An interesting approach to the challenges of cartilage regrowth is outlined here:
Articular cartilage is the tissue that lines joints such as hips, knees and shoulders, providing cushioning and smooth movement. Similar to bones and muscles, cartilage only stays healthy and strong through loading, or applying force, through physical activity. Until recently, researchers did not know how cartilage converts mechanical loading into the ion channel signals that promote growth. Understanding how cartilage senses mechanical loading could equip researchers with the knowledge needed to prevent or better treat joint diseases.
"Mechanical loading plays a critical role in the overall health of the cartilage. If we can figure out how cartilage cells sense mechanical loads, we can trick them into thinking they are being exercised or stop them from responding to abnormal loading. Think of it as artificial exercise for your cartilage."
Researchers looked at articular cartilage cells from pigs and focused on TRPV4, an ion channel abundant in cartilage cells that can be turned on during mechanical loading. When the researchers "exercised" the cartilage cells using mechanical loading, the cells sensed the loading and grew cartilage tissue. When they added a compound that blocked TRPV4, essentially turning off signals from the ion channel, the cartilage did not grow and the effects of the mechanical loading were lost.
Next, the researchers substituted mechanical loading for a chemical that activated TRPV4. Without having to exercise the cartilage, they observed the growth of cartilage even more so than with the mechanical loading. The findings suggest that TRPV4 is responsible for sensing mechanical loading in the cartilage. Now that they know that turning on TRPV4 can simulate the effects of mechanical loading in cartilage cells, the researchers are looking at ways to harness this potential.