Assessment of biological characteristics of mesenchymal stem cells labeled with superparamagnetic iron oxide particles in vitro.

Mesenchymal stem cell (MSC) transplantation provides a novel strategy for the treatment of human disease. MR imaging (MRI) is able to track transplanted stem cells labeled with superparamagnetic iron oxide (SPIO) in vivo. However, the effect of SPIO upon labeled MSCs remains unclear on a cellular level. In this study, the biological characteristics of rat MSCs labeled with home-synthesized SPIO particles were evaluated. The MSCs were isolated from the bone marrow of 5 adult Sprague-Dawley rats and labeled with home-synthesized SPIO particles at a final iron concentration of 20 µg/ml. Labeled MSCs were confirmed with Prussian blue staining and transmission electron microscopy. The quantity of iron per cell was determined by atomic absorption spectrometry. Cell viability, proliferation, membranous antigen and multiple differentiation ability were compared between labeled and unlabeled MSCs. The rat MSCs were effectively labeled and the labeling efficiency was approximately 100%, as revealed by Prussian blue staining. The SPIO particles located in the endosomal vesicles of the MSCs were confirmed by transmission electron microscopy. No significant differences were observed in cell viability, proliferation, membranous antigen and multiple differentiation ability between the labeled and unlabeled MSCs (P>0.05). In conclusion, MSCs are able to be effectively labeled by home-synthesized SPIO particles without influencing their main biological characteristics.