pH changes induced by EGT and ECT pulse delivery in tissues

F MAGLIETTI; S MICHINSKI; N OLAIZ; M CASTRO; C SUAREZ; G MARSHALL

Lucca

Conferencia; Bioelectrochemistry; 2012

Gordon Research Conference

Experimental evidence of the existence of pH fronts emerging from both electrodes during tissue reversible electroporation for conditions typical to many clinical studies found in the literature, is presented. It was also observed that those fronts are immediate and substantial. pH fronts are indirectly measured through the evanescence time, that is, the time taken by the tissue buffer to neutralize them. In order to compute the evanescence time, the evolution of a pH indicator was imaged at a series of time points, and a four-cluster fuzzy-c-means method was used to segment the pixels corresponding to the pH indicator at every frame. The evanescence time was computed as the time when the number of pixels was 10% of that in the initial frame. While in reversible electroporation (ECT) evanescence is very fast due to biological buffers present in the tissue (less than 10 s, though enough to cause minor injuries), in electrogenetransfer (EGT), evanescence is much slower and enough to denaturate plasmids. Remarkably, when any of the pulse parameters in EGT is reduced by one half, the evanescence time drops significantly. This has relevant implications for EGT treatment efficiency, since much less plasmid damaging occurs.