REHOVOT, Israel, (UPI) -- An experimental vaccine has proven effective in preventing total paralysis in rats with injured spinal cords, a finding researchers say suggests a similar vaccine may be used in treating such injuries in humans.

Dr. Michal Schwartz of the Weizmann Institute of Science, Rehovot, said the vaccine can "boost the body's own immune system" to prevent progressive damage from spinal cord injury. Schwartz reported her findings in Wednesday's issue of the Journal of Clinical Investigation.

Harvard researcher Dr. Howard Weiner said it is possible human trials of a spinal cord vaccine might begin in as little as two years. In the United States there are about 11,000 new spinal cord injuries each year with most occurring in men. The average age for spinal cord injury is 32.

In an interview with United Press International, Schwartz said the experimental treatment is intended for patients who have incomplete spinal cord injury, meaning the spinal cord connection to the brain is not completely severed.

Perhaps the most famous partial spinal cord injury victim is actor Christopher Reeve, whose 1995 fall from a horse broke two vertebrae in his neck and crushed his spinal cord. Although Reeve lost sensation in his arms, legs and torso, he did regain some function of the nerves immediately below the injury site.

Unlike Reeve's accident, most incomplete spinal cord injuries occur in car or motorcycle accidents. The initial "insult to the spine" does not, however, leave the patient paralyzed. Paralysis occurs, Schwartz said, "when the damage spreads to fibers that were not initially injured."

Schwartz said earlier work by her group suggested that in some people the immune system plays a role in limiting secondary damage from a spinal injury. She theorized a vaccine could effectively turbo-charge the immune system to make its protection more effective.

In the experiment, Schwartz injected the vaccine into rats whose spinal cords were injured by a blow from a metal rod.

"We used a single injection administered subcutaneously," Schwartz said. The vaccine is made of myelin peptide, one of the biologic building blocks that form the protein found in myelin, the protective sheath that surrounds nerve fibers.

Rats injected with the vaccine immediately after a spinal injury had better recovery of movement and function. Moreover, the rats did not progress to complete paralysis, as did unvaccinated rats.

Weiner, who was not involved in the study, said most people who have a spinal injury are "in the hospital being treated within less than eight hours of the injury" so a post-trauma vaccine is an appealing treatment option.

Schwartz said the vaccine could be "administered by paramedics in an ambulance because we are designing the vaccine for ease of administration."

Weiner said the vaccine being developed by Schwartz "is a promising new approach that offers real hope that this method may be available to help victims of spinal cord injury."

The research was funded by Proneuron Ltd. and by grants from the Glaucoma Research Foundation and the Alan Brown Foundation for Spinal Cord Injury.

(Reported by Peggy Peck in Cleveland.)