Scientists are developing tiny, wireless bioelectronics that can travel through the bloodstream and autonomously target specific brain regions for treatment.
In experiments with mice, these miniature devices were shown to identify and reach their target areas without human intervention and to be wirelessly powered, delivering precise electrical stimulation.
Such stimulation, known as neuromodulation, has shown promise in treating brain tumours and diseases such as Alzheimer’s disease and multiple sclerosis.
Because the electronic devices are integrated with living biological cells before injection, they are not recognised by the body’s immune system. They can cross the blood-brain barrier while leaving it intact. This maintains the barrier’s crucial protection of the brain.
The researchers demonstrated the use of this technology – ‘circulatronics’ – to target brain inflammation, a major factor in the progression of many neurological diseases.
They show that the implants can provide localised neuromodulation deep inside the brain, achieving high precision, to within several microns around the target area.
In addition, the biocompatible implants do not damage surrounding neurons.
Circulatronics technology has potential to make therapeutic brain implants accessible to all by eliminating the need for surgery.
This is according to Deblina Sarkar, the AT&T Career Development Associate Professor in the MIT Media Lab and the MIT Centre for Neurobiological Engineering, head of the Nano-Cybernetic Biotrek Lab, and the senior author of the study.
She is joined on the paper by lead author Shubham Yadav, an MIT graduate student, as well as others at MIT, Wellesley College, and Harvard University. The research was published in Nature BioTechnology.
Key to their operation is the high wireless power conversion efficiency of the tiny electronics. This enables the devices to operate deep within the brain while still harnessing sufficient energy for neuromodulation.
The researchers use a chemical reaction to bond electronic devices to cells. In the study, they fused the electronics with monocytes, a type of immune cell that targets areas of inflammation in the body.
They also applied a fluorescent dye, allowing them to trace the devices as they crossed the intact blood-brain barrier and self-implanted in the target brain region.
While this study explored brain inflammation, the researchers aim to use different cell types and engineer them to target specific brain regions.
Because the circulatronics devices are so tiny, they offer much higher precision than conventional electrodes. They can self-implant, forming millions of microscopic stimulation sites that match the exact shape of the target region.
Their small size also enables biocompatible devices to coexist with neurons without causing adverse effects. Through a series of biocompatibility tests, the researchers found that circulatronics can safely integrate into neurons without affecting brain processes underlying cognition or motor function.
After the devices have self-implanted in the target region, a clinician or researcher uses an external transmitter to emit near-infrared light, which powers the technology and enables electrical stimulation of the neurons.
The Sarkar lab is currently working on developing their technology to treat multiple diseases, including brain cancer, Alzheimer’s disease and chronic pain.
