Zebrafish embryos under microscope.

Fresh insights into how zebrafish repair their nerve connections could hold clues to new therapies for people with spinal cord injuries.

Researchers have pinpointed key molecules that prompt damaged nerve fibers in the fish to regenerate themselves. The findings could pave the way for treatments that help restore vital connections between the brain and muscles of the body that are lost after spinal cord injury.

For people and other mammals, damage to the spinal cord is permanent and results in irreversible paralysis. Zebrafish have the remarkable ability to regain full movement within four weeks of injury to their spinal cord.

Studies have shown that they are able to restore damaged connections and nerve cells in the spinal cord.

Scientists at the University of Edinburgh’s Centre for Neuroregeneration have pinpointed a key mechanism that helps the nerve connections to regrow.

They found that after injury, wound-healing cells called fibroblasts move into the site of damage.

These fibroblasts produce a molecule called collagen 12, which changes the structure of the support matrix that surrounds nerve fibers.

This enables the damaged fibers to grow back across the wound site and restore the lost connections.

The team found that fibroblasts are instructed to make collagen 12 by a chemical signal called wnt. Understanding these signals could hold clues for therapies to help heal the spinal cord after injury, the researchers say.

"In people and other mammals, the matrix in the injury site blocks nerves from growing back. We have now pinpointed the signals that remove this roadblock in zebrafish, so that nerve cells can repair connections that are lost after damage to the spinal cord," said Thomas Becker, of the Centre for Neuroregeneration at the University of Edinburgh.

The team next plans to check whether triggering wnt signals in other animals can help them to repair nerve connections damaged by spinal cord injuries

The study was published in the journal Nature Communications.