RAPID CELLULAR UPTAKE OF SUPERPARAMAGNETIC IRON OXIDE NANOPARTICLES BY USING LOW-INTENSITY ULTRASOUND

Nowadays, in cell therapies in-vivo monitoring of target cells has become highly desirable. For this purpose SPIO (Superparamagnetic Iron Oxide) nanoparticles are suitable as magnetic detectable markers of the transplanted cells by using non-invasive magnetic resonance imaging (MRI). To improve the labeling efficiency of cells by SPIO nanoparticles various methods such as using transfection agents or electroporation have been used, however with negative impact on cell viability. In this study we introduce a low-intensity therapeutic ultrasound as a safe and non-invasive method for cell labeling with SPIO nanoparticles. The human fibroblasts alone and with addition of SPIO nanoparticles were treated by commercial low-intensity ultrasound (BTL 4000, USA). By changing of starting parameters such as intensity (from 0.1 to 2 W/cm(2)), exposure time (1, 3 and 5 min) and various SPIO concentrations we have found the optimal labeling protocol having minimal impact on cell viability and maximal MRI contrast effect. The cellular uptake of SPIO nanoparticles was detected by Prussion blue staining and by atomic absorption spectroscopy (AAS). The viability of cells was determined by using MTT test. Contrast effect of labeled cells was confirmed by clinical 1.5 T MRI.