Single- and double-walled carbon nanotubes enhance atherosclerogenesis by promoting monocyte adhesion to endothelial cells and endothelial progenitor cell dysfunction

Background: the use of carbon nanotubes has increased lately. however,the cardiovascular effect of exposure to carbon nanotubes remains elusive. the present study investigated the effects of pulmonary exposure to single-walled carbon nanotubes (swcnts) and double-walled carbon nanotubes (dwcnts) on atherosclerogenesis using normal human aortic endothelial cells (haecs) and apolipoprotein e-deficient (apoe-/-) mice,a model of human atherosclerosis. methods: haecs were cultured and exposed to swcnts or dwcnts for 16 h. apoe-/- mice were exposed to swcnts or dwcnts (10 or 40 μg/mouse) once every other week for 10 weeks by pharyngeal aspiration. results: exposure to cnts increased the expression level of adhesion molecule (icam-1) and enhanced thp-1 monocyte adhesion to haecs. apoe-/- mice exposed to cnts showed increased plaque area in the aorta by oil red o staining and up-regulation of icam-1 expression in the aorta,compared with vehicle-treated apoe-/- mice. endothelial progenitor cells (epcs) are mobilized from the bone marrow into the circulation and subsequently migrate to the site of endothelial damage and repair. exposure of apoe-/- mice to high-dose swcnts or dwcnts reduced the colony-forming units of epcs in the bone marrow and diminished their migration function. conclusion: the results suggested that swcnts and dwcnts enhanced atherosclerogenesis by promoting monocyte adhesion to endothelial cells and inducing epc dysfunction. © 2016 the author(s).