Injured Spinal Cord: Rewire Nerves?
Study With Mice Shows Walking May Be Possible After Rewiring of Nerves
Jan. 7, 2008 -- Rewiring healthy nerves may offer a new way to increase the
odds of walking again after spinal cord injuries.
A new study shows rewiring nerve fibers near the injury site allowed mice to
walk again after a spinal cord injury.
Although these results are only preliminary, researchers say the findings
suggest that rewiring may be an easier way to restore walking after a spinal
cord injury. People with spinal cord injuries lose the ability to walk because
nerves in the spinal cord that send and receive signals to and from motor
neurons in the brain are severed and crushed.
Until now, efforts to restore movement have mainly focused on the difficult
task of finding ways to regrow these damaged nerve fibers.
But researchers say neurons within healthy portions of the spinal cord near
the injured portion rewire themselves after injury; harnessing this natural
healing power may provide a simpler and better way to regain walking after
spinal cord injury.
"Imagine the long nerve fibers that run between the cells in the brain
and lower spinal cord as major freeways," says researcher Michael
Sofroniew, MD, PhD, professor of neurobiology at the David Geffen School of
Medicine at UCLA, in a news release. "When there's a traffic accident on
the freeway, what do drivers do? They take shorter surface streets. These
detours aren't as fast or direct, but still allow drivers to reach their
"We saw something similar in our research," says Sofroniew.
"When spinal cord damage blocked direct signals from the brain, under
certain conditions the messages were able to make detours around the injury.
The message would follow a series of shorter connections to deliver the brain's
command to move the legs."
Rewiring After Spinal Cord Injury
In the study, researchers blocked half of the long nerve fibers in the
spinal cords of laboratory mice at different places along each side of the
spinal cord, leaving the center untouched. The center contains a series of
shorter nerve pathways, which send information over short distances up and down
the spinal cord.
"We were excited to see that most of the mice regained the ability to
control their legs within eight weeks," says Sofroniew. "They walked
more slowly and less confidently than before their injury, but still recovered
When they blocked the short nerve pathways in the center of the spinal cord,
this regained movement was lost, which confirmed that the nervous system had
rerouted the messages from the brain to the spinal cord.
Researchers say the results demonstrate that the spinal cord has the ability
to reorganize and rewire itself after injury.
"Our study has identified cells that we can target to try to restore
communication between the brain and spinal cord," says Sofroniew. "If
we can use existing nerve connections instead of attempting to rebuild the
nervous system the way it existed before injury, our job of repairing spinal
cord damage will become much easier."
The researchers say the next step is to learn how to entice nerve cells in
the spinal cord to grow and form new pathways that connect across or around the