To heal a wound, turn up the voltage
26 July 2006

Andy Coghlan


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."

From issue 2562 of New Scientist magazine, 26 July 2006, page 13

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