Updated

A groundbreaking treatment, that can almost completely restore the limb paralysis that follows a stroke, has been successfully tested on rats, scientists in California announced Tuesday.

Studies by biologists at University of California, Irvine, found that a material that occurs naturally in humans can restore 99 percent of movement in rats if applied to the brain days after a debilitating stroke.

At present, no drugs exist that can help victims recover from a stroke after days have elapsed, James Fallon, psychiatry and human behavior professor and senior co-author of the studies said.

"Now we have evidence there may be therapies that can repair damage to a significant degree long after the stroke," he said. "It's a completely unexpected and remarkable finding, and it's worth trying in humans."

In one of the team's studies published in the January edition of the journal Neuroscience, scientists discovered that injecting the human protein into rats one month after they suffered a stroke (equal to about a year for humans) led to the recovery of nearly all their movement.

Rats that did not receive treatment improved just 30 percent.

"It's becoming more and more clear that the brain is like any other organ - it has a lot of potential to regenerate," said Darius Gleason, a developmental and cell biology graduate student who worked on the study.

"We are just emulating nature by giving a little nudge to what the brain is trying to do itself."

The treatment is based on a protein called Transforming Growth Factor Alpha, which plays a role in tissue formation.