The field of optogenetics – which employs genetically encoded switches that turn neurons on or off with light – has taken a step forward; scientists have created flexible, implantable, wireless devices that can activate and potentially block pain signals in the body before they make it to the brain.
Image credit: Gereau Lab/Washington University
Scientists who have previously used light to activate nerve cells in animals had to attach the animals to wires, limiting their movability.
But in a new study published in the journal Nature Biotechnology, researchers from Washington University of Medicine in St. Louis, MO, and the University of Illinois have built on wireless technology to create the flexible devices that can be implanted under the skin – without the need for batteries.
They hope their implants will one day be used in different areas of the body to block pain that is not treatable with 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,” says study author Prof. Robert W. Gereau IV, from the Washington University Pain Center.
He explains that previously, such devices had to be “anchored” to bone, whereas the new devices are held in place with sutures.
The benefit of these new flexible devices – which contain microLED lights that activate specific nerve cells – is that they enable scientists to work with neurons in the spinal cord or other locations outside of the central nervous system.
For their recent study, Prof. Gereau and colleagues experimented with genetically engineered mice with light-sensitive proteins on specific nerve cells.
In order to establish that their implants could disrupt the pain pathway in nerve cells, the team triggered a pain response using light; as the mice walked through a certain area in a maze, the researchers activated the devices, causing discomfort for the mice. Then, when they left that area, the devices switched off, clearing the discomfort.
Understandably, the mice quickly learned to steer clear of that specific part of the maze.
The researchers explain that because the smaller devices are flexible and can be held in place with sutures, they could have potential uses around the bladder, stomach, intestines, heart or other organs.
Although their study demonstrated that their devices are able to deliver pain to mice, they explain that the same technology could now be used to block these pain signals, providing hope for patients with currently untreatable pain.
Commenting on their findings, the researchers write:
”We demonstrate the power of this technology by modulating peripheral and spinal pain circuitry, providing evidence for the potential widespread use of these devices in research and future clinical applications of optogenetics outside the brain.”
Prof. Gereau and colleagues explain that they designed their implants keeping in mind simple manufacturing processes that allow for mass production; as such, these devices could be made readily available for other researchers.
In August of this year, Medical News Today reported on an implantable device that uses the mouse’s own body to transfer radio frequency energy.