| Comments |
P.4002 left column 2nd paragraph: "The measurements were as follows. [Investigators] used [their] incremental technique as above to establish the electroporation threshold and its standard deviation for a population of K562 cells. This work was performed about a year after the work described earlier. [They] used a different population of K562 cells and measured a different threshold field. [They] then carried out two types of measurements. First, [they] exposed cells to a pulse sequence, waiting 1 min between pulses, but this time, instead of incrementally increasing the voltage, all of the pulses were at the same voltage, ∼2 standard deviations (∼20% in voltage or field) below the nominal threshold. Next [they] made measurements in which [they] exposed cells to pulses ∼2 standard deviations above the nominal threshold. The results are given in Table 2, and details of the measurements are included in the Supporting Information. Summarizing, the data indicate that the measured threshold poration field of a cell does not depend strongly on a previous history of smaller pulses. Of the six cells measured for the below threshold case, one average-sized cell porated on the first pulse and the rest stayed intact until they were lost by the optical tweezers—typically eight or nine pulses. For the eight cells in the above threshold case, all cells were porated by the first pulse. [They] conclude that [their] incrementally determined threshold differs (if at all) by much less that 20% from a putative “history-free” threshold in which each cell is exposed to just a single pulse. Most importantly, in no case did [they] observe any correlation between the cell size and the electric field required for poration." k562 myelogenous leukemia cell line |