Effects of static magnetic fields on natural or magnetized mesenchymal stromal cells: Repercussions for magnetic targeting

The magnetic targeting (MT) technique improves delivery of mesenchymal stromal cells (MSCs) to target sites. However, the moderate-intensity static magnetic fields (SMF) used for MT may exert adverse effects on MSCs. Thus, we aimed to evaluate the effects of SMF on MSCs in vitro. Cells were initially magnetized using citrate-coated magnetite nanoparticles. Then, control and magnetized MSCs were transferred to an in vitro MT system and exposed to 0.3–0.45 Tesla SMFs. MSC viability, morphology, ultrastructure, proliferation rates, differentiation, and immunomodulation were evaluated after 24 and 48 hours of exposure. MSCs temporarily lost viability and exhibited ultrastructural changes after exposure to SMFs, regardless of magnetization. Moreover, exposure to SMF reduced magnetized MSC proliferation rates. Nevertheless, MSCs remained functional (i.e., capable of differentiating, secreting repair mediators, and modulating alveolar macrophage phenotype). Thus, the experimental protocol tested in this experiment can be applied in future in vivo MT studies. In this study, the potential effects of static magnetic fields (SMF) on mesenchymal stromal cells (MSCs) were analyzed in an in vitro system. Natural (control) or magnetized MSCs were exposed for 24 and 48 hours to SMFs generated by a pair of neodymium magnets. At both time points, exposure to SMFs reduced the proliferation rates of magnetized MSCs and led to ultrastructural changes, the latter independent of magnetization. These ultrastructural changes may have contributed to loss of viability, observed from 48 hours. Nevertheless, MSCs remained functional (capable of differentiating, releasing reparative mediators, and modulating gene expression in alveolar macrophages). [Display omitted]