Researchers in New Zealand have demonstrated a minimally invasive technology that has effectively aided in restoring movement in paralyzed rats. This breakthrough could mean we're a big step closer to treating spinal cord injuries in humans and pets – which are presently incurable and often lead to a loss of motor function.
The University of Auckland team's tech takes the form of an ultra-thin implant designed to fit right on the injury site of a rat's spinal cord, to deliver controlled zaps of electricity.
Injuries to the spinal cord disrupt communication between the brain and body. The idea was spurred on from the fact that this column of nerve tissue does not regenerate effectively on its own. So with the implant, “the aim is to stimulate healing so people can recover functions lost through spinal-cord injury,” said Professor Darren Svirskis.
The specially developed biocompatible implants stimulated the regeneration of nerve fibers (axons), and the establishment of new connections across the injured area of the spinal cord through low-frequency electric field treatment. This involved delivering a pulse of alternating current with a small amplitude, and at a frequency of 2 Hz that has previously been shown to be effective in encouraging axon growth in lab settings.
For their study, the researchers tested two groups of rats with intermediate injuries to the spinal cord that resulted in almost no function of their hind limbs. The experiment group received 1 hour of EF treatment daily for 7-11 days, and then on weekdays only (5 days/week) for 12 weeks. The control group recovered naturally without this treatment.
The treatment led to significant improvements over natural recovery: rats that received the electric pulses showed significantly better recovery of hind limb function after 4 weeks, demonstrating enhanced coordination, paw position, and toe clearance. They also showed quicker withdrawal responses to a mechanical stimulus, indicating their touch sensitivity was recovering. You can see the difference in improvement between the rats that received the treatment and those that didn't in the video clip accompanying the team's paper in Nature Communications from last week.
Swiss researchers worked on something similar back in 2012. In that study, a chemical formulation was injected into a paralyzed rat's spine before the nerve tissue was stimulated with electricity. The rat was then fitted with a harness to assist with a physical rehabilitation program that helped it regain a degree of mobility. However, this new technology is minimally invasive, appears to support recovery of both movement and sensation, and does not cause damage to the spinal cord.
It's worth noting that rats have a greater capacity for spontaneous recovery after spinal cord injury than humans. So while that allowed the researchers an easier way to compare natural healing with their treatment, it also means that tackling loss of motor function in humans will require deeper study.
The team, which includes researchers from Sweden's Chalmers University of Technology, will continue to explore how different doses of low-frequency electric field treatment can affect recovery. The hope is to translate the findings into a medical device that could one day support people affected by spinal cord injuries.
Source: University of Auckland