Scientists claim to have unlocked the secrets of the zebra fish's remarkable ability to heal its spinal cord after injury, in a study which they say could lead to new effective therapies for paralysis patients.

Researchers at the Monash University in Australia found a protein, called fibroblast growth factor (fgf), plays a major role in the fish's amazing self-healing ability.

The findings, published in The Journal of Neuroscience, could eventually lead to new ways to stimulate spinal cord regeneration in humans, the researchers said.
Professor Peter Currie, who led the research, said when the spinal cord is severed in humans and other mammals, the immune system kicks in, activating specialised cells called glia to prevent bleeding into it.

"Glia are the workmen of nervous system. The glia proliferate, forming bigger cells that span the wound site in order to prevent bleeding into it. They come in and try to sort out problems. A glial scar forms," Prof Currie said in a statement.

However, the scar prevents axons, threadlike structures of nerve cells that carry impulses to the brain, of neighbouring nerve cells from penetrating the wound. The result is paralysis.

"The axons upstream and downstream of the lesion sites are never able to penetrate the glial scar to reform. This is a major barrier in mammalian spinal cord regeneration," Prof Currie said.

In contrast, the zebra fish glia form a bridge that spans the injury site but allow the penetration of axons into it.

The fish can fully regenerate its spinal cord within two months of injury. "You can't tell there's been any wound at all," Prof Currie said.

The scientists found that fgf controlled the shape of the glia, and accounted for the difference in the response to spinal cord injury between humans and zebra fish.

The study shows the protein could be manipulated in the zebra fish to speed up tissue repair even more, they said.

"The hope is that fgf could eventually be used to promote better results in spinal cord repair in people," Prof Currie added.