A vaccine given after a spinal cord injury can limit the spread of damage from the point of the trauma to surrounding nerve cells and fibers, preventing the development of complete paralysis, researchers said on Friday.

The novel idea of using a vaccine to boost the body's immune response in order to contain the damage after severe spinal cord injury was developed by researchers at the Weizmann Institute of Science in Rehovot, Israel.

Writing in this week's issue of the Journal of Clinical Investigation, the researchers said laboratory rats that had suffered severe spinal cord injuries were able to walk after being given the vaccine. The researchers said the vaccine was highly effective in partial cord injuries, but would not work in cases involving a complete severing of the spinal cord.

``Basically what this vaccination does is it stops the degeneration after the injury. So whatever was not damaged is still functioning and has not degenerated,'' neurobiologist Michal Schwartz, who led the research, said in an interview.

For several days or weeks following injury to the spinal cord, a cascade of damage spreads from the injury site, killing nerve cells and fibers that survived the original injury. This secondary degeneration can be even more destructive than the initial trauma.

Because of this, an injury that initially inflicted only partial damage to the nerve tissue in the spinal cord can trigger total paralysis.

Schwartz said the researchers searched for a way to rescue nerve cells and spinal cord fibers that were not damaged in the initial trauma.

In the study, the rats were inflicted with severe partial injury to the spinal cord that normally would cause paralysis in the hind limbs and in motor activity below the diaphragm.

Some of the rats were given a vaccine with peptides, or protein fragments, derived from the central nervous system. The peptides were chosen so that they would augment the protective mechanisms of the body's immune system without also causing an autoimmune disease in which the immune system runs amok and attacks the body. The other rats were untreated.

DRAMATIC RECOVERY OF LIMB MOVEMENT

Schwartz said rats that were vaccinated displayed dramatic recovery of limb movement. Rats without the treatment were totally paralyzed. The vaccinated rats also had much more healthy spinal cord nerve fibers than the untreated rats.

``The animals that were vaccinated were walking, without coordination some of them, some of them with coordination. So there was a significant recovery of function. And it's not due to regeneration, but it's due to protection from the spread of damage,'' Schwartz said.

Schwartz said Weizmann Institute scientists hope to test the vaccine approach in human clinical trials ``within a year.''

Schwartz said doctors would have a window of opportunity of at least a week after the initial injury to use the vaccine to contain the spread of damage. She also said that a similar approach may prove effective in other disorders of the central nervous system (which includes the brain and spinal cord), such as stroke or traumatic brain injury.

W. Dalton Dietrich, scientific director of the Miami Project to Cure Paralysis, part of the University of Miami School of Medicine, called Schwartz's work ``a very exciting direction of research'' based on ``a sound rationale.''

``This treatment with peptides to induce the natural protective mechanism of the immune system may be reducing the detrimental consequences of post-traumatic inflammation,'' Dietrich, a leading expert in the field, told Reuters.

About 11,000 people suffer spinal cord injuries annually in the United States--nearly half in vehicle accidents--and spinal cord injuries cost the United States $9.7 billion per year for medical care, equipment and disability support, according to the Christopher Reeve Paralysis Foundation.

Weizmann Institute researchers previously developed another immune-based treatment aimed at providing some degree of repair for the spinal cord after a complete injury. It is now in human clinical trials.