RESUMO
OBJECTIVES: The objectives of this study were to test cell-labeling methods to achieve intracellular labeling and T1 enhancement of cells on magnetic resonance imaging using a paramagnetic Gd@C82 fullerenol contrast agent, and to determine the effect of labeling on cell viability, metabolism, and differentiation capacity. MATERIALS AND METHODS: We tested the use of a transfection agent for labeling cells in culture with Gd@C82 fullerenol. Proliferation, viability, and differentiation assays of mesenchymal stem cell (MSC) cultures; light and electron microscopy of MSC and macrophages; and MRI of MSC, macrophage, and HeLa cervical carcinoma cell cultures in vitro and in vivo were performed to evaluate the labeled cells. RESULTS: Protamine sulfate transfection increased cell uptake of Gd@C82 fullerenols. The label was distributed in endosomes in the cytoplasm as shown by electron microscopy. High viability was shown for all cell lines and normal differentiation capacity was shown for MSCs. T1 of labeled MSC at 7 T was reduced 71% compared with unlabeled cells. CONCLUSIONS: Cellular labeling with Gd@C82 is feasible and can produce T1-enhanced cells on magnetic resonance imaging. This study suggests that further investigation of Gd fullerenols for tracking studies of viable cells, including stem cells, is warranted.