Scientists have developed soft and stretchable devices that can be implanted into the body to activate — and in theory, block — pain signals before they reach the brain, according to research published in Nature Biotechnology.
The researchers from the Washington University School of Medicine in St. Louis and the University of Illinois at Urbana-Champaign claim that these devices may one day be used to treat pain in various parts of the body that do not respond to other treatments.
“Our eventual goal is to use this technology to treat pain in very specific locations by providing a kind of ‘switch’ to turn off the pain signals long before they reach the brain,” said Robert Gereau IV, PhD, the Dr. Seymour and Rose T. Brown Professor of Anesthesiology and director of the Washington University Pain Center in St. Louis, Missouri, in a press release.
Previous pain-blocking devices have either used tethered fiber-optic cables that restrict the natural movement of animals, or have used light emitting diode (LED) arrays, which require physical bonding to an unmoving skeletal fixture such as the skull. These external fibers can be damaged by environmental factors outside the body,and can also damage surrounding neural tissue during insertion or fiber coupling because of the motion of the hard fibers against soft tissues.
Recent implantable devices also present challenges because they either could not be used on spatially challenging nerves or the spinal cord, or they are made of hard, thick materials,which limit their ability to integrate with soft tissues in the nervous system.
These new devices are soft, stretchable, contain microLED lights that can activate specified nerve cells, and do not require fixture to bone. They are instead implanted in the body with sutures.
The researchers demonstrated that their devices could affect pain signals with light by implanting them into mice that were genetically engineered to have light-sensitive proteins on some of their nerve cells. The mice walked through a maze, and when they reached a specific area, the devices lit up and caused a sensation of pain. When the mice left that area, the devices turned off and the pain subsided. The mice quickly learned to avoid the section of the maze that caused pain. The experiment would have been very difficult to do with old devices, which are externally tethered to a power source and would have inhibited the mice’s movements.