Scientists at Monash University in Australia have found how the zebrafish heals its spinal cord after injury.
The zebrafish, Danio rerio, is a tropical fish belonging to the family Cyprinidae. This species is a popular aquarium fish and is also an important model organism in scientific research. It has the amazing ability to regenerate fins, skin, the heart and the brain.
A new study in the describes the role of a protein in the remarkable self-healing ability of the fish. The finding could eventually lead to ways to stimulate spinal cord regeneration in humans.
“When the spinal cord is severed in humans and other mammals, the immune system kicks in, activating specialized cells called glia to prevent bleeding into it,” explained study co-author Prof Peter Currie.
“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.”
However, the scar prevents axons, threadlike structures of nerve cells that carry impulses to the brain, of neighboring 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 zebrafish 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.