Electrically-Assisted Nucleic Acids Delivery to Tissues In Vivo: Where Do We Stand?

Abstract

Electropulsation (electroporation) is a physical method for delivery of various molecules into the cells in vitro and in vivo. It is an expanding field due to its applicability in cancer therapy, where combined application of electric pulses and chemotherapeutic drugs is used for treatment of cutaneous and subcutaneous nodules of different malignancies. Another application of electropulsation in vivo is electrogene therapy, where after injection of naked plasmid DNA and delivery of electric pulses directly to the tissue the expression of gene of interest can be obtained. However, the transfection efficiency of this methodology in vivo is still lower than with viral vectors. Nevertheless, due to the lack of immunogenicity of the method, easiness of the preparation of large quantities of endotoxin free plasmid DNA, control and reproducibility of the method and the development of electropulsators approved for the clinical use, electrically-assisted nucleic-acid delivery holds a great potential for the clinical application. This aim of this minireview is to critically discuss the main limitations and obstacles associated with electrogene therapy and the failures and problems as well as the successes. Topics on electric field distribution in the tissue, electrode geometries, construction of plasmid, modulation of extracellular space, tissue damage, pro-inflammatory and immune response as well as blood flow modification associated with application of electric pulses and injection of naked DNA are presented with possible directions how to overcome these limitations. Furthermore, for successful electrogene therapy in clinical setting it is of utmost importance to elucidate the mechanisms of DNA transfer into the cells of tissues in vivo. This will enable appropriate selection of electric pulse parameters and plasmid DNA constructs for each particular intended use. In the long run, this review should encourage other scientists to consider electrically assisted gene delivery for gene therapy as it matures.

Control by pulse parameters of DNA electrotransfer into solid tumors in mice

“…They can be divided into three categories: parameters of electric pulses, construction of plasmid and histological characteristics of tumors. 4,5 By careful and specific selection of these factors, DNA distribution in the tumors, distribution of electric field affecting permeabilization and expression of therapeutic gene can be controlled and adjusted to specific gene therapy. In our study, the focus was on the influence of electric parameters for electrotransfection, with the aim of investigating whether the application of HV and LV pulses would result in effective transfection in tumors and also to test the hypothesis that the electrophoretic force is crucial (is the mechanism responsible) for transfection of tumors in vivo.…”

“…1,2 It is now recognized as one of the most promising alternatives to viral vectors for transfection of different tissues in vivo for therapeutic purposes. [3][4][5] Gene therapy using electropulsation as a gene delivery method has already entered clinical trials for the treatment of different tumor types in cancer patients and for vaccination. [6][7][8][9] Electrotransfer of plasmid DNA has been assayed and used in many different tissues, such as skin, muscle, liver, tumors, lung, cornea, kidney, brain, cartilage, bladder, carotid artery and tendon.…”

MicroRNAs targeting mutant K-ras by electrotransfer inhibit human colorectal adenocarcinoma cell growth in vitro and in vivo

“…[14][15][16] Electrically assisted gene delivery, called electrotransfection, increased transfection efficiency of either reporter genes or therapeutic genes compared with injection of gene alone. 17,18 To date several preclinical and clinical studies using electroporation (EP) and therapeutic genes for cancer treatment led to encouraging results demonstrating antitumor effectiveness. [19][20][21][22] Owing to high mutation rate of K-ras also in colorectal cancer, silencing of K-ras in colorectal cancer is an attractive therapeutic approach.…”

Vascular disrupting action of electroporation and electrochemotherapy with bleomycin in murine sarcoma

“…In vivo electroporation has found its place as a drug delivery system for chemotherapeutics, that is electrochemotherapy, and is currently under intensive investigation for delivery of therapeutic genes to normal tissues and tumours, that is gene electrotransfer (Neumann et al, 1982;Cemazar et al, 2006;Heller and Heller, 2006;Mir, 2006). Bleomycin (BLM) and cisplatin proved to be effective in electrochemotherapy for treatment of various tumours in mice, rats, cats, dogs and horses (Sersa et al, 2006b).…”