Powerful electrical pulses might zap tumours.
16 March 2004 HELEN PEARSON
Nanopulses can make cells commit suicide. © SPL
Using very short, very powerful electric shocks, researchers are
developing a way to jolt cancer cells into committing suicide, or
healthy cells into healing wounds.
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 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
In some of the latest work, Karl Schoenbach and Stephen Beebe of
the Center for Bioelectrics in Norfolk, Virginia, have shown that
the pulses can make blood platelets clump together in the first
stages of clotting. This is something that might ultimately
accelerate wound repair.
But 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."
Biologists already treat cells with mild electric shocks in the
laboratory, a technique called electroporation. These shocks make
temporary punctures in cell membranes so that cells can be pumped
full of experimental genes or proteins.
Schoenbach and his colleagues were the first to recognise that
you could use high-power, brief shocks to manipulate cells in other
ways. Working with electrical engineers in the late 1990s, they
discovered that such pulses fry bacteria and sterilize contaminated
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. Schoenbach's team
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.
Quite how nanopulses trigger cell suicide still leaves scientists
scratching their heads. One idea is that the shock flips molecules
in the cell membrane from the inside to the outside, which tells
surrounding cells of their imminent death. "It says 'get rid of
me,'" says Thomas Vernier, who is studying the technique at the
University of Southern California, Los Angeles.
However they work, the nanopulses are prompting a flurry of ideas
for their use. They might replace liposuction as a way to demolish
unwanted flab, or blast away the fatty plaques that cause heart
disease. "It is like asking what to do with a newborn baby," says
Weaver. "Our speculations probably will not pick up the most
© Nature News Service / Macmillan Magazines Ltd 2004