A researcher holding a mouse (© AP Images)
A Stanford University–led team has regrown brain cells in mice, giving hope for repairing nerve and brain damage in humans. (© AP Images)

Most scientists once thought that the brain cells of mammals, once damaged, could never be repaired. But researchers at Stanford University in California have regrown damaged optic nerves in mice, restoring hope that similar treatments could help people with glaucoma, Alzheimer’s disease and even spinal cord injuries.

How did they do it? With two methods: flipping on a “growth switch,” a gene that encourages growth of cells in the central nervous system, and “exercising” the eye by having mice look at displays of bold, shifting patterns.

“When we combined those two,” said Andrew Huberman, the lead researcher, “we saw this incredible synergistic effect. The neurons grew enormous distances — 500 times longer and faster than they would ordinarily.”

This strategy is actually what happens in the early brain, said Russell Van Gelder of the University of Washington, who was not involved with the study. “It suggests that the conversation that occurred between the brain and eye in development … can be revived.”

Not only did the neurons, or nerve cells, grow, but they seemed to know exactly where they were going during regeneration, according to Huberman. Although their restored vision wasn’t perfect, the study’s once-blind mice passed basic tests of visual ability.

The work gives researchers hope that diseases like glaucoma, which affects 70 million people around the world, could be reversed, and that other types of brain and nerve cells can be regrown in similar ways. This could mean restoring memory pathways damaged by Alzheimer’s or enabling movement after spinal cord damage.

“Before, there was nothing we could do,” said Zhigang He, a co-author of the paper. “Now, we need to think about what type of patient might be most likely to benefit from the treatment.”