Researchers at the University of Michigan and Jiangnan University in China have developed a type of artificial cartilage using Kevlar, a synthetic fiber better-known for its use in bullet-proof vests, and polyvinyl alcohol (PVA), a material used in hydrogel cartilage replacements. The new hybrid material combines the strength and water content of natural cartilage, and might be useful as a replacement for cartilage or other soft tissues in the body.
Artificial cartilage implants are in big demand, with 850,000 patients in the U.S. requiring surgery to remove or replace cartilage in the knee. However, developers of synthetic cartilage have traditionally had to choose between the material having the required amount of strength or the right water content.
A cartilage implant’s strength is key to help it to stand-up against the abrasion and deformation it will experience in a moving joint. However, the tissue needs to hold enough fluid to allow chondrocytes (cells that build cartilage) to grow, while cartilage’s strength and flexibility come from allowing water to escape when it deforms and then reabsorbing it later.
So far, researchers have been unable to tick off all these boxes when designing artificial cartilage. The researchers on the current project turned to Kevlar, a really strong synthetic fiber, and combined it with PVA, which can create hydrogels that hold a lot of water. Their “Kevlartilage” releases water under stress and later reabsorbs it like a sponge, just like natural cartilage. The Kevlar fibers form a mesh within the material, and the PVA hydrogel component traps water molecules inside.
In tests, even when the material contained up to 92% water, it maintained a similar strength as natural cartilage. The team has performed some preliminary biocompatibility work, and it looks like the material doesn’t harm adjacent cells, but they will need to conduct further work to see if the Kevlartilage can be used as a cartilage implant in patients. The material might also be useful to replace other soft tissues.
“We have a lot of membranes in the body that require the same properties. I would like to evaluate the space,” says Nicholas Kotov, a researcher involved in the study. “I will talk to doctors about where the acute need is and where this intersection of the properties will allow us to make best headway and biggest impact.”
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