THE IMPORTANCE OF ELECTRIC-FIELD DISTRIBUTION FOR EFFECTIVE IN-VIVO ELECTROPORATION OF TISSUES

Cells exposed to short and intense electric pulses become permeable to a number of various ionic molecules. This phenomenon was termed elect roporation or electropermeabilization and is widely used for in vitro drug delivery into the cells and gene transfection. Tissues can also b e permeabilized. These new approaches based on electroporation are use d for cancer treatment, i.e., electrochemotherapy, and in vivo gene tr ansfection. In vivo electroporation is thus gaining even wider interes t. However, electrode geometry and distribution were not yet adequatel y addressed. Most of the electrodes used so far were determined empiri cally. In our study we 1) designed two electrode sets that produce not ably different distribution of electric field in tumor, 2) qualitative ly evaluated current density distribution for both electrode sets by m eans of magnetic resonance current density imaging, 3) used three-dime nsional finite element model to calculate values of electric field for both electrode sets, and 4) demonstrated the difference in electroche motherapy effectiveness in mouse tumor model between the two electrode sets. The results of our study clearly demonstrate that numerical mod el is reliable and can be very useful in the additional search for ele ctrodes that would make electrochemotherapy and in vivo electroporatio n in general more efficient. Our study also shows that better coverage of tumors with sufficiently high electric field is necessary for impr oved effectiveness of electrochemotherapy.