Skin targeted DNA vaccine delivery using electroporation in rabbits II. Safety

The Achilles heel of gene-based therapy is gene delivery into the target cells efficiently with minimal toxic effects. Viral vectors for gene/DNA vaccine delivery are limited by the safety and immunological problems. Recently, nonviral gene delivery mediated by electroporation has been shown to be efficient in different tissues including skin. There are no detailed reports about the effects of electroporation on skin tissue, when used for gene/DNA vaccine delivery. In a previous study we demonstrated the efficacy of skin targeted DNA vaccine delivery using electroporation in rabbits Medi, B.M., Hoselton, S., Marepalli, B.R., Singh, J., 2005. Skin targeted DNA vaccine delivery using electroporation in rabbits. I. Efficacy. Int. J. Pharm. 294, 53-63]. In the present study, we investigated the safety aspects of the electroporation technique in vivo in rabbits. Different electroporation parameters (100-300 V) were tested for their effects on skin viability, macroscopic barrier property, irritation and microscopic changes in the skin. Skin viability was not affected by the electroporation protocols tested. The electroporation pulses induced skin barrier perturbation and irritation as indicated by elevated transepidermal water loss (TEWL) and erythema/edema, respectively. Microscopic studies revealed inflammatory responses in the epidermis following electroporation using 200 and 300 V pulses. However, these changes due to electroporation were reversible within a week. The results suggest that the electroporation does not induce any irreversible changes in the skin and can be a useful technique for skin targeted DNA vaccine delivery.