Abstract
When a cell is exposed to high-voltage, short electric pulses, the cell membrane can be opened transiently without causing permanent cell damage. This process is referred to as electroporation. Electroporation has been used to introduce the anticancer drug, bleomycin (BLM), into living cells. The new method of cancer treatment that combines electroporation and a chemotherapeutic agent has been named electrochemotherapy (ECT) . We evaluated the effects of ECT with intratumoral injection of BLM in a chemically induced gingival cancer model, in the hamster.
In this study, each electrical treatment regimen for ECT consisted of eight triangular direct current pulses with a width 99μs and a frequency of 1 Hz. Electric field strength, defined as the voltage applied to the electrodes divided by the distance between the electrodes placed on either side of the tumor, was 130V/mm. Electrical energy was transmitted through a pair of parallel plate electrodes or needle electrodes. Electrical treatment was performed immediately after intratumoral injection of BLM.
After a week, all animals that received ECT showed tumor volume reduction, while no antitumor effects were observed in the control groups. Although after two weeks the animals that received ECT using parallel plate electrodes showed regrowth of the tumor, the animals that received ECT using needle electrodes showed continuous tumor volume reduction, and one of six animals showed complete response after three weeks. These results indicated that ECT enhanced the antitumor effect of BLM. In particular, a needle electrode was more effective than a parallel plate electrode in a hamster gingival cancer model.
