Book of abstract 2008

Increased permeability of cell membrane by sonoporation
Alenka Maček Lebar1, Karel Flisar1, Mitja Lenarčič1, Rudi Čop2, Damijan Miklavčič1
1University of Ljubljana, Faculty of electrical engineering, Tržaška 25, 1000 Ljubljana, Slovenia;
2University of Ljubljana, The Faculty of Maritime Studies and Transport, Pot pomorščakov 4, 6320
Portorož, Slovenia
A cell membrane separates the interior of the cell from its exterior. The function of the cell
membrane is to maintain stable cell’s interior by regulating amounts and types of molecules
that enter or leave the cell. Sometimes however we need to deliver molecules into the
cell, which otherwise can not pass the membrane. Electroporation (application of high
voltage electric pulses) is one of the most widely used techniques that allow access to the
cell interior. Electroporation uses high voltage electrical pulses to make the cell membrane
transiently permeable. In the past years, it has been demonstrated that ultrasound could
cause similar effects. This ultrasound-mediated increase in cell membrane permeability
has been termed sonoporation. Sonoporation was initially demonstrated using 20 kHz
sonication.
The main purpose of this study was to evaluate if the application of megahertz frequency
ultrasound leads to enhanced membrane permeabilization and molecular uptake. We used
a 1-cm diameter planar 1 MHz ultrasound transducer which was leant against the chamber
containing cell suspension. The transducer was driven by a function generator with the
center frequency 1 MHz and power output of 10 W, 15 W and 20 W. Cell samples were
exposed to continuous ultrasound for 5, 10, 15 or 20 s. The cells were suspended at a
concentration of 1x106 cells/ml in a medium containing a fluorescent marker (Propidium
Iodide).
Cell membrane permeability was increased with increased time of cell exposure to
ultrasound.
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