40 Thousand volts, four thousand amperes, and over one hundred million watts squeezed into a cubic centimeter. You’d think that would be enough to vaporize just about anything, and it certainly doesn’t seem like the kind of electricity you’d want to apply to your body. But if our research continues to succeed as it has, years from now we’ll be asking some cancer patients to do just that. And it might just save their lives.
The trick is to apply that gargantuan jolt for only a few billionths of a second. That’s so brief a time that the energy delivered is a mere 1.6 joules per cubic centimeter—barely enough to warm a thimbleful of water by a third of a degree Celsius. But these powerful, ultrashort voltage pulses do something nothing else can—harmlessly slip past a cell’s exterior to shock the vital structures within.
The effects of such pulses of power on living tissue are profound and varied. Malignant tumors—in mice, at least—can be completely wiped out, even by significantly lower power levels; new genes can be efficiently inserted into living cells in the hope of correcting genetic defects; and immune-system cells can be marshaled to fight off invading microbes.
A new field of research, bioelectrics, is emerging to study these effects, as well as the naturally occurring electric fields in biological systems. Bioelectrics relies on a curious pairing of disciplines that until now have had almost nothing to do with each other: high-voltage engineering and cell biology. In particular, the new field depends on advanced pulsed power technology. That’s the ability to switch on and off thousands of amperes of current and just as many volts in mere nanoseconds (the kind of parameters needed to detonate nuclear bombs, it so happens).
The use of high voltages and currents to manipulate structures inside cells is barely five years old, but it is a fast-growing international research endeavor. The largest R&D program at the moment is being supported by the U.S. Air Force Office of Scientific Research, in Arlington, Va. That program supports work at a new center established jointly by Old Dominion University and Eastern Virginia Medical School, where we authors are working, as well as at several other institutions in the United States, including the Massachusetts Institute of Technology, the University of Texas Health Science Center, the University of Wisconsin–Madison, and Washington University. Progress in this program has already sparked interest and some excellent science at academic institutions in Japan, China, and the state of California. And more institutions, notably in the UK, France, and the state of Missouri, are planning bioelectrics research.
It’s easy to see the attractions for biologists and for engineers. For biologists, it’s the potential scientific payoff: these strong but exceedingly brief electric fields act as a kind of electrical probe, letting scientists prod key structures inside cells—making the cells expel certain vital chemicals or begin the production of others—with the aim of understanding basic biological processes. For engineers, it’s the opportunity to forge an important new application of pulsed power technology, which even 10 years ago was seldom used outside the military.
The most promising and practical result so far has been our recent discovery that certain pulsed electric fields can wipe out skin tumors in mice. Melanoma, the skin cancer we’ve worked with, is an extremely aggressive disease that kills about 8000 people a year in the United States alone. A few hundred pulses totaling just 120 microseconds of treatment shrank tumors in mice by 90 percent. A second treatment, days later, destroyed the tumors completely.
Biomedical science is, of course, littered with cancer cures that work in mice but fail or are impractical in humans. And it will be many years before we know if bioelectrics will even be worth testing in humans. Nevertheless, even at this early stage, bioelectrics seems to offer a totally new therapeutic avenue—one that could lead to a therapy free of the debilitating side effects of chemotherapy drugs and the tissue damage of radiation.
Continue reading the full article here: https://spectrum.ieee.org/biomedical/devices/zap
