This study evaluated the feasibility of using uncoated iron (II, III) oxide nanoparticles (IONP) obtained by electric explosion of wire in air for labelling living mesenchymal stromal cells and their subsequent visualization by magnetic resonance imaging (MRI) using 1.5T clinical MRI scanners. The uptake of uncoated IONP by MSC was demonstrated for the wide range of IONP concentration in the cell culture medium. The cells did not change their proliferative activity, viability, and the set of surface markers. IONP obtained by electric explosion of wire in an atmosphere of air had a shape close to spherical. The size of nanoparticles varied from 14 to 136 nm according to dynamic lateral light scattering, laser diffraction, and transmission electron microscopy. Particles up to 136 nm comprised 75%, and particles less than 36 nm --- 10% of the IONP powder. A wide range of particle sizes made it possible to select MRI parameters suitable for labelled cells detection in animal tissues both in the T2 mode and in the T1 relaxation mode.