Spider silk bridges the gap between busted nerves
So far as nature's wonder materials go, spider silk is right up there. Its tremendous strength and elasticity has seen it put to use as violin strings, car seats and possibly further down the track, electronics and gene therapy. Now scientists have uncovered another exciting application for it, using it to bridge the gap between served nerves that would otherwise struggle to be repaired.
One particularly challenging aspect of plastic and reconstructive surgery concerns nerve injuries more than five centimeters in length (two inches). These might occur following a grave accident or the removal of a tumor, and while surgeons can use grafts to reconnect severed nerves, this only works well up to distances of around four cm (1.6 in).
Scientists have been exploring ways to close the gap, and Christine Radtke from the Medical University of Vienna believes she has just the thing. Silk from Tanzania's golden orb-weaver spider is more tear-resistant than nylon, four times more elastic than steel and remains stable under temperatures up to 250° C (482° F). It is also boasts antibacterial properties and is waterproof, which is convenient for the Tanzanian fishermen that use it for fishing line.
Radtke has developed a new microsurgery technique that deploys the silk of the golden orb-weaver in veins as a way of reconnecting big breaks in nerve fibers. The technique has been tested in animal models, where it repaired nerve damage over a distance of six cm (2.3 in). These nerves fibers grew back together in a functional way within nine months, while the spider threads were naturally broken down by the body without causing a negative reaction.
"This acts almost like a rose trellis," explains Radtke. "The nerve fibers use the silk fibers to grow along in order to reconnect with the other end of the nerve. The silk provides the cells with good adhesion, supports cell movement and encourages cell division."
Radtke says several hundred meters of silk are need to mend a six-centimeter nerve gap. With 21 spiders in her lab that are harvested mechanically for silk once a week, she says 200 m (656 ft) of silk can be obtained within just 15 minutes.
The researchers are now working to certify spider silk as a medical device, so the technique can be tested in human trials. If things go well there, they imagine the technique could be applied to other medical problems such as meniscus and ligament injuries, deep burns and even some neurological diseases.