In vivo experiment of applying nanosecond pulsed electric fields on solid tumor

Abstract

Pulse electric fields conduct apoptosis to biological cells. Many studies have started to apply the phenomena to cancer therapy. In this study, we introduce the embryonated chick assay to the experiment applying nanosecond pulse electric fields on tumor. The embryonated chick assay has several advantages in experiments; this experiment is generically classified as in vivo. Many species of virus or rickettsia are available because of the low protective immunity. In some conditions, angiogenesis would be yielded so that the cancer tissue in body was well simulated. To preparation of many specimen materials, with large incubator, is easier than that for laboratory animal such as mice and rats. Nanosecond pulse electric fields (nsPEF) are applied on a tumor on the chorioallantoic membrane in an egg with needle electrodes. A pulsed power generator whose output pulse length is a nanosecond is used in this experiment. The tumor cells: EMT6/KU (mouse breast adenocarcinoma cells) adopted for the experiment are transplanted before several days in advance. The cells form a solid tumor. The needle electrode to apply nsPEF consists of a steeple stainless wire of 1 mm in diameter with a rubber sleeve. The two or four needle electrodes are inserted into the egg through a window on shell so as to tack the tumor in them. The tumors are retrieved from the eggs a few days after nsPEF application and are weighed. The control eggs without nsPEF application are also processed as the same procedure. Rejection-test are used for significant test on application of pulsed electric fields. The significant difference between weight of the tumor with nsPEF application and that of control was confirmed with the significant tests. The difference increased with the charging voltage of pulsed power generator. Another experiment is necessary not only to find the optimal experimental condition but to develop the experimental instruments for therapy.