Nanosecond pulsed electric fields as a novel drug free therapy for breast cancer: An in vivo study

Nanosecond pulsed electric fields (nsPEFs) is a novel non-thermal approach to induce cell apoptosis. NsPEFs has been proven effective in treating several murine tumors, but few studies focus on its efficacy in treating human tumors. To determine if nsPEFs is equally effective in treatment of human breast cancer, 30 human breast cancer tumors across 30 Balb/c (nu/nu) mice were exposed to 720 pulses of 100 ns duration, at 4 pulses per second and 30 kV/cm. Two weeks after treatment, the growth of treated tumors was inhibited by 79%. Morphological changes of tumors were observed via a 3.0T clinical magnetic resonance imaging (MRI) system with a self-made surface coil. Pulsed tumors exhibited apoptosis evaluated by TUNEL staining, inhibition in Bcl-2 expression and decreased blood vessel density. Notably, CD34, vascular endothelial growth factor (VEGF) and VEGF receptor (VEGFR) expression in treated tumors were strongly suppressed. To evaluate the might-be adverse effects of nsPEFs in healthy tissues, normal skin was treated exactly the same way as tumors, and pulsed skin showed no permanent damages. The results suggest nsPEFs is able to inhibit human breast cancer development and suppress tumor blood vessel growth, indicating nsPEFs may serve as a novel therapy for breast cancer in the future.