Labeling efficacy of superparamagnetic iron oxide nanoparticles to human neural stem cells:: Comparison of ferumoxides, monocrystalline iron oxide, cross-linked iron oxide (CLIO)-NH2 and tat-CLIO

Objective: We wanted to compare the human neural stem cell (hNSC) labeling efficacy of different superparamagnetic iron oxide nanoparticles (SPIONs), namely, ferumoxides, monocrystalline iron oxide (MION), cross-linked iron oxide (CLIO)-NH2 and tat-CLIO. Materials and Methods: The hNSCs (5 x 101 HB1F3 cells/ml) were incubated for 24 hr in cell culture media that contained 25 mu g/ml of ferumoxides, MION or CLIO-NH2, and with or without poly-L-lysine (PILL) and tat-CLIO. The cellular iron uptake was analyzed qualitatively with using a light microscope and this was quantified via atomic absorption spectrophotometry. The visibility of the labeled cells was assessed with MR imaging. Results: The incorporation of SPIONs into the hNSCs did not affect the cellular proliferations and viabilities. The hNSCs labeled with tat-CLIO showed the longest retention, up to 72 hr, and they contained 2.15 +/- 0.3 pg iron/cell, which are 59 fold, 430 fold and six fold more incorporated iron than that of the hNSCs labeled with ferumoxicles, MION or CLIO-NH2, respectively. However, when PILL was added, the incorporation of ferumoxides, MION or CLIO-NH2 into the hNSCs was comparable to that of tat-CLIO. Conclusion: For MR imaging, hNSCs can be efficiently labeled with tat-CLIO alone or with a combination of ferumoxides, MION, CLIO-NH2 and the transfection agent PLL.