We undertook a study of the anti-tumour effects of
hyperthermia, delivered via
magnetite cationic
liposomes (MCLs), on local tumours and lung
metastases in a mouse model of
osteosarcoma. MCLs were injected into subcutaneous
osteosarcomas (LM8) and subjected to an alternating magnetic field which induced a heating effect in MCLs. A control group of mice with tumours received MCLs but were not exposed to an AMF. A further group of mice with tumours were exposed to an AMF but had not been treated with MCLs. The distribution of MCLs and local and lung
metastases was evaluated histologically. The weight and volume of local tumours and the number of lung
metastases were determined. Expression of
heat shock protein 70 was evaluated immunohistologically.
Hyperthermia using MCLs effectively heated the targeted tumour to 45 degrees C. The mean weight of the local tumour was significantly suppressed in the
hyperthermia group (p = 0.013). The mice subjected to
hyperthermia had significantly fewer lung
metastases than the control mice (p = 0.005).
Heat shock protein 70 was expressed in tumours treated with
hyperthermia, but was not found in those tumours not exposed to
hyperthermia. The results demonstrate a significant effect of
hyperthermia on local tumours and reduces their potential to metastasise to the lung.