According to a new study in the journal Science Advances, it has been found that cartilage in human joints can repair itself through a process similar to that used by creatures such as salamanders and zebrafish to regenerate limbs.
Humans may not be able to regrow entire amputated limbs like salamanders can but we do have a “salamander-like” ability to regrow damaged cartilage.
The study could open the door to new treatments for joint injuries and diseases like osteoarthritis and perhaps even one day in the future lead to human limb regeneration.
Salamanders, axolotl, and other animals with regenerative abilities have a type of molecule called microRNA, which help regulate joint tissue repair. Humans have microRNA too, but our mechanism for cartilage repair is stronger in some parts of the body, the study found. For example, the microRNA molecules are more active in our ankles, and less active in our knees and hips.
“We were excited to learn that the regulators of regeneration in the salamander limb appear to also be the controllers of joint tissue repair in the human limb,” said Professor Ming-Feng Hsueh. “We call it our ‘inner salamander’ capacity.”
The study also found that the “age” of cartilage depends on its location in the body. Cartilage is “young” in the ankles, “middle-aged” in the knees, and “old” in the hips. This correlation lines up with how animals regenerate fastest at the furthest tips of their bodies, like tails or the ends of legs.
These combined factors of activity level of microRNA; and the age of cartilage together explain why ankle injuries heal faster than knee and hip injuries, and there are fewer instances of arthritis in the ankle compared to the other two areas.
Scientists have known for years that humans do have some regenerative capabilities, for instance, when children’s finger tips are amputated, it has been documented that the tip regrows when treated correctly.
This has potentially huge implications for athletes or people with joint injuries. MicroRNA could be injected into joints or developed into medicines that prevent or reverse arthritis, the study said. In the more distant future, it could even “establish a basis for human limb regeneration.”