Flexible spinal implant shows promise for paralysis

Researchers at Ecole Polytechnique Fédérale de Lausanne (EPFL) in Switzerland have developed a completely new technology that has enabled paralysed rats to move again. The spinal implant called e-Dura could potentially be used in humans too. Ayesha Salim speaks to co-researcher Stephanie Lacour to find out more.


For people that suffer from chronic back pain, spine implants usually offer a welcome respite from the pain. The spinal cord stimulator is usually implanted near a person’s spine to send electrical pulses to the spinal cord. But the problem with some of these implants is that they can cause problems for surrounding tissues. And there have been several cases where patients have incurred more injuries after having these spinal implants inserted in their backs. Some even leading to paralysis. But now a new type of spinal implant called e-Dura actually works naturally with the tissues it’s surrounded with. I am speaking on the phone to Stephanie Lacour, one of the researchers who helped develop it.

“Spinal cord implants on the market are primarily used (at least to my knowledge) for pain control. We have developed a completely new technology to make a surface implant that can be inserted below the [protective skin of the central nervous system] which allows us to not only deliver electric stimulation but also chemical stimulation.”

Lacour tells me that the idea for e-Dura came about from her meeting with Gregoire Courtine, the other researcher on the project. She says her lab was exploring how to make soft electronics, while Courtine was exploring how to restore locomotion following spinal cord injury: “We both evolved in parallel and then we both arrived at EPFL about three or four years ago. He had a need for an implant and we had the technology.”

The e-Dura is primarily made of silicon rubber which behaves like an elastic or rubber band – and this is what makes it unique – the ability to be flexible allowing it to move naturally on the spinal cord: “If you have an implant that can accommodate and follow those natural movements, then the integration works much better than if you have an implant that is sort of stuck and cannot stretch along,” Lacour says.

The e-Dura implant has been tested on rats and enabled paralysed rats to move again. Lacour tells me her lab conducted two studies comparing the effects of a stiffer implant on normal healthy rats with no spinal injuries with the more flexible e-Dura implant on rats with spinal injuries. She tells me how the stiffer implants over a period of weeks had a detrimental effect on the healthy rats: “The ones that were healthy to start with but had the stiff implant over time degraded. We had trained them to walk on the ladder and then over time they missed some steps.”

But the rats with spinal cord injuries started showing improvement with the e-Dura implant, to the point where the rats started to move. How did the implant work?

“We placed the device just below the site of injury, on the part of the spinal cord that was no longer connecting to the brain. We sort of substituted the information usually coming from the brain that activates the spinal circuitry to trigger movement in the limb.” Lacour tells me.

“So by applying a combined electrical stimulation and chemical stimulation which is based on a cocktail of neurotransmitters, then we were able to see the legs move again. This demonstrated that we not only had an implant that was soft but one that is functional and can deliver electronic stimulation over weeks.”

But Lacour emphasises that at this stage in the process, the rats cannot move by themselves: “If we don’t activate the electrode or the chemical stimulation then both legs will drag. But if we do apply chemical stimulation combined with the electric stimulation then we can see the leg moving. We decide when the leg moves, there is no voluntary decision from the rat at this stage.”

[Rat experiment video: https://www.youtube.com/watch?v=ejwEqpV8ak4]

How do you do those transmissions?

“When we do the experiment, the wire from the head connects to the external electronic and drug delivery system. The implant itself is connected to a connector that sits on the head of the rat. So we have a wire and a very narrow micro tube for the drug delivery and the reason we put it on the head is so the animal cannot reach it.”

The exciting prospect about this implant is that it could extend to humans and help the paralysed walk again. But Lacour says there are still many obstacles to overcome before this goal is achievable: “We need now to move forward and expand the validation of the longevity of the material. We tested it for two months and it is fine. But two months is not a lifetime so we also need to expand it as we are designing it so that the patient would be wearing the implant for many years.”

Lacour tells me that the researchers also need to get FDA approval for the new material that’s been developed for e-Dura. There is also the challenge of integrating the technology into a box in order to have a standalone system: “Ideally we want to aim for a system like a pacemaker where it is fully implanted into the body. So the patient can really be at home without going back and forth to the hospital.”

Despite some of these hurdles, the prospect for helping paralysis in humans is exciting and the experiment on the rats would not have been successful without the help of several groups working together, particularly her co-researcher Gregoire Courtine.

Lacour says this technology can also be implemented in other contexts – such as monitoring brain activity for neurodegenerative diseases: “It could potentially be very useful for patients with epilepsy where we can do long-term monitoring of epileptic seizures but it could also have application for Parkinson’s and other neurodegenerative diseases.”


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Ayesha Salim

Ayesha Salim is Staff Writer at IDG Connect

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