Electrochemotherapy (ECT) and irreversible electroporation (IRE) -advanced techniques for treating deep-seated tumors based on electroporation

* Correspondence: Damijan. [email protected] University of Ljubljana, Faculty of Electrical Engineering, Ljubljana, 1000, Slovenia When a cell is exposed to a sufficiently intense electric field (for a sufficient duration), local defects in the cell membrane appear and become permeable to molecules that otherwise cannot pass through it. This phenomenon is commonly known as electroporation but additional terms electropermeabilization and PEF (i.e. pulsed electric field) treatment are commonly used as well (the latter mainly in food processing area). In reversible electroporation, cell membrane permeabilization to molecules otherwise deprived of transmembrane transport mechanisms is a transient phenomenon as after some time membrane reseals and reestablishes its homeostatic semipermeable properties, allowing ions and other small molecules to passively cross. The cell can thus survive, though if the molecular transport disruptions to homeostasis is too great, the cell will die and the process is termed irreversible electroporation. During this period of increased membrane permeability, if the cell is surrounded by chemotherapeutics like bleomycin and cisplatin they are able to enter the cell and access their intracellular targets. In this way, the increased transport of chemotherapeutics due to electroporation increases the cytotoxic effects of certain drugs through potentiated mass transport permitted by the state of increased membrane permeabilization. This process is commonly referred to as electrochemotherapy and involves the combination of reversible electroporation and chemotherapy, allowing the latter to be successfully used as local tumor treatment [1]. If the number of pulses is too great, their duration too long, or the amplitude of the field to which the cell is exposed too intense, the cell dies due to irreversible electroporation presumably due to a loss of homeostasis. Irreversible electroporation was introduced as an ablation method for normal and tumor tissue and quickly gained much attention due to its non-thermal nature, enabling operators to spare critical structures of the tissue matrix, such as vessels, while successfully eradicating tumor cells. The term “non-thermal” refers to the mechanism of IRE, since cell death is due to membrane electroporation and not a temperature increase of the tissue; although Miklavcic and Davalos BioMedical Engineering OnLine 2015, 14(Suppl 3):I1 http://www.biomedical-engineering-online.com/content/14/S3/I1