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Restoring Function to Paralyzed Muscles with Light-activated Neurons from Stem Cells

Published : 2014-04-04
Author : University College London - Contact: Harry Dayantis - h.dayantis@ucl.ac.uk - Ph. 44-020-310-83844

🛈 Synopsis : New way to artificially control muscles using light has potential to restore function to muscles paralyzed by conditions such as motor neuron disease and spinal cord injury.

Main Digest

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.

A neuron (neurone or nerve cell) is an electrically excitable cell that processes and transmits information through electrical and chemical signals. These signals between neurons occur via synapses, specialized connections with other cells. Neurons can connect to each other to form neural networks. Neurons are the core components of the nervous system, which includes the brain, and spinal cord of the central nervous system (CNS), and the ganglia of the peripheral nervous system (PNS). Specialized types of neurons include: sensory neurons which respond to touch, sound, light and all other stimuli affecting the cells of the sensory organs, that then send signals to the spinal cord and brain; motor neurons that receive signals from the brain and spinal cord, to cause muscle contractions, and affect glandular outputs, and inter-neurons which connect neurons to other neurons within the same region of the brain or spinal cord, in neural networks.

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.

"Following the new procedure, we saw previously paralyzed leg muscles start to function," says Professor Linda Greensmith of the MRC Center for Neuromuscular Diseases at UCL's Institute of Neurology, who co-led the study. "This strategy has significant advantages over existing techniques that use electricity to stimulate nerves, which can be painful and often results in rapid muscle fatigue. Moreover, if the existing motor neurons are lost due to injury or disease, electrical stimulation of nerves is rendered useless as these too are lost."

Diagram showing how the system works (credit: Barney Bryson)
Diagram showing how the system works (credit: Barney Bryson)

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

"This new technique represents a means to restore the function of specific muscles following paralyzing neurological injuries or disease," explains Professor Greensmith. "Within the next five years or so, we hope to undertake the steps that are necessary to take this ground-breaking approach into human trials, potentially to develop treatments for patients with motor neuron disease, many of whom eventually lose the ability to breathe, as their diaphragm muscles gradually become paralyzed. We eventually hope to use our method to create a sort of optical pacemaker for the diaphragm to keep these patients breathing."

The light-responsive motor neurons that made the technique possible were created from stem cells by Dr Ivo Lieberam of the MRC Center for Developmental Neurobiology, King's College London.

"We custom-tailored embryonic stem cells so that motor neurons derived from them can function as part of the muscle pacemaker device." says Dr Lieberam, who co-led the study. "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."

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Cite Page: Journal: Disabled World. Language: English (U.S.). Author: University College London. Electronic Publication Date: 2014-04-04. Title: Restoring Function to Paralyzed Muscles with Light-activated Neurons from Stem Cells, Source: <a href=https://www.disabled-world.com/news/research/stemcells/neurons.php>Restoring Function to Paralyzed Muscles with Light-activated Neurons from Stem Cells</a>. Retrieved 2021-04-13, from https://www.disabled-world.com/news/research/stemcells/neurons.php - Reference: DW#143-10206.