Every year, up to 500,000 people suffer a spinal cord injury (SCI), which most likely leads to a life-long disability- or at least, that’s what was thought up until now. A new kind of implant, called “electronic dura mater” or “e-Dura”, recently presented in a paper published in Science, promises to open the way to innovative therapies to help people that have had a SCI walk again.
Developed by a group of researchers from the Swiss Federal Institute of Technology of Lausanne (EPFL) and the Scuola Superiore Sant’Anna of Pisa, the e-Dura device has the ambitious goal of “overcoming the ‘hard to soft’ mechanical mismatch between man-made devices and biological tissues” as described by the group leader Stéphanie Lacour. The shape and elasticity of this revolutionary implant closely replicates that of the dura mater, the thick protective membrane that surrounds the brain and the spinal cord. The mechanical properties of the e-Dura make it suitable for long-term biointegration since it can be implanted directly on the surface of the brain or spinal cord.
The dream of bringing paraplegic people back on their legs through surgical implantation of electrodes for the stimulation of neural tissues is not new. However, it has always been haunted by foreign body rejections and tissue inflammations due to the friction between the stiff implant and the soft tissues it is enveloped in. This new device is composed of stretchable gold interconnects, soft electrodes coated with a platinum-silicon composite and a fluidic microchannel that is used to locally deliver drugs. The electrodes are designed to both send electrical excitations and receive signals from the neural tissues and their exceptional stretchability allows deformations to take place in any direction without affecting the electrical conductivity. The softness of the implant makes it possible to insert it directly below the dura mater, to bring the electrodes in direct contact with the delicate neural tissues.
Scientists tested e-Dura on mice for a period of 6 weeks, along with a stiff implant fabricated for comparison and assembled using the standard practices for flexible neural implants. After 1-2 weeks following the insertion into the spinal cord, the stiff implant started giving problems. By the end of the sixth week, a significant compression of the spinal segments was observed. On the other hand, mice implanted with e-Dura were in similar physical conditions as those in the sham-operated control group. The implant smoothly integrated, conforming to the delicate spinal neural tissue. As the scientists hoped, locomotion was restored after a SCI thanks to the combined electrical and chemical stimulation provided to the neural tissues in the spot where the lesion took place. The local drug application provided by the fluidic microchannel ensured reduced side effects.
As further advantages, fabrication steps of e-Dura are remarkably simple reducing the cost of an implant, and its softness greatly reduces the complication of the surgical implantation procedure.
In a not so far future, patients who suffered a SCI might stand up and walk again.
FOR FURTHER INFORMATION: http://www.sciencemag.org/content/347/6218/159.full
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