A team of researchers at Washington University School of Medicine in St. Louis along with colleagues at the University of Illinois at Urbana-Champaign developed a wireless device just the width of a human hair that, they say, can be implanted in the brain to deliver drugs when activated by remote control. (See Figure 1)

Fig. 1 – Tiny, implantable devices are capable of delivering light or drugs to specific areas of the brain, potentially improving drug delivery to targeted regions of the brain and reducing side effects. (Credit: Alex David Jerez Roman)
Their research builds on earlier work in optogenetics, which makes individual brain cells sensitive to light and then activates those targeted populations of cells with flashes of light. The researchers made the tiny wireless devices capable of delivering drugs directly into the brain, using the remote push of a button.

“In the future, it should be possible to manufacture therapeutic drugs that could be activated with light,” said co-principal investigator Michael R. Bruchas, PhD, Associate Professor of Anesthesiology and Neurobiology at Washington University. “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.”

While previous attempts to deliver drugs to experimental animals required that the animals to be tethered to pumps and tubes restricting their movement, the new devices were built with four chambers to carry drugs directly into the brain. By activating brain cells with drugs and with light, the scientists explain that they are able to get an unprecedented look at the inner workings of the brain.

The technology, which has been demonstrated in mice, could one day be used to treat pain, depression, epilepsy, and other neurological disorders in people using targeted therapies to specific brain circuits, according to first author Jae-Woong Jeong, PhD, a former postdoctoral researcher at the University of Illinois and now assistant professor of electrical, computer and energy engineering at the University of Colorado, Boulder. “The device embeds microfluid channels and microscale pumps, but it is soft like brain tissue and can remain in the brain and function for a long time without causing inflammation or neural damage,” said Jeong.

As part of the study, the researchers showed that by delivering a drug to one side of an animal’s brain, they could stimulate neurons involved in movement, causing the mouse to move in a circle.

In other mice, shining a light directly onto brain cells expressing a light-sensitive protein prompted the release of dopamine, a neurotransmitter that rewarded the mice by making them feel good. The mice then returned to the same location in a maze to seek another reward. But the researchers were able to interfere with that light-activated pursuit by remotely controlling the release of a drug that blocks the action of dopamine on its receptors.

The researchers also believe that similar, more flexible devices could have applications in areas of the body other than the brain, including peripheral organs.

For now, the devices contain only four chambers for drugs, but in the future, the researchers hope to incorporate a design much like a printer’s ink cartridge so that drugs can continue to be delivered to specific cells in the brain, or elsewhere in the body, for as long as required without the need to replace the entire device.

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