X-Message-Number: 13451
Date: Sat, 01 Apr 2000 18:25:00 -0500
From: Jan Coetzee <>
Subject: Metal-like plastic stimulates nerve regrowth

Metal-like plastic stimulates nerve regrowth

SAN FRANCISCO, Mar 31 (Reuters Health) -- In laboratory experiments, a
plastic that conducts
electricity much like a metal has been shown to stimulate nerve regrowth
when it is wrapped
around severed nerves.

Dr. Christine Elizabeth Schmidt, a chemical engineer at the University
of Texas at Austin, said
that the special plastic also doubles the rate of new blood vessel
growth. This is a crucial step to
both nerve regeneration and wound healing.

Electrical fields and conductivity have long been known to enhance the
healing of bone, nerve
and other tissues, Schmidt said here at the national meeting of the
American Chemical Society.
The reasons are not fully understood, but probably involve changes in
how proteins are
absorbed, or how calcium moves around in the cell in the presence of
electrical fields.

Currently, in cases of severe nerve damage in the arms or legs, where a
large section of nerve is
lost -- as from an auto accident -- surgeons must harvest a nerve from a
less vital part of the body
and suture it to the injured nerve. But this requires two surgeries, and
causes injury to the area of
the body where the donor nerve was harvested.

In the current experiment, no outside electrical current was sent to the
plastic around the severed
nerves of rodents. Schmidt has just begun to study whether sending a
mild electrical charge
through wires to the plastic will further speed regrowth.

The special plastic, called polypyrrole, is an electroactive polymer.
Schmidt has found the
plastic to be safe when used surgically. She is also developing a form
that will dissolve naturally
in the body after the nerve regenerates.

The next step is to experiment with polypyrrole in larger mammals. If
the plastic eventually
proves successful for regenerating nerves in human limbs, it might
someday be used for nerves in
the spinal cord -- a much more difficult problem, Schmidt said. ``We're
working with some
surgeons who are very interested in this,'' she added.

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