Dalhousie research uses light to trigger previously unresponsive muscles in mice

HALIFAX – In a lab at Dalhousie University’s medical school, a few twitches of a mouse’s leg represent a big step forward for research into motor neuron disease.

A team of scientists at Dalhousie’s Medical School and the Brain Repair Centre harnessed the power of genetic manipulation and added the flash of an LED light available at any hardware store to achieve the discovery, which could have ramifications for people living with ALS.

“I think it’s one avenue, it’s not going to cure the disease,” said Dr. Victor Rafuse, professor in the Department of Medical Neuroscience and director of the Brain Repair Centre.

“Essentially, it’s just a new technology that can be explored to improve the quality of life of people who’ve lost function due to motor neuron disease or due to injury.”

Rafuse and his team, which includes Dr. Philippe Magown, Basavaraj Shettar, and assistant professor of medical neuroscience Dr. Ying Zhang, found a way to bypass the nervous system to activate unresponsive muscles in mice using light and genetics.

It’s a key discovery because in conditions like ALS, the nerve cells that control movement progressively degenerate.

“The nervous system controls the muscle and without the nervous system, the muscle is non-functional,” said Rafuse.

The team used genetics to insert a light-activated ion channel, first discovered in a single-celled aquatic algae, into the muscles of a group of mice.

The ion channel enabled the muscles to contract when stimulated with a blue LED light, which can be bought anywhere.

When the light is shone onto the mouse’s previously dead leg, it twitches.

“Blue light from a very off-the-shelf LED light can very efficiently not only control the muscle but do it in a way that’s almost indistinguishable from how the mouse can actually activate its own muscle,”said Rafuse.

Rafuse also said the light helps limit the atrophy, or degeneration of the muscle.

“If we just stimulated the muscle with light, through the skin, for one hour a day, we could not only prevent the atrophy, but very easily be able to control that muscle.”

The team’s next challenge is finding a way to transfer the successful results to humans.

The DNA manipulation needed to insert the light-sensitive ion channel can only be done on an embryo, which isn’t practical given that ALS symptoms aren’t usually seen until adulthood.

“Ultimately what we’d like to be able to do is follow up on these studies and find a way to express these channels in muscle without the use of genetics,” said Rafuse.

“You can’t manipulate human genetics.

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If it was ever successfully transferred to humans, the technology could have many potential uses.

Rafuse suggests maybe one day, a human with nerve damage to their hand would be able to restore some function.

“If they wore a glove with LED shining the lights in different patterns you might be able to restore simple grasping motions for these individuals,” he said.

There’s also the possibility of stimulating the diaphragm in ALS patients with respiratory problems.

The research has been published in the most recent issue of the journal Nature Communications.