Paralysed mice walk again after injection with “dancing molecules”

November 15, 2021
Paralysed mice walk again after injection with “dancing molecules”

Researchers at Northwestern University have found a breakthrough way to reverse paralysis resulting from spinal cord injuries after treatment with a single injection containing “dancing molecules” allowed paralysed mice to walk again in just four weeks. The injectable liquid contains two types of modified peptides that repair damaged neurons within the spinal cord by triggering cascade signals – one peptide sets off a signal that regenerates axons, while the second reduces scarring and promotes the regrowth of blood vessels and myelin.

The liquid gels into a nanofibre structure that mimics the extracellular matrix surrounding the spinal cord. The gel matrix allows the molecules to move around to find the right receptors in the cells, andallowed the peptides to stick around for longerthan usual before the gel biodegrades after about 12 weeks.

“The signals used in the study mimic the natural proteins that are needed to induce the desired biological responses,” said research assistant professor Zaida Álvarez. “However, proteins have extremely short half-lives and are expensive to produce. Our synthetic signals are short, modified peptides that – when bonded together by the thousands – will survive for weeks to deliver bioactivity. The result is a therapy that is less expensive to produce and lasts much longer.”

Neurons in the spine transmit crucial signals between the brain and muscles, so damage to these can make even simple movements difficult or impossible. The new therapy can repair this damage more thoroughly byregenerating axons, reducing scar tissue formation, replenishing the insulating myelin layer around axons, increasing production of blood vessels, and increasing the number of motor neurons that survive damage.

The researchers said that the therapy could initially be used to prevent paralysis in patients after major trauma, such as falls, sporting injuries or traffic accidents. It could also be applied to a range of other diseases.

“The key innovation in our research, which has never been done before, is to control the collective motion of more than 100,000 molecules within our nanofibres,” said materials scientist and lead researcher Samuel Stupp. “By making the molecules move, ‘dance’ or even leap temporarily out of these structures, known as supramolecular polymers, they are able to connect more effectively with receptors. […] our fundamental discovery about controlling the motion of molecular assemblies to enhance cell signaling could be applied universally across biomedical targets.”

The researchers are planning to present the new treatment to the US Food and Drug Administration to begin the process of approval for human use.

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