6 min

Artificial spider silk used to build spare organs of the future

My Hedhammar is building smart climbing frames made of artificial spider silk. These climbing frames can then be used as matrix for culturing cells to make the spare organs of the future. The ultimate aim is to be able to repair damaged tissue of all kinds, e.g. insulin-producing cell islets, skin, corneas and cardiac muscle tissue.

My Hedhammar

Associate Professor of Biochemistry

Wallenberg Academy Fellow 2013

Institution:
KTH Royal Institute of Technology

Research field:
Protein technology and tissue regeneration

Spider silk is in many ways a unique material: it is very strong, yet thin and elastic. A material with these properties can be put to many uses. So it has been the dream of many researchers to be able to understand and copy the characteristics of spider silk and make an artificial version.

A project of this kind was under way at the Swedish University of Agricultural Sciences (SLU) when My was a doctoral student, and she joined the project when she had completed her doctorate.

“It was absolutely fantastic to be able to have a go at something so exciting, and it was there I began to develop my own approach.”

Before a spider spins its threads and weaves its web, the proteins that will become silk are stored as a viscous fluid in a gland inside its body. These proteins are called spidroins and are particularly difficult to work with since, unlike most other proteins, they are not water-soluble; they want to change into a material.

At SLU My Hedhammar and her colleagues aimed to understand the mechanisms that control the transformation from a viscous fluid into dragline silk, and to identify the part of the protein that is necessary to form artificial spider silk. They also succeeded in producing a miniature version of spidroin that can be mass-produced with the help of genetically modified bacteria. These artificial proteins then spontaneously form fibers that resemble spider silk.

Bioactive climbing frame

As a Wallenberg Academy Fellow, My is continuing her research at KTH Royal Institute of Technology in new facilities, with new equipment, with her own research team and with new objectives.

“Artificial spider silk has a structure that resembles natural spider silk. It is strong, elastic, temperature-stable and chemically stable. In addition, it is biocompatible, which means that the body’s immune system accepts the material as if it were the body’s own.”

These properties mean that artificial spider silk is ideal for repairing parts of our body that are no longing working properly.

“Our goal is to use the spider silk to develop a material that can be used to repair parts of the body, such as a large wound or a defective heart.”

My and her research team are therefore currently working on making three-dimensional structures out of spider silk and building various forms of bioactivity into these structures. They are also studying how the structures can then be used to culture cells and manufacture artificial tissue.

One might say that we are making a sort of “intelligent climbing frame” with instructions. The climbing frame gives the cells support and stability and thereby the ability to grow into three-dimensional tissue. The instructions tell the cells what they will be, so that they can join together to form whole, living and functioning tissue.

“First of all, it has meant that we have been able to move to KTH, which is an environment with the right infrastructure for pursuing this line of research. Second, long-term funding of this kind means that we can be more ambitious and dare to be a little more innovative. Having five years to achieve our aims is a golden opportunity in this field.”

Modern molecular biotechnology

When it comes to the instructions, the researchers are using modern molecular biotechnology to build various forms of bioactivity found in natural tissue into the artificial spider silk threads. For instance, special adhesive proteins are put in positions on the “climbing frames” where the cells are intended to adhere. Various kinds of growth factors are also added at strategic points on the “climbing frame”. These tell the cells how they should develop.

“We cannot decide exactly where tendons and blood vessels are to be formed, for example, but we can control the proportion of blood vessels and tendons in artificial tissue. If we want to have an entire blood vessel, we can also apportion bioactivity that stimulates the formation of blood vessels along a limited area, and the cells will then arrange themselves correctly and form a blood vessel.”

The final stage in this research chain, which involves adding cells and culturing them to create the spare organs of the future, is being carried out in collaboration with experts on different tissue types. For example, My is currently collaborating with medical experts in the field of insulin-producing cell islets, skin, bones and cardiac muscle tissue.

“The ultimate goal is to be able to use this material to repair virtually any tissue in the future.”

Genuinely curious

My Hedhammar has always been interested in nature, and like many other researchers, she describes herself as genuinely curious. She also says that there has always been an engineer within her; she has always been technology-driven. In other words, she has wanted to understand and not merely accept the relationships between things and how they work.

Her current research spans several scientific fields, including biochemistry, materials science and cell biology.

“Working with a multidisciplinary approach is difficult, but it is fun too because you learn new things the whole time. Quite simply, it is really enjoyable and inspiring to work on something you understand right from the outset.”

Text Anders Esselin
Translation Maxwell Arding
Photo Magnus Bergström

 

Glossary

Biocompatible
This means that the body’s immune system is inclined to accept the material as if it were the body’s own.

Spidroins
Long proteins in spider silk.