In the same way that a salamander can regrow a damaged limb, humans can regrow cartilage in their joints after a hefty fall.
A discovery made by a research team from Duke University Medical Center could have major implications for the medical field. In a paper published to Science Advances, the team said that it has discovered cartilage in human joints can be grown again in a similar way to when a salamander regrows a limb after it has been cut off.
The discovery of the cartilage repair mechanism was surprising in that it is found to be more effective in ankle joints, but less so in hips. The finding could potentially lead to treatments for osteoarthritis, the most common joint disorder in the world, but also advances that today seem like science fiction.
“We believe that an understanding of this ‘salamander-like’ regenerative capacity in humans, and the critically missing components of this regulatory circuit, could provide the foundation for new approaches to repair joint tissues and possibly whole human limbs,” said senior author Virginia Byers Kraus.
Could slow arthritis
As part of the research, Kraus and her team devised a way to determine the age of proteins using internal molecular clocks integral to amino acids, which convert one form to another with predictable regularity.
Newly created proteins have almost no amino acid conversions, while older proteins will have many. By understanding this process, the team could find out how old key proteins in human cartilage were.
After scans with sensitive mass spectrometers, the team found that cartilage in ankles is young, middle-aged in the knee, and old in the hips. This correlation between the age of human cartilage and its location in the body is similar to limb repair that occurs in certain animals, which regenerates faster at its furthest reaches.
This discovery also helps explain why it takes longer for a knee injury to recover versus ankle injuries that have faster recovery times. This process is regulated by mircoRNAs that are more active in animals such as the salamander that can regrow limbs.
Their existence in humans, the team said, is down to an evolutionary artefact that lingers on in us through joint tissue repair. These microRNAs could be developed as medicines that might prevent, slow or reverse arthritis.