Evaluating the effect of USPIO nanoparticles for 21 days post magnetic cell labeling

Introduction: To evaluate the long-term viability, iron content stability and labeling efficiency of mammalian cells when using the ultra small, superparamagnetic, iron oxide nanoparticles with plain surfaces (USPIO) for magnetic cell labeling. MATERIALS AND METHODS: Iron oxide magnetic nanoparticles (MNP) were manufactured locally and by Micromod GmBH, Rostock, Germany. Tests were carried out in four groups of 5 flasks of 5.5*10⁶ AD-293 embryonic kidney cells. The cell lines were incubated with both products for 24 hours with 4 different iron concentrations (0, 0.25, 0.5 and 0.7 mg/mL) with and without protamine sulfate (USPIO-Pro or MNP-Pro), washed with PBS and centrifuged at 900 rpm for cleaning the unbounded MNPs three times. Iron uptake using MNP-Pro was evaluated with Prussian blue test, MRI imaging, ICP test and cell viability. The iron concentrations in the media were also assessed at different time points. Statistical tests for significant differences between original and labeled cells were performed. RESULTS: There were no significant differences in cell viability between the control group of cells and those groups with iron uptake at the specified iron concentrations. The average iron uptakes ratio compared to the control group was (114±1 ). The MRI images at post-labeling days 1 and 21 showed (75 ± 4)% and (22 ± 5)% signal decrements compared to the control, respectively. The Prussian blue test showed that 98% of the cells were labeled and the media iron concentration did not affect the cell iron-uptake. CONCLUSION: Magnetic cellular labeling with the MNPPro complex had no short or medium term (3 weeks) toxic effects on embryonic kidney cells. These results hold promise for MRI monitoring of the temporal migration of cells into tissues and the development of cell tracking strategies for the repair or replacement of tissues and other novel cell therapies.