Lab-grown cartilage grown shows similar mechanical and chemical properties to natural cartilage, which allows our joints to move smoothly, according to a new study.
The biomedical engineers from University of California, Davis, created a lab-grown tissue similar to natural cartilage by giving it a bit of a stretch, they wrote in their Nature Materials study. The tissue, growing it under tension but without a supporting scaffold, and it shows similar mechanical and biochemical properties to natural cartilage.
Articular cartilage provides a smooth surface for our joints to move, but it can be damaged by trauma, disease or overuse. Once damaged, it does not regrow and is difficult to replace. Artificial cartilage that could be implanted into damaged joints would have great potential to help people regain mobility. Natural cartilage is formed by cells called chondrocytes that stick together and produce a matrix of proteins and other molecules that solidifies into cartilage. Bioengineers have tried to create cartilage, and other materials, in the lab by growing cells on artificial scaffolds. More recently, they have turned to “scaffold-free” systems that better represent natural conditions.
On top, the lab-grown cartilage. The lower image shows computer modeling of strain distribution across the artificial tissue. Credit: Athanasiou lab, UC Davis
The team grew human chondrocytes in a scaffold-free system, allowing the cells to self-assemble and stick together inside a specially designed device. Once the cells had assembled, they were put under tension — mildly stretched — over several days. They showed similar results using bovine cells as well. The new material had a similar composition and mechanical properties to natural cartilage, they found. It contains a mix of glycoproteins and collagen, with crosslinks between collagen strands giving strength to the material.
Experiments with mice show that the lab-grown material can survive in a physiological environment.
The next step is to put the lab-grown cartilage into a load-bearing joint, to see if it remains durable under stress.