Ultrasmall superparamagnetic iron oxide nanoparticles acutely promote thrombosis and cardiac oxidative stress and DNA damage in mice

Abstract

Background: Ultrasmall superparamagnetic iron oxide nanoparticles (USPIO) are being developed for several biomedical applications including drug delivery and imaging. However, little is known about their possible adverse effects on thrombosis and cardiac oxidative and DNA damage.

Methods: Presently, we investigated the acute (1 h) effect of intravenously (i.v.) administered USPIO in mice (0.4, 2 and 10 μg/kg). Diesel exhaust particles (DEP; 400 μg/kg) were used as positive control.

Results: USPIO induced a prothrombotic effect in pial arterioles and venules in vivo and increased the plasma plasminogen activator inhibitor-1 (PAI-1). Both thrombogenicity and PAI-1 concentration were increased by DEP. The direct addition of USPIO (0.008, 0.04 and 0.2 μg/ml) to untreated mouse blood dose-dependently induced in vitro platelet aggregation. USPIO caused a shortening of activated partial thromboplastin time (aPTT) and prothrombin time (PT). Similarly, DEP administration (1 μg/ml) triggered platelet aggregation in vitro in whole blood. DEP also reduced PT and aPTT. The plasma levels of creatine phosphokinase-MB isoenzyme (CK-MB), lactate dehydrogenase (LDH) and troponin-I were increased by USPIO. DEP induced a significant increase of CK-MB, LDH and troponin I levels in plasma. The cardiac levels of markers of oxidative stress including lipid peroxidation, reactive oxygen species and superoxide dismutase activity were increased by USPIO. Moreover, USPIO caused DNA damage in the heart. Likewise, DEP increased the markers of oxidative stress and induced DNA damage in the heart.

Conclusion: We conclude that acute i.v. administration of USPIO caused thrombosis and cardiac oxidative stress and DNA damage. These findings provide novel insight into the pathophysiological effects of USPIO on cardiovascular homeostasis, and highlight the need for a thorough evaluation of their toxicity.

Keywords: Comet assay; Oxidative stress; Thrombosis; Toxicity; Ultrasmall superparamagnetic iron oxide nanoparticles.

Fig. 1

Transmission electron micrographs of the ultrasmall superparamagnetic iron oxide nanoparticles suspension showing the presence of nanosized particles

Fig. 2

Thrombotic occlusion time in pial arterioles (a) or venules (b) 1 h after the intravenous administration of ultrasmall superparamagnetic iron oxide nanoparticles (USPIO), diesel exhaust particles (DEP) or saline (control) in mice. *P < 0.05, **P < 0.01 and ***P < 0.001 compared with the corresponding saline-treated group. Data are mean ± SEM (n = 6–8)

Fig. 3

Plasminogen activator inhibitor-1 (PAI-1) concentrations in plasma, 1 h after the intravenous administration of ultrasmall superparamagnetic iron oxide nanoparticles (USPIO), diesel exhaust particles (DEP) or saline (control) in mice. *P < 0.05 and ***P < 0.001 compared with the corresponding saline-treated group. Data are mean ± SEM (n = 6)

Fig. 4

Direct in vitro effect after the administration of ultrasmall superparamagnetic iron oxide nanoparticles (USPIO), diesel exhaust particles (DEP) or saline (control) on platelet aggregation in whole blood of untreated mice. Platelet aggregation in untreated whole blood 3 min after the addition of either saline or USPIO was assessed. The degree of platelet aggregation following USPIO exposure was expressed as a percent of control (saline-treated blood). Data are mean ± SEM (n = 4). *P < 0.001 compared with saline-treated blood within the same group

Fig. 5

Prothrombin time (PT, a) and activated partial thromboplastin time (aPTT, b) measured 1 h after the intravenous administration of ultrasmall superparamagnetic iron oxide nanoparticles (USPIO), diesel exhaust particles (DEP) or saline (control) in mice. *P < 0.01 and **P < 0.001 compared with the corresponding saline-treated group. Data are mean ± SEM (n = 4–6)

Fig. 6

Lactate dehydrogenase (LDH, a) and creatine phosphokinase-MB (b) and troponin-I (c) in plasma 1 h after the intravenous administration of ultrasmall superparamagnetic iron oxide nanoparticles (USPIO), diesel exhaust particles (DEP) or saline (control) in mice. *P < 0.05, **P < 0.01 and ***P < 0.001 compared with the corresponding saline-treated group. Data are mean ± SEM (n = 4–6)

Fig. 7

Lipid peroxidation (LPO, a), reactive oxygen species (ROS, b) and superoxide dismutase (D) levels in heart tissues 1 h after the intravenous administration of ultrasmall superparamagnetic iron oxide nanoparticles (USPIO), diesel exhaust particles (DEP) or saline (control) in mice. *P < 0.01 and **P < 0.001 compared with the corresponding saline-treated group. Data are mean ± SEM (n = 6–8)

Fig. 8

DNA migration in the heart tissues, 1 h after the intravenous administration of ultrasmall superparamagnetic iron oxide nanoparticles (USPIO), diesel exhaust particles (DEP) or saline (control) in mice. Images illustrating the quantification of the DNA migration by the Comet assay under alkaline conditions, in control (b), USPIO (c–e) or DEP (f). *P < 0.001 compared with the corresponding saline-treated group. Data are mean ± SEM (n = 5)