Electroporation of prostate cancer cells for drug delivery

Electroporation has been shown to be a powerful method to temporarily disrupt biological barriers and thereby enhance drug delivery. However, incomplete understanding of electroporation mechanisms and dependence on electrical parameters has limited quantitative predictions of molecular uptake and cell viability. To provide a rational basis for designing electroporation protocols we used flow cytometry to quantify uptake and viability for more than 200 different experimental conditions over a range of field strengths, pulse lengths, number of pulses, and cell and solute concentrations with single-cell suspensions. Semi-empirical models were then developed and used to optimize electroporation protocols. With the ultimate goal of electroporating tissues, our single-cell methods were extended to multicellular tumor spheroids to study the effects of increasing biological complexity. Spheroids mimic tumor microregions where drug delivery to the interior cells is more difficult due to poor vascular supply. Their symmetric nature allows for cell layers to be stripped off concentrically so that each layer can be analyzed separately. Combined with confocal microscopy, this study shows that the inner layers of the spheroid are more susceptible to electroporation potentially due to changes in cell state due to nutrient deprivation. These results are being used to develop a rational approach for designing in vivo electroporation protocols