The role of pH fronts in electrotherapy and electrochemotherapy

G. MARSHALL; F. MAGLIETTI; P. TURJANSKI; N. OLAIZ; S. MICHINSKI; C. SUAREZ; F. V. MOLINA

Buenos Aires

Workshop; Electric Fields Effects in Tumors: Biophysical Foundations and Clinical Experiences; 2010

A common characteristic in reversible electroporation or electrochemotherapy(ECT), irreversible electroporation (IRE) and electrogenetherapy (EGT) isthe application of pulsed electric elds (PEF). Here we present experimentalmeasurements and theoretical predictions of ion transport during in vitro gelPEF for conditions typical to many clinical studies of ECT found in the literature.They unveil the presence of pH fronts emerging from both electrodes.Since these pH fronts might give rise to tissue necrosis or plasmid damage, bothcritical phenomena in the PEF-derived techniques mentioned, it is importantto quantify their extent and evolution. Experiments and theory seems to implythat pH fronts in PEF are immediate and substantial and suggest waysto predict and control them. A tracking technique is used to follow the spacetime evolution of pH fronts where it is found that they scale in time as t1=2,characteristic of a predominantly diusion-controlled process. It is well knownthat extreme pH fronts also arise during electrotherapy (ET, electrical treatmentwith constant electric elds) whose main goal is tumor tissue necrosis.Comparing, for the same dosage, pH spatiotemporal distribution in PEF andET, we observe that it is larger in the former, suggesting that tissue necrosiscould also be greater. These results suggest that, an adequate election of electrictreatment parameters based on this kind of mathematical models may beuseful in controlling tissue necrosis or plasmid damage associated to pH changesinduced by PEF-derived treatments.