Paralyzed Mice Walk Again

tags: paralysis, nanotechnology, medicine

A group of lab mice were intentionally paralyzed by cutting their spinal cords. As a result, they ended up dragging their hind legs behind them instead of scurrying around as mice do. But a group of these mice have partially recovered movement in their hind legs without the aid of surgery or drugs, thanks to a new field of medical research known as regenerative medicine.

Samuel Stupp and his colleagues are several of the pioneers in the field regenerative medicine, and they have developed a liquid that is injected into the severed spines of these mice that restores their ability to move within six weeks. This liquid contains nanostructures filled with tiny designer molecules that were developed by Stupp and his colleagues at Northwestern University.

If this research works as well in humans as it does in mice, it will considerably brighten the future of those who suffer from Alzheimer's and Parkinson's diseases, as well as those who have survived spinal cord injuries.

"It's just the very beginning, so this is extremely early," said Stupp. "We are introducing these nanostructures in the brain of mice that have Parkinson's disease. We have seen very interesting functional recovery."

When a spinal cord is severed, glial cells create a "glial scar" that prevents the spinal cord from healing itself. This process takes only a few weeks. However, the experimental mice in Stupp's lab can move because Stupp's injected designer molecules prevented the formation of a glial scar.

Stupp's team discovered a special biological signal that encourages stem cells in the body that have not yet developed into specialized cells to differentiate into new neurons, thus making regeneration possible. This same molecular signal triggers the growing neurons to send out axons; fibers that extend out from these cells to attach to other cells, thus allowing the brain to regain control of the body's movements and functions, such as moving the legs.

"We see regenerated axons across the lesion," Stupp said. "That's the exciting part. Regeneration of axons across the lesion is very significant."

Unless encouraged to develop into neurons, these stem cells instead differentiate into glial cells, thus making recovery much more difficult by reinforcing the spinal blockage.

But what happens to the nanostructures after they have done their work? Will they remain behind, causing havoc in the body?

"These nanostructures are completely biodegradable," Stupp said. "They disappear within weeks."

But Stupp and his colleagues' work might be only part of the solution. They might find that nanostructures make great drug delivery systems, but certain medical solutions may require the introduction of stem cells, so that controversy isn't likely to go away. But perhaps a combination of nanotechnology and traditional medical procedures might be just what the doctor ordered.

Cited story.