A new way to artificially control muscles using light, with the potential to restore function to muscles paralysed by conditions such as motor neuron disease and spinal cord injury, has been developed by scientists at UCL and King’s College London, co-led by Professor Linda Greensmith of the MRC Centre for Neuromuscular Diseases at UCL’s Institute of Neurology.
The technique involves transplanting specially-designed motor neurons created from stem cells into injured nerve branches. These motor neurons are designed to react to pulses of blue light, allowing scientists to fine-tune muscle control by adjusting the intensity, duration and frequency of the light pulses.
In the study, published this week in Science, the team demonstrated the method in mice in which the nerves that supply muscles in the hind legs were injured. They showed that the transplanted stem cell-derived motor neurons grew along the injured nerves to connect successfully with the paralyzed muscles, which could then be controlled by pulses of blue light.
Muscles are normally controlled by motor neurons, specialized nerve cells within the brain and spinal cord. These neurons relay signals from the brain to muscles to bring about motor functions such as walking, standing and even breathing. However, motor neurons can become damaged in motor neuron disease or following spinal cord injuries, causing permanent loss of muscle function resulting in paralysis
The light-responsive motor neurons that made the technique possible were created from stem cells by Dr Ivo Lieberam of the MRC Centre for Developmental Neurobiology, King’s College London.
Further information:
Bryson, Machado, Crossley, Stevenson, Bros-Facer, Burrone, Greensmith & Lieberam (2014) Optical-control of muscle function by transplantation of stem cell-derived motorneurons in mice. Science Vol. 344 no. 6179 pp. 94-97
DOI: 10.1126/science.1248523
Iyer, S.M. & Delp, S.L. (2014) Optogenetic regeneration Science, Vol. 344 no. 6179 pp. 44-45. DOI: 10.1126/science.1253088
The Graham Watts Laboratories for Research into Motor Neuron Disorders
Video animation explaining the new technique
Image: Diagram showing how the system works (credit: Barney Bryson)