Brain implants seem to offer many possibilities for patients with neurological problems. They may be able to help reduce seizures in people with epilepsy, bring sight to people who are blind, or restore function to paralyzed limbs, for some examples. Patients are even already being implanted with these devices, with varying degrees of success. And scientists have now shown that after a device is implanted into the brain, bacteria can invade the implant site. This invasion can cause inflammation, and seems to disrupt the effectiveness of these devices over time. The findings, which may help make these implants safer by bringing attention to the problem, have been reported in Nature Communications.
“Understanding the role of bacteria in implant performance and brain health could revolutionize how these devices are designed and maintained,” said senior study author Professor Jeff Capadona, Case Western Reserve University’s vice provost for innovation, among other appointments.
In this work, the researchers used a mouse model to implant devices into the brain, and observe the effects. Bacteria in the mouse brains were identified, and the scientists also characterized the gut bacteria of these mice. Not only were bacteria found in the brain with the implant, the investigators also determined that some of these bacteria were linked to the gut.
The blood brain barrier is an essential and unique shield that keeps many substances out of the brain. But the insertion of brain implants disrupts that barrier. The study authors suggested that this disruption may also be allowing microbes into the brain.
When the mice were treated with antibiotics, there was less bacteria in the brain. The devices were also working better than they did when antibiotics were not used. However, antibiotic use was not feasible over the long term because it damaged the implant's efficacy.
Some of the bacteria that were identified in the brains have previously been associated with neurodegenerative disorders like Alzheimer’s and Parkinson’s.
“This is a paradigm-shifting finding,” said first study author George Hoeferlin, Ph.D. “For decades, the field has focused on the body’s immune response to these implants, but our research now shows that bacteria, some originating from the gut, are also playing a role in the inflammation surrounding these devices.”
The researchers also suggested that this phenomenon is also occurring in human patients with brain implants. More research is needed to conform that finding.
“If we’re not identifying or addressing this consequence of implantation, we could be causing more harm than we’re fixing,” Capadona said. “This finding highlights the urgent need to develop a permanent strategy for preventing bacterial invasion from implanted devices, rather than just managing inflammation after the fact. The more we understand about this process, the better we can design implants that work safely and effectively.”
Now, the researchers want to learn more about the microbes that could be associated with shunts that are used in the brain.
Sources: Case Western Reserve University, Nature Communications
