Effect of surface modification on the distribution of magnetic nanorings in hepatocellular carcinoma and immune cells

Magnetic nanomaterial-mediated magnetic hyperthermia is a localized heating treatment modality that has been applied to treat aggressive cancer in clinics. In addition to being taken up by tumor cells to function in cancer therapy, magnetic nanomaterials can also be internalized by immune cells in the tumor microenvironment, which may contribute to regulating the anti-tumor immune effects. However, there exists little studies on the distribution of magnetic nanomaterials in different types of cells within tumor tissue. Herein, ferrimagnetic vortex-domain iron oxide nanorings (FVIOs) with or without the liver-cancer-targeting peptide SP94 have been successfully synthesized as a model system to investigate the effect of surface modification of FVIOs (with or without SP94) on the distribution of tumor cells and different immune cells in hepatocellular carcinoma (HCC) microenvironment of a mouse. The distribution ratio of FVIO-SP94s in tumor cells was 1.3 times more than that of FVIOs. Immune cells in the liver tumor microenvironment took up fewer FVIO-SP94s than FVIOs. In addition, myeloid cells were found to be much more amenable than lymphoid cells in terms of their ability to phagocytose nanoparticles. Specifically, the distributions of FVIOs/FVIO-SP94s in tumor-associated macrophages, dendritic cells, and myeloid-derived suppressor cells were 13.8%/12%, 3.7%/0.9%, and 6.3%/1.2%, respectively. While the distributions of FVIOs/FVIO-SP94s in T cells, B cells, and natural killer cells were 5.5%/0.7%, 3.0%/0.7%, and 0.4%/0.3%, respectively. The results described in this article enhance our understanding of the distribution of nanomaterials in the tumor microenvironment and provide a strategy for rational design of magnetic hyperthermia agents that can effectively regulate anti-tumor immune effects.