Highly focalised thermotherapy using a ferrimagnetic cement in the treatment of a melanoma mouse model by low temperature hyperthermia

Purpose: Evaluation of the effectiveness of highly focalised thermotherapy (HFT) in a melanoma mouse model, using a ferrimagnetic cement (FC) and repeated low hyperthermia treatments. Materials and methods: A melanoma mouse model was induced with B16F10 cells in C57BL6 mice. The FC, injected into the tumour, was used as the magnetic vehicle for HFT. FC location within the tumour was assessed by radiography and its capability to generate heat, when exposed to an external high frequency magnetic field (HFMF), monitored by thermal camera. The HFT treatment consisted of three HFMF exposures, with 48-h intervals, each one lasting 30 min, with a 5-6 degrees C tumour temperature increase. At the end of the experiment, FC samples were characterised by scanning electron microscopy (SEM) and energy dispersion spectroscopy (EDS). The presence of iron contents was analysed in the tumour, lungs, liver and spleen. Histological evaluation and immunohistochemical staining for caspase-3 were performed. Tumour growth was monitored during the experiment. Results: Surface analysis showed FC stabilisation within the tumour, and iron was absent. The thermal camera confirmed the localised temperature increase in the tumour. HFT treatments inhibited the tumour growth by similar to 70% compared to controls. This was due to cell destruction by necrosis and apoptosis. Conclusions: The HFT, using the FC, proved to be a minimally invasive technique that statistically inhibited tumour growth. Results suggested that this methodology seems to be a promising technique for the treatment of solid tumours, allowing repeated low hyperthermia treatments, which can be easier and less traumatic than other hyperthermia techniques.