X-Message-Number: 11838
Date: Thu, 27 May 1999 21:29:47 -0400
From: Jan Coetzee <>
Subject: re-growing spinal cord

Researchers Regrow Severed Spinal Cords In Rats

By Maggie Fox, Health and Science Correspondent

WASHINGTON (Reuters) - Researchers said Thursday they had coaxed the
severed spinal
cords of rats into re-growing and said it may soon be possible to do the
same in humans.

The researchers, at Massachusetts General Hospital, said they still were
not sure just how the
cells were told to start growing. But when they damaged one branch of a
nerve, it somehow
signaled another branch to re-grow.

``We have actually tricked nerve cells into growing beyond the area of a
spinal cord injury by
switching them into an actively growing state,'' Dr. Clifford Woolf, who
led the study, said in a

``While the particular approach we used cannot be applied in humans, it
points us in a promising
new direction. The question is no longer whether spinal cord
regeneration is possible but how it
will be achieved.''

Most nerve cells re-grow when cut, but those in the spinal column are
more stubborn.
Researchers do not know why -- whether it is because a scar stops them
from regenerating, or
the chemicals that signal growth just cannot get through.

Many teams of scientists have had varying success with physical bridges
that bring severed
spinal cord cells back together, or chemicals that instruct cells to
grow. Others have tried
immune cells injected into the injured area.

Woolf's team took a different tack.

Nerves, which are bundles of nerve cells, have two branches. The
peripheral branch goes out
into the body -- to the skin, the muscles, the joints and so on.

Another branch consists of bundles of axons -- the long, thin strands
that connect nerve cells --
stretching up the spinal cord and into the brain.

The peripheral branches usually heal just fine, while the central branch
often does not.

Woolf's team worked with rats to see if the peripheral branch gets some
kind of signal that the
central branch does not. ``One possibility may be that when a peripheral
neuron is damaged, it
can still switch on the growth program but the central neuron may not be
able to,'' he said in a
telephone interview.

In their rats they damaged the peripheral branch of the sciatic nerve,
which is the main sensory
nerve to the leg. At the same time they damaged the spinal cord.

Writing in the journal Neuron, they said the results were striking, with
numerous new axons
growing around the damaged area of the spinal cord.

They did not completely heal the break, however, so Woolf's team thought
perhaps ``priming''
the nerve might help. They first damaged the peripheral branch, waited a
week, and then cut the
spinal cord.

This really worked. ``It primed the cell into a growth state, so that at
the time it was injured it
was ready to grow. We got growth that spanned the injured site,'' Woolf
said. ``We have shown
that if we can switch these cells into a state where they can grow, they
will grow -- even the
central branch.''

Obviously such a thing could not be tested in humans as it would be
unethical to deliberately
injure a human's spinal cord. But if the signaling chemicals involved
could be identified, it
might be possible to use them to treat a spinal cord injury.

``Once we figure it out we should be apply to apply this to humans,''
Woolf said.

Woolf thinks there might be a window of opportunity of about a week
during which growth
could be induced. ``The trigger might be a growth factor that switches
on a whole broad range of
proteins that allow the cell to grow,'' he said.

The Spinal Cord Injury Association says between 10,000 and 12,000 people
in the United States
suffer from traumatic spinal cord injuries every year.

Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=11838