Delivery of DNA into bladder via electroporation

Intravesical nerve growth factor antisense therapy for bladder hypersensitivity induced by psychological stress

This study assessed the relationship between NGF expression in the bladder and bladder hypersensitivity caused by psychological stress using water avoidance stress (WAS) in rats by modulating the NGF expression using intravesical liposome-complexed NGF antisense oligonucleotide (OND) therapy on WAS-induced bladder dysfunction. Female Wistar rats were divided into control and WAS groups, the latter of which received WAS sessions for 10 days with or without the OND pretreatment. Rats underwent cystometry with or without intravesical application of low-dose protamine sulfate (LD-PS), or pain behavior measurements after LD-PS application. After functional evaluations, the bladder was harvested for histology and molecular studies. WAS rats with or without LD-PS showed shortened intercontraction intervals and increased pain behaviors compared to control rats, which was improved by OND-treatment. Histological studies revealed that LD-PS provoked urothelial exfoliation in WAS rats. Compared to controls, protein assay showed increased NGF levels, and RT-PCR showed increases of TRPV1 and TRPA1 and a decrease in Cx43 in WAS rat bladders, which were improved by OND-treatment. WAS caused bladder hypersensitivity, which was improved by NGF antisense OND treatment. NGF upregulation in the bladder may be a therapeutic target for the treatment of psychological stress-induced bladder dysfunction.

Site-targeted non-viral gene delivery by direct DNA injection into the pancreatic parenchyma and subsequent in vivo electroporation in mice

The pancreas is considered an important gene therapy target because the organ is the site of several high burden diseases, including diabetes mellitus, cystic fibrosis, and pancreatic cancer. We aimed to develop an efficient in vivo gene delivery system using non-viral DNA. Direct intra-parenchymal injection of a solution containing circular plasmid pmaxGFP DNA was performed on adult anesthetized ICR female mice. The injection site was sandwiched with a pair of tweezer-type electrode disks, and electroporated using a square-pulse generator. Green fluorescent protein (GFP) expression within the injected pancreatic portion was observed one day after gene delivery. GFP expression reduced to baseline within a week of transfection. Application of voltages over 40 V resulted in tissue damage during electroporation. We demonstrate that electroporation is effective for safe and efficient transfection of pancreatic cells. This novel gene delivery method to the pancreatic parenchyma may find application in gene therapy strategies for pancreatic diseases and in investigation of specific gene function in situ.

Electro-gene transfer to skin using a noninvasive multielectrode array

Because of its large surface area and easy access for both delivery and monitoring, the skin is an attractive target for gene therapy for cutaneous diseases, vaccinations and several metabolic disorders. The critical factors for DNA delivery to the skin by electroporation (EP) are effective expression levels and minimal or no tissue damage. Here, we evaluated the non-invasive multielectrode array (MEA) for gene electrotransfer. For these studies we utilized a guinea pig model, which has been shown to have a similar thickness and structure to human skin. Our results demonstrate significantly increased gene expression 2 to 3 logs above injection of plasmid DNA alone over 15 days. Furthermore, gene expression could be enhanced by increasing the size of the treatment area. Transgene-expressing cells were observed exclusively in the epidermal layer of the skin. In contrast to caliper or plate electrodes, skin EP with the MEA greatly reduced muscle twitching and resulted in minimal and completely recoverable skin damage. These results suggest that EP with MEA can be an efficient and non-invasive skin delivery method with less adverse side effects than other EP delivery systems and promising clinical applications.

Electroporation and ultrasound enhanced non-viral gene delivery in vitro and in vivo

Non-viral vectors are less efficient than the use of viral vectors for delivery of genetic material to cells in vitro and especially in vivo. However, viral vectors involve the use of foreign proteins that can stimulate both the innate and acquired immune response. In contrast, plasmid DNA can be delivered without carrier proteins and is non-immunogenic. Plasmid gene delivery can be enhanced by the use of physical methods that aid the passage of the plasmid through the cell membrane. Electroporation and microbubble-enhanced ultrasound are two of the most effective physical delivery methods and these can be applied to a range of different cell types in vitro and a broad range of tissues in vivo. Both techniques also have the advantage that, unlike viral vectors, they can be used to target specific tissues with systemic delivery. Although electroporation is often the more efficient of the two, microbubble-enhanced ultrasound causes less damage and is less invasive. This review provides an introduction to the methodology and summarises the range of cells and tissues that have been genetically modified using these techniques.