Injection of 'dancing molecules' could prevent or reverse paralysis, a new mice study shows

• Scientists developed an injection that seems to prevent paralysis in mice with spinal cord injuries.
• They're hopeful that it could prevent or reverse paralysis in humans as well.

Samuel Stupp didn't expect many surprises inside his lab after a 40-year career as a scientist. But something magical happened recently: His research team at Northwestern University developed an injection that seemed to prevent mice with spinal cord injuries from becoming paralyzed.

A paper published last week in the journal Science outlines how the first-of-its-kind therapy works — a complex process that involves dancing molecules, electrical signals, and growing blood vessels.

"It's the most important paper I've ever written, because I have never integrated so deeply so many parts of science," Stupp, a professor at Northwestern, told Insider.

At the moment, no existing therapies can reverse paralysis — and spinal cord injuries don't heal on their own. So patients rely on anti-inflammatory drugs and physical therapy to relieve pain and repair injuries in small ways.

Stupp's therapy, on the other hand, has the potential to prevent people with severe spinal cord injuries from becoming paralyzed — assuming the results of his mice study also hold true for humans. Eventually, he said, a new version of that same treatment could help people regain feeling or movement after paralysis has already set in.

'Dancing molecules' help instruct cells to repair and regenerate themselves

A spinal cord injury either damages or severs axons — the long tails of neurons (nerve cells) that carry electrical signals instructing the body to feel or move. After an injury, scar tissue often builds up, preventing axons from regenerating, which is why people become permanently paralyzed.

Stupp's therapy not only reduced scar tissue, but also regenerated axons in mice. It also reformed myelin — a fatty layer that coats axons, like insulation surrounding electrical wires — which helps axons grow. Furthermore, it signaled the body to produce blood vessels, which are necessary for cells to repair themselves.

Mice with spinal injuries in the study were able to walk again within four weeks of receiving the treatment.

The drug is administered as a liquid injection the day after an injury occurs. That liquid contains tiny fibers — each one consisting of hundreds of thousands of molecules bonded together. As soon as the liquid touches the spinal cord tissue, those fibers form a gel.

"Our tiny fibers collapse together into a network or matrix that looks like natural tissue," Stupp said. "This is probably part of why it is so safe and biocompatible, and so effective — because cells see an environment that's very similar to what they normally see."

Once the therapy is introduced to the body, it's ready to perform its main function: instructing cells to repair and regenerate themselves. Stupp's research team programmed the molecules to move, or "dance," by mutating their amino acid chains. That increased the odds of the molecules coming in contact with cell receptors, the proteins that receive the body's electrical signals.

"The molecules inside of those tiny fibers are very dynamic," Stupp said. "They can reversibly leap out of the fiber and come back into the fiber. They're just dancing around."

By touching cell receptors, the molecules trigger axons to regenerate, myelin to reform, and blood vessels to grow. The more the molecules danced, the more successful the treatment seemed to be in preventing paralysis.

Researchers hope to study the drug in human trials next

The dancing molecules are "a true discovery for any kind of therapy for disease," Stupp said. Eventually, he said, they could be used to regenerate tissues in other parts of the central nervous system. That suggests that similar drugs could help treat strokes or neurodegenerative diseases like Parkinson's and Alzheimer's.

But first, Stupp has to demonstrate that the spinal cord treatment works in humans. Humans aren't mice, so the results of successful animal trials often don't translate to people.

Stupp plans to submit his research to the Food and Drug Administration in early 2022, he said. Assuming the FDA approves, Stupp said he's hopeful that the drug could advance directly to human trials — perhaps in people with severe spinal cord injuries for whom no other treatments are available.

He's optimistic that the drug would be safe in humans, he added, since it's mostly made up of compounds found naturally in the body like lipids and amino acids. It's also biodegradable, meaning the body breaks it down easily.

"The therapy basically in a few weeks is completely gone," Stupp said. "It biodegrades into nutrients for the cell."

The treatment seems to have a long-lasting effect, Stupp added — though the researchers only observed mice for 12 weeks after the injection.

"I don't see any reason why it wouldn't be permanent," he said.