Regrown Brain Cells Give Blind Mice a New View

Researchers at Stanford University have coaxed brain cells involved in vision to regrow and make functional connections—helping to upend the conventional dogma that mammalian brain cells, once damaged, can never be restored. The work was carried out in visually impaired mice but suggests that human maladies including glaucoma, Alzheimer’s disease and spinal cord injuries might be more repairable than has long been believed.
Frogs, fish and chickens are known to regrow brain cells, and previous research has offered clues that it might be possible in mammals. The Stanford scientists say their new study confirms this and shows that, although fewer than 5 percent of the damaged retinal ganglion cells grew back, it was still enough to make a difference in the mice’s vision. “The brain is very good at coping with deprived inputs,” says Andrew Huberman, the Stanford neurobiologist who led the work. “The study also supports the idea that we may not need to regenerate every neuron in a system to get meaningful recovery.”
Other researchers praised the study, published Monday in Nature Neuroscience. “I think it’s a significant step forward toward getting to the point where we really can regenerate optic nerves,” says Don Zack, a professor of ophthalmology at Johns Hopkins University who was not involved in the research. He calls it “one more indication that it may be possible to bring that ability back in humans.”
Earlier studies had suggested that axons—the long arms that extend from neurons and conduct signals—could regrow in this way, but the Stanford research is the first to demonstrate this extent of regrowth and visual restoration, says Zack, who also co-directs the Johns Hopkins Center for Stem Cells and Ocular Regenerative Medicine. The study shows that a regenerating axon can grow in the right direction, forming the connections needed to restore function. “They can essentially remember their developmental history and find their way home,” Huberman says. “This has been the next major milestone in the field of neural regeneration.”

http://www.scientificamerican.com/article/regrown-brain-cells-give-blind-mice-a-new-view/