University of Miami researchers have discovered that cells
from the olfactory
nerve in the nose, which carries smell signals to the
brain, can help generate new
nerve growth in damaged or severed spinal cords.
Findings by UM's Miami Project to Cure Paralysis, reported
in the Journal of
Neuroscience in May, provide a new avenue for inquiry in
the worldwide efforts to
develop a method to reverse spinal cord damage.
Paralysis is irreversible because nerve cells in the brain
and spinal cord do not
regenerate naturally. Healthy nerve fibers act like
electrical circuits, carrying
messages to and from the brain. Serious spinal cord injury
interrupts the circuits,
and so far, scientists have been unable to devise a way to
stimulate the nerve fibers
to reconnect and restore the circuit.
The most promising strategies have involved transplanting
cells from other parts of
the nervous system that do regenerate, particularly
``peripheral nerves,'' which run
to the muscles of the arms and legs.
Researchers have succeeded at getting such nerve fibers to
regenerate within
implants from peripheral nerves. But proteins in the spinal
cord usually prevent the
regenerated nerve fibers from growing into the spinal cord
and connecting with
nerve cells beyond the point of injury.
In research with laboratory rats, Mary Bartlett Bunge and
Miami Project
colleagues found that olfactory nerve cells are able to
grow through the proteins
that normally block nerve growth. As the olfactory cells
progress into the spinal
cord, the nerve fibers grow with them. Nerve fibers grew
two inches into the rats'
spinal cords, researchers found.