Department of Biotechnology, Graduate School of Engineering, Nagoya University, Chikusa-ku.
'Magnetite cationic liposomes (MCL)' were developed as a means to generate intracellular hyperthermia. Affinity of the MCL to glioma cells was ten times higher than that of magnetite 'neutral' liposomes due to the electrostatic interaction based on the positive charge of the MCL. Heat generation of the MCL was studied using agar phantoms and small pellets of rat glioma cells. When a high-frequency magnetic field, 118 kHz, 384 Oe was applied to glioma cells in the presence of MCL, the glioma cell pellet of 80 microl (5.4 mm in diameter) was heated to over 43 degrees C and all the cells died after 40 min irradiation owing to the hyperthermic effect. The terminal temperature of the cell pellet was proportional to the pellet volume when other parameters were constant. It thus appears that the MCL can heat a tumor of more than 80 microl in volume to above 42 degrees C.