Brain implant that restores arm, leg movements developed by scientists

By Mark Waghorn via SWNS

A brain implant that restores arm and leg movements has been developed by British scientists.

It boosts connections between neurons and the limbs - offering hope to accident and stroke victims.

It worked in rats that had lost the use of their arms - meaning paralyzed patients may be able to get back mobility.

The "biohybrid" device combines flexible electronics and human stem cells – the body's 'reprogrammable' master cells – to better integrate with the nerve and drive function.

Project leader Dr. Damiano Barone, from Cambridge's Department of Clinical Neurosciences, said: "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.

"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."

To perform even the simplest movement, our nervous system has to coordinate hundreds of muscles.

A huge challenge when attempting to reverse injuries that result in the loss of a limb or the loss of function of a limb is the inability of neurons to regenerate and rebuild disrupted circuits.

Previous attempts at brain implants have mostly failed. Scar tissue tends to form around them over time.

Dr. Barone and colleagues got around this problem by sandwiching a layer of muscle cells between the electrodes and the living tissue.

The device integrated with the host's body. The cells survived for the duration of the 28-day experiment, the first time this has been achieved over such a long period.

Combining two advanced therapies overcame all the shortcomings - improving functionality.

To improve sensitivity, the researchers wanted to design something that could work on the scale of a single nerve fiber, or axon.

Dr. Barone explained: "An axon itself has a tiny voltage. 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 device is thin enough to be attached to the end of a nerve. A layer of stem cells was then placed on the electrode.

It's the first time that this type of stem cell, called an induced pluripotent stem cell, has been used in a living organism in this way.

Dr.Barone said: "These cells give us an enormous degree of control. 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."

The biohybrid was implanted into the paralyzed forearm of the rats. The transformed stem cells integrated with the damaged nerves in the forearm.

Signals from the brain that control movement were picked up. If connected to the rest of the nerve or a prosthetic limb, the device could help restore movement.

The cell layer also improved the function of the device by improving resolution and allowing long-term monitoring inside a living organism.

The approach has multiple advantages over other attempts to restore function in amputees - including being so small insertion would only require keyhole surgery.

The device could also be used to control prosthetic limbs by interacting with specific axons responsible for motor control.

Co-first author Amy Rochford said: "This interface could revolutionize the way we interact with technology.

"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."

Losing use of the arms and hands - ranging from struggling to bend the wrist to complete paralysis - are among the most life-altering complications of stroke and severe spinal cord injury.

Even mild immobility significantly limits quality of life and independence - making it an important focus in the field of neuro-rehabilitation.

Co-first author Dr. Alejandro Carnicer-Lombarte said: "This technology represents an exciting new approach to neural implants, which we hope will unlock new treatments for patients in need."

Currently, there are no therapies or medical technologies that provide motions and dexterity - skills that set primates and humans apart from other mammals.

They include rotating the arm in the shoulder, bending it at the elbow, flexing and extending the wrist and altering the grip by changing positions of individual fingers.

It allows for extremely complex control of the way we hold objects and otherwise interact with the world.

That amazing ability is also what makes getting arm and hand movement back extraordinarily difficult.

Project co-leader Professor George Malliaras said: "This was a high-risk endeavour, and I'm so pleased it worked.

"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."

The researchers are now working to further optimize the devices and improve their scalability.

The team have filed a patent application on the technology with the support of Cambridge Enterprise, the University’s technology transfer arm.

While extensive research and testing will be needed before it can be used in humans, the device is a promising development for amputees or those who have lost function of a limb or limbs.

The results are reported in the journal Science Advances.