Making Nerves Glow Could Make Surgery Safer
CREDIT: Quyen Nguyen
A team of surgeons and biochemists from the University of California at San Diego has come up with a way to make nerve tissue glow temporarily. The technique could help doctors avoid accidentally severing nerves during surgery and minimize the risk of post-operational numbness and paralysis.
The process involves creating a virus-like probe that will stick to a nerve cell, carrying a fluorescent tag with it. The researchers report that it has been successful in mice.
I'm a head and neck surgeon, and in my line of work, preservation of nerves is really important, said Quyen Nguyen, a collaborator on the project. Surgeons spend a lot of time training to recognize where they should be.
In many scenarios, finding and mapping nerves is a matter of trial and error. Surgeons use an approach called electromyography, in which they slowly probe unidentified tissue with the tip of an electrode. When the electrode comes into contact with a motor nerve, the associated muscle twitches. A beep signals the hits back to the surgeon.
The approach helps surgeons to know where nerves are, but not to see them any better. And it only works with motor nerves, leaving the sensory fibers that relay our feeling of touch completely vulnerable.
We wanted to have a visual guide, Nguyen told InnovationNewsDaily.
She and her colleagues came up with an idea to label nerve tracts with fluorescent tags so that the entire system would suddenly become visible when seen under the right light. All they had to do was find a way to make the tags stick preferentially to nerve tissue.
Fortunately for their research, there are viruses, called phages, that specialize in grabbing onto bacterial cells by fusing to chemicals on the cell membrane.
By looking at the way phages stick to human cells, researchers could design synthetic probes to behave the same way and label tissues in the body.
The group found a phage specific to nerves and synthesized only that part that anchors in the foreign cell. They then attached a fluorescent label to the probe, so that every cell it stuck to would light up.
The team first tried the probe on mice. Two hours after injecting it into the bloodstream, all of the nerves became fluorescent and contrasted vividly with the surrounding tissue.
If the technique passes all the hurdles of clinical trials, it could be especially useful when removing tumors that grow around sensory nerve bundles, Nguyen said. The risk of sensory nerve damage is particularly troubling when removing tumors in the prostate gland, as it can leave patients incontinent.
The first results in mice suggest that the probe is neither toxic nor disruptive to normal nerve functions. The protein fragment was quickly metabolized by the mice, meaning that patients wouldn't have fluorescent nerves forever.
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