Development of intravascular targeting hyperthermia using dextran magnetite complex

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This is a fundamental study to develop an "intravascular targeting hyperthermia" , in which a deep seated tumor is heated using an intravascularly administered magnetic material together with an externally applied AC magnetic field. As a heat generating material, we employed dextran magnetite complex (DM) , which is a kind of 'magnetic fluid'. The heat production of DM in an AC magnetic field is much higher than previously reported multidomain ferrite particles due to a different mechanism of heat generation. We designed two DM-containing embolic materials, a DM/Lipiodol(]SY.encircledR.[) emulsion and a DM/degradable starch microsphere (DM/DSM) suspension. In vitro experiments showed that the heat generating capacity of DM was not reduced in these preparations. When these materials were injected into the renal arteries of Japanese white rabbits, they achieved selective heating (over 10ﾟC/10min.) of the embolized kidney following exposure to a 100kHz AC magnetic field of approximately 1 … More 5000 A/m. The average iron concentration in the embolized kidney was 4.9 (]SY.+-.[) 2.4mg Fe/g tissue. A similar experiment with a VX2 tumor transplanted in the liver of a rabbit demonstrated sufficient heating of the tumor. With current composition of DM containing embolic material, DM escapes into systemic circulation and is trapped by reticulo endothelial system (RES) within 6 hours of intraarterial administration. Moreover, an experiment using C3H mouse model revealed that the heat generating capacity of DM is decreased as it is metabolize13EA01 : This is a fundamental study to develop an"intravascular targeting hyperthermia" , in which a deep seated tumor is heated using an intravascularly administered magnetic material together with an externally applied AC magnetic field. As a heat generating material, we employed dextran magnetite complex (DM) , which is a kind of 'magnetic fluid'. The heat production of DM in an AC magnetic field is much higher than previously reported multidomain ferrite particles due to a different mechanism of heat generation. We designed two DM-containing embolic materials, a DM/Lipiodol(]SY.encircledR.[) emulsion and a DM/degradable starch microsphere (DM/DSM) suspension. In vitro experiments showed that the heat generating capacity of DM was not reduced in these preparations. When these materials were injected into the renal arteries of Japanese white rabbits, they achieved selective heating (over 10ﾟC/10min.) of the embolized kidney following exposure to a 100kHz AC magnetic field of approximately 15000 A/m. The average iron concentration in the embolized kidney was 4.9 (]SY.+-.[) 2.4mg Fe/g tissue. A similar experiment with a VX2 tumor transplanted in the liver of a rabbit demonstrated sufficient heating of the tumor. With current composition of DM containing embolic material, DM escapes into systemic circulation and is trapped by reticulo endothelial system (RES) within 6 hours of intraarterial administration. Moreover, an experime Less