Goo-like biomaterial helps cartilage regenerate in joints

Resembling a rubbery goo, the material provides a chemical and physical framework for natural regrowth of cartilage, a crucial element in our joints that does not heal by itself. The Northwestern team tested the new material in the leg joints of sheep, which are similar to human knee joints. Within six months, evidence of enhanced repair was observed, including the growth of new cartilage containing the natural biopolymers that provide mechanical resilience in joints. The work will be published this week in the Proceedings of the National Academy of Sciences.

“Cartilage is a critical component in our joints,” said Northwestern’s Prof Samuel Stupp, who led the study.

“When cartilage becomes damaged or breaks down over time, it can have a great impact on people’s overall health and mobility. The problem is that, in adult humans, cartilage does not have an inherent ability to heal. Our new therapy can induce repair in a tissue that does not naturally regenerate. We think our treatment could help address a serious, unmet clinical need.”

The material is a complex network of molecular components that mimic cartilage’s natural environment in the body. A bioactive peptide in the material binds to transforming growth factor beta-1 (TGFb-1) — an essential protein for cartilage growth and maintenance. The material also features modified hyaluronic acid, a natural polysaccharide present in cartilage and the lubricating synovial fluid in joints. 

“Many people are familiar with hyaluronic acid because it’s a popular ingredient in skincare products,” said Stupp. “It’s also naturally found in many tissues throughout the human body, including the joints and brain. We chose it because it resembles the natural polymers found in cartilage.”

To test the material, the team applied it to sheep with cartilage defects in the stifle joint, a complex joint in the hind limbs similar to the human knee. According to Stupp, testing in a sheep model was vital, as sheep cartilage is difficult to regenerate, similar to human cartilage. 

“A study on a sheep model is more predictive of how the treatment will work in humans,” said Stupp. “In other smaller animals, cartilage regeneration occurs much more readily.”

With further development, the Northwestern team believes the biomaterial could potentially be used to prevent full knee replacement surgeries, treat degenerative diseases like osteoarthritis and repair sports-related injuries like ACL tears.