Can people with spinal injuries walk and run, researchers probe in new study

An international research team has successfully recovered muscular mobility in a model of paralysed mice using organic neurons. Prof. Tae-Woo Lee (Department of Materials Science and Engineering, Seoul National University, Republic of Korea) and Prof. Zhenan Bao headed the team (Department of Chemical Engineering, Stanford University, US).

The outcome was published in the prestigious international journal “Nature Biomedical Engineering.” The nerves are easily harmed by a variety of factors, including physical injury, genetic factors, secondary problems, and ageing. The nerves are crucial for life activities and also have a substantial impact on quality of life. Additionally, some or all of their body functions are permanently lost due to poor bio-signaling because once nerves are injured, they are difficult to rebuild.

The traumatic account of a celebrity’s spinal cord injury occasionally makes the news. Despite the dramatic advances in medicine and biology, the medical problem of nerve injury, which has existed since the dawn of humanity, has remained a mystery to science, and there doesn’t appear to be any clear solution in the near future.

Damaged nerves have been treated in a variety of ways, including surgical procedures and drugs, but it is still nearly difficult to restore damaged or degraded nerve functioning.

Functional Electrical Stimulation (FES), a technique used often in clinical practise for the rehabilitation of patients with neurological impairment, uses computer-controlled signals. This involves applying electrical stimulation to muscles that are no longer arbitrary controlled in neuropathy patients in order to trigger muscle contraction, resulting in functionally effective motions in the biological body while being constrained in a particular space.

These conventional approaches, however, have drawbacks that make them unsuitable for patients to use on a long-term basis in their daily lives. This is because they use sophisticated digital circuits and computers for signal processing to stimulate muscles, which uses a lot of energy and has poor biocompatibility.

By using a stretchable, low-power organic nanowire neurormorphic device that mimics the structure and functionality of real nerve fibres, the research team was able to control the movement of mice’s legs solely with artificial nerves, eliminating the need for a complicated and large external computer. The stretchy artificial nerve comprises of a hydrogel electrode for signal transmission to the leg muscles, an organic artificial synapse that mimics a biological synapse, and a strain sensor that models a proprioceptor that senses muscle movements.

Because the researchers controlled the mouse legs’ movement and the force with which their muscles contract in line with the frequency of the action potentials conveyed to it, the artificial synapse performs smoother and more lifelike leg motions than the standard FES.

Furthermore, the artificial proprioceptor monitors the mouse’s leg movement and delivers real-time feedback to the artificial synapse to reduce muscle injury from excessive leg movement.

A paralysed mouse was taught to kick the ball, walk, and run on the treadmill by the researchers. Furthermore, by taking samples of recorded signals from the motor cortex of moving animals and manipulating the legs of mice through artificial synapses, the study team demonstrated the potential use of artificial nerves in the future for voluntary movement.

The neuromorphic technology, which is gaining interest as a next-generation computer device by simulating the behaviour of a biological neural network, has a new application feasibility that was discovered by the researchers. The researchers showed that the neuromorphic field would be utilised in other sectors, including biomedical engineering and biotechnology, in addition to computers.

According to Prof. Tae-Woo Lee, “Neural injury is still seen as a major scientific challenge from the past to the present despite the amazing medical breakthroughs, and without a fresh discovery, it will still be a difficult problem to overcome in the future. The study’s relevance is best summed up by the phrase, “This research provides a fresh advance in overcoming nerve damage in an engineering method using neuromorphic technology, not in a biomedical way. “An engineering approach to overcoming nerve damage will provide a new road to improve the quality of life for those suffering from linked diseases and disorders,” the author further stated.

Prof. Zhenan Bao highlighted the study’s potential, noting that it “has offered a cornerstone for patient-friendly, more realistically useable wearable neural prosthetics, away from the existing form factor” through the development of flexible artificial nerves for patients with injured nerves. This gave rise to hopes that “The underlying technology of the stretchy artificial nerve may be used to numerous medical wearable technologies,” as she put it.

The study team stated a wish to continue the work with therapeutic applications beyond primates and animals such as mice in the future. This suggests that new techniques and therapies for human nerve damage, including as spinal cord injury, peripheral nerve damage, and neurological impairments such as Lou Gehrig’s, Parkinson’s, and Huntington’s disease, may be available.