3-D printed tube could regrow nerves

The 3-D printed guide could help regrow motor and sensory nerves.

by Ryan Faircloth

University of Minnesota researchers are working on finding a way to repair the motor and sensory functions in rats with damaged nerves by 3-D printing new ones.
Their preliminary research, published  earlier this month, could lead to the creation of custom nerves for humans, too.
Researchers are using a 3-D printer to create connections between two sides of a severed nerve, which, if applied to people, would open doors to fixing more complicated nerve breaks.
Current methods of nerve repair allow surgeons to stretch nerve ends back together or put a link between both ends, but they’re limited to repairing nerves traveling in a straight line, said University neuroscience professor Steve McLoon.
Because some injuries involve nerves with more complex structures, fixing them can be challenging and sometimes impossible, said Michael McAlpine, the study’s lead researcher and a mechanical engineering associate professor.
The 3-D printer’s non-linear nerve connections are made from silicone and attached on either end of a damaged nerve, McAlpine said, allowing the nerve to regrow inside the tube over time.
Researchers measure the exact proportions of the damaged nerve, which are then plugged into a computer connected to the printer, McAlpine said. The printer can use those measurements to design the connection to fit the exact shape of the damaged nerve.
Making the silicone tube “anatomically perfect,” he said, takes anywhere from 30 minutes to an hour.
Dr. Yasushi Nakagawa, a neuroscience associate professor, said he thinks the new technology will be useful in regenerating nerves that were once difficult to regrow. 
“I think getting the proper scaffold for regrowing [nerve fibers] is very helpful in nerve injury … because you have to get the nerve growing in the right place,” Nakagawa said.
Along with making the synthetic nerve connection itself, the printer creates proteins and chemicals that stimulate the nerve to regenerate itself, which can take up to three months, McAlpine said.
So far, the tube has only been tested on rats with a severed sciatic nerve — which connects the lower half of the body to the spine — but McAlpine said he hopes the team will be able to take the next step toward human trials.
Eventually, McAlpine said, he would like to create a library of unique nerve measurements to help patients in need of emergency nerve repair.
Nakagawa said the technology could be helpful to trauma patients, and he hopes the 3-D printer process will be applied to treating nerves in the spinal cord.
“Theoretically, I believe this 3-D model will improve accuracy of regrowth,” he said.