| Ultrawideband electric field pulses have been shown to be effective for electroporation of mammalian cells at electric field strengths accessible to current pulsed-power technology. Dramatic cell killing (up to a factor of 103) was achieved by loading Jurkat cells with bleomycin via UWB electroporation. UWB pulses were as effective as conventional electroporation pulse treatments for enhancement of bleomycin effectiveness. Such treatments permitted increased killing of cells at reduced concentrations of antibiotic agent. The clinical implications of this advance include faster tumor growth reduction with reduced drug side effects to the patient.; Cells were exposed to UWB pulses with ∼100 kV/cm peak electric field and ∼100 ns pulse width. These pulses were of interest because, unlike conventional electroporation waveforms, they contained a large high-frequency energy content that could be coupled to tissue by methods not involving direct contact electrodes.; Electroporation by UWB pulses was shown to be consistent with classical theoretical models and conventional electroporation with long pulses and lower electric field strengths. At the shortest pulse lengths and highest applied electric field strengths, UWB pulses were effective in permeabilizing mammalian cell membranes to small molecular species (and, by default, ions) by the creation of small pores, despite the inability of such pulses to create sufficiently large pores for transmembrane transport of genes and proteins.; The exact mechanism of cell death was not determined. However, all cell observations were consistent with a high intracellular concentration of bleomycin following application of UWB pulses, leading to massive DNA damage and cell death. This result was achieved using a very low extracellular concentration of bleomycin. Measurements of caspase activation and externalization of membrane phosphatidylserine in treated cells demonstrated that caspase-mediated apoptosis was not the dominant mechanism of cell death. |
PDF Full Text Request