Cartilage neither heals nor regenerates after damage, so artificial cartilage could help many people with joints damaged by wear, injury or disease. Lab-grown cartilage grown with tension (top) shows similar mechanical and chemical properties to natural cartilage, which allows our joints to move smoothly. The lower image shows computer modeling of strain distribution across the artificial tissue. Image credit: Athanasiou lab, UC DavisBy creating lab-grown tissue that mimics natural cartilage, biomedical engineers at the University of California, Davis, are hoping to be a step closer to offering relief to sufferers of joint damage.

The study, which is published in the journal Nature, details how once articular cartilage is damaged (due to disease, overuse or trauma), it doesn’t grow back and is hard to replace. The creation of artificial cartilage could possibly restore mobility to people with joint damage.

Although bioengineers have tried to create artificial cartilage before, UC Davis bioengineers put the assembled cells under tension (mildly stretched) for several days.

"As they were stretched, they became stiffer," said Jerry Hu, a research engineer and co-author on the study. "We think of cartilage as being strong in compression, but putting it under tension has dramatic effects."

The result was a “stretchy” material that resembled the composition and mechanical properties of natural cartilage.

"In this comprehensive study, we showed that we can finally engineer tissue that has the tensile and compressive characteristics of native tissue," said Professor Kyriacos Athanasiou, Department of Biomedical Engineering. "The artificial cartilage that we engineer is fully biological with a structure akin to real cartilage. Most importantly, we believe that we have solved the complex problem of making tissues in the laboratory that are strong and stiff enough to take the extremely high loads encountered in joints such as the knee and hip."