The effects of a shear flow on the uptake of LDL and acetylated LDL by an EC monoculture and an EC-SMC coculture

To elucidate the mechanisms of localized genesis and development of atherosclerosis and anastomotic intimal hyperplasia in man, a coculture of bovine aortic endothelial cells (ECs) and smooth muscle cells (SMCs) was prepared, and the effects of a shear flow on the uptake of lipoproteins by the cells was studied by incubating the EC-SMC coculture as well as an EC monoculture with a culture medium containing either DiI-LDL or DiI-Ac-LDL and subjecting to a laminar shear flow. It was found that in both the presence and absence of a shear flow that imposed the ECs an area mean shear stress of 13.3 dynes/cm(2), the uptake of LDL by an EC-SMC coculture was much greater than that by an EC monoculture, whereas that of Ac-LDL was almost the same. The uptake of LDL by an EC monoculture increased slightly by being exposed to a shear flow, whereas that by an EC-SMC coculture did not. In contrast to this, the uptake of Ac-LDL by both an EC monoculture and an EC-SMC coculture decreased drastically by a shear flow, suggesting that the action of a shear flow on the uptake of Ac-LDL by vascular cells is very different from that of LDL.