Exploring and validating heating dynamics in a radio-frequency electromagnetic field-based resonant chamber for mouse hyperthermia research

ABSTRACT

Mild whole-body hyperthermia has been shown to have anti-tumor effects through an immune-modulating mechanism. Before it is widely applied in the clinic, tremendous mechanistic research in animals is necessary to adhere to evidence-based principles. The radio frequency electromagnetic field (RF-EMF) based heating facility could be a good choice for hyperthermia treatment, but the heating characteristics of a facility, including structure design, electromagnetic and thermal dosimetry, and the biologic effects of hyperthermia, need to be well elucidated. Here, we reported the heating characteristic study on a resonant chamber (RC) excited by a 1800 MHz solid source. The EMF in the RC was stirred by 24 static reflectors, which resulted in the standard deviation of electric field intensity being below 3 dB in the EM homogeneity evaluation. For the exposure scenario, six free-moving mice were loaded into separate cases and exposed simultaneously in the RC. The EMF energy absorption and distribution in exposed mice were calculated with the 12-plane-waves method of numerical simulation. Different levels of core body temperature increment in exposed mice were achieved through regulation of the source output power. Overexpression of heat shock proteins (HSPs) was detected in the liver, lung and muscle, but not in the brain of the exposed mice. The levels of representative inflammatory cytokines in the serum, TNF-α and IL-10 increased post RC exposure. Based on the heating characteristic study and validation, the applied RC would be a qualified heating system for mild whole-body hyperthermia effect research in mice.

Plain-language summary

Mild whole-body hyperthermia has potential anti-tumor effects by modulating the immune system. A radio frequency electromagnetic field (RF-EMF)-based heating facility emerges as a suitable option for hyperthermia treatment. However, a qualified heating facility for scientific research must elucidate its heating characteristics and validate the biological effects associated with hyperthermia. In this study, we report the characteristics of a rodent heating chamber using EMF energy. The special structure of the chamber not only achieved efficient EMF usage but also ensured the homogeneity in EMF spatial distribution, animal EM absorption, and EMF-caused biological effects. Our work may offer insights for designing a low-cost yet reliable heating facility for scientific research.

KEYWORDS:

• Resonant chamber
• mild whole-body hyperthermia
• numerical simulation
• body temperature
• heat shock proteins

Acknowledgments

We would like to show our great appreciation for Dr. Tongning Wu and Dr. Jie Zhang for their hospitable and professional technical assistance.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Author contributions

Lijiao Jiao: Methodology. Tao Zhang: Methodology. Peng Gao: Validation. Chao Zhou: Methodology. Xiang Mei: Methodology, Wenjun Zhang: Formal analysis. Yonghui Lu: Formal analysis, Lei Zhang: Writing – Review & Editing. Huifeng Pi: Project administration. Zhengping Yu: Supervision. Zhou Zhou: Supervision. Mindi He: Conceptualization, Supervision, Writing – Review & Editing.

Data availability statement

The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.

Ethical approval

The animal study protocol was approved by the Committee for Animal Care of Army Medical University at the Faculty of Animal Breeding and Biology (permission No. 20223260, date of approval 28.02.2022).

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/15368378.2024.2361873.

Additional information

Funding

This work was supported by grants from the National Natural Science Foundation of China (No. 82273604), Key Laboratory of Electromagnetic Radiation Protection (Ministry of Education, China) and Innovation Project Grants of Army Medical University, China (2019XYY01).