New implant lets paralyzed rats walk again

By Jesse Emspak

The e-Dura implant( EPFL 2015)

An experimental flexible implant that connects directly to the spinal cord might someday lead to a treatment for people with spinal cord injuries, and could possibly help people with paraplegia move again, researchers say.

Now, researchers at the Swiss Federal Institute of Technology in Lausanne have built such an implant. They call the soft, stretchable device "e-dura," after the dura mater, which is one of the layers of protective membranes that surround the brain and spinal cord. The researchers implanted the device into rats it rests on the spinal cord, and delivers electric signals, as well as drugs, to the surrounding nerves, triggering them to fire impulses.

In experiments, paralyzed rats that were implanted with the device regained the ability to walk, with some help.

Previously, it had been difficult for scientists to find a way to connect an electronic device to the spinal cord without damaging it. One obstacle is that electronics are made of stiff materials, whereas the spinal cord and its protective covering are more flexible.

"The spinal cord expands and relaxes," saidStphanie Lacour, chairwoman of neuroprosthetic technology at the institute and one of the leaders of the new research. "If you have a hard, nondeformable material, the friction and rubbing cause inflammation."

To make the e-dura, Lacour's team used a polymer for the implant's basic structure, and gold for the electrodes. The implant also has tiny channels for drug delivery. [5 Crazy Technologies That Are Revolutionizing Biotech]

Although gold is flexible, it doesn't stretch. To make the metal more elastic, the researchers laid it down in layers just 35 nanometers (0.000035 milimeters) thick, with tiny cracks in the layers. This turned the gold into a meshlike structure that could stretch.

To test the implants, the scientists did a series of experiments on rats. First, the researchers looked at whether the e-dura integrated well with the rats' bodies, to minimize the chance that their bodies would reject it. They tested three groups of animals: one that was implanted with the e-dura, a second that got an implant made of a stiffer material and a third that underwent surgery but received no implant. (The third group served as a control.)

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New implant lets paralyzed rats walk again