Cellular camouflage

July 1, 2018
Cellular Stealth

The Lieber Lab’s brain-like neural implants could help prevent and treat neurological disease

 
By Caitlin McDermott-Murphy

 

The brain is a hostile environment. Hot, humid, and outfitted with a personal immune system, it’s unwelcoming to even the most resilient visitor. Researchers have learned much from new brain imaging technologies, but there’s only so much surveillance that can be performed from outside the cranial walls. To learn more, they need a spy.

Clinicians already use neural implants to produce deep brain stimulation and ease symptoms of neuromuscular diseases like Parkinson’s. But many of these implant designs cannot sustain symbiosis with the brain. Some are too large; others fail to camouflage. Once the brain identifies the foreign object, it rallies its immune system to fight. Over time, the resultant inflammation and scar tissue can isolate the device and impede its ability to perform.

Now, Charles M. Lieber, the Joshua and Beth Friedman University Professor of Chemistry, has invented a way to disguise his sensors in the brain’s harsh ecosystem. He and his lab created an ultra-flexible mesh—like a microscopic fishing net—that mimics brain tissue. The mesh holds sensors as small as a single neuron, or roughly three nanometers wide. Comparatively, a single strand of hair, about 75,000 nanometers wide, would dwarf the device.

“By designing the mesh electronics such that all key properties are neuromorphically similar to neural tissue,” Lieber explains, “we eliminate chronic immune response that is found with all other probes and medical implants, which are more like thorns in your tissue.”

The Lab’s sensors camouflage so well that, just three months post-placement, brain tissue surrounds and merges with the mesh. These biocompatible electronics can endure far longer than the typical sensor. Instead of days to weeks, they can last for months, or even years. And, insertion does not require surgery. Instead, the team can draw the flexible mesh into a syringe and inject it into its host. There, it unfurls its porous net without disturbing the natural surroundings.

This technique, Lieber notes, “opens up unprecedented opportunities for high-resolution, longitudinal studies to interrogate age-dependent neural circuit evolution underlying neurodegenerative processes—such as the memory decline and learning impairment associated with Alzheimer’s disease—from a single-neuron perspective.”

In a recent world first, Lieber and post-doctoral fellow Guosong Hong used the mesh electronics to study the retina of live, active mice. Previous research required removal of the retina, which prevented scholars from observing how retinal cells communicate and behave over time. But the team had a solution: their mesh net “unrolls inside the eye and conformally coats the highly curved retina without compromising normal eye functions.”

For the first time in the history of retinal research, Lieber and Hong recorded retinal activity over not just hours but weeks, and discovered that retinal cells are active in shifts. Some cells increased their activity during the day while others took over at night, according to Hong. Next, he plans to use this technique to study glaucoma and, eventually, gain a strong enough understanding of the disease to develop new treatment options.

In time, the Lieber Lab’s camouflage nets could deliver precious inside information from the most mysterious human frontier. With neurological disorders affecting more and younger segments of our population than ever before, this knowledge is critical. The Lieber Lab’s innovative implants may just provide the cellular espionage we need to crack the code and reverse this troubling trend.

 

See also: Faculty, Research, Lieber