Scientists move toward helping paralysis patients
Sun Jan 6, 2008 1:13pm EST
WASHINGTON (Reuters) - Scientists have figured out how mice can
regain some ability to walk after spinal cord injuries, and hope this
insight can lead to a new approach to restoring function in people
paralyzed by similar damage.
The research, published on Sunday in the journal Nature Medicine,
showed that the brain and spinal cord are able to reorganize
functions after a spinal cord injury to restore communication at the
cellular level needed for walking.
Mice given partial spinal cord injuries in the laboratory gradually
were able over a period of about eight to 10 weeks to regain the
ability to walk, although not as well as before the injury, according
to the scientists.
After this partial spinal cord injury, the brain and spinal cord
underwent a sort of spontaneous rewiring to control walking even in
the absence of the long, direct nerve highways that normally connect
the brain to the walking center in the lower spinal cord, the
researchers said.
"This is not the end of a story. This is the beginning of a story,"
said Dr. Michael Sofroniew, a professor of neurobiology at the David
Geffen School of Medicine at the University of California at Los
Angeles who led the research.
"We have identified what appears to be a previously unrecognized
mechanism for recovery of function after these kinds of injuries. And
we need to understand it better and learn how to exploit it better,
through doing the right kind of rehab training and through figuring
out ways to stimulate this kind of recovery," Sofroniew added in a
telephone interview.
The spinal cord passes through the neck and back and contains nerves
that transport messages between the brain and the rest of the body. A
spinal cord injury -- from a car accident, for example -- can cause
paralysis below the site of the injury. There is no cure for such
paralysis, and many scientists have been frustrated by their failure
to find one.
SPINAL CORD DAMAGE
Spinal cord damage obstructs the pathways the brain uses to transit
messages to the nerve cells that control walking. Experts had thought
the only way someone with such an injury could walk again was to
somehow regrow the long nerve highways linking the brain and base of
the spinal cord.
But what they found in this study was that when spinal cord damage
blocked direct signals from the brain, the messages were able to make
detours around the injury. Rather than using the long nerve highways,
the message would be transmitted over a series of shorter connections
to deliver the brain's command to move the legs, the researchers said.
Sofroniew used a traffic analogy. "If you have a big freeway going
somewhere, then that's the fastest route to take. If that gets
blocked and you can't get through, an alternative way might be simply
to get off the freeway and use shorter interconnected side streets to
get around," Sofroniew said.
The researchers blocked half the long nerve fibers on each side of
the spinal cord but did not disturb its center, which has a connected
series of shorter nerve pathways that convey information over short
distances up and down the spinal cord.
The researchers then blocked the short nerve pathways in the center
of the spinal cord, which caused paralysis to return. This confirmed
the nervous system had rerouted messages from the brain to spinal
cord using these shorter pathways.
The researchers said they now hope to figure out how to encourage
nerve cells in the spinal cord to grow and form new pathways that
connect across or around an injury, permitting the brain to direct
these cells and avert paralysis.
http://www.reuters.
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StemCells subscribers may also be interested in these sites:
Children's Neurobiological Solutions
http://www.CNSfoundation.org/
Cord Blood Registry
http://www.CordBlood.com/at.cgi?a=150123
The CNS Healing Group
http://groups.yahoo.com/group/CNS_Healing
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