Toxicology studies of a superparamagnetic iron oxide nanoparticle in vivo

Objectives: This report presents toxicological profile available on a superparamagnetic iron oxide (SPIO) nanoparticle in vivo. Materials and Methods: Single- and repeat-dose toxicity studies were performed with SPIO given subcutaneously in mice. Results: The SPIO nanoparticle exhibited a low toxicity profile, with no treatment-related deaths and few transient clinical signs. SPIO was taken up and distributed in heart, spleen, liver, lung, kidney, brain decreasingly within 24 hours after injection. After repeated injections for 10 days, the accumulation of iron on organs studied is slight, indicating that iron is eliminated fast at 100 mg/kg given subcutaneously in mice. At histopathology, no iron-positive pigment was observed in macrophages of multiple organs (mainly heart, liver, spleen, lung, kidney, brain). Conclusion: The results of most of the studies demonstrated low hazard potential in mice following acute injection to the SPIO nanoparticle tested in this program. All effects observed are unlikely to occur in clinical practice because of the single low dosing in humans.