Targeting Hyperthermia by RF Inductive Heating for Selective Heating of Cancer

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1. Improvement of RF specific heating deviceCharacteristics of particulate heating mediators in radiofrequency (RF) capacitive hyperthermia were investigated. Four ferromagnetic ferrite particles (Cu(II)Fe(III)2O3, Mg(II)Fe(III)2O3, Mn(II)Fe(III)2O3, and Ni(II)Fe(III)2O3) in addition to magnetite particles and other non-ferromagnetic metal oxide particles (a-Fe2O3, a-Alumina, Ag(II)O, and ZnO) were tested using 8 MHz RF heating device. As a result, ferromagnetic particles could generate heat specifically in RF capacitive, but non-ferromagnetic particles could not. In addition, dispersiblity of particles was an important parameter for heat generation.2. Preparation of biocompatible heating mediatorMagnetite needle, in which magnetite particles are molded into needle-shape, was developed and we applied it as a heating mediator for intracellular hyperthermia. We investigated the hyperthermic effect on solid subcutaneous gliomas in the femoral region of female F344 rats. The tumor tissue completely disappeared in many rats exposed to a magnetic field, and the needles were simply administered through a syringe. The magnetite needle will be a novel and potentially effective mediator of hyperthermia that can be used to treat other malignant solid tumors without severe side effects.3. Specific heating and effect of magnetic particles in RF heatingMagnetite cationic liposomes (MCLs) were injected in a rat tumor on femur and an 8 MHz-RF capacitive heating was applied to the rat under the conditions of 'mild heating'. The MCLs-injected tumor was heated over 43℃ whereas it was only heated until 41℃ in the case of the rats injected no MCLs. The necrotic area of tumor was observed in the heated rat.4. Safety of heating mediatorNo toxico effect of heating mediator was observed in all invetigations.