Iron oxide nanoparticles as potential agents for combined radiotherapy

Background. Iron oxide nanoparticles (NP) represent a promising theranostic platform for combined radiotherapy: the reactivity of iron oxide enhances oxidative stress of tumor cells associated with irradiation while magnetic properties may provide additional feature as controlled delivery.Aim. To study the potency of heparinized iron oxide NP in experimental antitumor therapy.Materials and methods. The synthesis of iron oxide NP was carried out by chemical precipitation followed by magnetic separation, the resulting sol was stabilized with heparin. For each batch of newly synthesized particles, the hydrodynamic diameter was determined, IR spectrometry, X-ray diffraction analysis, and scanning electron microscopy were performed. The MX-7 tumor model of rhabdomyosarcoma chosen for the study was transplanted into female C3HA mice; NP were administered intratumorally or intravenously, once a day, according to the “5–2–5” scheme. Fractional irradiation (1–2 Gy / fraction; 1.3±0.15 Gy / min) was carried out after NP administration.Increasing life expectancy (ILE), the degree of tumor growth inhibition (TGI), a pathomorphological assessment of the lung, liver, spleen and tumor node was carried out for all experimental mice.Results. As a result of the study, it was found that when administered intratumorally, heparinized iron oxide NP are retained inside the tumor, providing a moderate additive effect, compared with isolated radiotherapy in the first week of irradiation (TGI = 40 % (day 6), TFD = 10 Gy, p 0.05), however, with an increase in tumor volume by the end of the second week, the treatment regimen was not more effective than radiotherapy. with a combination of radiotherapy and intravenous administration of NP, the effect was observed within two weeks (TGI = 43 % (day 6), TGI = 29 % (day 14), TFD = 10 Gy; p 0.05; ILE = 54 %, TFD = 20Gy; p 0.05).Conclusion. The studied iron oxide nanopreparation enhanced capacity of radiation therapy to inhibit tumor growth when administered intravenouslyin experimental mice with rhabdomyosarcoma and irradiated subsequently.