Magnetic Resonance Nanotherapy for Malignant Tumors

Magnetic resonance effect can induce double-strand breaks in DNA through induction of reactive oxygen species by the electromagnetic field. The aim of this paper is to study the possible use of the magnetic resonance effect for magnetic nanotherapy of Lewis lung carcinoma. The study was carried out on 40 C57Bl/6 mice bearing Lewis lung carcinoma. Animals were divided into four groups: (1) control (without treatment); (2) сonventional doxorubicin (DOXO) (Pfizer) administration; (3) administration of a mechano-magneto-chemically synthesized nanocomplex (MMCS) comprising ferromagnetic commercial nanoparticles <50 nm (Sigma-Aldrich) and paramagnetic DOXO; and (4) administration of the MMCS nanocomplex with following whole-body electromagnetic irradiation (EI) produced by a magnetic resonance tomography (MRT) system Intera 1.5T (Philips Medical Systems) in animals. Magnetic resonance imaging of magnetic nanocomplex (MNC) had slightly greater heterogeneity due to the presence of iron oxide nanoparticles. The combination therapy of MNC and EI by MRT had maximal antitumor effect and minimal of the average number of lung metastatic foci per mouse. The temperature inside the tumor reached 37°С. Electron spin resonance signal of Lewis lung carcinoma with g-factor of 2.25–2.42 indicating the presence of P-450 cytochrome was not detected among all investigated groups. This suggests the violation in electron transfer regulation of mitochondrial electron transport chain of tumor cells during anticancer therapy. The proposed hypothetical model of MNC action for magnetic nanotherapy is based on the well-known fact that various parameters of the external magnetic field can switch spin-controlled states of free radical pairs and modulate redox reactions in tumor and normal tissues.