The scientists believe the implants one day may be used using wireless technology in different parts of the body to fight pain that does not respond to other therapies.
“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 co-senior investigator Robert W. Gereau IV, PhD, the Dr. Seymour and Rose T. Brown Professor of Anesthesiology and director of the Washington University Pain Center.
The study is published online in the journal Nature Biotechnology.
The devices are soft and stretchable and can be implanted into parts of the body that move. The devices previously developed by the scientists had to be anchored to bone.
“But when we’re studying neurons in the spinal cord or in other areas outside of the central nervous system, we need stretchable implants that don’t require anchoring,” said Gereau.
The devices are held in place with sutures. Like the previous models, they contain microLED lights that can activate specific nerve cells. Gereau said he hopes to use the implants to blunt pain signals in patients who have pain that cannot be managed with standard therapies.
The researchers experimented with mice that were genetically engineered to have light-sensitive proteins on some of their nerve cells. To demonstrate that the implants could influence the pain pathway in nerve cells, the researchers activated a pain response with light. When the mice walked through a specific area in a maze, the implanted devices lit up and caused the mice to feel discomfort. Upon leaving that part of the maze, the devices turned off, and the discomfort dissipated. As a result, the animals quickly learned to avoid that part of the maze.
The experiment would have been difficult with older optogenetic devices, which are tethered to a power source and can inhibit the movement of the mice.