Abstract #1869

SPIO-Loaded Unilamellar Polyion Complex Vesicles (SPIO-Cy5-PICsomes) as a High Relaxivity Contrast Agent for Tumor Detection

Daisuke Kokuryo¹, Yasutaka Anraku², Akihiro Kishimura², Sayaka Tanaka³, Mitsunobu R. Kano⁴, Nobuhiro Nishiyama³, Tsuneo Saga¹, Ichio Aoki¹, Kazunori Kataoka²,³

¹Molecular Imaging Center, National Institute of Radiological Sciences, Chiba, Japan; ²Graduate School of Engineering, The University of Tokyo, Tokyo, Japan; ³Graduate School of Medicine, The University of Tokyo, Tokyo, Japan; ⁴Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan

A newly developed SPIO-loaded and fluorescence dye (Cy5)-labeled polyion complex nanocarrier, termed SPIO-Cy5-PICsome, composed of two biocompatible oppositely charged block copolymers was applied to evaluate its ability to detect small tumors with MRI. In vitro r₂ of the SPIO-Cy5-PICsomes was 2.54 times higher than that of free ferucarbotran. In in vivo experiments using subcutaneously xenografted mice, MR signal from the tumor changed during the 3 hours after SPIO-Cy5-PICsome administration. A small tumor was also detected at 24 hours after administration. SPIO-Cy5-PICsomes are a powerful nanocarrier with the potential to detect small and early-stage tumor for early diagnosis.