Comparative Efficacy of a Biocompatible Citrate-Functionalized Magnetic Fluid Mediating Radiofrequency Hyperthermia and Magnetohyperthermia to Treat Ectopic Ehrlich-Solid-Tumor-Bearing Elderly Mice

Abstract

Objective: We aimed to evaluate the efficacy of a biocompatible citrate-functionalized magnetic fluid (NPCit) sample in mediating hyperthermia, using two types of alternated (AC) magnetic field equipment operating in two different ways: a portable apparatus, generating an electromagnetic field in MHz range (radiofrequency range; radiofrequency hyperthermia-RFHT) developed by our research group (CMagMHG), and a commercial one working in kHz range (magnetohyperthermia-MHT) (Magnetherm, NanoTherics Ltd, Newcastle, United Kingdom), to treat ectopic Ehrlich-solid-tumor-bearing elderly mice. Methods:Females intraperitoneally anesthetized with ketamine (80 mg/kg) and xylazine (10 mg/Kg) were subcutaneously inoculated with Ehrlich ascitic tumor cell suspension (1.03 × 10 6 viable cells) in the upper head region for solid form implantation. After 48 hours, mice received one of four treatments: (a) filtered water and no tumor implantation (negative control); (b) tumor inoculation and no treatment (tumor control); (c) intratumoral injection of NPCit (40 µL) containing 18 × 10 18 particles/mL and 13 minutes' exposure to CMagMHG, operating at 1MHz, 40 Oe field amplitude; (d) intratumoral injection of NPCit and 13 minutes' exposure to Magnetherm, assembled with 17-turn coil, capacitive box B22, operating under 330 kHz, 4.9 A, 25 V and maximum field strength 170 Oe. Treatments occurred once daily for three consecutive days. Tumor histopathology and semi-quantitative analysis of necrosis area served to assess tumor aggressiveness and regression. Possible acute side effects were assessed by animals' body and spleen weight and hemogram.Results: NPcit showed adequate biocompatibility and was effective in mediating RFHT and MHT, which promoted significant increases in necrosis area using both equipment types. Conclusion:Our findings evidence the potential use of NPcit mediating hyperthermia for future use as an adjuvant in breast cancer therapy.

Combination of selol nanocapsules and magnetic hyperthermia hinders breast tumor growth in aged mice after a short-time treatment

“…The literature has also reported the biocompatibility of maghemite nanoparticles coated with citrate on tumor-bearing mice, in both non-elderly and aged animals [11,26,[53][54][55]. The doses (iron concentration and nanoparticle amount), dosage regimes and administration routes differ considerably between studies, which make comparisons inaccurate.…”

“…Ascitic fresh Ehrlich tumor cells were injected into the peritoneal cavity of the mice and collected after seven days. After that, around 1×10 7 cells were grafted orthotopically into the right fifth mammary gland to obtain the solid tumor form [25,26]. Every two days, all the tumor volume measurements 0.5 × (length × width 2 ) [27] were recorded using a stainless hardened digital calipers ® to obtain the approximate tumor volume (in units of mm 3 ).…”