The plastic tube that helps injured nerves grow together

A minor injury to the nerves outside the brain and spine can be repaired either by transplantation or by pulling out the nerves a little. But in case of major nerve damage in the arm, for example, it becomes more difficult.

But in a new study, US researchers have tested using a small tube loaded with so-called GDNF proteins to cause broken nerves in some macaques' arms to grow together. According to the researchers, the pipes that you operate in should be broken down by itself in the body.

"They are converted into carbon dioxide that you exhale and water that you exhale," says Kacey Marra of the University of Pittsburgh, one of the researchers behind the study.

Klas Kullander, researcher in neuroscience at Uppsala University, finds the study interesting.

- It is an exciting and attractive study. There are occasional studies like this that improve nerve growth and it is always a matter of being able to prove that it will actually help people. But this looks very promising.

However, he believes that side effects could occur with precisely GDNF, which is the so-called growth factor that causes the nerves to grow. GDNF has the ability to possibly affect the pain system in the body.

- It could lead to increased pain sensitivity, but the study does not include such measurements, says Klas Kullander.

Kacey Marra replies that they did not see any increased pain in the monkeys they did the tests on.

- We have looked closely at the side effects of GDNF in the animals and we have not seen any, she says.

What many people may think of when talking about plastic surgery tubes in the body is Paolo Macchiarini's infamous throat surgery that led to a number of patients dying. How safe is it to actually put plastic into the body?

- We did not use stem cells (as Macchiarini reports). Macchiarini's work is very different from ours. We have done mechanical tests to confirm that our nerve conductors have the correct mechanical properties. It's not at all like his failed attempt, ”says Kacey G. Marra.

If all goes well, when do you think these tubes can be tested on humans?

- We hope to get approval to do the first study on humans in 2021, says Kacey G. Marra.

The study was published in the journal Science Translational Medicine.