Graduation Year

2009

Document Type

Dissertation

Degree

Ph.D.

Degree Granting Department

Molecular Medicine

Major Professor

Richard Heller, Ph.D.

Co-Major Professor

Kenneth Ugen, Ph.D.

Keywords

Gene therapy, Vascular endothelial growth factor (VEGF), Fibroblast growth factor-2 (FGF-2), Angiogenesis, Wound healing

Abstract

Gene therapy techniques delivering exogenous angiogenic growth factors, such as vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (FGF-2), are currently being investigated as potential treatments for ischemia resulting from a variety of conditions, such as peripheral artery disease (PAD) and chronic wounds. Despite these intense efforts, a viable clinical option to promote therapeutic neovascularization remains elusive. Electroporation is a simple in vivo method to deliver normally impermeable molecules, such as plasmid DNA, to a variety of tissues including skin and muscle. This study investigated intradermal injection of plasmids encoding angiogenic growth factors with electroporation as a novel therapeutic approach to increase perfusion in areas of ischemia. Two common animal models of ischemia were employed: a skin flap model, used to study wound healing, and a hindlimb ischemia model, used to investigate potential therapies for PAD.

In the skin flap model, delivery of plasmid VEGF with electroporation significantly increased VEGF expression for 5 days after delivery compared to injection of the plasmid alone. While the increase in VEGF expression was short-term, it significantly increased expression of the downstream angiogenic growth factor endothelial nitric oxide synthase, as well as perfusion and healing in the distal area of the skin flap. To facilitate the translation of electroporation to the clinic, a novel electrode configuration was previously designed for cutaneous delivery of plasmids to a large surface area. The design of the Multielectrode Array allows for delivery to a large surface area without the need to increase the applied voltage. Conditions for plasmid delivery with this electrode were optimized and it was then utilized to deliver plasmid FGF-2 (pFGF) to the hindlimb ischemia model. FGF-2 expression, perfusion, and angiogenesis were assessed.

FGF-2 expression was significantly higher for 10 days after treatment with pFGF with electroporation compared to injection of pFGF alone. This increase in FGF-2 expression induced a significant increase in perfusion and angiogenesis in the ischemic limb. The research presented here suggests intradermal injection of plasmids encoding angiogenic factors by electroporation is a novel potential therapeutic approach to increase perfusion to areas of ischemia and promote wound healing.

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