Effects of Burst Electromagnetic Wave Focusing and Their Combination With Nanosecond Pulsed Electric Fields on HeLa S3 Cells

Abstract

Burst electromagnetic waves focusing, nanosecond pulsed electric fields (nsPEF), and their combinations were applied to HeLa S3 cells to investigate their respective biological effects. The research was motivated by its application for cancer therapy. Burst electromagnetic waves, characterized by high-frequency (800 MHz) and narrow-band signals, were applied through a focusing system consisting of an ellipsoidal reflector and a radiating antenna. Burst widths of electromagnetic waves were adjusted to 1 and 5 ms. For nsPEF exposure, a magnetic pulse power modulator with an 80-ns pulsewidth and repetition frequencies of 0.5 and 1 pulse per second was employed. Cervical cancer cells (HeLa S3) subjected to electric fields were cultured in an incubator for 24 h and stained using propidium iodide to monitor the cell death rate. Sole application of burst electromagnetic waves was found not to change the cancer cell survival, while sole application of nsPEF suppressed the cells growth. The combination of nsPEF and focused burst electromagnetic wave was found to be very effective in producing maximum cell death rate. The results show the importance of the exposure combination component, as a first step, to design a more efficient and less-invasive cancer therapy system.