Magnetic-nanoparticle-mediated intracellular
hyperthermia has the potential to achieve localized
tumor heating without any side effects. The technique consists of targeting magnetic nanoparticles to
tumor tissue followed by application of an external alternating magnetic field that induces heat through Néel relaxation loss of the magnetic nanoparticles. The temperature in
tumor tissue is increased to above 43°C, which causes
necrosis of
cancer cells, but does not damage surrounding normal tissue. Among magnetic nanoparticles available,
magnetite has been extensively studied. Recent years have seen remarkable advances in magnetite-nanoparticle-mediated
hyperthermia; both functional magnetite nanoparticles and alternating-magnetic-field generators have been developed. In addition to the expected
tumor cell death,
hyperthermia treatment has also induced unexpected
biological responses, such as
tumor-specific immune responses as a result of
heat-shock protein expression. These results suggest that
hyperthermia is able to kill not only local
tumors exposed to heat treatment, but also
tumors at distant sites, including metastatic
cancer cells. Currently, several research centers have begun clinical trials with promising results, suggesting that the time may have come for clinical applications. This review describes recent advances in magnetite nanoparticle-mediated
hyperthermia.