Novel tumor-ablation device for liver tumors utilizing heat energy generated under an alternating magnetic field

Fe3O4-solamargine induces apoptosis and inhibits metastasis of pancreatic cancer cells

Fe3O4-magnetic liposome (MLP) can deliver drugs to target tissues and can increase drug efficacy. The present study aimed to investigate the effects of solamargine (SM) and Fe3O4-SM in pancreatic cancer (PC). Cell viability was detected using a Cell Counting kit‑8 assay. Apoptosis and cell cycle progression was tested using a flow cytometry assay. A scratch assay was used to examine cell metastasis. Quantitative polymerase chain reaction, western blot analysis or immunohistochemical analysis were performed to determine the expression of target factors. Magnetic resonance imagining (MRI) and terminal deoxynucleotidyl-transferase-mediated dUTP nick end labelling were conducted to detect tumor growth and apoptosis in vivo, respectively. It was demonstrated that Fe3O4-SM inhibited cancer cell growth via a slow release of SM over an extended period of time. SM was revealed to induce apoptosis and cell cycle arrest. Furthermore, SM decreased the expression of X-linked inhibitor of apoptosis, Survivin, Ki‑67, proliferating cell nuclear antigen and cyclin D1, but increased the activity of caspase-3. It was also observed that SM inhibited tumor cell metastasis by modulating the expression of matrix metalloproteinase (MMP)-2 and TIMP metallopeptidase inhibitor-2. Furthermore, the phosphorylation of protein kinase B and mechanistic target of rapamycin was suppressed by SM. Notably, the effect of SM was enhanced by Fe3O4-SM. The malignant growth of PC was decreased by SM in vivo. Furthermore, the expression of Ki‑67 was decreased by SM and Fe3O4-SM. Additionally, cell apoptosis was increased in the Fe3O4-SM group, compared with the SM group. The present study illustrated the antitumor effect and action mec-hanism produced by SM. Additionally, it was demonstrated that Fe3O4-SM was more effective than SM in protecting against PC.

Consideration of different heating lengths of needles with induction heating and resistance system: A novel design of needle module for thermal ablation

Thermal ablation using alternating electromagnetic fields is a promising method to treat tissues including tumors. With this approach, an electromagnetic field is generated around an induction coil, which is supplied with high frequency current from a power source. Any electrically conducting object, which is placed in the electromagnetic field, is then heated due to eddy currents. Basic principles underlying this novel thermotherapy needle system are internal induction and resistance heating. This presents a new design of a standard gauge 18 percutaneous trans-hepatic cholangiography needle module combined with a compact power source. Three needle modules containing coils of different lengths were used to locally heat up different volumes of tissues in in vitro experiments on pig livers. Temperature on the inside surface of the needle was controlled and monitored through a K-type thermocouple. By using this needle module system, no two-section or ferromagnetic nanoparticle-coated needles were required; the system worked well with the SUS-304 stainless-steel needle. Successful results were demonstrated in the in vitro experiments on pig livers with different heating lengths of 10, 20, and 30 mm needles. With low power sources, needles could be heated up to a high temperature. The novel design of the needle module incorporated with a high frequency power source was thus shown to be a promising technology for tissue ablation. Bioelectromagnetics.38:220-226, 2017. © 2016 Wiley Periodicals, Inc.

Ferromagnetic glass-coated microwires with good heating properties for magnetic hyperthermia

The heating properties of Fe_71.7Si₁₁B_13.4Nb₃Ni_0.9 amorphous glass-coated microwires are explored for prospective applications in magnetic hyperthermia. We show that a single 5 mm long wire is able to produce a sufficient amount of heat, with the specific loss power (SLP) reaching a value as high as 521 W/g for an AC field of 700 Oe and a frequency of 310 kHz. The large SLP is attributed to the rectangular hysteresis loop resulting from a peculiar domain structure of the microwire. For an array of parallel microwires, we have observed an SLP improvement by one order of magnitude; 950 W/g for an AC field of 700 Oe. The magnetostatic interaction strength essential in the array of wires can be manipulated by varying the distance between the wires, showing a decreasing trend in SLP with increasing wire separation. The largest SLP is obtained when the wires are aligned along the direction of the AC field. The origin of the large SLP and relevant heating mechanisms are discussed.

Evaluation of ghost cell survival in the area of radiofrequency ablation

Background and Aim

Researchers have demonstrated dead cells in radiofrequency ablation (RFA) lesions that have morphological similarities to viable tumor cells and are thus referred to as ghost cells. However, studies on how long ghost cells persist have not been systematically performed.

Methods

A tumor model was established by implanting VX2 tumor tissue into the livers of 48 New Zealand rabbits. Two weeks later, these tumors were eliminated with RFA. The lesions were resected at 0 weeks, 1 week, 2 weeks, 4 weeks, 8 weeks, or 12 weeks after treatment, and samples were stained either with hematoxylin and eosin (HE) or nicotinamide adenine dinucleotide (NADH). The presence of the cells and the morphological changes that they underwent were examined by light microscopy.

Results

Four weeks after RFA, there were no obvious morphological changes observed in HE-stained ghost cells, and NADH staining revealed no viable cells. Eight weeks after RFA, the cell structure became indistinct. Twelve weeks after RFA, ghost cells were no longer present.

Conclusions

The morphological characteristics of ghost cells are maintained for at least 4 weeks, during which time HE staining cannot be used to differentiate ghost cells from residual tumor cells. NADH staining for cell viability is necessary to differentiate residual tumor cells from ghost cells. This evidence adds to our understanding of the mechanisms of RFA when used on solid tumors.

Tumor local chemohyperthermia using docetaxel-embedded magnetoliposomes: Interaction of chemotherapy and hyperthermia

BACKGROUND AND AIM

We have studied and reported the usefulness of tumor local chemohyperthermia at a low-grade temperature below 43°C with docetaxel-embedded magnetoliposome (DML) and an applied alternating current magnetic field. However, the mechanisms of this treatment and the dynamics of the injected docetaxel were not investigated in our previous study. Thus, we investigated the interaction of chemotherapy and hyperthermia in the treated tumor.

METHODS

Human MKN45 gastric cancer cells were implanted in the hind limbs of Balb-c/nu/nu mice. DML, magnetite-loaded liposome, and docetaxel were injected into the tumors with or without being exposed to an alternating current magnetic field. Docetaxel and tumor necrosis factor-α concentrations, the cell cycle, and cell death rates in the tumor were examined.

RESULTS

Docetaxel concentrations were significantly higher in the DML-injected group than in the docetaxel-injected group 3 days after injection. A G2/M peak was observed 1 day after treatment in the DML-injected and exposed group and the docetaxel-injected group, while it was observed 3 days after treatment in the DML-injected without heating group and the magnetite-loaded liposome group. The tumor cell death rate gradually increased in the DML-injected group, with or without being exposed, while it gradually decreased after its peak in other groups. The tumor necrosis factor-α concentration in the tumor treated with DML with heating remained at a high level on the 7th day after treatment, while it decreased after its peak in other groups.

CONCLUSION

The antitumor effect of this treatment derives from a combination of hyperthermia and chemotherapy locally in the tumor.