Paralyzed mice walk again with breakthrough new treatment

A revolutionary new treatment allowed paralyzed mice to walk again in a month, with just one injection.

Get up and walk; this is what might have been exclaimed by American researchers at Northwestern University, who recently accomplished an almost biblical feat. With all kinds of treatment, they were able to cure paralysis in mice with spinal cord injuries in just one injection!

For decades, science has sought to cure paralysis. This is particularly complicated, because unlike many of their ilk, central nervous system cells are unable to regenerate on their own. This unfortunately includes the spinal cord, with sometimes terrible implications; when it is badly damaged, the person often finds himself suffering from irreversible paralysis.

This consequence is due to the spinal cord structure. Like the brain, it is partly made up of neurons. These are slightly different from those in the brain, but work the same way. In practice, they transmit information in the form of an electrical signal, through a “cable” called an axon. It is these axons that are damaged in paralyzed people, and which science seeks to repair – without success so far.

The axon is the “electric cable” that allows neurons to send signals through the nervous system. © Bruce Blaus – WikiCommons

A ballet of “dancing” nanofibers

“Today, there is no therapeutic solution that can trigger regeneration of the spinal cord,” says Samuel I. Stupp, lead author of the study. To overcome this problem, many researchers have already tried stem cell-based protocols; an approach which has already shown its full potential in bioengineering and regenerative medicine. But in their work, published in the prestigious Science, this team opted for a radically different approach.

Rather than trying to replace neurons with stem cells, they bet on a vast network of nanofibers. When the treatment is injected, these nanofibers agglomerate to form a dense and elastic network. This will play the role of connective tissue, that is to say the structural part of our anatomy that holds everything else in place. It thus serves as a framework, a little like steel bars in a reinforced concrete structure.

Once that support structure is in place, there is still the hard part. For the actual repair, the researchers chose to strike a blow stone. Because the nanofibers in question do not only serve as guardians. They serve as masters of ceremonies during a extremely well coordinated molecular ballet. Under their impetus, hundreds of thousands of neighboring molecules set in motion in search of a specific biological receptor.

A regenerative chemical signal

Once they have found their receiver, these “dancing molecules”Stabilize and begin to emit a chemical signal. This in turn stimulates the axon growth and the blood vessels that supply them over a long period of time. This allows to gradually restore cellular communication between neurons, and therefore regenerate the spinal cord.

As often in animal biology, the guinea pigs were sacrificed at the end of the experiment. The goal: to observe changes at the cellular level. The researchers found that all the important parts of the severed axons had regenerated correctly. This confirms the success of the manipulation on this scale. In addition, this made it possible to confirm that there was no trace of the initial injection; all the fibers have been biodegraded to serve as food for convalescent cells.

Almost endless therapeutic applications

This is not the first time that a team of researchers has returned the use of its limbs to a paralyzed mouse; this honor goes to a team of German researchers who published their works last January. On the other hand, it is the very first time that a treatment makes it possible to do it so reliably, quickly, and in a single punctual injection. In addition, this approach suggests very clear avenues for improvement; this is particularly important, as it opens the door to concrete therapeutic solutions.

Researchers still have their work cut out for them. First, they want to further improve the ability of fibers to find their receptor, which would speed up processing even more. On the strength of their extremely convincing results, they now hope to receive authorization to proceed directly to a clinical trial in humans. In the not-so-distant future, therefore, we may see a real ray of hope arrive for 250,000 to 500,000 people who suffer from spinal cord injuries every year around the world.

But the best part is that the potential applications of this technology do not end with paralysis. In theory, it would be possible to cure lots of serious diseases related to the central nervous system. Because functionally speaking, the structure repaired by researchers is similar to that affected in the course of Parkinson’s, Alzheimer’s or Charcot. Best of all, the potential applications of this system extend beyond the nervous system. “This fundamental discovery on the control of molecular assemblies could be applied universally, to all biomedical targets.“, Concludes Stupp.

The text of the study is available here.

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