Safety and effectiveness of nano-pulse stimulation™ technology to treat acne vulgaris of the back.

BACKGROUND AND OBJECTIVES: This feasibility study describes the effects of Nano-pulse stimulation™ (NPS™) technology using the CellFX™ System on acne vulgaris of the back with the objectives of demonstrating safety and effectiveness. The CellFX System applies nanosecond pulses of electrical energy to induce highly localized regulated cell death (RCD) in the cellular structures of the targeted zone with no thermal effect on the tissue and negligible effects on surrounding non-cellular components. STUDY DESIGN/MATERIALS AND METHODS: Seventeen subjects were enrolled at two sites with thirteen subjects completing treatment. Three 7 X 7 cm regions containing at least five bacne lesions each were identified, one region treated with the CellFX across three treatment sessions, the second region treated as a sham using microneedle tip placement without delivering energy, and the third as an untreated control. RESULTS: CellFX-treated areas showed an average reduction of acne lesions of 82% by 90 days post-last procedure. Acne improvement was observed in 100% of CellFX-treated regions compared to 39% improvement in Sham regions and 31% improvement in the control regions. The most common skin effects were erythema and hyperpigmentation observed in 23% and 92% of the subjects, respectively, at the last timepoint. No serious adverse events were reported. CONCLUSIONS: CellFX is a safe and effective procedure for clearing back acne.

Multicenter, prospective feasibility study of Nano-Pulse Stimulation™ technology for the treatment of both nodular and superficial low-risk basal cell carcinoma.

Background: Nano-Pulse Stimulation™ (NPS™) therapy is a new, non-thermal bioelectric modality that applies ultrashort pulses of electric energy to trigger regulated cell death (RCD) in treated tissues. Instead of initiating necrosis by heating or freezing, NPS therapy permeabilizes intracellular organelles to activate the cell's own self-destruct pathway of programmed or regulated cell death. Unlike cryotherapeutic procedures that can both damage structural tissues and diffuse into the periphery beyond the margins of the lesion, NPS therapy only affects cells within the treated zone leaving surrounding tissue and acellular components unaffected. Methods: In this study we treated 37 basal cell carcinoma lesions on 30 subjects (NCT04918381). The treated lesions were photographed on 3-, 7-, 14-, 30- and 60-days after treatment. All subjects then underwent surgical excision for histological examination of the treated tissue. Results: 92% of the BCC lesions (34 of 37) showed complete histological clearance of BCC. Histologic analysis of the 3 cases where residual BCC was noted indicated that full energy coverage was not achieved, which could be remedied with an improved treatment guide to standardize and optimize the CellFX® procedure based on NPS technology. Conclusion: The CellFX procedure was shown to be safe and effective for the treatment of low-risk nodular and superficial BCC lesions.

Nano-pulse stimulation™ therapy (NPS™) is superior to cryoablation in clearing murine melanoma tumors.

Background: Nano-Pulse Stimulation™ Therapy (NPS™) is a new, bioelectric modality that applies ultrashort pulses of electric energy to trigger regulated cell death in treated tissues. Instead of initiating necrosis by heating or freezing, NPS therapy permeabilizes intracellular organelles to activate the cell's own self-destruct pathway of programmed or regulated cell death. Unlike cryotherapies that can both damage structural tissues and diffuse into the periphery beyond the margins of the lesion, NPS only affects cells within the treated zone leaving surrounding tissue and acellular components unaffected. Methods: We generated melanoma tumors in mice by injecting B16-F10 cells intradermally and compared the efficacy and resulting skin damage from Nano-Pulse Stimulation Therapy with that of cryoablation in clearing these tumors. Results: The results of the study demonstrate that NPS is superior at clearing B16-F10 melanoma lesions. NPS permanently eliminated up to 91% of all tumor lesions with a single treatment compared to cryoablation that only eliminated up to 66%. Importantly, NPS permanently eliminated these lesions with no recurrence and with minimal dermal fibrosis, underlying muscle atrophy, permanent hair follicle loss or other markers of permanent skin damage. Conclusions: These findings suggest that NPS is a promising new modality for the clearance of melanoma tumors and is a more efficacious, less damaging approach than cryoablative methods for the treatment of aggressive malignant tumors.

Airborne particulate concentration during non-thermal nano-pulse stimulation wart clearance is negligible compared to thermal modalities.

OBJECTIVES: As clinicians continue to implement safety protocols amid the global pandemic, considerations to mitigate potential viral transmission of airborne particulates (plume) generated from certain dermatologic procedures are of growing interest. This study intended to measure the change in airborne particulate matter using a non-thermal energy modality called nano-pulse stimulation (NPS) and compare levels of concentration to common thermal modalities (CO2 laser and electrocautery). NPS is a new non-thermal modality that applies nanosecond pulses of electrical energy to induce regulated cell death in cellular structures while sparing the surrounding acellular structure of the dermis. MATERIALS AND METHODS: The study used a Condensation Particle Counter during four types of dermatologic procedures: (1) using non-thermal NPS for the clearance of cutaneous, nongenital warts; (2) an electrocautery treatment of warts; (3) a CO2 laser for facial resurfacing; and (4) an electrocautery procedure for a facelift. Four subjects and a total of 11 warts were treated with NPS while a particle counter was used to detect the average particles per cubic centimeter once per second. The same particle counter was used, for comparison, during a wart removal procedure using electrocautery for comparison, and for control, during a skin resurfacing procedure with a CO2 laser and a facelift in which electrocautery was used. RESULTS: Only one of the 11 NPS wart procedures generated any detectable change in the particulate concentration and that change was negligible in comparison to the increase in particulate concentration measured during the CO2 laser resurfacing and the electrocautery use during a facelift procedure. CONCLUSIONS: Procedures using non-thermal NPS technology do not generate significant plume when applied to eliminate warts, suggesting it is unlikely that this new energy modality would release viral DNA into the air.

Safety and Efficacy of Nano-Pulse Stimulation Treatment of Non-Genital, Cutaneous Warts (Verrucae).

BACKGROUND AND OBJECTIVES: This study describes the effects of nano-pulse stimulation (NPS) technology on the common verruca with the objectives of demonstrating efficacy and safety. NPS technology applies nanosecond pulses of non-thermal electrical energy to induce highly localized regulated cell death in the cellular structures of the targeted zone with negligible effects on surrounding non-cellular structures. Previous clinical studies applying NPS to common, benign skin lesions have demonstrated safety and efficacy in clearing seborrheic keratoses and sebaceous hyperplasia. STUDY DESIGN/MATERIALS AND METHODS: Sixty-two subjects were enrolled at a total of five sites. One hundred and ninety-five study verrucae up to 10 mm wide were treated with NPS delivered by a console-based handheld applicator (CellFX® System; Pulse Biosciences) and follow-ups occurred every 30 days with the option to retreat at 30, 60, and 90 days. There were 62 untreated controls and 46% of the treated verrucae were recalcitrant. RESULTS: Overall, 75.3% (70/93) of the common verrucae, 72.7% (8/11) of the flat verrucae, and 43.8% (14/32) of the plantar verrucae treated with NPS were completely clear by 60 days following the last treatment and did not recur within the 120-day observation period. The majority (54%) of verrucae cleared with a single NPS procedure. The most common treatment site reactions were erythema (50.5%) and eschar formation (23.4%) on Day 30 and on Day 120 mild erythema was present in 14% of the cases and hyperpigmentation in 18.5%. No serious adverse events were reported. A particle counter was used during 11 NPS procedures on verrucae and no significant plume generation was detected during these procedures. CONCLUSIONS: NPS is a safe and effective procedure for removing non-genital, cutaneous verrucae. Lasers Surg. Med. © 2021 The Authors. Lasers in Surgery and Medicine published by Wiley Periodicals LLC.

A dose-response study of nanosecond electric energy pulses on facial skin.

Nanosecond pulsed electric fields, also known as Nano-Pulse Stimulation or NPS, can trigger regulated cell death to clear skin lesions that are cellular in nature. Before treating facial lesions, it is important to demonstrate the effects of these pulses on normal facial skin. Here we have applied a range of NPS energies to the epidermis and dermis of normal facial skin scheduled for excision to establish a safe dose range of energies prior to use in clinical applications. This was an open-label, non-randomized study under the direction of a single Principal Investigator. The time course of the treated tissue changes was determined by histological analysis. All energy settings generated a delayed epidermal loss followed by re-epithelialization by day 7 and a normal course of healing. One day after NPS treatment, the cellular membranes of the treated epidermis were intact, but their nuclei no longer stained with H&E, resulting in a hollow appearance that has been referred to as "ghost cells." Cellular structures in the dermis, such as sebaceous glands and melanocytes, exhibited regulated cell death observed by 1 day post treatment. Melanocytes recovered to their normal density within 7 days. The 60-day samples indicated that epidermis, hair follicles, and eccrine glands appeared normal. The selective effect of NPS treatment on cellular structures in the epidermal and dermal layers suggests that this non-thermal modality of energy delivery is ideal for treating cellular targets including benign and malignant skin lesions. NPS skin treatments provide a promising method for clearing skin lesions with a cellular basis.

Nano-Pulse Stimulation Induces Changes in the Intracellular Organelles in Rat Liver Tumors Treated In Situ.

BACKGROUND AND OBJECTIVES: Nano-pulse stimulation (NPS) therapy is the application of ultrafast pulses of high amplitude electrical energy to tissues to influence cell function. Unique characteristics of these pulses enable electric field penetration into the interior of cells and organelles to generate transient nanopores in both organelle and plasma membranes. The purpose of this study is to document the temporal and physical changes in intracellular organelles following NPS therapy using electron microscopy. STUDY DESIGN/MATERIALS AND METHODS: Liver tumors were induced in five buffalo rats by implanting syngeneic McA-RH7777 hepatocellular carcinoma cells into the surgically exposed livers. Tumors were allowed to grow for 1 week and then the surgically exposed livers were treated in situ with NPS energy delivered at a sufficient level to trigger regulated cell death in the tumor. Samples of NPS-treated and control tissue were removed and fixed for electron microscopy at 1 minute, 5 minutes, 30 minutes, 2 hours and 4 hours after exposure. RESULTS: Measurements of cellular organelles indicate strong swelling following NPS therapy exposure compared with untreated controls. The mean diameter of the mitochondria increased by 55% within 1 minute and then by 2.5-fold by 2 hours post-NPS therapy. The rough endoplasmic reticulum (RER) cisternae swelled immediately after NPS therapy with reduced swelling by 30 minutes and loss of structural integrity by 2 hours. The Golgi apparatus appears swollen in images collected 1 and 5 minutes after NPS therapy and was no longer detected at 30 minutes and 2 hours post-NPS therapy. By 4 hours after NPS therapy, a nascent Golgi apparatus was detected in many of the images. The plasma membrane lost its well-defined morphology and became less linear, exhibiting discontinuities as early as 1 minute post-NPS energy exposure and the nuclear envelope became subjectively less distinct over time. CONCLUSIONS: NPS therapy at sufficient energy levels causes the rapid swelling of organelles, disintegration of the RER, breaks in the plasma membrane and blurs the borders of the nuclear envelope. These changes in the mitochondria and RER are indicative of a regulated cell death process. These immediate physical changes to vital cell organelles are likely to trigger subsequent regulated cell death mechanisms observed in other studies of NPS therapy. Lasers Surg. Med. © 2020 The Authors. Lasers in Surgery and Medicine published by Wiley Periodicals, Inc.

A dose-response study of a novel method of selective tissue modification of cellular structures in the skin with nanosecond pulsed electric fields.

BACKGROUND AND OBJECTIVES: This study describes the effects of nanosecond pulsed electric fields (nsPEF) on the epidermis and dermis of normal skin scheduled for excision in a subsequent abdominoplasty. NsPEF therapy applies nanosecond pulses of electrical energy to induce regulated cell death (RCD) in cellular structures, with negligible thermal effects. Prior pre-clinical studies using nsPEF technology have demonstrated the ability to stimulate a lasting immune response in animal tumor models, including melanoma. This first-in-human-use of nsPEF treatment in a controlled study to evaluate the dose-response effects on normal skin and subcutaneous structures is intended to establish a safe dose range of energies prior to use in clinical applications using nsPEF for non-thermal tissue modification. STUDY DESIGN/MATERIALS AND METHODS: Seven subjects with healthy tissue planned for abdominoplasty excision were enrolled. Five subjects were evaluated in a longitudinal, 60-day study of effects with doses of six nsPEF energy levels. A total of 30 squares of spot sizes 25mm2 or less within the planned excision area were treated and then evaluated at 1 day, 5 days, 15 days, 30 days, and 60 days prior to surgery. Photographs were taken over time of each treated area and assessed by three independent and blinded dermatologists for erythema, flaking and crusting using a 5-point scale (0 = low, 4 = high). Punch biopsies of surgically removed tissue were processed and evaluated for tissue changes using hematoxylin and eosin, trichome, caspase-3, microphthalmia transcription factor, and elastin stains and evaluated by a dermatopathologist. The skin of two subjects received additional treatments at 2 and 4 hours post-nsPEF and was evaluated in a similar manner. RESULTS: Most energy settings exhibited delayed epidermal loss followed by re-epithelization by day 15 and a normal course of healing. Histologic analysis identified the appearance of activated caspase-3 at two and four hours after nsPEF treatment, but not at later time points. At the 1-day time point, a nucleolysis effect was observed in epidermal cells, as evidenced by the lack of nuclear staining while the epidermal plasma membranes were still intact. Cellular structures within the treatment zone such as melanocytes, sebaceous glands, and hair follicles were damaged while acellular structures such as elastic fibers and collagen were largely unaffected except for TL6 which showed signs of dermal damage. Melanocytes reappeared at levels comparable with untreated controls within 1 month of nsPEF treatment. CONCLUSIONS: The selective effect of nsPEF treatment on cellular structures in the epidermal and dermal layers suggests that this non-thermal mechanism for targeting cellular structures does not affect the integrity of dermal tissue within a range of energy levels. The specificity of effects and a favorable healing response makes nsPEF ideal for treating cellular targets in the epidermal or dermal layers of the skin, including treatment of benign and malignant lesions. NsPEF skin treatments provide a promising, non-thermal method for treating skin conditions and removing epidermal lesions. © 2019 The Authors. Lasers in Surgery and Medicine Published by Wiley Periodicals, Inc.

Safety and Efficacy of Nanosecond Pulsed Electric Field Treatment of Seborrheic Keratoses.

BACKGROUND: Nanosecond pulsed electric field technology (also known as Nano-Pulse Stimulation or NPS) is a nonthermal, drug-free, energy-based technology that has demonstrated effects on cellular structures of the dermis and epidermis in previous clinical studies. OBJECTIVE: To evaluate the safety and efficacy of a single NPS treatment for clearing seborrheic keratoses (SKs). MATERIALS AND METHODS: This study was a prospective, randomized, open-label, multisite, nonsignificant risk trial in which each subject served as their own control. Fifty-eight subjects had 3 of 4 confirmed SK lesions treated, resulting in 174 total treated lesions. Subjects returned for 5 to 6 follow-up evaluations and photographs. RESULTS: At 106 days after NPS treatment, 82% of treated seborrheic keratoses were rated clear or mostly clear by the assessing physician. Seventy-one percent of lesions were rated clear or mostly clear by the 3 independent reviewers based on the 106-day photographs. All treated subjects returned for all study visits, and 78% of the subjects were satisfied or mostly satisfied with the outcome of the treatment. No adverse events were reported. CONCLUSION: The NPS procedure was well tolerated and effective in the removal of SKs.

Safety and Efficacy of Nanosecond Pulsed Electric Field Treatment of Sebaceous Gland Hyperplasia.

BACKGROUND: Nanosecond pulsed electric field (nsPEF) technology involves delivery of ultrashort pulses of electrical energy and is a nonthermal, drug-free technology that has demonstrated favorable effects on cellular structures of the dermis and epidermis. OBJECTIVE: Determine the tolerability and effectiveness of nsPEF treatment of sebaceous gland hyperplasia (SGH). METHODS: This study was a prospective, randomized, open-label, multisite, nonsignificant risk trial in which each subject served as their own control. After injection of local anesthetic, high-intensity, ultrashort pulses of electrical energy were used to treat 72 subjects resulting in a total of 222 treated lesions. Subjects returned for 3 to 4 follow-up evaluations with photographs. RESULTS: At the final study visit, 99.6% of treated SGH lesions were rated clear or mostly clear and 79.3% of the subjects were satisfied or mostly satisfied with the outcome. At 60 days after nsPEF treatment, 55% of the lesions were judged to have no hyperpigmentation and 31% exhibited mild post-treatment hyperpigmentation. At the last observation for all lesions, 32% of the 222 lesions were noted as having slight volume loss. CONCLUSION: Nanosecond pulsed electric field procedure is well tolerated and is very effective in the removal of SGHs. TRIAL REGISTRATION: ClinicalTrials.gov NCT03612570.

Application of Pulsed Electric Fields to Cancer Therapy.

This review covers the use of pulsed electric fields in cancer therapy. It is organized into three sections based on pulse length, millisecond domain, microsecond domain, and nanosecond domain. The predominant application of pulsed electric fields is the modification of the permeability of cellular membranes, sometimes referred to as electroporation. This has been used in many different ways for cancer treatment. These include introducing genes into the tumor cells to activate an immune response, introducing poisons into the tumor cells, initiating necrosis using irreversible electroporation, and initiating immunogenic cell death with nanopulse stimulation.

Nano-Pulse Stimulation Therapy for the Treatment of Skin Lesions.

Nano-Pulse Stimulation (NPS) therapy applies nanosecond pulsed electric fields to cells and tissues. It is a nonthermal modality that uses ultrashort pulses of electrical energy in the nanosecond domain. The cellular response to this therapy can be quite varied depending on the number of pulses applied and the total energy delivered. Reviewed in this study are some clinical trial data describing the effects of NPS therapy on normal skin as well as three different skin lesions as part of the first commercial application of this technology. NPS therapy has been found to clear seborrheic keratosis lesions with an 82% efficacy and sebaceous gland hyperplasia with a 99.5% efficacy. Pilot studies on warts indicated that 60% of the NPS-treated warts were completely cleared within 60 days. NPS therapy can be used to treat cellular lesions in the epidermis and dermis without affecting noncellular components such as collagen and fibrin.

Nano-Pulse Stimulation induces immunogenic cell death in human papillomavirus-transformed tumors and initiates an adaptive immune response.

Nano-Pulse Stimulation (NPS) is a non-thermal pulsed electric field modality that has been shown to have cancer therapeutic effects. Here we applied NPS treatment to the human papillomavirus type 16 (HPV 16)-transformed C3.43 mouse tumor cell model and showed that it is effective at eliminating primary tumors through the induction of immunogenic cell death while subsequently increasing the number of tumor-infiltrating lymphocytes within the tumor microenvironment. In vitro NPS treatment of C3.43 cells resulted in a doubling of activated caspase 3/7 along with the translocation of phosphatidylserine (PS) to the outer leaflet of the plasma membrane, indicating programmed cell death activity. Tumor-bearing mice receiving standard NPS treatment showed an initial decrease in tumor volume followed by clearing of tumors in most mice, and a significant increase in overall survival. Intra-tumor analysis of mice that were unable to clear tumors showed an inverse correlation between the number of tumor infiltrating lymphocytes and the size of the tumor. Approximately half of the mice that cleared established tumors were protected against tumor re-challenge on the opposite flank. Selective depletion of CD8+ T cells eliminated this protection, suggesting that NPS treatment induces an adaptive immune response generating CD8+ T cells that recognize tumor antigen(s) associated with the C3.43 tumor model. This method may be utilized in the future to not only ablate primary tumors, but also to induce an anti-tumor response driven by effector CD8+ T cells capable of protecting individuals from disease recurrence.

Nano-Pulse Stimulation is a physical modality that can trigger immunogenic tumor cell death.

BACKGROUND: We have been developing a non-thermal, drug-free tumor therapy called Nano-Pulse Stimulation (NPS) that delivers ultrashort electric pulses to tumor cells which eliminates the tumor and inhibits secondary tumor growth. We hypothesized that the mechanism for inhibiting secondary tumor growth involves stimulating an adaptive immune response via an immunogenic form of apoptosis, commonly known as immunogenic cell death (ICD). ICD is characterized by the emission of danger-associated molecular patterns (DAMPs) that serve to recruit immune cells to the site of the tumor. Here we present evidence that NPS stimulates both caspase 3/7 activation indicative of apoptosis, as well as the emission of three critical DAMPs: ecto-calreticulin (CRT), ATP and HMGB1. METHODS: After treating three separate cancer cell lines (MCA205, McA-RH7777, Jurkat E6-1) with NPS, cells were incubated at 37 °C. Cell-culture supernatants were collected after three-hours to measure for activated caspases 3/7 and after 24 h to measure CRT, ATP and HMGB1 levels. We measured the changes in caspase-3 activation with Caspase-Glo® by Promega, ecto-CRT with anti-CRT antibody and flow cytometry, ATP by luciferase light generation and HMGB1 by ELISA. RESULTS: The initiation of apoptosis in cultured cells is greatest at 15 kV/cm and requires 50 A/cm2. Reducing this current inhibits cell death. Activated caspase-3 increases 8-fold in Jurkat E6-1 cells and 40% in rat hepatocellular carcinoma and mouse fibrosarcoma cells by 3 h post treatment. This increase is non-linear and peaks at 15-20 J/mL for all field strengths. 10 and 30 kV/cm fields exhibited the lowest response and the 12 and 15 kV/cm fields stimulated the largest amount of caspase activation. We measured the three DAMPs 24 h after treatment. The expression of cell surface CRT increased in an energy-dependent manner in the NPS treated samples. Expression levels reached or exceeded the expression levels in the majority of the anthracycline-treated samples at energies between 25 and 50 J/mL. Similar to the caspase response at 3 h, secreted ATP peaked at 15 J/mL and then rapidly declined at 25 J/mL. HMGB1 release increased as treatment energy increased and reached levels comparable to the anthracycline-treated groups between 10 and 25 J/mL. CONCLUSION: Nano-Pulse Stimulation treatment at specific energies was able to trigger the emission of three key DAMPs at levels comparable to Doxorubicin and Mitoxantrone, two known inducers of immunogenic cell death (ICD). Therefore NPS is a physical modality that can trigger immunogenic cell death in tumor cells.

Nanoelectroablation of Murine Tumors Triggers a CD8-Dependent Inhibition of Secondary Tumor Growth.

We have used both a rat orthotopic hepatocellular carcinoma model and a mouse allograft tumor model to study liver tumor ablation with nanosecond pulsed electric fields (nsPEF). We confirm that nsPEF treatment triggers apoptosis in rat liver tumor cells as indicated by the appearance of cleaved caspase 3 and 9 within two hours after treatment. Furthermore we provide evidence that nsPEF treatment leads to the translocation of calreticulin (CRT) to the cell surface which is considered a damage-associated molecular pattern indicative of immunogenic cell death. We provide direct evidence that nanoelectroablation triggers a CD8-dependent inhibition of secondary tumor growth by comparing the growth rate of secondary orthotopic liver tumors in nsPEF-treated rats with that in nsPEF-treated rats depleted of CD8+ cytotoxic T-cells. The growth of these secondary tumors was severely inhibited as compared to tumor growth in CD8-depleated rats, with their average size only 3% of the primary tumor size after the same one-week growth period. In contrast, when we depleted CD8+ T-cells the second tumor grew more robustly, reaching 54% of the size of the first tumor. In addition, we demonstrate with immunohistochemistry that CD8+ T-cells are highly enriched in the secondary tumors exhibiting slow growth. We also showed that vaccinating mice with nsPEF-treated isogenic tumor cells stimulates an immune response that inhibits the growth of secondary tumors in a CD8+-dependent manner. We conclude that nanoelectroablation triggers the production of CD8+ cytotoxic T-cells resulting in the inhibition of secondary tumor growth.

Angiogenesis is induced and wound size is reduced by electrical stimulation in an acute wound healing model in human skin.

Angiogenesis is critical for wound healing. Insufficient angiogenesis can result in impaired wound healing and chronic wound formation. Electrical stimulation (ES) has been shown to enhance angiogenesis. We previously showed that ES enhanced angiogenesis in acute wounds at one time point (day 14). The aim of this study was to further evaluate the role of ES in affecting angiogenesis during the acute phase of cutaneous wound healing over multiple time points. We compared the angiogenic response to wounding in 40 healthy volunteers (divided into two groups and randomised), treated with ES (post-ES) and compared them to secondary intention wound healing (control). Biopsy time points monitored were days 0, 3, 7, 10, 14. Objective non-invasive measures and H&E analysis were performed in addition to immunohistochemistry (IHC) and Western blotting (WB). Wound volume was significantly reduced on D7, 10 and 14 post-ES (p = 0.003, p = 0.002, p<0.001 respectively), surface area was reduced on days 10 (p = 0.001) and 14 (p<0.001) and wound diameter reduced on days 10 (p = 0.009) and 14 (p = 0.002). Blood flow increased significantly post-ES on D10 (p = 0.002) and 14 (p = 0.001). Angiogenic markers were up-regulated following ES application; protein analysis by IHC showed an increase (p<0.05) in VEGF-A expression by ES treatment on days 7, 10 and 14 (39%, 27% and 35% respectively) and PLGF expression on days 3 and 7 (40% on both days), compared to normal healing. Similarly, WB demonstrated an increase (p<0.05) in PLGF on days 7 and 14 (51% and 35% respectively). WB studies showed a significant increase of 30% (p>0.05) on day 14 in VEGF-A expression post-ES compared to controls. Furthermore, organisation of granulation tissue was improved on day 14 post-ES. This randomised controlled trial has shown that ES enhanced wound healing by reduced wound dimensions and increased VEGF-A and PLGF expression in acute cutaneous wounds, which further substantiates the role of ES in up-regulating angiogenesis as observed over multiple time points. This therapeutic approach may have potential application for clinical management of delayed and chronic wounds.

Measurement and simulation of Joule heating during treatment of B-16 melanoma tumors in mice with nanosecond pulsed electric fields.

Experimental evidence shows that nanosecond pulsed electric fields (nsPEF) trigger apoptosis in skin tumors. We have postulated that the energy delivered by nsPEF is insufficient to impart significant heating to the treated tissue. Here we use both direct measurements and theoretical modeling of the Joule heating in order to validate this assumption. For the temperature measurement, thermo-sensitive liquid crystals (TLC) were used to determine the surface temperature while a micro-thermocouple (made from 30 µm wires) was used for measuring the temperature inside the tissue. The calculation of the temperature distribution used an asymptotic approach with the repeated calculation of the electric field, Joule heating and heat transfer, and the subsequent readjustment of the electrical tissue conductivity. This yields a temperature distribution both in space and time. It can be shown that for the measured increase in temperature an unexpectedly high electrical conductivity of the tissue would be required, which was indeed found by using voltage and current monitoring during the experiment. Using impedance measurements within t(after)=50 µs after the pulse revealed a fast decline of the high conductivity state when the electric field ceases. The experimentally measured high conductance of a skin fold (mouse) between plate electrodes was about 5 times higher than those of the maximally expected conductance due to fully electroporated membrane structures (G(max)/G(electroporated))≈5. Fully electroporated membrane structure assumes that 100% of the membranes are conductive which is estimated from an impedance measurement at 10 MHz where membranes are capacitively shorted. Since the temperature rise in B-16 mouse melanoma tumors due to equally spaced (Δt=2 s) 300 ns-pulses with E=40 kV/cm usually does not exceed ΔΤ=3 K at all parts of the skin fold between the electrodes, a hyperthermic effect on the tissue can be excluded.