Abstract
Cells exposed to short and intense electric pulses become permeable to a number of various ionic molecules. This phenomenon was termed electroporation or electropermeabilization and is widely used for in vitro drug delivery into cells and gene transfection. The present work is a trial to study the effect of single exponential pulsed electric field (PEF) using intensity range 0.3 to 5.7 KV /cm and 1 m sec duration on human malignant glioma cells (U251MG). Under electrical conditions maintaining cell viability, no permeabilization can be detected for macromolecules such as DNA for pulse durations shorter than 1m sec. The aim of this study was to find optimum values of field strengths: First, to maintain cell viability for gene transfection and electrochemotherapy for further investigations. The above range of field strengths was used because a strong increase in the electric field intensity may increase transport of macromolecules, but as it may induce a loss in cell viability, indicated by the morphological observations in this study; it is associated with a decrease in plasmid expression. Second, to investigate the influence of PEF on metastatic biomolecules secreted in the cultured media such as matrix metalloproteinases (MMPs). MMPs enzyme activity was reduced at electric field intensities (0.3 - 1.15 KV/cm) by a factor of (25 - 100%). It is recommended to use the field intensity 0.85 KV/cm to put the glioma cells under biochemical stress during the electroporation protocol using single exponential pulse and 1 ms duration.