We have discovered a new, drug-free therapy for treating solid skin tumors. Pulsed electric fields greater than 20 kV/cm with rise times of 30 ns and durations of 300 ns penetrate into the interior of tumor cells and cause tumor cell nuclei to rapidly shrink and tumor blood flow to stop. Melanomas shrink by 90% within two weeks following a cumulative field exposure time of 120 μs. A second treatment at this time can result in complete remission. This new technique provides a highly localized targeting of tumor cells with only minor effects on overlying skin. Each pulse deposits 0.2 J and 100 pulses increase the temperature of the treated region by only 3 °C, ten degrees lower than the minimum temperature for hyperthermia effects. KeywordsSkin cancer; Cancer therapy; Tumor; Pulsed electric fields; Pyknosis; Inhibiting angiogenesis; DNA; Nucleus Electric fields have been employed in several different types of cancer therapy. Some of these involve radiofrequency or microwave devices that heat the tumor to greater than 43 °C to kill the cells via hyperthermia [1,2]. Others use pulsed electric fields to permeabilize the tumor cells to allow the introduction of toxic drugs or DNA [3][4][5]. We have discovered that ultrashort electrical pulses can be used as a purely electrical cancer therapy that kills tumors without hyperthermia or drugs. Previous work from this laboratory found that fibrosarcoma tumors treated in vivo with ten 300 ns pulses exhibited a reduced growth rate compared to control tumors in the same animal [6]. Here, we report that when melanoma tumors are treated with four hundred of these pulses, tumors shrink by 90% within two weeks and a subsequent treatment can result in complete remission.The main characteristics of these nanosecond pulsed electric fields (nsPEF) are their low energy that leads to very little heat production and their ability to penetrate into the cell to permeabilize intracellular organelles [7,8] and release calcium [9][10][11] from the endoplasmic reticulum [11]. They provide a new approach for physically targeting intracellular organelles with many applications, including the initiation of apoptosis in cultured cells [12][13][14] and tumors [6], enhancement of gene transfection efficiency [13,14], and inhibiting tumor growth [6]. During the past year, we have treated over 300 murine melanomas in 120 mice with 40 kV/cm electric field pulses 300 ns in duration with dramatic results. Every tumor exposed to 400 such pulses exhibits rapid pyknosis and reduced blood flow and shrinks by an average of 90% within two The efficacy of this nsPEF treatment depends on two separate electric field parameters: pulse duration and amplitude. The effect of pulse duration can be understood by considering the process of membrane charging when the cell is placed in an electric field. Ions in the cell interior will respond to the electric field by moving in the field direction and charging the highly resistive membrane until they experience no further force. By definition this will only occur ...

No abstract

Fossil resources-free sustainable development can be achieved through a transition to bioeconomy, an economy based on sustainable biomass-derived food, feed, chemicals, materials, and fuels. However, the transition to bioeconomy requires development of new energy-efficient technologies and processes to manipulate biomass feed stocks and their conversion into useful products, a collective term for which is biorefinery. One of the technological platforms that will enable various pathways of biomass conversion is based on pulsed electric fields applications (PEF). Energy efficiency of PEF treatment is achieved by specific increase of cell membrane permeability, a phenomenon known as membrane electroporation. Here, we review the opportunities that PEF and electroporation provide for the development of sustainable biorefineries. We describe the use of PEF treatment in biomass engineering, drying, deconstruction, extraction of phytochemicals, improvement of fermentations, and biogas production. These applications show the potential of PEF and consequent membrane electroporation to enable the bioeconomy and sustainable development.

The stratum corneum (SC) is the main barrier to molecular and ionic transport across mammalian skin and has been extensively studied by others at low voltages (U(skin)(t) < 10 V) in order to partially characterize the skin. Here we use one or more exponential pulses (tau pulse = 1 ms) and a temperature of 25 +/- 2 degrees C and found that the low voltage passive electrical properties (impedance) change rapidly and significantly if these pulse result in U(skin),0 > 40 V. In contrast, the dynamic resistance (describing passive electrical behavior in a nonlinear range) changes dramatically by application of pulses between 40 V and 80 V and then it settles at levels between 50 omega and 100 omega. We also found that recovery of the low voltage electrical parameters after pulsing depends mainly on the voltage, and, for multiple pulse protocols, on the number of pulses. For single pulses of U(skin),0 approximately 90 V or less the electrical recovery was almost complete, returning to within 0.90 of the pre-pulse value. In contrast, larger pulses result progressively in decreased recovery. The recovery for pulses > 90 V revealed several characteristic times, suggesting the involvement of different processes. For multiple pulses with U(skin),0 > 130 V almost no recovery of the transdermal resistance, R(skin), was evident (returning to < 0.10 of pre-pulse values), i.e., essentially permanent changes in the stratum corneum occurred. This is similar to that of single bilayer membrane electroporation, for which a transition from reversible to irreversible behavior occurs as transmembrane voltage is increased. Thus, these results are consistent with the hypothesis that 'high-voltage' pulses cause electroporation within the SC, i.e., that elevated transmembrane voltage result in creation of new aqueous pathways ('pores') across SC lipid regions.