Peripheral nerves send messages from the brain and spinal cord to other parts of the body so that, for example, muscles move when you walk or the brain tells you that your feet are cold. Peripheral nerves are easily damaged and the brain’s ability to communicate with muscles and organs is impaired.
The standard treatment for repairing damaged peripheral nerves is auto graft, in which surgeons remove the damaged part and replace it with a nerve from elsewhere in the body. A nerve graft is taken from a sensory nerve that carries sensation to an area of the skin where it is not vital to have sensation. But the success rate of neural grafts can be hit or miss.
Researchers from the University of Oxford and the Medical University of Vienna, who combined two types of natural silk taken from silkworms (Bombyx mori) and golden orb spiders (Trichonephila edulis), have created a new nerve guide for nerve regeneration over longer distances.
Silk is composed of fibroin and sericin proteins. Both of these silks are environmentally friendly, elastic and strong. It has been found that silk fibroin promotes wound healing by increasing cell proliferation and growth. Spider silk also has significant mechanical properties such as tensile strength and high flexibility.
For the first time, researchers combined the characteristics of regenerated silk fibroin with the tubes and filaments of natural spider silk to create a silk-in-silk structure.
The wall of this structure is made of silkworm silk fibroin and is filled with spider silk fibers that act as an internal guiding structure.
The nerve guide was tested on mice whose right sciatic nerve was severed and a 10 mm gap was created in it. The researchers found that the damaged nerves adapted to the silk nerve guide, and these nerves grew along the silk strands and successfully connected the two severed ends.
Lorenz Semmler, the principal investigator of these researchers, says: “In our study, it was found that peripheral nerves function well when such threads are made of silk, and spider silk seems to be more suitable for conductors.”
Using natural materials to create neurotransmitters has obvious advantages over synthetic materials. Spider silk is biodegradable and produces very little immune response in animal models. The porous nature of silk can allow the incorporation of bio active molecules to promote nerve regeneration over longer distances.
The researchers hope that their discovery will pave the way for the development of an “external” neuroconductor to treat peripheral nerve damage in humans.
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