Study finds whether people with spinal injury can walk and run

SEOUL: 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 findings were published in the highly regarded international journal "Nature Biomedical Engineering."

A multitude of circumstances, including physical damage, hereditary factors, secondary issues, and ageing, can all injure the nerves. The nerves are essential for living activities and have a significant influence on the quality of life.

Furthermore, some or all of their body functions are permanently lost owing to inadequate bio-signalling since nerves are difficult to regenerate once damaged. The harrowing narrative of a celebrity's spinal cord damage reaches the headlines every now and again. Despite enormous developments in medicine and biology, the medical problem of nerve damage, which has existed since the birth of civilization, has remained a mystery to science, and no apparent cure appears to be on the horizon.

Damaged nerves have been treated in a number of methods, including surgical treatments and medicines, but restoring damaged or impaired nerve function remains challenging. Functional Electrical Stimulation (FES), is a method often utilised in clinical practice to rehab patients with neurological impairment, using computer-controlled impulses. This entails administering electrical stimulation to muscles in neuropathy patients that are no longer freely regulated in order to activate muscular contraction, resulting in functionally useful motions in the biological body while being limited in a certain location.

These traditional techniques, however, have disadvantages that make them inappropriate for patients to employ in their everyday lives on a long-term basis. This is due to the fact that they require complex digital circuits and computers for signal processing in order to activate muscles, which consumes a lot of energy and has poor biocompatibility.

The research team was able to control the movement of mice's legs solely with artificial nerves by using a stretchable, low-power organic nanowire neuromorphic device that mimics the structure and functionality of real nerve fibres. This eliminated the need for a complicated and large external computer.

The flexible artificial neuron is made up of a hydrogel electrode for signal transmission to the leg muscles, an organic artificial synapse that resembles a biological synapse, and a strain sensor that simulates a proprioceptor, which detects 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.

The researchers taught a paralysed mouse to kick the ball, walk, and run on the treadmill. Furthermore, the study team illustrated the possible use of artificial nerves in the future for voluntary movement by obtaining samples of recorded signals from the motor cortex of moving animals and controlling the legs of mice through artificial synapses.

The researchers uncovered a new application possibility for neuromorphic technology, which is attracting interest as a next-generation computing device by imitating the behaviour of a biological brain network. In addition to computers, the researchers demonstrated that the neuromorphic field might be useful in other fields such as biomedical engineering and biotechnology. Prof. Tae-Woo Lee claims that "Despite incredible medical advancements, neural damage remains a major scientific issue from the past to the present, and without a new discovery, it will be a difficult problem to conquer in the future.

"This research delivers a fresh development in overcoming nerve injury in an engineering technique employing neuromorphic technology, not in a biological one, says the study's abstract. "An engineering approach to overcoming nerve damage would pave the way for persons suffering from related diseases and disorders to enhance their quality of life," added the author.

Prof. Zhenan Bao emphasised the study's significance, stating that it "has provided a cornerstone for patient-friendly, more genuinely usable wearable neural prosthetics, away from the present form factor" by developing flexible artificial nerves for patients with wounded nerves.

As she described it, "the basic technology of the flexible artificial nerve may be adapted to several medical wearable solutions." 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.