Tiny device 'could repair damaged nerves'

Tiny computer-generated implants “can help restore feeling in severely injured limbs”, according to the Daily Mail.

The news is based on tests of a type of tiny scaffold designed to help nerves in the limbs reconnect after they have been damaged. The honeycomb-like device contains tiny channels designed to guide the growth of nerve cells and speed up their repair. The device is also made of a substance that dissolves in the body, meaning it would not need to be removed using tricky surgery if used in patients.

This interesting work is still at an early stage, and so far has only been tested in a laboratory, where scientists looked at whether nerve cells could be grown on the scaffold. This means it is a long way from human testing, as we still don’t know whether it can repair nerves in living creatures such as rats. Further experimental clinical studies will be required to see if it aids nerve growth in animals, and whether any nerve repair performed will improve functions such as movement. It should be noted that the device is being developed to aid the repair of the peripheral nervous system which controls the limbs and body, and not to repair the spinal cord, which is part of the central nervous system. However, the researchers state that if successful, the treatment of other types of nerve damage could be investigated.

Where did the story come from?

The study was carried out by researchers from the University of Sheffield, Laser Zentrum Hannover eV in Germany and the University of North Carolina in the US. It was funded by the UK Engineering and Physical Sciences Research Council and the German Research Foundation. The study was published in the scientific journal Biofabrication.

This story was accurately reported by BBC News and the Daily Mail.

What kind of research was this?

The human nervous system is incredibly complex and nuanced, and damage to the fine thread-like nerve fibres can cause permanent movement problems or even paralysis. Given our current level of technology, trying to repair damaged nerves poses significant challenges in medicine. The peripheral nervous system can regrow naturally and heal small injuries, but larger injuries require surgical intervention. However, this process is difficult and uncertain, and requires a donor nerve, causing loss of sensation at the donor site.

In this laboratory-based study, researchers made and tested an experimental “nerve guidance conduit” to see if it was suitable for growing nerve cells. Nerve guidance conduits are tiny structures intended to encourage and guide the regrowth of nerves. In the future, it is hoped they could be used to aid recovery in the peripheral nervous system. Recovery to peripheral nervous system damage is possible, but it is hoped that nerve guidance conduits could improve the rate of recovery and the distance over which recovery can occur.

In this research, the conduit was designed in the form of a “honeycomb” structure intended to guide regrowth through a number of small channels. The conduit is made from a biodegradable substance called photopolymerizable polylactic acid resin. It is hoped that after recovery, the conduit could be absorbed by the body and, therefore, would not need to be removed.

This initial study aimed to determine whether the conduit could in principle be used to grow nerve cells in the laboratory, rather than testing its use in nerve regrowth and repair after an induced injury.

What did the research involve?

The researchers manufactured the polylactic acid resin and made the scaffold using two different techniques. It was made of a “photopolymerizable” substance, which means that light can be used to build up structures by fusing individual molecules. In this case, the light was delivered using lasers, allowing a fine degree of control and the ability to make very small, fine structures. The researchers then used micromolding to generate multiple copies of identical scaffolds. Micromolding allows the scaffold to be produced quickly and cheaply.

The researchers then performed a number of biological tests, to check that the material could support nerve cell growth and to ensure that it did not damage the cells’ DNA.

What were the basic results?

The researchers tested whether the polylactic acid resin used to make the scaffold could support the growth of human neuronal cells. They also tested growing rat Schwann cells as they have been shown to be important in repairing damaged nerves. Schwann cells grow alongside nerve cells and support their functions.

The researchers found that both types of cells could grow on the polylactic acid resin, and that there was no evidence of DNA damage if the resin was washed in alcohol before use. They also found that the Schwann cells could grow normally on the 3D scaffold.

How did the researchers interpret the results?

The researchers concluded that polylactic acid scaffolds “are potential platforms for peripheral nerve repair studies”.

Conclusion

Nerve damage can cause significant loss of mobility and physical functioning, whether it occurs in the central nervous system (the brain and spinal cord) or the peripheral nervous system, which connects the limbs and body to the spinal cord. While it is technically possible to repair damage to the peripheral nervous system, the process is challenging, slow and not guaranteed to work.

This study has described a scaffold made of a biodegradable compound that supports the growth of two types of cell in the peripheral nervous system: the neural and Schwann cells. This suggests that the honeycomb scaffold could be used in the future to aid recovery to nerve damage in the peripheral nervous system, by guiding nerve regrowth through a number of small channels. The biodegradable scaffold would then dissolve over time, meaning it would not need to be extracted later.

Overall, this initial study has shown that the scaffold is able to support neural cell growth in the laboratory. However, this is early-stage research and further clinical studies will be required to see if it aids nerve growth in animals and then humans. Also, it remains to be seen whether the regrowth it promotes can improve functions after nerve damage.