Samuel Stupp has a bunch of mice that used to drag their hind legs behind them when they crawled around his Illinois lab, but they have miraculously regained at least partial use of their rear legs.
Astonishingly, their severed spinal cords have been repaired, at least partly, without surgery or drugs.
All it took was a simple injection of a liquid containing tiny molecular structures developed by Stupp and his colleagues at Northwestern University. Six weeks later, the mice were able to walk again. They don't have their former agility, but their injuries should have left them paralyzed for life.
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The mice in Stupp's lab can move about better these days because the designer molecules attacked the precise reason why a spinal cord is unable to heal itself. When the cord is severed, glial cells in the body create a scar called a "glial scar."
"The scar appears within weeks after the injury and this basically paralyzes the patient forever," Stupp said. "The scar is like a physical blockade that prevents axons from regenerating and growing."
Axons are fibers that extend out from nerve cells and attach to other cells, thus allowing the brain to command the body to carry out its functions, like moving its legs. Stem cells present in the body that have not yet developed into a specialized cell should be able to differentiate into new neurons, thus making regeneration possible, but often the stem cells become glial cells instead, making recovery that much more difficult by reinforcing the "blockade."
A couple of years ago, Stupp said, his team discovered that it could pack its nanostructure with a biological signal that commands the stem cells to turn into neurons, not glial cells. The same signal, he said, orders the axons to grow.
And that's just what Stupp and his colleagues found when they dissected the damaged spinal column in some of the mice.
"We see regenerated axons across the lesion," he said. "That's the exciting part. Regeneration of axons across the lesion is very significant."
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