Scientists have developed an innovative injectable “goo” that has shown promising results in regrowing cartilage, a breakthrough that could revolutionize the treatment of joint damage in humans. Although the new biomaterial has only been tested on sheep so far, researchers are optimistic about its potential to repair joint damage caused by degenerative diseases like osteoarthritis and sports injuries such as anterior cruciate ligament (ACL) tears.

Cartilage, the flexible tissue lining joints like the knees, plays a crucial role in cushioning and protecting bones from grinding against each other during movement. However, as we age or due to injury, this vital tissue deteriorates, leading to joint pain and reduced mobility. “When cartilage becomes damaged or breaks down over time, it can have a great impact on people’s overall health and mobility,” said Samuel Stupp, co-author of the study and director of Northwestern University’s Simpson Querrey Institute for BioNanotechnology. “The problem is that, in adult humans, cartilage does not have an inherent ability to heal.”

Unlike many other tissues, cartilage lacks an active blood supply, which hinders its natural healing process. This limitation often necessitates surgical interventions, such as microfracture surgery, where damaged cartilage is removed, and holes are drilled into the underlying bone to stimulate the growth of new cartilage. However, the newly formed fibrocartilage from this procedure is typically weaker and less durable than the original hyaline cartilage.

Stupp and his team have now created an injectable biomaterial designed to regenerate hyaline cartilage, offering a potentially more effective solution. Detailed in a study published on August 5 in the journal PNAS, this new therapy can induce repair in tissues that do not naturally regenerate. Once injected into a joint, the biomaterial recruits a protein called transforming growth factor-beta1 (TGF-b1), which is known to promote cartilage repair. The goo also contains hyaluronic acid, a complex carbohydrate that encourages stem cells to form cartilage.

The researchers tested the biomaterial on sheep with cartilage defects in their stifle joints, which closely resemble human knees. Six months after a single injection, the treated sheep exhibited significant cartilage growth and improved joint repair. The new cartilage closely resembled natural hyaline cartilage, outperforming traditional TGF-b1 injections given to a comparison group of sheep.

Looking ahead, the research team hopes to replicate these results in humans. “By regenerating hyaline cartilage, our approach should be more resistant to wear and tear than microfracture surgery,” Stupp noted. This advancement could provide a long-term solution to joint pain and mobility issues, potentially reducing the need for invasive joint reconstruction surgeries, such as full knee replacements.

By Impact Lab