Researchers have developed an injectable therapy that can repair tissue damage and reverse paralysis in mice within four weeks. The study was published in Science.
Spinal cord injuries are a major challenge to scientists as the central nervous system, including the brain and spinal cord, does not repair itself following injury or degenerative disease. As such, less than 3% of people with complete spinal injury recover even basic physical functions, and around 30% are hospitalized at least once per year after the initial injury. In the US alone, almost 300,000 people have a spinal cord injury.
"Receptors in neurons and other cells constantly move around," said Samuel I. Stupp, lead author of the study, "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 nanofibers. 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."
Enabling more connection to receptors triggers cascading signals which go on to induce spinal cord repair. One signal repairs axons, which are long extensions from neurons that send signals between the brain and the rest of the body. Damage to axons results in a loss of sensation.
The second signal promotes the regrowth of lost blood vessels that nourish neurons and other cells needed for tissue repair. The therapy also causes myelin to rebuild around axons, which strengthens their communicative ability.
"The signals used in the study mimic the natural proteins that are needed to induce the desired biological responses. However, proteins have extremely short half-lives and are expensive to produce," said Zaida Álvarez, first author of the study. "Our synthetic signals are short, modified peptides that -- when bonded together by the thousands -- will survive for weeks to deliver bioactivity. The end result is a therapy that is less expensive to produce and lasts much longer."
The researchers are now in conversation with the Food and Drug Administration (FDA) to arrange for human trials for the drug among those with few other treatment options. Meanwhile, they say that their underlying discovery of 'supramolecular motion' may be applied to other therapies and targets such as stroke and neurodegenerative diseases like ALS, Parkinson's disease, and Alzheimer's disease.