Histopathological and immunological changes induced by magnetite nanoparticles in the spleen, liver and genital tract of mice following intravaginal instillation

Recently, vaccination against sexually transmitted diseases as well as tumor therapy using new systems such as nanomaterials is a promising strategy. For successful usefulness of magnetite nanoparticles (MNPs) in medical applications through the vaginal route, it is essential to understand their biological fate and cellular toxicity in the animal tissues. This study aims to investigate the biodistribution, histopathological and immunological impacts of MNPs on in the liver, spleen and genital tract tissues of female mice after the intravaginal instillation. MNPs were observed within spleen and liver parenchyma as well as vaginal stroma after 3 days and 2 weeks of the instillation, and completely cleared from the vaginal stroma tissue after 6 weeks. Splenic lymphocytes of treated spleen were characterized with anisokaryosis; anisochromia. Quantitatively, the number of megakaryocyte and lymphocyte nuclei size in the spleen were highly increased after instillation of MNPs. MNPs caused acute inflammation in the liver and tarsal joints dermal. Immunologically, MNPs induced the vaginal secretion IgA and Bcl-2 reactivity in the hepatocytes, the expression of fucose residues and number of BM8⁺ cells in the genital tract tissues after instillation. Our data indicated that MNPs could influence the splenic lymphocytes and hepatocytes as well as the cellular and humoral immune responses in the mice genital tract tissues after 2 weeks of intravaginal instillation. This information could be useful for avoiding the side effects of MNPs when used in medical applications. Further investigations about the safety and toxicity of MNPs should be achieved before their use in the medical field.