A brain implant was made to restore arm and leg movements. This newest device was developed by British scientists and their goal was to boost connections between neurons and the paralyzed limbs. This invention provides hope to those who have lost mobility to what was once important to them.
What the device does is combine flexible electronics and human stem cells, which is the body’s ‘reprogrammable’ master cells, in order to seamlessly integrate with the nerve and access limb function once again.
There have been previous attempts at using neural implants to restore limb function once, but they have failed. That’s because the scar tissue that forms after can be found around the electrodes as time passes. The tissue limits or stops the connection between the device and the nerve. So, what they did is sandwich a layer of muscle cells that have been reprogrammed from stem cells between the electrodes and the living tissue in rats. The inventors discovered that the device made can finally be integrated with the host’s body. Thus, scar tissue formation was prevented in the process.
The cells were placed on the electrode for the 28-day experiment and had survived all throughout. This was the first time this kind of experiment was monitored for this time period. The researchers claimed that with the combination of two advanced therapies for nerve regeneration, cell therapy and bioelectronics, and put it in one device, they were able to overcome the shortcomings of the two types of approaches. Hence, they were able to make improvements on functionality and sensitivity.
“This was a high-risk endeavor, and I’m so pleased that it worked,” said Professor George Malliaras from Cambridge’s Department of Engineering. He had co-led the research made. “It’s one of those things that you don’t know whether it will take two years or ten before it works, and it ended up happening very efficiently.”
“This interface could revolutionize the way we interact with technology,” also shared co-first author Amy Rochford, who worked with the professor’s team. “By combining living human cells with bioelectronic materials, we’ve created a system that can communicate with the brain in a more natural and intuitive way, opening up new possibilities for prosthetics, brain-machine interfaces, and even enhancing cognitive abilities.”
Still, further intensive and extensive research and testing is required before the device can be applied for human use. However, this shows a promising development for amputees or those people who have lost limb function. The results were reported this month in the journal Science Advances.
There is also the huge challenge when attempting to reverse the injuries. One of which is the inability of neurons to regenerate and rebuild the disrupted neural circuits in the brain.
“If someone has an arm or a leg amputated, for example, all the signals in the nervous system are still there, even though the physical limb is gone,” Dr. Damiano Barone said. He is from Cambridge’s Department of Clinical Neurosciences and he also co-led the research. “The challenge with integrating artificial limbs, or restoring function to arms or legs, is extracting the information from the nerve and getting it to the limb so that function is restored.”
A possible answer to this problem is to implant a nerve in the large muscles of the shoulder and to attach electrodes to it. However, there is a problem, and that is a scar tissue forms around the electrode. Moreover, it is only possible to extract surface-level information from the electrode that they’ll use.
To get a finer resolution, any implant for restoring function would require extracting much more information coming from the electrodes. When it comes to enhancing sensitivity, they are looking into designing a device that may be efficient on the scale of a single nerve fiber, or what they call axon.
“An axon itself has a tiny voltage,” Barone explained. “But once it connects with a muscle cell, which has a much higher voltage, the signal from the muscle cell is easier to extract. That’s where you can increase the sensitivity of the implant.”
The researchers were able to design a biocompatible flexible electronic device that’s made thin enough to be attached to a nerve ending. A layer of stem cells, which have been reprogrammed into muscle cells, was mounted on the electrode. This is the first time ever that this kind of stem cell, called an induced pluripotent stem cell, has been used on any living thing in this method.
“These cells give us an enormous degree of control,” Barone said. “We can tell them how to behave and check on them throughout the experiment. By putting cells in between the electronics and the living body, the body doesn’t see the electrodes, it just sees the cells, so scar tissue isn’t generated.”
In order to test out its effectivity, the Cambridge biohybrid device was implanted into the paralyzed forearm of the rats. The stem cells first had to be transformed into muscle cells before this happened and then integrated with the nerves in the forearm of the rats. While the rats were not able to regain movement in their forearms, the device had successfully picked up the signals from the brain, those that controlled movement. If this were to be connected to the rest of the nerve or a prosthetic limb, it may just restore movement.
The cell layer used also improved the device’s function by enhancing resolution and allowing long-term monitoring from within. The best part is that the cells survived the 28-day experiment. This is the first time it has happened.
The researchers say that this newest approach comes with several advantages, especially compared to previous attempts to restore function for amputees. Aside from a more seamless integration and long-term stability, the device is small enough to be implanted. In fact, a keyhole surgery would suffice. Previous neural interfacing technologies when it comes to restoring function need complex patient-specific interpretations of cortical activity to be linked to muscle movements. On the other hand, this Cambridge-developed device is highly scalable because it makes use of ‘off the shelf’ cells coming from the University’s Kotter lab, which are owned by synthetic biology company bit.bio.
Aside from the potential for the restoration of function for those who have lost the use of a limb or limbs, this device may also be able to control prosthetic limbs by interacting with specific axons for motor control.
“This technology represents an exciting new approach to neural implants, which we hope will unlock new treatments for patients in need,” said co-first author Dr Alejandro Carnicer-Lombarte. He is also from the Department of Engineering.
The researchers are currently looking into further optimizing the devices and improving scalability. They have also filed a patent application with the help of Cambridge Enterprise, the University’s technology transfer arm, the one that supports its commercialization.
Recommended For You
