WEDNESDAY, Oct. 9, 2019 (HealthDay News) — Humans may lack the salamander skill of regrowing a limb, but a new study suggests they do have some capacity to restore cartilage in their joints.
The findings run counter to a widely held belief: Because the cartilage cushioning your joints lacks its own blood supply, your body can’t repair damage from an injury or the wear-and-tear of aging.
And that, in part, is why so many people eventually develop osteoarthritis, where broken-down cartilage causes pain and stiffness in the joints.
But that lack of blood supply does not mean there’s no regenerative capacity in the cartilage, according to Dr. Virginia Byers Kraus, the senior researcher on the new study.
In fact, her team found evidence that human cartilage can, to some degree, renew itself, using a molecular process similar to the one that allows a salamander to grow a new limb.
The researchers are calling it the “inner salamander capacity.”
“For the first time, we have evidence that the joint has the capacity to repair itself,” said Kraus, a professor at Duke University School of Medicine, in Durham, N.C.
Specifically, she explained, that capability exists in a “gradient.” It’s greatest in the ankle, less apparent in the knee, and lowest in the hip.
And that makes sense if this repair capability is an artifact of evolution, according to Kraus. Animals that regenerate tissue have the greatest capacity for it in the distal portions of the body — the parts “most likely to get chewed off.”
Dr. Scott Rodeo, an orthopedic surgeon not involved in the study, said the findings raise some interesting questions.
For one, he said, could this be a partial explanation for why osteoarthritis is common in the knees and hips, but not the ankles?
“It’s been assumed that it’s related to the biomechanics of the joints,” said Rodeo, an attending surgeon at the Hospital for Special Surgery, in New York City.
But this study, he said, suggests there might be intrinsic differences in the joints’ ability to repair cartilage.