response to endothelin-1. MSMCs were spindle-shaped and grew in hills and valleys showing features previously described
for vascular SMCs. Conversely, ISMCs displayed a polygonal and epithelioid shape, grew mainly as a monolayer, and had a higher
proliferative rate. Both cell types expressed alpha-smooth muscle actin and were negative for Factor VIII-RAg. ISMCs produced
large amounts of a laminin and type IV collagen-rich extracellular matrix which had a characteristic pericellular distribution.
ISMCs, but not MSMCs, rapidly contracted collagen gels in response to endothelin-1. This study indicates that the normal rat
aorta contains two types of SMCs located in anatomically distinct regions of the vessel wall. Because of their functional
characteristics, the SMCs isolated from the intimal aspect of the aorta may play an important role in physiologic as well
as pathologic conditions. |
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Keywords: | aorta atherosclerosis collagen endothelin endothelium smooth muscle cells |
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