How a Silkworm's Threads Could Repair Spinal Cords

A remarkable number of companies have managed to spin off from silkworms, and for good reason. Turns out that silk has several qualities that make it remarkably suitable for spinal nerves to grow on, according to a new paper published in Scientific Reports. In theory, that would make it a prime material to use for experiments like those that try to reconnect neurons and fix spinal cord injuries. 

Naturally, the authors of this new paper, all of whom are based in the United Kingdom, have started a company to capitalize 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.

It’s not like silk is completely 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.

Silk is actually made of chains and sheets of a protein called fibroin. The way the fibroin is arranged can vary depending on what type of silkworm produced it. Bombyx mori worms make most of the silk used in sutures. But processed silk from another species, Antheraea pernyi, seemed to provide a much better surface for spinal nerves to grow, which the researchers already knew from previous studies.

But they still needed to figure out if Antheraea pernyi's silk met all the necessary criteria to work in humans. Was the silk “sticky” enough for nerve cells to grow? Would it be stiff enough to support the cells without setting off an attack from the human immune system? Would it fade away eventually, allowing the nerves to stand on their own without requiring a second operation to remove the silk?

Antheraea_pernyi_6th_instar_5_sjh Not just a pretty face, this Antheraea pernyi worm could produce a silk that spinal nerves can grow on. Shawn Hanrahan/Wikimedia Commons

The answer to those questions were all yes. It could work in a human. In fact, some of the nerves grew along the silk threads “surprisingly rapidly,” the authors noted. But for now, the material has only been tested in rats. And having a material is not enough; research on regenerating spinal cord neurons is ongoing. 

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.

Even seven years ago, there were people investigating how silk could treat brain diseases. One group made electrodes for brains with silk and used them in cats to show that they could be used to treat epilepsy, Reuters reported.

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