In vivo transdermal delivery of large molecules by pressure-mediated electroincorporation and electroporation: a novel method for drug and gene delivery

Successful development of a noninvasive topical-based delivery system of therapeutic agents, with a handy applicator, will allow for targeted and efficient in vivo gene transfer without the potential for adverse events compared with viral methods. It also allows localized drug delivery into the skin without systemic side effects. In recent years there has been an increased interest and challenge in the delivery of macromolecules through a thin outermost layer of the skin, the stratum corneum (SC). This layer acts as a significant physical barrier to drug and gene transfer into the skin. Here we report the use of pressure-mediated electroincorporation (PMEI) to deliver Lupron Depot microspheres (2-20 mu m) loaded with leuprolide acetate into hairless mouse skin and into human skin xenografted onto immunodeficient nude mice. We also demonstrate the ability to transfer the lacZ reporter gene (6.8 kb) into the hairless mouse skin by pressure-mediated electroporation (PMEP). The transfer of macromolecules is achieved by pulsed electric fields and subsequent pressure from caliper-type electrodes on topically applied microspheres or gene constructs. The ratio of efficiency to deliver Lupron Depot microspheres across the SC between pulsing and control is a factor 100 for human skin xeno raft. In the case of hairless mice, the ratio is a factor 18. With electrical pulses and post-pulse pressure, the maximum depth of lacZ gene expression in the dermis and transfected cells were achieved at 370 mu m and 457 cells mm(-2), respectively. Gene expression was observed only in the hair follicles in the case of the control. The applications of the technique could extend to peptides, proteins, oligonucleotides and genes, and open up a new perspective of topical delivery for the treatment of skin diseases. (C) 1997 Elsevier Science S.A.