In vivo gene introduction into keratinocytes using jet injection

Successful keratinocyte gene therapy requires the development of efficient methods of gene transfer to keratinocytes. Jet injection of a solution containing DNA can be used to transfer genes to several tissues in vivo. In this article, we tried to introduce DNA into rat and human keratinocytes using this method. First, we fired a beta-gal expression vector into rat skin at several distances using a jet injector and examined beta-gal activity in the epidermal keratinocytes. The highest activity in keratinocytes was found when the plasmid was fired at 10 cm from the skin surface; the activity lessened as the firing distance became shorter than 10 cm. Next, we transplanted human skin on to a nude rat, fired the vector into the human skin from a distance of 10 cm and examined the beta-gal activity. We also injected the same amount of plasmid with a needle to compare jet with needle injections. The results showed that jet injection of the naked DNA could introduce and express DNA in human keratinocytes in vivo and that jet injection exhibited much higher activity than needle injection. Jet injection of the naked DNA will provide a method for keratinocyte gene therapy in the future.