The promotion effect of novel magnetic nanoparticles on atherosclerotic plaque vulnerability in apolipoprotein E-/-mice

Although manufactured magnetic nanoparticles (NPs) are currently used in many fields, NPs have potential toxicity on cardiovascular system especially atherosclerosis. In our previous study, we prepared novel Fe3O4 nanoparticles surface-coated with aminoguanidine (Fe3O4-AG NPs) which could remove acid dyes from aqueous solution efficiently. To understand its biocompatibility to atherosclerotic plaque vulnerability, we investigated the effects of the nanoparticles on human umbilical vein endothelial cells (HUVECs) in vitro and plaque stability in vivo. Fe3O4-AG NPs were taken up by HUVECs and induced HUVEC apoptosis. Fe3O4-AG NP injection remarkably promoted plaque vulnerability at low-dose (0.5 mg/kg) but not high-dose (5.0 mg/kg) in apolipoprotein E-/- (ApoE(-/-)) mice. Further study indicated that Fe3O4-AG NP-induced atherosclerotic plaque vulnerability was tightly linked to bioactivity of nitric oxide (NO). A significant decrease in NO production was induced which coincided with the inhibition of endothelial nitric oxide synthase (eNOS) activity in serum and endothelium of plaque in ApoE(-/-) mice injected with low-dose Fe3O4-AG NPs in vivo and HUVECs treated with low-dose Fe3O4-AG NPs in vitro. Thus, the low concentration of Fe3O4-AG NPs presented toxicity to atherosclerosis. Our results indicated that the use of Fe3O4-AG NPs to improve aqueous solution pollution should be cautious due to the potential toxicity.