Silk from wild Asian worms could help repair spinal, brain injuries

Silk from Asian wild silkworms – duly cleaned and sterilised, of course - has properties well suited for spinal cord repair following injury, according to a study.

The modified silk may also have the potential to aid repair following brain injury, researchers said.

Currently there is no cure for serious spinal cord trauma, in part because spinal nerves are unable to cross the scar tissue barrier and the cavity that forms in the cord after the injury.

Researchers from University of Oxford and University of Aberdeen in the UK discovered that modified silk from the Antheraea pernyi (AP) silk spinner had important properties desirable in a scaffold suitable for spinal repair.

The authors of this new paper, all of whom are based in the United Kingdom, have been prompt to start a company to capitalise on their work. The company, Oxford Biomaterials, has also been trying to work out if their spider silk-based product, Spidrex, could also treat some knee injuries or create a better graft for blood vessels.

Silk is far from being foreign to physicians. The sutures doctors use to close up cuts and incisions can be made of silk. But that silk is generally made from a different worm than the one the Oxford researchers studied.

The modified silk would be a 'scaffold' that bridges the spinal injury cavity, supporting nerve growth across damaged region, researchers said.

It has the correct rigidity: if it is too rigid it can harm the surrounding spinal cord tissue, but if it is too soft the nerves would fail to grow across it, they said.

The study, published in the journal Scientific Reports, found that AP silk has a repeated 'RGD' chemical sequence on its surface that binds to receptors on the nerve cells, encouraging them to attach to the material and grow along it.

Additionally the silk does not trigger a response by the immune system cells that would be present in the spinal cord, therefore minimising inflammation, researchers said.

The AP silk degrades gradually over time. So, after it has supported the early growth of nerves across the injury site, the material dissolves gradually and these pioneer nerves take over the role as scaffold, supporting further nerve growth, the authors said.

Spinal injuries affect up to 500,000 people globally every year. It can have devastating effects for people who suffer them, including loss of motor and sensory function below the level of injury, and bladder, bowel, and sexual dysfunction, researchers said.

"AP silk may also have the potential to aid repair following brain injury," said Wenlong Huang from the University of Aberdeen.

"These are still early bench-based studies but they certainly seem to show that AP silk has fantastic properties, especially suitable for spinal repair, and we look forward to researching this further," Huang said.

This is yet another, and at this stage by far the most important and exciting, example of the value of silks and their derivatives in modern medicine, with its emphasis on using natural regeneration for healing major as well as minor wounds, said Fritz Vollrath from University of Oxford.

Oxford is not the only group to explore some wacky applications for silk. Those same properties could also be used to store blood samples, for example. One startup, Cocoon Biotech, is trying to use silk to treat arthritis, STAT reported in 2015. Another company, Vaxess, is testing to see if silk proteins could help store and transport medications that are sensitive to things like heat, for example, according to Newsweek.