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Many studies have tested the application of pulsed electric fields to tumors during cancer therapy. In this study, we used an embryonic chick assay to test the effects of nanosecond pulsed electric fields (nsPEFs) on a solid tumor. Our experiments used the embryonic chick assay, which is classified as in vivo experiment, because it has several advantages. Mouse breast adenocarcinoma cell line EMT6/KU was used to produce tumor cells for the experiment. The cells were inoculated for several days before the test and nsPEFs were applied using needle electrodes to solid tumors formed on the chorioallantoic membrane of eggs. A pulsed power generator with a pulse output length of 1.5 ns was used in this experiment. The tumors were dissected from the eggs after several days of nsPEF application and weighed. The mean weight of tumors treated with pulses was less than that of the control. The difference between the weight of the tumor after nsPEF application and that of the control was significant. The difference increased with the charging voltage of the pulsed power generator, with significant different observed when the charging voltage of the pulsed power generator was >2.85 kV. The mean tumor weight of the group that experienced discharges infrequently occurred on or under CAM was significantly smaller than that of the group that did not experience.

Many studies on cancer therapy apply conduct of apoptosis by pulse electric fields have been actively started. In this study, in vivo experiment of applying nanosecond pulse electric fields (nsPEFs) on solid tumors are carried out. To advance this study, we adopt the embryonated chick assay, which can easily prepare a large number of samples for test, compared to typical animal experiments. The tumor cells: EMT6/KU (mouse breast adenocarcinoma cells), were planted with capillary on chorioallantoic membrane in fertilized chicken egg. After four days from this process, nsPEFs of 2ns pulse-width were applied on the solid tumor. The tumors were dissected from eggs after three days from the nsPEFs application and were weighed. The control eggs without nsPEFs application were also processed with the same procedure. Difference of the weights of the pulse-treated and controls tumors was confirmed to be significant by using statistics processing. The weights of the tumors decreased with increase of charging voltage of generator. Tumors treated with nsPEFs exhibited apoptosis by TUNEL staining.

Bioelectrics has become a notable field of pulsed power application at the present day. Cancer therapy using apoptosis with nanosecond pulsed electric fields (nsPEFs) has been studied in laboratories. We introduced embryonic chick assay to study in vivo. The embryonic chick assay has several advantages and is categorized as in vivo experiment. Many samples can be prepared with low cost by the assay. This study adopted EMT6/KU (mouse breast adenocarcinoma cells) as tumor cells, which formed a solid tumor on the chorioallantoic membrane (CAM) of a fertilized hen egg in the assay. Nanosecond pulsed electric fields with width of 1.5 ns were applied on the solid tumor on CAM with needle electrodes. Stainless wires of 1 mm in diameter were used as the needle electrodes. The two or four needle electrodes were used in this experiment. The solid tumor was dissected and extracted from the egg on a three days after application of nsPEF and was then weighed. The controls of tumor sample were also prepared without nsPEF application. Significance test on the weight of tumors was adopted to determine the effect of nsPEFs application. The difference of weight between the tumor with nsPEF application and control was significantly confirmed. The difference enlarged with the charging voltage of pulsed power generator.