New research shows that paralyzed mice walk again

People paralyzed because of spinal cord injuries may glean some hope from new research carried out in mice.

Scientists in the United States say they have worked out a way for mice to regain some of their ability to walk following damage to their spinal cord and they believe this discovery may lead to a new approach to restoring function in people paralyzed by similar damage.

According to the researchers they have shown that the brain and spinal cord are able to reorganize functions after a spinal cord injury and restore communication at the cellular level needed for walking.

The scientists at the University of California, Los Angeles (UCLA) found that mice which were given partial spinal cord injuries in the laboratory were gradually, over a period of about 8 to 10 weeks, able to regain some of the ability to walk.

The researchers say following the partial spinal cord injury, the brain and spinal cord underwent a type 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.

Dr. Michael Sofroniew, a professor of neurobiology at the David Geffen School of Medicine UCLA ,who led the research, says they have identified what appears to be a previously unrecognized mechanism for recovery of function after such injuries.

Dr. Sofroniew says this process needs to be better understood in order that it can be exploited.

He suggests this could be done by the right kind of rehabilitation therapy and by working out ways to stimulate such recovery.

The spinal cord which passes through the neck and back contains nerves that transport messages between the brain and the rest of the body and a spinal cord injury can obstruct the pathways the brain uses to transit messages to the nerve cells that control walking.

A spinal cord injury can cause paralysis below the site of the injury for which there is no cure; patients usually experience greater paralysis when injury strikes higher in the spinal column.

Many experts believe the only way someone with such an injury can walk again is for the nerve highways linking the brain and base of the spinal cord to regrow and the failure to come up with a cure has frustrated many scientists.

The UCLA study has found that when spinal cord damage blocked direct signals from the brain, the messages were able to make detours around the injury and instead of 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.

In the study 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.

They then blocked the short nerve pathways in the center of the spinal cord, which caused paralysis to return and this action confirmed that the nervous system had rerouted messages from the brain to the spinal cord using these shorter pathways.

Most of the mice in the study regained the ability to control their legs within eight weeks and though they walked more slowly and less confidently than before their injury, they still recovered mobility.

The researchers are now hoping to find some way to encourage nerve cells in the spinal cord to grow and form new pathways that connect across or around an injury in order to restore the cellular communication required for movement.

The discovery say the researchers could lead to new therapies for the millions who suffer from traumatic spinal cord injuries and offer new strategies for restoring mobility.

The research is published in the journal Nature Medicine.