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Transfection of HeLa-cells with pEGFP plasmid power-assisted by impedance electroporation

Glahder, J; Norrild, B; Persson, Mikael B and Persson, Bertil R LU (2005) In Biotechnology and Bioengineering 92(3). p.267-276
Abstract
Bioimpedance spectrometry was applied to study cell viability and pEGFP plasmid-transfection efficiency in electroporation (EP) of 20,000 HeLa cells with 0.3 mu g DNA in 90 mu l low conductivity 0.32 M sucrose medium of pH 7.5. Monopolar rectangular pulses, of field strength 75 V/mm, and pulse length 0.1 ms were applied in 1-16 repetitions with a 10-sec pause interval between pulses. Surviving cells were stained by crystal violet and counted using a confocal microscope. Transfected cells were fixed with 10% formaldehyde and counted as green spots in a fluorescence microscope. In the present investigation we used the method of bioimpedance spectrometry to analyze the effect of EP on survival and transfection ratio of cells in suspension. DC... (More)
Bioimpedance spectrometry was applied to study cell viability and pEGFP plasmid-transfection efficiency in electroporation (EP) of 20,000 HeLa cells with 0.3 mu g DNA in 90 mu l low conductivity 0.32 M sucrose medium of pH 7.5. Monopolar rectangular pulses, of field strength 75 V/mm, and pulse length 0.1 ms were applied in 1-16 repetitions with a 10-sec pause interval between pulses. Surviving cells were stained by crystal violet and counted using a confocal microscope. Transfected cells were fixed with 10% formaldehyde and counted as green spots in a fluorescence microscope. In the present investigation we used the method of bioimpedance spectrometry to analyze the effect of EP on survival and transfection ratio of cells in suspension. DC and low-frequency AC currents preferably pass through the medium due to the high impedance of the cell membrane. At frequencies above 10 kHz the impedance of the cell membrane starts to decrease and the impedance value of the cell suspension approach a lower limit value R-infinity at infinite frequency. Recording of electrical impedance spectra of cells in culture was performed over a frequency range of 10 Hz to 125 kHz, allowing separation of the contribution from extracellular space and that of the cell membranes. A parallel resistance capacitance model of the cell suspension was used to evaluate the response of applying EP pulses. The values of the collective membrane resistance R-M decay exponentially (r(2) = 0.995) with the number of applied pulses. The ratio of the extrapolated value of the intact membrane resistance before pulsing, R-M,(O), and the value R-M,R-N after each pulse makes an index of the effect of electroporation on the cells. The ratio R-M,R-N/R-M,(O) as well as the relative change of the dissipation factor, tan delta, on the "Loss Change Index" (LCI) fits well a dose-response model (r(2) = 0.98) with the number of applied pulses. The changes in the model parameters membrane resistance Delta R-M = [1- R-M,(N)/R-M,o] and loss factor [1- tan delta(O)/tan Omega(N)] correlate well with the transfection ratio and fraction of dead cells. Those parameters were used for power-assisted electroporation in monitoring, controlling, and optimizing the EP procedure. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
electro-pulsation, cell survival, bioimpedance spectrometry, cell membrane, permeabilization, MLS-pulse sequence
in
Biotechnology and Bioengineering
volume
92
issue
3
pages
267 - 276
publisher
John Wiley & Sons
external identifiers
  • wos:000232910000002
  • pmid:16161165
  • scopus:27744473896
ISSN
1097-0290
DOI
10.1002/bit.20426
language
English
LU publication?
yes
id
136fe80c-cb2e-4352-8098-6c7d6e7fa619 (old id 216705)
date added to LUP
2007-09-22 20:23:57
date last changed
2017-10-01 03:37:19
@article{136fe80c-cb2e-4352-8098-6c7d6e7fa619,
  abstract     = {Bioimpedance spectrometry was applied to study cell viability and pEGFP plasmid-transfection efficiency in electroporation (EP) of 20,000 HeLa cells with 0.3 mu g DNA in 90 mu l low conductivity 0.32 M sucrose medium of pH 7.5. Monopolar rectangular pulses, of field strength 75 V/mm, and pulse length 0.1 ms were applied in 1-16 repetitions with a 10-sec pause interval between pulses. Surviving cells were stained by crystal violet and counted using a confocal microscope. Transfected cells were fixed with 10% formaldehyde and counted as green spots in a fluorescence microscope. In the present investigation we used the method of bioimpedance spectrometry to analyze the effect of EP on survival and transfection ratio of cells in suspension. DC and low-frequency AC currents preferably pass through the medium due to the high impedance of the cell membrane. At frequencies above 10 kHz the impedance of the cell membrane starts to decrease and the impedance value of the cell suspension approach a lower limit value R-infinity at infinite frequency. Recording of electrical impedance spectra of cells in culture was performed over a frequency range of 10 Hz to 125 kHz, allowing separation of the contribution from extracellular space and that of the cell membranes. A parallel resistance capacitance model of the cell suspension was used to evaluate the response of applying EP pulses. The values of the collective membrane resistance R-M decay exponentially (r(2) = 0.995) with the number of applied pulses. The ratio of the extrapolated value of the intact membrane resistance before pulsing, R-M,(O), and the value R-M,R-N after each pulse makes an index of the effect of electroporation on the cells. The ratio R-M,R-N/R-M,(O) as well as the relative change of the dissipation factor, tan delta, on the "Loss Change Index" (LCI) fits well a dose-response model (r(2) = 0.98) with the number of applied pulses. The changes in the model parameters membrane resistance Delta R-M = [1- R-M,(N)/R-M,o] and loss factor [1- tan delta(O)/tan Omega(N)] correlate well with the transfection ratio and fraction of dead cells. Those parameters were used for power-assisted electroporation in monitoring, controlling, and optimizing the EP procedure.},
  author       = {Glahder, J and Norrild, B and Persson, Mikael B and Persson, Bertil R},
  issn         = {1097-0290},
  keyword      = {electro-pulsation,cell survival,bioimpedance spectrometry,cell membrane,permeabilization,MLS-pulse sequence},
  language     = {eng},
  number       = {3},
  pages        = {267--276},
  publisher    = {John Wiley & Sons},
  series       = {Biotechnology and Bioengineering},
  title        = {Transfection of HeLa-cells with pEGFP plasmid power-assisted by impedance electroporation},
  url          = {http://dx.doi.org/10.1002/bit.20426},
  volume       = {92},
  year         = {2005},
}