The discovery was surprising because oncomodulin does not belong to a family of molecules known for promoting growth, says Benowitz. Yet tests on cultured nerve cells showed that the molecule was capable of promoting up to 50 percent more growth than known growth promoters, says Benowitz. Following this, the group was able to show that oncomodulin can regenerate the crushed optic nerve of healthy adult rats after two weeks, without the need to stimulate an inflammatory response.

"We know that it works by binding to a receptor on the surface of the nerve cells," says Benowitz. "This activates a signalling pathway that turns on a group of genes required to make nerves grow."

"He's certainly added a new tool to our arsenal," says Silver. But there's still a long way to go. Restoring sight in humans would still require the regeneration of the optic nerve several times further than was achieved in the current experiments. And first it remains to be seen if oncomodulin will have the same neurotrophic effect on humans.

The next steps are to see what effect the protein has on other types of nerve cells and if there is any danger of causing damage to other parts of the brain. Preliminary tests by Benowitz's group are hopeful, though; the oncomodulin has had some effect on nerve cells other those in the optic nerve. And that, says Berry at the University of Birmingham, "has implications for spinal-cord regeneration."