During surgery, accidental nerve severing can result in pain, numbness and even paralysis. Now, researchers at the University of California–San Diego (UCSD) have introduced a possible solution to these potential problems in the operating room: an injectable fluorescent peptide that specifically recognizes peripheral nerves.

“We wanted to develop a probe that will allow us to see the nerve before we can encounter them, even if the nerve is injured,” says UCSD head and neck surgeon Quyen Nguyen, who led the study.

Surgeons are trained to know where our nerves are and where they run in our bodies. The trouble is that there are no direct imaging tools, and when nerves are already damaged or are buried in tumors, existing tools that rely on indirect measures of electrical conductance cannot easily identify them.

To tackle this issue, Nguyen and her colleagues identified a fluorescent peptide that binds proteins specific to the peripheral nerves. In a study published this week in Nature Biotechnology, the UCSD team found that within two hours of injecting their probes into laboratory mice, the peripheral nerves lit up and could easily be distinguished from the surrounding implanted tumor tissue.

By injecting in another fluorescent peptide that specifically labels tumor margins, developed by the team in 2010, Nguyen says surgeons should now be able cut out tumors while still preserving the surrounding nerves.

The following video of a mouse with a tumor in its leg shows in principle how this could work in the operating room. By switching between white and fluorescent light sources, a surgeon could visualize the tumor and the surrounding blood vessels, then the tumor margin (green) and finally the nerve that is partially buried by the tumor (aqua).