(Vienna, 10 October 2021) Within one year, the research team led by Christine Radtke from the Department of Plastic, Reconstructive and Aesthetic Surgery at the Medical University of Vienna has received two grants from the Austrian Science Fund (FWF) for its research projects on nerve regeneration using spider silk. In these projects, researchers are investigating the various properties of spider silks and whether spider silks and hydrogels are suitable materials for filling synthetic nerve conduits.
Regenerating damaged nerves is one of the greatest hurdles in reconstructive surgery. Despite continuous efforts to improve recovery, patients' quality-of-life is often marred by complications and/or follow-up surgery. One method of surgically treating a damaged nerve without transplantation is to use artificial nerve conduits. These are tubes that are sutured to both parts of the damaged nerve and support the growth of cells and nerve fibres. They provide a guide structure for the regeneration of axons and at the same time avoid the disadvantages of transplantation by generating endogenous material. However, hollow conduits have their limitations, as they have not yet resulted in successful regeneration of more extensive nerve damage of more than three centimetres. Christine Radtke and her colleagues are now investigating spider silk fibres as a promising filling material for synthetic conduits, so that more extensive nerve injuries can also be treated.
Spider threads connect damaged nerves
The team led by Christine Radtke has been researching the use of spider silk in nerve regeneration for several years now. Spider threads have unparalleled properties such as high elasticity and strength, as well as good heat resistance and biocompatibility. In addition, when they are used in nerve conduits, Schwann cells, which are an important part of the nerve regeneration process, adhere to the spider silk and move specifically along the fibres. Since spider silk is a natural material with limited availability, Radtke's team is investigating the material properties of the fibres in one of the two FWF-funded projects in order to find out what properties a synthetic material would need to have for medical applications. This involves examining silks from different species of spider to determine their chemical, mechanical, structural and morphological properties, both when the fibres are wet and when they are dry.
In the second research project, spider silk is being investigated in combination with other materials as a filling for nerve conduits. In animal models, it was shown that spider silk fibres used as filling material in vein grafts successfully repair nerve damage over the critical length of six centimetres. "The next step is to replace the vein grafts with filled synthetic conduits. To do this, we fill the conduits with spider silks and hydrogels, which we assume offer ideal conditions for nerve regeneration when combined," said Christine Radtke, explaining the current project. While the silk acts as a guide structure for axon regeneration, hydrogels provide a three-dimensional matrix that mimics body tissue and confers structural integrity, preventing the long conduits from collapsing. "We assume that spider silk fibres embedded in hydro-gel have the potential to improve artificial conduits so that they can become an equivalent alternative to nerve grafts for long nerve injuries," said Radtke.
The two projects "The ideal conduit in peripheral nerve regeneration" and "Why Schwann cells like spider silk" will be funded by the FWF up until 2024. Working on the research projects, alongside Department Head Christine Radtke as project manager, are Helga Lichtenegger, Aida Naghilou, Lorenz Semmler and Flavia Millesi. Helga Lichtenegger is an expert in biomaterials and structural and mechanical characterisation techniques. Aida Naghilou brings her extensive experience in spectroscopy, optics and cell culture studies of nerve regeneration to the project. Lorenz Semmler is a specialist in the assessment of various functional outcome parameters in animal models and Flavia Millesi established multicolour immunofluorescence panels as well as migration assays, which allow detailed analysis of the cellular characteristics of spider silks.