title: Enhanced gene expression of systemically administered plasmid DNA in the liver with therapeutic ultrasound and microbubbles.
abstract: Ultrasound-mediated delivery (USMD) of novel therapeutic agents in the presence of microbubbles is a potentially safe and effective method for gene therapy offering many desired characteristics, such as low toxicity, potential for repeated treatment, and organ specificity. In this study, we tested the capability of USMD to improve gene expression in mice livers using glycogen storage disease Type Ia as a model disease under systemic administration of naked plasmid DNA. Image-guided therapeutic ultrasound was used in two studies to provide therapeutic ultrasound to mice livers. In the first study, involving wild-type mice, control animals received naked plasmid DNA (pG6Pase 150 μg) via the tail vein, followed by an infusion of microbubbles; the treated animals additionally received therapeutic ultrasound (1 MHz). Following the procedure, the animals were left to recover and were subsequently euthanized after 2 d and liver samples were extracted. Reverse transcription polymerase chain reaction (RT-PCR) assays were performed on the samples to quantify mRNA expression. In addition, Western blot assays of FLAG-tagged glucose-6-phosphatase (G6Pase) were performed to evaluate protein expression. Ultrasound-exposed animals showed a 4-fold increase in G6Pase RNA in the liver, in comparison with control animals. Furthermore, results from Western blot analysis demonstrated a 2-fold increased protein expression in ultrasound-exposed animals after two days ( p < 0.05). A second pilot study was performed with G6Pase knockout mice, and the animals were monitored for correction of hypoglycemia over a period of 3 weeks before tissue analysis. The RT-PCR assays of samples from these animals demonstrated increased G6Pase RNA in the liver following ultrasound treatment. These results demonstrate that USMD can increase gene expression of systemically injected naked pDNA in the liver and also provide insight into the development of realistic approaches that can be translated into clinical practice.
authors: Philips Research North America, Briarcliff Manor, NY, USA. balasundar.raju@philips.com
authors: Balasundar I
authors: BI
authors: Raju
authors: Evgeniy
authors: E
authors: Leyvi
authors: Ralf
authors: R
authors: Seip
authors: Shriram
authors: S
authors: Sethuraman
authors: Xiaoyan
authors: X
authors: Luo
authors: Andrew
authors: A
authors: Bird
authors: Songtao
authors: S
authors: Li
authors: Dwight
authors: D
authors: Koeberl
mesh_terms: D000818:Animals; D015153:Blotting, Western; D004247:DNA / Q000008:administration & dosage* / Q000235:genetics* / Q000493:pharmacokinetics; D015316:Genetic Therapy / Q000379:methods; D005952:Glucose-6-Phosphatase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008099:Liver / Q000737:chemistry / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D045423:Microbubbles; D010865:Pilot Projects; D010957:Plasmids / Q000008:administration & dosage* / Q000235:genetics* / Q000493:pharmacokinetics; D014162:Transfection / Q000379:methods*; D014465:Ultrasonics / Q000379:methods*
chemical_list: D004247:DNA; D005952:Glucose-6-Phosphatase