title: Electroporator with automatic change of electric field direction improves gene electrotransfer in-vitro.
abstract: BACKGROUND
  Gene electrotransfer is a non-viral method used to transfer genes into living cells by means of high-voltage electric pulses. An exposure of a cell to an adequate amplitude and duration of electric pulses leads to a temporary increase of cell membrane permeability. This phenomenon, termed electroporation or electropermeabilization, allows various otherwise non-permeant molecules, including DNA, to cross the membrane and enter the cell. The aim of our research was to develop and test a new system and protocol that would improve gene electrotransfer by automatic change of electric field direction between electrical pulses.
  
  
  METHODS
  For this aim we used electroporator (EP-GMS 7.1) and developed new electrodes. We used finite-elements method to calculate and evaluate the electric field homogeneity between these new electrodes. Quick practical test was performed on confluent cell culture, to confirm and demonstrate electric field distribution. Then we experimentally evaluated the effectiveness of the new system and protocols on CHO cells. Gene transfection and cell survival were evaluated for different electric field protocols.
  
  
  RESULTS
  The results of in-vitro gene electrotransfer experiments show that the fraction of transfected cells increases by changing the electric field direction between electrical pulses. The fluorescence intensity of transfected cells and cell survival does not depend on electric field protocol. Moreover, a new effect a shading effect was observed during our research. Namely, shading effect is observed during gene electrotransfer when cells are in clusters, where only cells facing negative electro-potential in clusters become transfected and other ones which are hidden behind these cells do not become transfected.
  
  
  CONCLUSIONS
  On the basis of our results we can conclude that the new system can be used in in-vitro gene electrotransfer to improve cell transfection by changing electric field direction between electrical pulses, without affecting cell survival.
authors.affiliation: University of Ljubljana, Faculty of Electrical Engineering, TrZaska 25, Ljubljana, Slovenia. matej.rebersek@fe.uni-lj.si
authors.forename: Matej
authors.initials: M
authors.lastname: Rebersek
authors.forename: Cécile
authors.initials: C
authors.lastname: Faurie
authors.forename: Masa
authors.initials: M
authors.lastname: Kanduser
authors.forename: Selma
authors.initials: S
authors.lastname: Corović
authors.forename: Justin
authors.initials: J
authors.lastname: Teissié
authors.forename: Marie-Pierre
authors.initials: MP
authors.lastname: Rols
authors.forename: Damijan
authors.initials: D
authors.lastname: Miklavcic
mesh_terms: D004247:DNA / Q000008:administration & dosage* / Q000493:pharmacokinetics*; D004574:Electromagnetic Fields; D018274:Electroporation / Q000295:instrumentation* / Q000379:methods*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*; D014162:Transfection / Q000295:instrumentation* / Q000379:methods*
chemical_list: D004247:DNA