IN-VIVO GENE-TRANSFER TO SKIN AND WOUND BY MICROSEEDING

Background. Gene transfer to skin has many potential applications but lacks a safe, practical delivery method. This report presents a new te chnique, microseeding, for in vivo gene transfer to skin and wounds an d for DNA-mediated vaccination. The plasmid DNA solution was delivered directly to the target cells of the skin by a set of oscillating soli d microneedles driven by a modified tattooing device. Materials and me thods. Skin and partial-thickness excisional wounds in pigs were micro seeded with either hEGF expression plasmid or beta-galactosidase expre ssion plasmid. Human EGF was also delivered by single injection or par ticle bombardment. hEGF expression in wound fluid and in target tissue was determined by ELISA with anti-hEGF-specific antibodies. Additiona lly, weanling pigs were microseeded with a hemagglutinin of swine infl uenza virus expression plasmid and production of anti-HA-specific anti bodies was determined by blocking ELISA.Results. hEGF expression in mi croseeded partial thickness wounds (5664 pg/site) and skin sites (969 pg/site) peaked 2 days after transfection being four- to seven-fold hi gher than gene transfer by a single intradermal injection and two- to three-fold higher than particle-mediated gene transfer. The beta-galac tosidase expressing cells were detected in dermis and epidermis. Pigs microseeded with HA expression plasmid were protected from infection b y the Swine influenza virus. Conclusions. These results demonstrate th at microseeding is a simple and effective method for in vivo gene tran sfer to skin and wounds and is more efficient than single injection an d particle-mediated gene transfer. (C) 1998 Academic Press.