While hyperthermia has been shown to induce a variety of cytotoxic and sensitizing effects on cancer tissues, the thermal dose–effect relationship is still not well quantified, and it is still unclear how it can be optimally combined with other treatment modalities. Additionally, it is speculated that different methods of applying hyperthermia, such as water bath heating or electromagnetic energy, may have an effect on the resulting biological mechanisms involved in cell death or in sensitizing tumor cells to other oncological treatments. In order to further quantify and characterize hyperthermia treatments on a cellular level, in vitro experiments shifted towards the use of 3D cell spheroids. These are in fact considered a more representative model of the cell environment when compared to 2D cell cultures. In order to perform radiofrequency (RF)-induced heating in vitro, we have recently developed a dedicated electromagnetic field applicator. In this study, using this applicator, we designed and validated an experimental setup which can heat 3D cell spheroids in a conical polypropylene vial, thus providing a reliable instrument for investigating hyperthermia effects at the cellular scale.

Combination of therapies is a common strategy in cancer treatment. Such combined therapies only have merit provided that there is superior therapeutic outcome with fewer side effects, compared to single therapies. Here, this work explores the possibility to combine chemotherapy with radionuclide therapy using polymeric micelles as a delivery vehicle. For this purpose, this work prepares poly(ε-caprolactone-b-ethylene oxide) (PCL-PEO) micelles and load them simultaneously with paclitaxel (PTX) and ¹⁷⁷Lu(III). This work chooses a 3D tumor spheroid composed of glioblastoma cells (U87) to evaluate the combined treatment. The diffusion of the micelles in the spheroid is investigated by confocal laser scanning microscopy (CLSM) and light-sheet fluorescence microscopy (LSFM). The results show that the micelles are able to penetrate deep into the spheroid within 24 h of incubation and mainly accumulated around or in the lysosomes once in the cell. Subsequently, this work evaluates the cell killing efficiency of the single treatments (PTX or ¹⁷⁷Lu(III)) versus combined treatment (PTX + ¹⁷⁷Lu(III)) by measuring the growth of the spheroids as well as by performing a cell-viability assay. The results indicate that the combined therapy achieves a superior therapeutic outcome with better cell growth inhibition and cell killing efficiency compared to the single treatments.

The evaluation of the biological effects of therapeutic hyperthermia in oncology and the precise quantification of thermal dose, when heating is coupled with radiotherapy or chemotherapy, are active fields of research. The reliable measurement of hyperthermia effects on cells and tissues requires a strong control of the delivered power and of the induced temperature rise. To this aim, we have developed a radiofrequency (RF) electromagnetic applicator operating at 434 MHz, specifically engineered for in vitro tests on 3D cell cultures. The applicator has been designed with the aid of an extensive modelling analysis, which combines electromagnetic and thermal simulations. The heating performance of the built prototype has been validated by means of temperature measurements carried out on tissue-mimicking phantoms and aimed at monitoring both spatial and temporal temperature variations. The experimental results demonstrate the capability of the RF applicator to produce a well-focused heating, with the possibility of modulating the duration of the heating transient and controlling the temperature rise in a specific target region, by simply tuning the effectively supplied power.