Histological study of the biodynamics of iron oxide nanoparticles with different diameters

Keiko Tsuchiya¹, Norihisa Nitta¹, Akinaga Sonoda¹, Ayumi Nitta-Seko¹, Shinichi Ohta¹, Hideji Otani¹, Masashi Takahashi¹, Kiyoshi Murata¹, Katsutoshi Murase², Satoshi Nohara², Kenichi Mukaisho^3
1Department of Radiology, Shiga University of Medical Science, Otsu, Shiga, ²The Nagoya Research Laboratory, Meito Sangyo Co, Ltd, Kiyosu, Aichi, ³Department of Pathology, Shiga University of Medical Science, Otsu, Shiga, Japan

Abstract: The biodynamics of ultrasmall and small superparamagnetic iron oxide (USPIO and SPIO, respectively) particles that were injected intraperitoneally into 36 C57BL/6 mice were investigated chronologically. Their distribution was studied histologically at six time points by measuring iron-positive areas (µm²) in organ sections stained with Prussian blue. The uptake of the differently sized particles was also compared by cultured murine macrophages (J774.1). Iron-positive areas in the liver were significantly larger in the mice injected with USPIO than those injected with SPIO at the first three time points (P < 0.05). The amount of USPIO in the lung parenchyma around the airway was larger than that of SPIO at four time points (P < 0.05); distribution to the lymph nodes was not significantly different. The amount of iron was significantly larger in SPIO- than USPIO-treated cultured cells (P < 0.05). In conclusion, it is suggested that intra peritoneally injected USPIO particles could be used more quickly than SPIO to make Kupffer images of the liver and that both agents could help get lymph node images of similar quality.

Keywords: USPIO, SPIO, contrast agent, biodistribution, histology