Electrical Nanopulses Might Kill Tumors

By Roland Piquepaille

Killing cells affected by cancer while leaving healthy ones alone is not a new idea (check here or there for example). But, in "Ultra-fast shocks scramble cells," Nature describes a new approach based on electrical nanopulses. These electric shocks last only a few billionths of a second while reaching during this very short amount of time power levels of terawatts. They also are very intriguing, apparently forcing cancer cells to commit suicide.

The technique involves blasting cells with nanopulses. These are high-power electrical bolts that last a few billionths of a second. They deliver millions of volts - enough power to light up a city, but each burst lasts much less than the blink of an eye.

Longer shocks blow a cell apart, but researchers have found that the fleeting nanopulses leave the cell membrane unaffected while mixing up its insides. Now they are working out how to vary the timing and intensity of the shocks to make cells behave in specific ways.

Here are two images showing how ultrashort pulses affect the intracellular structure, leaving the cell membrane intact (Credit: Center for Bioelectrics).

Is this technique ready for human deployment? Not quite yet.

There is plenty to be worked out before the human body is zapped with nanopulses. James Weaver, who studies electrical effects in cells at the Massachusetts Institute of Technology, Boston, says they are at an early stage: "There are maybe ten papers published showing that something dramatic is happening."

One puzzling aspect of this technique is the electric shocks are pushing cells to commit suicide. Scientists are not sure why.

One of the most significant discoveries was that nanopulses make mammalian cells commit suicide, rather than blowing them up. This is a relatively gentle way of killing, because scavenger cells come and swallow the debris. By contrast, long electric shocks explode cells and liberate toxic molecules that cause inflammation and pain.

For this reason, researchers hope to use nanopulses to kill cancer cells while leaving healthy tissue intact. Karl Schoenbach's team at the Center for Bioelectrics in Norfolk, Virginia, has already shown that the pulses can shrink mouse tumours by over 50%, and is working on catheters or non-invasive ways to deliver the shocks to the body.

For more information about their research projects, you can look at this page or check this presentation (PDF format, 19 pages, 1.31 MB).

Source: Helen Pearson, Nature, March 16, 2004