Her research is hanging by a thread

Anna Rising is working on a unique project – creating spider silk using bacteria. The material could in the future be used for the healing of wounds and repairing damaged nerves.

Anna Rising. Photo: Mattias Ahlm

Text: Lotta Fredholm. First published in Swedish in the magazine Medicinsk Vetenskap no 3, 2012

How did you become interested in spider silk?

"I'm a vet, originally, and ended up by chance in an EU-financed doctoral project where the goal was to produce spider silk. According to measurements, the strongest silk is found among Euprosthenops australis spiders, and I started by sending out emails around the world to locate these spiders. I heard back from the Spider Club of South Africa who told us we were welcome to come to South Africa and collect spiders. We did, and after a few weeks we came home with 104 spiders."

Then what happened?

"We extracted DNA from the spiders and it turned out the gene that encodes the silk protein is gigantic. But we only used a small part of the gene, barely a tenth of it, and injected it into E.coli bacteria which could then produce silk. They make the proteins in a soluble form, but when we collect the purified protein in test tubes, very strong threads are spontaneously formed: They can withstand temperatures of 260 degrees Celsius and ethanol baths.

To some extent they resemble the fibrillae formed by Alzheimer's disease which is why we are at the Alzheimer's centre at Karolinska Institutet. In addition to silk, we can now also create foam and films from the material."

How can spider silk be used in medical research?

"We have recently published a study where the spider silk is used as a matrix to culture neural stem cells. These cannot attach themselves directly to the plastic plate - a biological surface is required. Currently, animal proteins are often used as matrix, but due to the risk of contamination, cells cannot be used clinically and the material is subject to variability. However, our material is created from bacteria and we know exactly what it contains. Another advantage is that it is stable enough for cells growing on or in the material to, for example, be transferred from the dish and into a patient. We now hope to create three-dimensional matrices to be able to cultivate cells, and eventually it may be possible to create entire tissues.

In a separate project, diabetes researchers use the silk as a base for making insulin-producing beta cells divide and multiply outside of the body. The idea here is that the cells will then be reintroduced into the body in a way that combats diabetes."

In a few years time, how could your spider silk be usable in a clinical context?

"I think it might be possible to use the thread itself, maybe as a suture material or to heal wounds. It is said that the ancient Romans put whole spider's webs on the wounds of their horses, and legend has it that spider's webs speed up the healing of wounds. There are also studies that show that spider silk allow damaged peripheral nerves to heal . This is where I think our manufactured silk may be of use. But we need to be able to demonstrate that the material is safe to implant into the body."

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