A study conducted by researchers at Duke University claims that humans have the ability, like some animals, to regenerate joint cartilage. Hope for patients with osteoarthritis.
Do humans share the ability of salamanders and zebrafish to regenerate cartilage?
This is the astonishing discovery made by Duke University researchers, in the USA. In a study published on October 9 in Science Advancesthey explain that they have identified a cartilage repair mechanism in the ankle and hip joints that could ultimately lead to the treatment of osteoarthritis.
In France, 10 million people are affected by this degenerative disease, which remains incurable to this day. The treatments available are so-called “symptomatic” treatments, that is to say, intended to relieve pain and stiffness, but have little effect on the natural course of the disease. The only therapeutic options available, such as micrografting or fitting a prosthesis, all turn out to be invasive and/or painful for patients, and often have limited efficacy.
“We believe that an understanding of this salamander-like regenerative capacity in humans, and what elements are sorely lacking in this regulatory circuit, could provide the basis for new approaches to repair joint tissue and possibly entire human limbs. “, explains Virginia Byers Kraus, professor in the departments of medicine, pathology and orthopedic surgery at Duke.
Determine the age of the cartilage
The first step in the study conducted by the researchers was to determine the age of the cartilage proteins. They were able to observe that the newly created proteins in the tissues contain very low or zero amino acid conversion rates. On the contrary, older proteins display high amino acid levels.
The researchers then discovered that the age of the cartilage largely depended on where it was in the body. Thus, the cartilage in the ankles is young, it is middle-aged in the knee and old in the hips. As in salamanders, this correlation between the age of human cartilage and its location in the body corresponds to the way in which the cartilage regenerates: the more it is at the distant extremities, the younger it is.
For the study authors, this discovery explains why injuries to the knees and, especially, the hips take a long time to recover and often turn into osteoarthritis, while ankle injuries heal faster and become less often severely arthritic.
The key role of microRNAs
Another discovery made by the researchers: that of the role of microRNAs, enzymes used in particular to regulate the expression of genes and which are more active in animals which can “repair” their limbs, their fins or their tail.
As in humans, the activity of these microRNAs varies greatly depending on where they are found: it was higher in the ankles than in the knees and hips and higher in the upper layer of cartilage than in the lower layers. deep in the cartilage.
For the researchers, this means that these microRNAs could be developed as drugs that could prevent, slow down or reverse osteoarthritis. “We think we could help these regulators completely regenerate degenerated cartilage in an arthritic joint. If we can figure out which regulators we’re lacking compared to salamanders, we may even be able to add the missing components and develop a means of one day regenerating part or all of an injured human limb”, explains Professor Kraus. “We believe this is a fundamental repair mechanism that could apply to many tissues, not just cartilage.”
.
