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TO HEAL A WOUND, TURN UP THE VOLTAGE
By Andy Coghlan
New Scientist
July 26, 2006
http://www.newscientist.com/article.ns?id=mg19125624.400
It may sound like something out of Frankenstein, but electric
currents
applied to the skin could potentially speed up wound healing.
Ironically,
though the phenomenon was reported 150 years ago by the German
physiologist
Emil Du Bois-Reymond, it has been ignored ever since.
Now Josef Penninger of the Austrian Institute of Molecular
Biotechnology in
Vienna and Min Zhao of the University of Aberdeen, UK, have
demonstrated
that natural electric fields and currents in tissue play a vital
role in
orchestrating the wound-healing process by attracting repair
cells to
damaged areas.
The researchers have also identified the genes that control the
process. "We
were originally sceptical, but then we realised it was a real
effect and
looked for the genes responsible," Penninger says. "It's not
homeopathy,
it's biophysics."
Cells and tissues essentially function as chemical batteries,
with
positively charged potassium ions and negatively charged
chloride ions
flowing across membranes. This creates electric field patterns
all over the
body. When tissue is wounded this disrupts the battery,
effectively
short-circuiting it. Penninger and his colleagues realised that
it is the
resulting altered fields that attract and guide repair cells to
the damaged
area.
The researchers grew layers of mouse cells and larger tissues,
such as
corneas, in the lab. After "wounding" these tissues, they
applied varying
electric fields to them, and found they could accelerate or
completely halt
the healing process depending on the orientation and strength of
the field
(Nature, vol 442, p 457).
Next, they set about finding which genes were involved. They
looked at those
already known to make repair cells migrate under the influence
of chemical
growth factors and attractants, and found that their level of
expression
could be influenced by electric fields. "We have not reinvented
the cells'
genetic migration machinery," says Penninger. "We have simply
shown that
electric fields switch them on too." The gene expression of
several types of
repair cells was affected, including neutrophils and
fibroblasts.
They then focused on one particular gene known to prepare cells
for
migration, and another that halts the process. When the team
knocked out the
migration "promoter" gene, wounds exposed to electric fields
healed more
slowly. They healed faster when the migration "blocker" was
knocked out.
The next stage is to investigate ways of manipulating the
phenomenon to
accelerate healing, says Mark Ferguson, a wound-healing
specialist at the
University of Manchester, UK. "For many years there have been
anecdotal
reports of the effects of electrical currents on wound healing,"
he says.
"This paper not only demonstrates the effects of electrical
currents on
cellular migration to wound defects, it also provides a
mechanistic
understanding of how such signals alter cell behaviour."
...........
Audio: Listen to Colin McCaig, also from the University of
Aberdeen, discuss
electricity and wound healing with New Scientist's Caroline
Williams (mp3
file):
http://media.newscientist.com/data/images/ns/av/mg191256244A1.mp3
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