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Title: Targeted delivery of nucleic acids to skin using microneedles
Author: Chong, Rosalind
Awarding Body: Cardiff University
Current Institution: Cardiff University
Date of Award: 2013
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Nucleic acid therapies may have significant potential for effectively treating genetic, hyper-proliferative or malignant skin conditions caused by aberrant gene expression. To be effective, the restorative pDNA or inhibitive siRNA must access the viable skin layers and cells in a stable and functional form, preferably without painful administration. Microneedles are able to penetrate the stratum corneum skin barrier in a minimally invasive manner to allow targeted delivery of therapeutic macromocules. To date, there are limited studies reporting the delivery of nucleic acids, particularly siRNA, to the skin using microneedle devices. A range of in vitro, ex vivo and in vivo skin models was developed to characterise nucleic acid delivery and functional response. In vitro studies conducted in both continuous and primary keratinocyte cultures provided proof-of-concept of efficient and non-toxic cell uptake and gene silencing with siRNA and moderately efficient gene expression with pDNA. In initial studies, pDNA and siRNA was pre-complexed with lipid-based transfection reagents, however, in the case of siRNA, coating of the lipoplexes onto microneedles resulted in a reduction in functionality. Hence, modified self-delivery (sd) siRNA formulations were used in subsequent microneedle delivery experiments. Stainless steel microneedles coated with reporter pDNA or sd-siRNA were successful in penetrating the stratum corneum barrier of ex vivo viable human breast skin. It was difficult to demonstrate equivocally both plasmid gene expression and functional gene silencing in the skin explants, which only remain viable for short periods. Delivery of pDNA and sd-siRNA to in vivo mouse skin however, resulted in demonstrable gene expression and gene silencing, particularly evident at the protein level, in an established transgenic reporter mouse skin model. Overall, these investigations generally support the use of the coated steel microneedles for the simple and potentially self-administrable delivery of nucleic acids to the skin.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: R Medicine (General)