Weird magic neurons in the spine can make people with paralysis walk again

However, a team of international researchers has recently made nine patients with severe spinal cord injuries (SCIs) walk again. They claim to have identified neurons that can restore mobility in patients with SCI. This new and interesting development raises great hopes for people suffering from chronic paralysis.

Curing chronic paralysis with electric stimulation

Chronic paralysis is caused due to spinal cord injuries that result in loss of movement and sensation in some or all body parts. Although no treatment promises permanent recovery, there are therapies that can bring improvement in a patient’s condition. Epidural electrical stimulation (EES) is one such approach where doctors implant electrodes inside the spinal cord region to restore mobility in patients.

These electrodes restore the disrupted flow of electric current between the upper (cervical) and lower (lumbar) spinal cord regions. Along with EES, the patient also undergoes physiotherapy, which eventually allows him or her to regain their lost body movements. During their study, the researchers gave EES therapy to nine patients suffering from chronic spinal cord injury.

Within five months of rehabilitation and EES therapy, the subjects started walking again. There have been some previous experiments as well that showed similar success with EES therapy, but this time, the researchers also made an interesting observation. They noticed that as the patients regained their walking ability, the neuronal activity in their lumbar spinal cord region got reduced.

This encouraged them to examine the neuronal changes that take place inside the body of a subject during the EES treatment.

Which neurons can make people walk again

The researchers decided to create a mouse model having similar characteristics to that of EES rehabilitation in humans. The authors said, “The sustained recovery of walking (in the nine patients) suggested that EESREHAB remodels the spinal cord. We speculated that this remodeling must be reflected in the activity of neurons during walking.”

They further added, “Identifying the neuronal subpopulations selected during the recovery of walking with EESREHAB would require a preclinical model in which genetically defined neuronal subpopulations could be cataloged, dissected, and manipulated. Therefore, we established a translational framework in mice to replicate the key technological and therapeutic features of EESREHAB in humans.”

The authors also mapped the genetic expression in the spinal cord neurons of the mouse model. While studying the model and the map, they came across a type of excitatory neuron in the lumbar spinal cord that, when activated, allowed a model to walk after a spinal cord injury. What’s more interesting is that these cells, referred to as SCVsx2::Hoxa10 neurons, are not required for walking action in normal people.

These findings suggest that SCVsx2::Hoxa10 neurons could be a type of recovery-promoting cells that get triggered during EES treatment, re-establish the lost neuronal connection, and finally, enable a patient with chronic paralysis to walk.

However, the researchers believe that there could be other neurons as well in our nervous system that might be involved in the recovery process. So additional research is required to find such cells and understand the impact of EES further.

The study is published in the journal Nature.