Scientists describe ‘dancing molecules’ capable of repairing spinal cord injuries

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Paralysis resulting from spinal cord injury almost always meant lifelong illness. Now researchers at Northwestern University believe the disease, at least in some cases, may be preventable.

In an article published in the peer-reviewed journal Science, the scientists write that after an injection of an injectable therapy of “dancing molecules”, damaged tissues of mice with severe spinal cord injury were repaired, reversing the paralysis in one month.

The therapy has not been tested in humans, but an in vitro test of human cells in petri dishes showed that the cells responded to therapy, giving hope that one day humans might also benefit from it. a treatment.

The brain, spinal cord, and central nervous system lack the ability to repair themselves after injury, and as such, spinal cord injury is the leading cause of paralysis in the United States, study finds survey conducted by the Centers for Disease Control and Prevention. In the United States, nearly 300,000 people are living with a related injury and less than 3% of those who have suffered a complete injury will recover basic physical functions, notes the National Spinal Cord Injury Statistical Center.

Currently, there is no therapy to trigger regeneration of the spinal cord, study author Samuel Stupp, an expert in regenerative medicine, explained in a press release. This is largely due to basic biology. Axons, which help transmit and enable communication throughout the body, cannot regenerate in the central nervous system of adults, making them unable to repair themselves in extreme cases. Following trauma, it is difficult to prevent or avoid permanent paralysis.

This is where science comes in.

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“Injury to the spinal cord causes paralysis because it damages or cuts axons, the long tails that serve as ‘electrical cables’ to neurons in the spinal cord that transmit electrical signals back and forth between the brain and the rest of the body. . Axon damage interferes with our ability to smell and move, ”Stupp told Snopes. “Our therapy signals damaged or severed neurons to initiate axon regeneration, thereby restoring critical electrical signals.”

The therapy involved is what’s called a polymer, a specialized liquid gel made up of chains of natural or man-made molecules linked together.

As part of their study, the researchers injected recently paralyzed mice with a single shot of a specialized polymer known as the “supramolecular polymer” into the tissues around the spinal cord. Once injected, the polymer gels into a “complex network of nanofibers” that mimic the extracellular matrix (ECM) of the spinal cord, a vital component of all tissue. Stupp described this particular polymer as a “three-dimensional mesh of nanoscale fibrils that resembles what surrounds cells in most tissues, including neurons in the spinal cord.”

The supramolecular polymer mimics the natural proteins that would be needed in the body to induce such repairs to send communicative “bioactive signals” that prompt cells to repair and regenerate areas surrounding the spinal cord. First, the molecules of the polymer connect to receptors where they trigger two signals essential for repairing the spinal cord: regeneration of axons and regrowth of blood vessels.

“Receptors in neurons and other cells are constantly moving,” Stupp said. “The key innovation of our research, which has never been done before, is to control the collective movement of more than 100,000 molecules within our nanofibers. By moving, “dancing” or even temporarily jumping molecules out of these structures, known as supramolecular polymers, they are able to connect to receptors more efficiently.

Not only did their research reveal that axons could regenerate, but they also found that scar tissue, which can create a physical barrier to regeneration and repair, was diminished. An insulating layer of axons that help transmit electrical signals, myelin, has been shown to reform as blood vessels form to deliver nutrients to the injury site.

In four weeks, the microphone was able to work again.

But any testing in humans is still a long way off, and it’s unclear whether the same results will translate. The scientists also used the therapeutics on in vitro tests on human cells in petri dishes and found that cellular activity was becoming more active, suggesting that human cells were at least responding. In the human body, cells and receptors are in constant motion and when they move faster, the theory is that they will come into contact with more receptors.

“If the molecules are slow and not so ‘social’, they may never come into contact with the cells,” Stupp explained.

If it works in humans, the theory follows that the therapy could be applied to people who have recently suffered major trauma to prevent paralysis. But it is not clear to what extent the therapy could heal existing or long-term injuries. Stupp says it may be possible to use similar therapy for patients who are already paralyzed, but such work will require more research to formulate therapy in a different form – a goal his team is currently working on.

“Supramolecular polymers are an exciting new emerging area in the field of materials that have very different properties from conventional polymers. The difference is that in conventional polymers (eg plastics) the thousands or more of structural units that make up these molecules (macromolecules) are linked by very strong bonds which are difficult to break, ”Stupp told Snopes.

“In supramolecular polymers, structural units are linked by weaker forces so that they can be more dynamic. This is how we activate the “dance” of molecules, which means that molecules (with biological signals in this case) move a lot collectively and we have discovered for the first time that this movement is essential for efficient signaling of molecules. receivers.

This is, he said, the scientific breakthrough now described.

Stupp told Snopes his team plans to contact the U.S. Food and Drug Administration in 2022 to move forward with approval for a human clinical trial.

Sources

Armor, Brian S., et al. “Prevalence and Causes of Paralysis – United States, 2013.” American Journal of Public Health, Vol. 106, no. 10, October 2016, p. 1855-57. DOI.org (Crossref), https://doi.org/10.2105/AJPH.2016.303270.

Axons: The cable transmission of neurons. July 25, 2017, https://qbi.uq.edu.au/brain/brain-anatomy/axons-cable-transmission-neurons.


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