One of the toughest kinds of tissue to repair once it’s been damaged by injury of disease, is nerve tissue. Depending on where the neuropathy occurs, nerve damage is often a lifelong change; some nerves never heal, other might, partially, over years or decades. And doctors, try as they might, can’t accurately predict whether a nerve will regain function sometime after the damage occurred.
In cases of very small areas of tissue damage or loss along a nerve, harvesting another piece of nerve tissue from the patient allows the doctor to create a graft for the damaged area. But where entire nerves are too degenerated to regain function, or the physical trauma to the nerve tissue is too extensive, doctors don’t really have effective solutions; you can’t harvest that much tissue to use as a graft – you would just create the same issue in another part of the body.
Enter: the Orb Weaver.
Common Orb Weavers are known for their round, colorful, sometimes spiky bodies, and, as per the name, their beautiful, and surprisingly strong webs. Orb Weavers are part of a huge family of spiders – some 20000+ species, but that doesn’t mean they aren’t special. Female orb weaving spiders use several kinds of silk to produce their webs, including one they produce and apply a “glue” made of peptides to. And they can whip out one of these intricate pieces of engineering in no time. It follows, then, that these spiders (A) produce a lot of silk, and (2) produce strong, resilient silks.
Spider Silk for Repairing Neuropathy in Preliminary Studies
Spider silk isn’t new to medicine – Roman-Graeco cultures collected spider webs to use to stop wounds from bleeding. 2000 years later, modern medical technology has learned that spider silk has several properties that make it useful for use in tissue repair, including nerve tissue.
What’s so special about spider silk?
- By weight, it’s stronger than steel.
- It’s primarily built of proteins, amino acids and peptides.
- It doesn’t cause adverse immune responses.
- It’s thinner than a human hair, but much thicker and stronger than silkworm silk.
- More flexible than nylon.
However, there are challenges to sustainably (and ethically) harvesting spider silk on industrial levels. Mostly because spiders are not social creatures, and eat each other if they live in groups. Silkworms are docile, so they can be farmed on industrial levels. Some researchers get around this with some pretty creative methods:
- Genetically altering silkworms to produce more spider-like silk.
- Genetically altering goats to produce spider silk in their milk. (No; really.)
- Splicing spider genes into coli bacteria.
All these methods, though, don’t truly replicate spider silk. The silkworm silk is still weaker, the goat silk occurs in irregular structure, sometimes with lumps, and the E. coli silk is weak and more elastic than the real thing. Medical researchers are trying to create artificial spider silks that are able to be made on industrial levels, but so far, the Orb Weavers have kept how they spin their super-strong silk a mystery of nature.
Still, these knock-off spider silks still prove promising for other uses, like in Kevlar, glues, and coatings for medical implant devices. And, the bacteria silk has potential for other kinds of meshes for damaged tissues.
Artificial Spider Silk Nerve Grafts vs Autologous Nerve Grafts
As we discussed earlier, effectively repairing nerve damage or neuropathy in a patient is a challenge for doctors and surgeons of all kinds. That’s why the medical community is so excited about the application of artificial spider silk nerve grafts. The protein-dense construction of the spider silk make it’s staying time in the perfect range for nerve grafts. It attracts healing cells and supports the damaged area, but it also biodegrades completely, as a graft eventually should.
Autologous nerve grafts, the current industry standard for nerve repair, are somewhat effective, and cannot be rejected by the immune system, since they’re native tissue. But the healing properties they attract aren’t consistently effective. These procedures often result in partial regeneration, which may prove inconsequential or adverse to a patient’s quality of life, as partial nerve regeneration can result in uncomfortable tingling, numbness, or even pain.
Nerve grafts that utilize spider silk, however, look like they have potential to outdo autologous nerve grafts on all levels:
- One 2011 study on 6cm-long tibial nerve defects in sheep showed spider silk grafts attracted more healing cells, increased axonal growth, and remyelination of the nerve. The spider silk grafts also repaired the electrical abilities of the nerves, resulting in functional recovery.
- A 2008 study on 20mm-long sciatic nerve defect in rats had similar results.
- A 2014 study where spider silks were observed in a lab setting, researchers found that when small amounts of neuronal tissue was applied to spider silk that had been wrapped around steel frames, generation of nerve tissue within 24 hours of application. This included the creation and proliferation of new neurites that wrapped around and between the spider silk to fill the gaps and maximize surface area contact with the spider silk.
- Another notable finding in recent studies on the medical use of spider silk include one that found coating spider silk grafts with an antimicrobial gel causes the spider silk to keep antibiotic properties for at least 5 days. Being able to create soft tissue grafts of spider silk that at once attract healing cells and release antibiotics has countless implications for multi-phase, extended wound healing, like with ulcers and 3rd-degree burns.
See? Those wolf-spider-lookalikes, and the black and yellow giants in your garden aren’t only good for keeping ants and silverfish out of your house, and their abandoned homes are much more than cobwebs to be swept away. But… still sweep them away, though.