As the control center for the body, it’s essential that the brain is protected from harm. One such shielding mechanism is the organ’s blood-brain barrier, a highly selective filter that acts to keep potentially toxic substances out and thus help preserve the brain’s delicate tissues and chemical balance. But because this barrier is so good at its job, it unfortunately means that if something goes wrong in the brain, it’s incredibly tricky to get therapeutic substances inside to reach target areas.
Scientists are therefore working on developing ways to subvert this problem, and one team seems to have come up with an intriguing possibility: a tiny, drug-loaded device as thin as a strand of hair that could be implanted into the brain for the targeted delivery of therapeutics. And as they’ve designed the system to be wireless, it can be activated by a remote control, adding further precision.
“Now, we literally can deliver drug therapy with the press of a button,” co-first author Jordan McCall from Washington University School of Medicine said in a statement. “We’ve designed it to exploit infrared technology, similar to that used in a TV remote.”
For the investigation, published in Cell, scientists began by engineering an incredibly thin device consisting of four chambers to carry the therapeutics and microscopic pumps to release them. Using soft, malleable materials, the device is designed to not cause damage to delicate brain tissue or prompt inflammatory responses following implantation, but it’s robust enough to provide prolonged function.
To test out their invention, the researchers inserted them into one side of a mouse’s brain involved in motor control and remotely triggered the release of a neuronal stimulant, which caused the animals to run around in a circle.
Next, they took their investigation one step further by combining it with a technique known as optogenetics. As the name suggests, this combines genetics with light. More specifically, it involves engineering a specific set of cells to produce a light-sensitive protein that can be stimulated or inhibited with a specific wavelength of light.
By targeting dopamine-producing cells, the researchers were able to use light to trigger the release of this “feel good” reward chemical when mice entered specific areas of a maze. This meant that in subsequent tests, even without stimulation, the animals would choose to return to these locations in order to seek the same reward. But when the researchers used their device to release a drug that prevents dopamine from sticking to cells, they successfully interfered with this light-driven pursuit.
“In the future, it should be possible to manufacture therapeutic drugs that could be activated with light,” co-principal investigator Michael Bruchas said in a statement. “With one of these tiny devices implanted, we could theoretically deliver a drug to a specific brain region and activate that drug with light as needed. This approach potentially could deliver therapies that are much more targeted but have fewer side effects.”
Ultimately, the researchers hope to target neural circuits involved in pain, epilepsy or even depression, but for now its use in animal models could help further our knowledge of the links between brain function and behavior.