Topical Gene Electrotransfer to the Epidermis of Hairless Guinea Pig by Non-Invasive Multielectrode Array

Abstract

Topical gene delivery to the epidermis has the potential to be an effective therapy for skin disorders, cutaneous cancers, vaccinations and systemic metabolic diseases. Previously, we reported on a non-invasive multielectrode array (MEA) that efficiently delivered plasmid DNA and enhanced expression to the skin of several animal models by in vivo gene electrotransfer. Here, we characterized plasmid DNA delivery with the MEA in a hairless guinea pig model, which has a similar histology and structure to human skin. Significant elevation of gene expression up to 4 logs was achieved with intradermal DNA administration followed by topical non-invasive skin gene electrotransfer. This delivery produced gene expression in the skin of hairless guinea pig up to 12 to 15 days. Gene expression was observed exclusively in the epidermis. Skin gene electrotransfer with the MEA resulted in only minimal and mild skin changes. A low level of human Factor IX was detected in the plasma of hairless guinea pig after gene electrotransfer with the MEA, although a significant increase of Factor IX was obtained in the skin of animals. These results suggest gene electrotransfer with the MEA can be a safe, efficient, non-invasive skin delivery method for skin disorders, vaccinations and potential systemic diseases where low levels of gene products are sufficient.

Thermal Assisted In Vivo Gene Electrotransfer

“…An in vivo surface array was designed that incorporated features from both the 4PE and MEA [23, 28-31]. This new array consisted of four electrodes with 5mm length and 5mm gap.…”

“…The tissue remained at 43°C for approximately 10 seconds, allowing adequate time for pulsing at a range of voltages from 50-125V for luciferase experiments and 50-100V for GFP experiments. Based on our previously published results with a similar electrode, pulse number, time between pulses and pulse length were maintained at 8 pulses, 150ms, and 150ms, respectively [23, 29, 31]. …”

“…To minimize cellular damage or discomfort, a multi-electrode array (MEA) was designed. This applicator consisted of 16 flat pin electrodes 2mm apart in a 4X4 array [23, 29, 31]. The electrode covered the same tissue area as the 4PE but smaller electrode distances and an increased number of electrodes allowed for enhanced directional control and a reduction in applied voltage.…”

Improved Specificity of Gene Electrotransfer to Skin Using pDNA Under the Control of Collagen Tissue-Specific Promoter

“…Studies imply that cells transfected by skin gene electrotransfer reside in different skin regions: in epidermis (Guo et al 2013;Lin et al 2001;Pavselj and Preat 2005), in dermal layer (fibroblasts and mononuclear cells) (Drabick et al 2001;Lin et al 2001;Pavselj and Preat 2005;Zhang et al 2002) and even in the hypodermis and subcutaneous muscle layer (Roos et al 2009). The transfection to the specific region of the skin depends on the electrode selection, electrical parameters, injection technique, animal species, dose of plasmid administered and the plasmid design (Guo et al 2013).…”

“…The transfection to the specific region of the skin depends on the electrode selection, electrical parameters, injection technique, animal species, dose of plasmid administered and the plasmid design (Guo et al 2013). Furthermore, effective gene transfer to multiple cells and cell types within the electric field can pose a problem in terms of cell specificity of gene delivery.…”