Superparamagnetic iron oxide (SPIO) nanoparticles are very useful in cell imaging; meanwhile, however, biosafety concerns associated with their use, especially on therapeutic stem cells, have arisen. Most studies of biosafety issues focus on whether the nanoparticles have deleterious effects. Here, we report that Ferucarbotran, an ionic SPIO, is not toxic to human mesenchymal stem cells (hMSCs) under the conditions of these experiments but instead increases cell growth. Ferucarbotran-promoted cell growth is due to its ability to diminish intracellular H2O2 through intrinsic peroxidase-like activity. Also, Ferucarbotran can accelerate cell cycle progression, which may be mediated by the free iron (Fe) released from lysosomal degradation and involves the alteration of Fe on the expression of the protein regulators of the cell cycle.
