DMSA-Fe₃O₄Nano-magnetic Fluid Hyperthermia-mediated Experimental Study Of Rabbit VX₂Tumor

Background and PurposeUsing the principle that Tumor tissue compared with normal tissue is moresensitive to high temperature, tumor tissue is heated to above42℃, the tumor cellsthan normal cells can’t tolerate continuous high temperature, which occurred not thedegree of apoptosis or necrosis, this method of treatment of malignant tumors wascallde the hyperthermia （hyperthemia）. Hyperthermia, such as radiofrequencyablation, microwave, laser coagulation, high-energy focused ultrasound, thesehyperthermia technologise have different degrees of impairment, such as poor tumortissue targeting ability, the heat energy lower than its predecessor, the temperaturewithin the tumor elevated rapidly which easy to damage the surrounding normaltissue, its clinical application is subject to these certain conditions. In recent years,magnetic nanoparticles targeted positioned within the tumor, and then the magneticnanoparticles were sent to make heat production in alternating magnetic field, so thattumor cell growth was inhibited or inducted to the apoptosis of tumor cells, thismagnetic-mediated hyperthermia （magnetically mediated hyperthermia of MMH）technology appeared to solve the problems of temperature measurement, control ofhyperthermia, the accurate positioning of the lesion, and leaded to obtain betterresults in hyperthermia. Rabbit hind limb VX₂soft tissue tumor models, the tumorgrows superficial and can be palpated from the surface, and the rich tumor bloodsupply. Therefore it suit to hyperthermia which can use various magnetic materialsimport methods in MMH. The DSMA-Fe₃O₄magnetic fluids are injected directly intothe local tumor, the feeding artery and peripheral intravenous respectively. Thealternating magnetic field induced hyperthermia treatment of rabbit hind VX₂softtissue tumor. We reserch the effect of magnetic hyperthermia treatment of rabbit VX₂tumor, and a preliminary evaluation could be made on the effect of differentadministration on the rabbit VX₂tumor hyperthermia. Materials and Methods20New Zealand rabbits, VX₂tumor of rabbit hindlimb models, received theexamination of16-slice spiral CT, which measured tumor size by the unenhanced andenhanced scans after14days. and these rabbits were randomly divided into fourgroups. Group A （control group）, group B （local injection of magnetic fluid group+hyperthermia）, group C （MHD arterial infusion group+hyperthermia）, Group D（magnetic fluid intravenously group+hyperthermia）. Different ways ofadministration and implementation of each group of rabbits, the rabbits were put intoan alternating magnetic field and induced hyperthermia. The magnetic fieldmeasurements were used by fiber-optic thermometers, which were put into the tumorcenter, tumor margin, the normal muscle tissue and rectum.14days after treatment,these rabbits were measured again by CT scans in order to get the tumor volume andtumor growth rate （TGR）.Tumor volume, the values of tumor growth, the values of the pointtemperatures were used analysis of variance between the two groups, and grouppairwise comparisons were used the LSD method. The tumor growth rate was usedthe single-factor analysis of variance.Results20rabbits after inoculation14days, the model which confirmed by CT scanwere built successfully, tumor formation was100%. Two rabbits death in themodeling process due to improper anesthesia, two rabbits death in CT scan due toimproper anesthesia, and an experimental rabbit was found that no tumor growth byCT scan.20the establishment of the VX₂tumor of rabbit hindlimb model rabbits weredivided into four groups by random number table method.The tumor size of eachgroup [group A, group B, group C and group D （7.08±1.16） cm3（7.81±1.07） cm³（7.47±1.05） cm³（7.18±2.08） cm³was no significant （F=727, p=0.551）.In the group B and C, the temperature of the tumor center （46.01℃,40.38℃）and marginal zone （40.35℃,42.57℃） were significantly higher than the normalmuscle tissue （35.73℃,35.37） and rectum （35.69℃,35.25℃）（P <0.05）, while the temperatures were not increased significantly in the group A and D. Fourteen daysafter treatment, the growth rate of the tumor was （1119.9±179.40）%, and the volumeof the tumor increased to （47.54±9.12）folds in the control group; the growth rate andthe volume of the tumor decreased to （354.81±59.5）%and （9.79±2.7） foldsrespectively in group C; the data show the growth rate and the tumor volume decreaseto （441.04±29.61）%and （12.35±1.12）folds in group B. After hyperthermiatreatment, the tumor volume between group A and D shows no significant differences（P>0.05）, while the tumor volume in group B and C decreased notablely relative tothe control（P <0.05）, as well as the tumor growth rate.ConclusionAlternating electromagnetic field mediated DSMA-Fe₃O₄nano-magnetic fluidhyperthermia significantly inhibits tumor growth of rabbit VX₂tumor.