title: Optimal salt concentration of vehicle for plasmid DNA enhances gene transfer mediated by electroporation.
abstract: In vivo electroporation has emerged as a leading technology for developing nonviral gene therapies, and the various technical parameters governing electroporation efficiency have been optimized by both theoretical and experimental analysis. However, most electroporation parameters focused on the electric conditions and the preferred vehicle for plasmid DNA injections has been normal saline. We hypothesized that salts in vehicle for plasmid DNA must affect the efficiency of DNA transfer because cations would alter ionic atmosphere, ionic strength, and conductivity of their medium. Here, we show that half saline (71 mM) is an optimal vehicle for in vivo electroporation of naked DNA in skeletal muscle. With various salt concentrations, two reporter genes, luciferase and beta-galactosidase were injected intramuscularly under our optimal electric condition (125 V/cm, 4 pulses x 2 times, 50 ms, 1 Hz). Exact salt concentrations of DNA vehicle were measured by the inductively coupled plasma-atomic emission spectrometer (ICP-AES) and the conductivity change in the tissue induced by the salt in the medium was measured by Low-Frequency (LF) Impedance Analyzer. Luciferase expression increased as cation concentration of vehicle decreased and this result can be visualized by X-Gal staining. However, at lower salt concentration, transfection efficiency was diminished because the hypoosmotic stress and electrical injury by low conductivity induced myofiber damage. At optimal salt concentration (71 mM), we observed a 3-fold average increase in luciferase expression in comparison with the normal saline condition (p < 0.01). These results provide a valuable experimental parameter for in vivo gene therapy mediated by electroporation.
authors.affiliation: School of Chemistry and Molecular Engineering, Seoul National University, Seoul, Korea.
authors.forename: Min-Jae
authors.initials: MJ
authors.lastname: Lee
authors.forename: Soon-Shin
authors.initials: SS
authors.lastname: Cho
authors.forename: Hyung-Suk
authors.initials: HS
authors.lastname: Jang
authors.forename: Young Shin
authors.initials: YS
authors.lastname: Lim
authors.forename: Ji-Ran
authors.initials: JR
authors.lastname: You
authors.forename: Jangwon
authors.initials: J
authors.lastname: Park
authors.forename: Hearan
authors.initials: H
authors.lastname: Suh
authors.forename: Jeong-a
authors.initials: JA
authors.lastname: Kim
authors.forename: Jong-Sang
authors.initials: JS
authors.lastname: Park
authors.forename: Duk-Kyung
authors.initials: DK
authors.lastname: Kim
mesh_terms: D000818:Animals; D004247:DNA / Q000008:administration & dosage* / Q000378:metabolism; D016503:Drug Delivery Systems; D004553:Electric Conductivity; D018274:Electroporation / Q000379:methods; D004926:Escherichia coli / Q000235:genetics; D005260:Female; D018014:Gene Transfer Techniques; D017930:Genes, Reporter; D015316:Genetic Therapy / Q000379:methods*; D007273:Injections, Intramuscular; D008156:Luciferases / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D009994:Osmolar Concentration; D014677:Pharmaceutical Vehicles / Q000008:administration & dosage*; D010957:Plasmids / Q000235:genetics / Q000378:metabolism*; D012965:Sodium Chloride / Q000494:pharmacology*; D014162:Transfection; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D014677:Pharmaceutical Vehicles; D012965:Sodium Chloride; D004247:DNA; D008156:Luciferases; D001616:beta-Galactosidase