Researchers at the University of Iowa Health Care, US, are working on an injectable bioactive gel that encourages self-healing of cartilage caused by knee injuries, with hopes it will result in a minimally invasive, practical and inexpensive approach for repairing cartilage and preventing osteoarthritis.

Athletes and other active wellness fanatics everywhere are at risk of knee injuries – the current surgical options for which are costly, can have complications, and can be ineffective in the long run. A cheap alternative, however, in the form of a bioactive gel, could eventually become a retail option for health clubs, spas and sports centres.

The study, published in the journal Arthritis and Rheumatology is an investigation based on the previous discovery that certain ‘precursor’ cells within normal cartilage can mature into new cartilage tissue. This was surprising at the time because of the long-held assumption that cartilage is one of the few tissues in the body that cannot repair itself.

Discovered by lead author Yin Yu, a graduate student, the team also identified molecular signalling factors that act like homing beacons for these ‘precursor’ cells. In the most recent study, these cells migrated to the signals and filled in the injury site. Subsequent application of a growth factor caused the cells to mature into normal cartilage that repaired the injury.

“The new cartilage integrates seamlessly with the undamaged tissue, it has good structural properties and looks like normal cartilage,” said Yu.

The new tissue is not as mechanically strong as normal cartilage, but the stress caused by physical therapy and exercise may improve these properties.

“There’s really no cure for osteoarthritis except for total joint replacement, which is not particularly suitable for younger patients because the artificial joints wear out and need to be replaced multiple times,” said James Martin, PhD, assistant professor of orthopaedics and rehabilitation. “Our approach aims to leverage the body’s own capacity for repair and what we’ve shown is that cartilage does have regenerative potential, you just have to manipulate it just right.”

Yu and Martin plan to start animal trials within a year and if the results are positive they hope to be ready to start human trials in about five years, with the ultimate goal of commercialising the product – the ingredients of which are all already FDA-approved in the US for human use.