Muscle paralysis can be caused by a number of factors, but injured motor neurons that no longer conduct signals from the brain to control muscle movement are often the underlying condition. While electrical stimulation holds promise for overcoming certain types of paralysis, damaged motor neurons prevent even that approach. Researchers from University College London and King’s College London have just reported in journal Science on a new light-based technique that restores muscle movement in mice with injured motor neurons.
The mice had new motor neurons, that were generated from embryonic stem cells, grafted onto the injured nerves. The neurons were engineered to depolarize when illuminated via a light-sensitive ion channel that was genetically introduced into the cells. When blue light was introduced to the grafted cells, the muscles contracted. The team believes that within five years clinical trials of the technology, in the form of an optical pacemaker, will be underway in human patients, hopefully including people that were otherwise told they’ll be permanently in a wheelchair. Additionally, the same approach may help restore the functionality of the diaphragm in certain patients living on a ventilator.
“We custom-tailored embryonic stem cells so that motor neurons derived from them can function as part of the muscle pacemaker device.” said Dr. Ivo Lieberam, co-author of the study, in a statement. “First, we equipped the cells with a molecular light sensor. This enables us to control motor neurons with blue light flashes. We then built a survival gene into them, which helps the stem-cell motor neurons to stay alive when they are transplanted inside the injured nerve and allows them to grow to connect to muscle.”