Superparamagnetic γ-Fe2O3 Nanoparticles Influence the Differentiation of Dendritic Cells from Human Blood Monocytes

The impact of magnetic nanoparticles (MNPs) on the differentiation of human blood monocytes into dendritic cells (DCs) was studied with focus on potential enhancement of immunotherapy efficacy by targeted delivery of MNPs-loaded DCs to lymph nodes using an external magnetic field. Spherical γ-Fe2O3 MNPs sized ~14 nm were obtained by laser target evaporation technique followed by synthesis of stabilized water-based suspension. Their physicochemical properties were characterized in detail. Monocytes were differentiating to DCs at two experimental conditions to define the effect of “extracellular” nanoparticles and MNPs uptaken by cells. The immunophenotype of DCs was analyzed by flow cytometry. Secretory activity of cells was measured by enzyme-linked immunosorbent assay (ELISA). Monocytes actively acquired MNPs and retained them during differentiation into DCs. The differentiation process was not interrupted by MNPs, but the phenotype of DCs was modified compared to native DCs: MNPs enhanced the expression of receptors functionally important for interaction with T-lymphocytes and increased secretion of pro-inflammatory cytokines. At the same time, they inhibited the expression of CD86 costimulatory receptor and stimulated the production of tolerogenic cytokine IL-10. The impact of MNPs on monocytes-DCs differentiation is most likely due to engulfed nanoparticles. However, the contribution of MNPs adhered to cells’ surface cannot be excluded.