Highly efficient electro-gene therapy of solid tumor by using an expression plasmid for the herpes simplex virus thymidine kinase gene

Abstract

We report successful electro-gene therapy (EGT) by using plasmid DNA for tumor-bearing mice. Subcutaneously inoculated CT26 tumor was subjected to EGT, which consists of intratumoral injection of a naked plasmid encoding a marker gene or a therapeutic gene, followed by in vivo electroporation (EP). When this treatment modality is carried out with the plasmid DNA for the green fluorescent protein gene, followed by in vivo EP with the optimized pulse parameters, numerous intensely bright green fluorescent signals appeared within the tumor. EGT, by using the ''A'' fragment of the diphtheria toxin gene significantly inhibited the growth of tumors, by about 30%, on the flank of mice. With the herpes simplex virus thymidine kinase gene, followed by systemic injection of ganciclovir, EGT was far more effective in retarding tumor growth, varying between 50% and 90%, compared with the other controls. Based on these results, it appears that EGT can be used successfully for treating murine solid tumors.

In vivo electroporation-mediated transfer of interleukin-12 and interleukin-18 genes induces significant antitumor effects against melanoma in mice

“…Following systemic administration with ganciclovir, the growth of tumors was significantly inhibited, suggesting the usefulness of electroporation for in vivo gene therapy. 12 As far as we know, however, there have been few reports in which a cytokine gene was delivered into tumors by means of the electroporation.…”

Electroporation-mediated and EBV LMP1-regulated gene therapy in a syngenic mouse tumor model

“…On the other hand, gene transfer by in vivo electroporation, a procedure that involves DNA injection followed by application of electric fields, is effective for introducing DNA into mouse muscle, 26 skin, 27 rat liver, 28 and tumors. 19,29 Earlier data show that use of in vivo electroporation enhances plasmid DNA uptake in tumor tissue, resulting in expression within the tumor. [30][31][32][33] Furthermore, in vivo electroporation is a safe and nontoxic delivery system.…”

“…Studies in animal models demonstrate that HSVtk/ GCV treatment exerts antitumor effects in various cancers. 15,19,[39][40][41] Direct injection of GCV concurrent with the therapeutic transcriptional cassette appears to have an advantage over delivery via the i.p. method.…”

“…Tumor volume was calculated using the formula: V ¼ a  b 2 /2, where V represents volume (mm 3 ), a is the maximum tumor diameter, and b is the minimum tumor diameter. 19 …”

Focused ultrasound (HIFU) induces localized enhancement of reporter gene expression in rabbit carotid artery

“…As a result, a variety of methods to increase the effectiveness of nonviral vectors have been investigated, such as electroporation, application of DNA to accelerated gold particles, and exposure to controlled pressure. [6][7][8][9] Although these methods have been demonstrated to enhance transfection efficiencies in a variety of tissues and cell types, widespread clinical application of many gene transfer strategies await further improvements on gene transfer methodology. In addition, many therapeutic strategies would benefit from a noninvasive means of directing gene transfer to a specific tissue site.…”