text | Xu Rui
The implant consists of a flexible strip with small channels for chemicals to flow through. Image source: Northwestern University
Applying ice to the injured area can relieve pain. Now, a strip-shaped implant can achieve the same effect.
The study, published June 30 in science, reports that the implant is made of biodegradable materials and is designed to reduce postoperative pain. It relieves pain by "cooling" the nerve fibers in the body. The implant is absorbed by the body as pain subsides after surgery.
A study testing a prototype of the implant in rats found that the implant cooled nerve fibers to 10 degrees Celsius, reducing pain signals sent to the brain.
Better ways to relieve pain are urgently needed because current opioids can be addictive, and ice packs or cooling patches can provide temporary relief but can be uncomfortable and potentially damaging to use over time. skin.
Therefore, John Rogers of Northwestern University hopes to "drug" directly on the pain nerves.
The implant developed by Rogers' team is a thin, flexible strip that contains tiny channels for chemicals to flow through. One end can be wrapped around nerve fibers like a cuff, and the other end emerges from the skin and is connected to a small pump.
Nitrogen gas and the harmless liquid perfluoropentane (PFP) are pumped through small channels. The above chemicals mix at the distal end of the implant strip, causing the PFP to evaporate to create a cooling effect. Subsequently, the PFP gas and nitrogen return to the pump through the third channel and are separated again, turning the PFP back into a liquid.
The implant also contains a temperature sensor that monitors and regulates the cooling effect. The implant was tested by the
research team. They implanted it around the sciatic nerve in the legs of three rats with injured paws. Three weeks later, when each rat's paw was pressed with a sensitive measuring device, it took seven times more force to retract the leg with the implant cooling device turned on.
"That's a good sign that our implants are numbing their paws," Rogers said.
After 6 months, the device had been absorbed by the rats and no nerve damage was observed.
Rogers said the team now needs to continue testing the implant in animals to see how much nerves it can cool and for how long without causing harm.
Francis McGlone of Liverpool John Moores University in the United Kingdom said such implants may be most useful in patients with severe, long-term pain, a condition that is difficult to treat with opioids without developing tolerance.
McGlone points out that many pain relief methods that have previously worked in mice are ineffective in humans, but it is well established that cooling nerves impedes function in rats. "This is basic biological physiology. The basic principles are safe."
Related paper information:
https://doi.org/10.1126/science.abl8532
