Researchers are a step closer towards helping paralyzed individuals walk again as a team from École Polytechnique Fédérale de Lausanne (EPFL) and colleagues develop flexible implants that can be used on the spinal cord directly without causing inflammation and damage.
So far, EPFL scientists have been able to get paralyzed rats walking on their own again after a few weeks with the help of chemical and electrical stimulation. To apply the method to humans, multifunctional implants that can withstand long periods of installation on the spinal cord will be needed. This has prompted the development of the e-Dura implant, a small device that closely mimics mechanical properties in living tissues while delivering pharmacological substances and electric impulses.
As the device will be implanted underneath the dura mater, a protective envelope in the brain or spinal cord, e-Dura takes care of the problem the surface implants have. It is where rejection, scar tissue buildup and inflammation results from nerve tissues rubbing against an implant. The e-Dura implant has also been designed to be as elastic as the living tissues around it so inflammation and friction are kept to a minimum.
When a prototype of the e-Dura implant was placed on rats, the device was not rejected and no damage was reported even after two months have lapsed. Traditional implants would have already caused dramatic damage to nerve tissue within that time period.
"Our e-Dura implant can remain for a long period of time on the spinal cord or the cortex, precisely because it has the same mechanical properties as the dura mater itself. This opens up new therapeutic possibilities for patients suffering from neurological trauma or disorders, particularly individuals who have become paralyzed following spinal cord injury," explained Stéphanie Lacour, Bertarelli Chair in Neuroprosthetic Technology from EPFL and one of the authors for the study.
The e-Dura implant features electronic elements that stimulate the spinal cord from the point of injury. Cracked cold electric conducting tracks cover the silicon substrate while electrodes are built using a composite of platinum beads and silicon, all allowing flexible movement without hampering electrical conductivity. A fluidic microchannel is also in place to deliver neurotransmitters for reanimating nerve cells under injured tissues.
Other authors for the study include: Grégoire Courtine, Zhigang Suo, Silvestro Micera, Janos Voros, Alexandre Larmagnac, Simone Duis, Natalia Pavlova, Qihan Liu, Nicolas Vachicouras, Rafael Fajardo Torres, Leonie Asboth, Tomislav Milekovic, Marco Capogrosso, Jerome Gandar, Eduardo Martin Moraud, Nikolaus Wenger, Quentin Barraud, Arthur Hirsch, Pavel Musienko and Ivan Minev.