Robert H. Carpenter

Electrical Enhancement of Formulated Plasmid Delivery in Animals

Electroporation has been shown to significantly increase plasmid transfer to the skeletal muscle, but this procedure is also implicated in muscle damage. We are reporting a highly efficient in vivo transfer of a plasmid formulated with poly-(L-glutamate) (PLG) into murine, canine and porcine muscle fibers using electric pulses of low field intensity. In mice and pigs, the use of secreted embryonic alkaline phosphatase (SEAP) as the indicator gene caused increased PLG expression by 2–3 fold compared to naked plasmid; while delivery of a PLG-plasmid formulation to dogs showed a 10-fold increase in serum SEAP levels compared to plasmid alone. Muscle lesions were reduced by the protective PLG. Thus, PLG may constitute a useful adjuvant for increased expression and reduced muscle trauma to plasmid DNA delivered by electroporation.

Long-term effects of plasmid-mediated growth hormone releasing hormone in dogs

Geriatric and cancer-afflicted patients often experience decreased quality of life with cachexia, anemia, anorexia, and decreased activity level. We have studied the possibility that a myogenic plasmid that expresses growth hormone releasing hormone (GHRH) can prevent and/or treat these conditions. We administered plasmid to 17 geriatric and five cancer-afflicted companion dogs with an average age of 10.5±1.0 and 11.3±0.6 years at enrollment, respectively. Effects of the treatment were documented for at least 180 days post-treatment, with 10 animals followed for more than 1 year post-treatment, on average 444±40 days. Treated dogs showed increased IGF-I levels, and increases in scores for weight, activity level, exercise tolerance, and appetite. No adverse effects associated with the GHRH plasmid treatment were found. Most importantly, the overall assessment of the quality of life of the treated animals increased. Hematological parameters such as red blood cell count, hematocrit, and hemoglobin concentrations were improved and maintained within their normal ranges. We conclude that intramuscular injection of a GHRH-expressing plasmid is both safe and capable of improving the quality of life in animals for an extended period of time in the context of aging and disease. The observed anabolic and hematological responses to a single dose of this plasmid treatment may also be beneficial in geriatric patients or patients with cancer-associated anemia and/or cachexia.