How Spider Webs Might Be Used to Repair Your Tissues in The Future
Like most people, I’m scared of spiders. I jump merely at the sight of the eight-legged creatures. I even jump when I spot a ball of thread which remotely resembles a spider. Interestingly, the fear of spiders, also known as arachnophobia, is thought to be genetic.
A study in babies was conducted by Hoehl et al. in 2017 and babies showed increased pupil dilation when they were shown a picture of a spider. The paper concluded that this cannot be learned behaviour as they are still too young to know spiders are feared by adults, thus the fear is likely to have genetic roots.
Some people do not fear spiders at all, in fact, quite the opposite, they keep them as pets!
I personally do not want a pet tarantula any time soon, but what I can appreciate is that spiders are incredibly clever and creative. One only has to take a look outside and find their beautifully spun webs to realise this.
Spider webs have inspired acoustics, architectural design and much more. There are so many types of web structures: orb, funnel, sheet, cob and woolly.
You’re probably familiar with the classic hexagonal design of the orb web, however, only 15% of spiders are orb-weavers and some species of spiders don’t make any webs at all.
The evolutionary history of spider webs
Spiders have been around for almost 400 million years! Fossils have given scientists an indication of the evolutionary history of spider webs and the variety of webs spiders create (see diagram below).
As insects began to take flight, spiders evolved to make better traps for their prey. Take Scoloderus for example, the ladder design specifically targets moths, on each rung the moth tumbles closer and closer to the fangs of the spider.
Teridiosoma is also a very clever design when the flying insect sticks to the diamond structure of the web, the thin string of web is released and wraps around the insect securing it in place.
Spiders do not learn to create webs like how we learn to walk or how birds learn to fly. It is something they are born to do, which makes them even more fascinating and frightening. How do they know how to create these intricate patterns and trap their victims so precisely without ever being taught?
Another reason why it is a good thing that spiders are not human-sized!
Biomechanical Properties of Spider Webs & their application in Medicine
Spider webs are made of silk proteins. Proteins are made of chains of amino acids (AA) held together by peptide bonds. Alanine and glycine are the main AA’s found in spider silk, the way these specific AA’s bond and the beta-sheet they form gives rise to silks high tensile strength.
This strength as well as other biochemical properties of silk has been taken advantage of for centuries. In Tanzania, the silk of the golden-orb weaver is so strong that it is used to make fishing nets.
Not only does silk have an application in day to day life, but also in medicine. Back in the 17th century, ancient Greeks and Romans used spider webs for suture material and to heal wounds of injured soldiers.
The stickiness of the web, anti-microbial properties and the fact that the immune system does not treat silk as a foreign substance makes the application of spider webs for tissue repair very attractive to scientists.
There is an issue with farming spiders for silk as they tend not to do well in cramped conditions and too many spiders close together results in cannibalism. For this reason, the silk proteins are often made in a lab using recombinant methods.
Currently, spider webs are being researched for their potential use in repairing blood vessels, tendon tears, diabetic ulcers, facial reconstruction and much more.
With regards to healing tendon injuries and other ligament tears, the conventional suture material i.e. Nylon has its downfalls as it is often rejected by the body. So finding a material that can not only do a better job but can integrate into the body without rejection is extremely appealing.
A study by the University of Vienna tested spider silk as a suture material for stabilising injured tendons. The silk was braided and made to form suture material, the strength of the material was put to the test.
After 1000 fatigue cycles the sutures were still in good condition, showing that they were durable and provided similar tensile strength as Nylon except with no reduction in strength over time. These promising results have inspired scientists to look at using spider webs for repairing other parts of the body.
In recent years, researchers from Germany have been studying the potential use of spider webs in treating neural diseases. The scientists use silk proteins to make minuscule tubular structures, which can be implanted in the brain and help guide nerve cells so they know which direction to grow.
The current methods of encouraging nerve cells to reconnect involve using grafts but this only works over short distances (i.e. 4cm). Silk proteins can work over a longer distance (6cm), this has been demonstrated in animal models.
What is more, neural degeneration improves in less than a year. The silk protein encourages cell division, adhesion and is biodegradable which reinforces why it’s much better than the current materials physicians use.
There is definitely a lot of potential in the use of spider silk in modern medicine. The Greeks and Romans were definitely onto something… you might even be thinking, why has this not being done already?
Although scientists know the genetic code of the silk proteins made from spiders, the properties of silk made in a lab are not exactly the same as native silk.
As mentioned earlier, farming spiders is a difficult task (no.1 they eat each other), spiders also need special conditions to produce silk. Stress, climate, temperature etc. can all affect the quality of the silk. Thus, to produce high-quality silk in large enough quantities for medicine is a challenge.
However, now that we know that silk has a lot of promise in healing tendons, tissues and even nerve cells perhaps more human trials will occur in the next few decades and we will find a way to overcome this challenge and any others that may arise.
The next time you spot a spider’s web, step back to admire it. Who knows, one day it might just save your life.
