In vitro Study Of Pulsed Electric Field Influence On Human Brain Tumor Cells

Abstract

In vitro electroporation has been used to introduce DNA and drugs into cells. The present work is a trial to study the effect of single exponential pulsed electric field (PEF) using intensity range 0.3 kV/cm to 1.65 kV/cm and lmsec 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 I msec. 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 Joss in cell viability, which 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 angiogenic metastatic biomolecules secreted in the cultured media mainly. Vascular endothelial growth factor (VEGF) level . remained nearly constant in the conditioned media of the cells harvested at 3 days as the intensity of the electric pulse increased until it reached 1.3kV/cm. After this critical value VEGF level increased by 2.5 folds in the conditioned media. VEGF level was nearly constant in the conditioned media of the cells harvested at 6 days as the intensity of the electric pulse increased which indicated that the effect of field intensity on VEGF level was temporary. Matrix metalloproteinases (MMPs) enzyme activity was reduced at electric field intesities (0.3kV/cm-1.15kV/cm) by a factor of (25%-100%). It is recommended to use the field intensity 0.85kV/cm to put the glioma cells under biochemical stress during the electroporation protocol using single exponential pulse and lmsec duration.