The skin presents an attractive target for the delivery and expression of plasmid DNA pDNA. Potential therapeutic benefits from cutaneous gene therapy approaches include the correction or alleviation of inherited skin disorders genodermatoses and genetic vaccination. The skin is a particularly suitable portal for genetic vaccination due to its innate immunogenic capabilities. However, delivery of pDNA to the epidermis is severely constrained by the stratum corneum SC, low transfection efficiency and rapid loss of pDNA associated with epidermal cells. Microfabricated microneedles are employed as a means of penetrating the SC for macromolecular delivery. Solid silicon microneedles with different heights and tip morphologies were made by careful manipulation of the etching process, along with hollow silicon microneedles and solid polymer microneedles. To address the low transfection efficiency and rapid loss of pDNA in skin, hydrogels formed from smart polymers were investigated to provide sustained release reservoirs of pDNA. Gene delivery studies were performed in freshly maintained ex vivo human skin delivery formulations of reporter plasmid pCMVp and pEGFP-Nl and a therapeutic plasmid pCMV.M were applied to skin prior to microneedle application and maintenance in an optimized organ culture system. The results indicate that it is possible to deliver and express genes in the epidermis using microneedles. However, morphology of microneedles, their application protocol, and pDNA formulation all contribute to the efficiency of trans-gene expression.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:584165 |
| Date | January 2007 |
| Creators | Pearton, Marc |
| Publisher | Cardiff University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://orca.cf.ac.uk/55676/ |
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