Methods forin VivoTissue Electroporation Using Surface Electrodes

Abstract

Electroporation of tissues has many potential biomedical applications, including transdermal and targeted drug delivery. Although there are established protocols for electroporation of single cells, electroporation of tissues remains largely unexplored. Here we describe methods for in vivo tissue electroporation with surface electrodes, where either (a) molecules are provided at the outer surface of skin and electroporation is caused in order to transport molecules across the skin or (b) molecules are injected into an animal and internal tissue cells are electroporated to enhance up-take of the injected molecules. Factors considered in our experimental design include selection of electrode material and electrode/tissue geometry. Electrode materials were used which could accommodate a high instantaneous current density and were expected not to form harmful electrochemical products. Due to the complex heterogeneous nature of tissues, the choice of electrical pulse parameters was guided by, but not based solely on, results from single-cell systems. Multiple pulses appeared to be useful in causing electroporation of tissues located deeper than the skin's stratum corneum. Secondary problems which resulted from the direct muscle stimulation associated with pulsing were also considered. Developing methods for in vivo tissue electroporation required an interdisciplinary approach, involving both high-voltage electric fields and the basic properties of living tissue.