Investigation of frequency response of apoptosis induction to budding yeast by burst pulse electric field for cancer treatment

Pulsed power technology has possibility to be able to provide new method for cancer treatment. Applying a pulsed high electric field with nanosecond duration time onto a cancer cell can induce apoptosis into that. As the first stage, we have used budding yeast that is a eukaryotic cell, as a model organism of the cancer cell. We investigated the influence on the cell by changing the frequency and field strength of pulse electric field in the experiment. PI (Propidium iodide) and ANNEXIN-V of fluorescent stain has been used for detecting of apoptosis. The differences in fluorescence staining at PI and ANNEXIN-V were investigated at 2 MHz to 200 MHz. Burst pulse generating equipment with single frequency was used for the experiment. Pulse electric field was applied to the budding yeast using this equipment. At the 2 MHz, cell death that can be observed by PI occurred immediately after applying the electric field. This result shows that the dielectric breakdown occurs in the cell membrane at 2 MHz. At 70 MHz, cell death that can be observed by PI occurred after several hours. This result shows that the influence to the cell is given inside at 70 MHz. This is related to a cell cycle. The cell cycle is performing restoration and stop in order to not leave abnormalities and defects to species. If apoptosis is caused in damaged cell, cytolysis occurs within the cell cycle. Therefore the cell staining by PI fluorescent stain occurs a few hours later. Therefore it is speculated the apoptosis was induced in the cell at 70 MHz. Moreover we confirmed apoptosis induction at 70 MHz by ANNEXIN-V which detects the earlystage apoptosis.