|Malone, P. Brandon|
Submitted to: Federation of American Societies for Experimental Biology Conference
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/2/2003
Publication Date: 3/1/2003
Citation: Draghia-Akli, R., Ellis, K.J., Hill, L., Malone, P., Fiorotto, M.L. 2003. High-efficiency growth hormone-releasing hormone plasmid vector administration into skeletal muscle mediated by electroporation in pigs. Federation of American Societies for Experimental Biology Conference. 17:526-528. Interpretive Summary: The work describes a method whereby gene therapy can be developed to increase and control the production of growth hormone in mammals. A chemical stimulus (called a vector) was inserted under the skin of piglets which are observed to be larger at several time points over the next 53 days than control (non-injected) animals. At the end of the study, the injected larger animals had a lower fat content and increased bone density. The type of treatment, when projected, may be useful for treating children with low growth hormone levels.
Technical Abstract: We report here a very efficient method for the in vivo transfer of therapeutic plasmid DNA into porcine muscle fibers by using electric pulses of low field intensity. We evaluated delivery of 0.1-3 mg of plasmid vectors that encode reporter secreted-embryonic alkaline phosphatase (SEAP) or therapeutic growth hormone releasing hormone (GHRH). Reporter gene studies showed that internal needle electrodes give a 25-fold increase in expression levels compared with caliper electrodes in skeletal muscle in swine. Dose and time courses were performed. Pigs injected with 0.1 mg plasmid had significantly greater weight gain than controls over 53 days (22.4 +/- 0.8 kg vs. 19.7 +/- 0.03 kg, respectively; P<0.01). The group treated with GHRH-expressing plasmid at 14 days of age demonstrated greater weight gain than controls at every time point (25.8 +/- 1.5 kg vs. 19.7 +/- 0.03 kg; P<0.01). Body composition studies by dual X-ray absorbitometry showed a 22% decrease in fat deposition (P<0.05) and a 10% increase in bone mineral density (P<0.004). Our studies demonstrate that by optimizing the electroporation method, favorable physiological changes, such as enhanced weight gain and improved body composition, can be obtained at extremely low plasmid doses in a large mammal.