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Scientists have learned how to build tiny bridges in the brain. As this ScienCentral News video explains, the idea is to help the brain heal after an injury.
Helping the Brain Heal
Whether it's from surgery, an accident or stroke, when the brain is injured, the damage is usually permanent. Most of the time, the cells of the brain don't grow back. But two researchers at Massachusetts Institute of Technology are working to change that.
The bridges assemble themselves from protein fragments called peptides, which are injected into the injured area. The bridges are similar to the normal structures among brain cells.
"It would be easy to fool an anatomist into thinking that this was part of the brain," says Schneider about these bridges that are smaller than the width of a human hair. He adds that "it's functioning like it's part of the natural material that fills spaces between the nerve cells in the brain." The peptide nano-bridges are not permanent. After a while they dissolve.
Writing in Proceedings of the National Academy of Sciences (PNAS), the two reported that when they did this in hamsters with severed optic nerves, axons -- the long arms of brain cells -- grew across the bridges and re-established connections, restoring partial sight in the hamsters.
Tests with the hamsters then showed that a functional level of sight had, in fact returned. Says Ellis-Behnke, "This is actually, we think, the first time that the brain has been repaired to this level in any mammal."
image: National Stroke Association
Explains Schneider, "With this material, the wound edges come together. They appear to knit themselves together. So, instead of this gap, you have material coming together and you get bridges of tissue that appear to be compatible for axon growth, because axons will follow those ridges right across the wound."
But Ellis-Behnke cautions that this is only part of the puzzle, noting, "We think we will have to add … other things that will help coax axons into the material and then reconnect into the correct structures." He adds that, "This is one aspect of what we think will be a therapy for regeneration. There is not one thing that will go ahead and fix this problem."
Additionally, in these tests, there was only a short time between the injury and the injection of the nano bridge material. He notes that in the real world, except for damage done during brain surgery, injuries in the brain "are chronic or they have a time delay between the time of injury and the time of treatment."
They next want to treat hamsters that have injuries that are a month old, to see if the brain responds as well as it did with a new injury. Says Ellis-Behnke, "If we can do that, then we think we might be able to return a certain level of quality of life to some of these people who have had a stoke, which is the goal of our lab."
Ellis-Behnke is also hopeful that the team's nano-bridge material could be used in surgical situations where wounds are fresh. He notes that every time "you make a cut you are killing or damaging axons or neurons." He says if anything could be done to lessen the impact of brain surgery, "That would be great." He hopes such a use could be three to five years away.