In vivo cutaneous interferon-γ gene delivery using novel dicationic (gemini) surfactant-plasmid complexes

Background Localized scleroderma (morphea and linear scleroderma) is a connective tissue disease, accompanied by excessive proliferation and deposition of collagen within the skin, inflammation, vasculopathy and a deranged immune system. Interferon gamma (IFN gamma), an inhibitor of collagen synthesis and an immunomodulator, could be a potential therapeutic agent if it could be delivered into or expressed locally in affected skin in a non-invasive manner. In this study, the feasibility of topical delivery of the IFN gamma gene and expression of IFN gamma were investigated in mice. Methods Novel dicationic (gemini) surfactant (spacer length n = 2-16; alkyl chain m = 12 or 16)-DNA complexes were formulated and characterized by circular dichroism and atomic force microscopy to select gemini analogues with the highest transfection efficiency (TE). Transfection and cellular expression of IFN gamma from the bicistronic pGTmCMV.IFN-GFP plasmid were evaluated in PAM 212 keratinocyte culture by ELISA and fluorescence microscopy. Topical delivery of plasmid using liposomal and nanoemulsion systems, based on gemini surfactant 16-3-16, was evaluated in mice by IFN gamma expression analysis. Results In vitro TE was found to be dependent on the spacer length of the gemini surfactant, with the C3 spacer showing the highest activity (both 12-3-12 and 16-3-16). Both gemini cationic liposomes and gemini nanoemulsion (3 x 25 mu g DNA/animal) produced significantly higher levels of IFN gamma in the skin (359.4 and 607.24 pg/cm(2)) compared to naked DNA (135.69 pg/cm(2)) or a liposomal Dc-chol formulation (82.15 pg/cm(2)). IFN gamma expression in the lymph nodes was higher in the animals treated with gemini liposomes (422.74 pg/animal) compared to the nanoemulsion formulation (131.27 pg/animal) or the Dc-chol formulation (82pg/animal). Conclusions The feasibility of topical delivery of pGTmCMV.IFN-GFP plasmid in mice using gemini cationic surfactant based delivery systems was demonstrated. IFN gamma expression after treatment with gemini-DNA formulations in the skin was 3-5-fold higher compared to the treatment with naked DNA (p < 0.05), and 4-6-fold higher than the Dc-chol-DNA complex, indicating a significant advance in topical DNA delivery across intact skin in vivo Copyright (c) 2005 John Wiley & Sons Ltd.