The MR tracking of transplanted ATDC5 cells using fluorinated poly-l-lysine-CF3

Magnetic resonance (MR) imaging using super-paramagnetic iron oxides (SPIOs) is a powerful tool to monitor transplanted cells in living animals. However, since SPIOs are negative contrast agents it is difficult to track transplanted cells in bone and cartilage that originally display low signals. In this study, we examined the feasibility of tracking with fluorescein isothiocyanate (FITC)-labeled poly-l-lysine-CF3 (PLK-CF3) using mouse ATDC5 cells, a stem cell line of bone and cartilage cells. FITC-labeled PLK-CF3 was easily internalized by ATDC5 cells by adding it into culture medium. No acute or long-term toxicities were seen at less than 160 μg/ml. Labeled cells transplanted into the cranial bone of mice were detected for at least 7 days by MR images. FITC-labeled PLK-CF3 is a useful positive contrast agent for MR tracking in bone and cartilage.