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Biohybrid Device Shows Promise for Restoring Function in Paralysed Limbs

A new type of neural implant designed to improve the connection between the brain and paralysed limbs has been demonstrated by UK scientists in a proof-of-concept trial in rats. 

The device combined bioelectronics and stem cells to improve integration with nerves, researchers at the University of Cambridge reported in the journal Science Advances.

A major challenge for reversing the effect of injury to the peripheral nervous system is the inherent inability of neurons to regenerate and to rebuild disrupted neural circuits. "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," said Dr Damiano Barone from the university's Department of Clinical Neurosciences, who co-led the research.

Implantable neurotechnology and cell therapy are rapidly developing as potential effective treatments, but the technique faces a number of obstacles, including cell damage from the original injury, and the tendency for scar tissue to form around the implant.

Sandwiching Muscle Cells Between Electrodes and Living Tissue

To get round those limitations, the Cambridge scientists designed a biocompatible flexible electronic device, thin enough to be attached to the end of a nerve, over which a layer of stem cells, reprogrammed into muscle cells, was placed. "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,” explained Dr Barone.

The biohybrid device was tested by implanting it into the paralysed forelimb of the rats. The team reported that although the rats did not have function restored to their limb, the device was able to pick up the signals from the brain that control movement. The cell layer was found to improve function of the device, prevented scar tissue forming, improved resolution, and allowed monitoring during the 28-day trial. According to the scientists, this was the first time that cells had been demonstrated to survive an extended experiment of this kind.

"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," said Amy Rochford from Cambridge's Department of Engineering, and the study's first co-author. According to co-first author, Dr Alejandro Carnicer-Lombarte, also from the Department of Engineering, the technology "represents an exciting new approach to neural implants, which we hope will unlock new treatments for patients in need".

In a press release, the University of Cambridge said that the technology relied on a precision cellular reprogramming technology, known as opti-ox, and supplied by the university's Kotter lab, "that enables a faithful execution of genetic programmes in cells, allowing them to be manufactured consistently at scale". 

The research was partly funded by the Engineering and Physical Sciences Research Council, part of UK Research and Innovation, Wellcome, and the European Union's Horizon 2020 Research and Innovation Programme.