Unlike some creatures, humans cannot regenerate their limbs – but a new study suggests we have a hidden "salamander-like" ability to regenerate cartilage in the body, a finding that can help treat joint injuries and even arthritis. Using 1965 mass spectrometry techniques, researchers were able to identify a mechanism by which tissue is repaired around the ankles, knees, and thighs – and this is similar to the mechanism used by amphibians to sprout new feet.
This is the first time researchers have comprehensively hunted for signs of regeneration in human tissue and it seems that in some joints we are better at repairing cartilage than anyone had previously thought. If scientists manage to build on this, these healing properties could be further enhanced.
"We believe that understanding this" salamander-like "regenerative capacity in humans and the critically missing components of this regulatory scheme may provide the basis for new approaches to the repair of joint tissues and possibly entire human limbs," says Virginia physiologist Bayers Kraus of Duke University in North Carolina.
The team collected 1
They began their analysis by determining the age of cartilage protein, finding that the proteins in the knee were younger than those in the hip – as in, they showed less signs of natural aging, The ankle proteins were still younger
This may explain why the hips and knee joints are more susceptible to arthritis than the ankles and why injuries to the former usually take longer. Interestingly, it also coincides with animals with regenerative abilities, in which regeneration usually occurs more easily at the tips of the body than at the core.
Protein readings also coincide with further study of miRNA levels: these molecules regulate the cartilage recovery process, and again they are more active in self-healing animals such as salamanders and zebrafish.
"We were excited to learn that the regulators of salamander limb regeneration appear to be the controllers of joint repair in the human limb," says Ming-Feng Hesheh, a physiologist at Duke University. "We call it 'inner salamander capacity.'
"We believe we could strengthen these regulators to regenerate the fully degenerated arthritis cartilage," says Kraus. "If we can figure out what regulators we are missing compared to salamanders, we may even be able to add back the missing components and work out a way to someday regenerate some or all of the wounded human limb."
Researchers believe that the presence of miRNAs can be traced at some point away from our evolutionary history. According to their results, miRNA molecules were more active in the ankles than in the knees, and more active in the knees than in the hips.
Mixing miRNAs with other compounds to be used as targeted drugs is a new field of research, but in the case of enhancing our regenerative capacity, it is not yet clear what these other compounds may be. If further studies can shed some light on this, we may consider treating osteoarthritis, for example, a type of arthritis caused by the destruction of cartilage around the bones.
We are still very far from this type of treatment, let alone being able to recover our hands and feet. So far, further studies could investigate whether cells near our limbs are actually substantially better for regeneration or whether they are simply in a biological environment that is more suitable for cartilage regeneration.
Finding this initial link between human and animal regeneration is promising. nonetheless: this is one of the many ways that scientists have looked at how the human body could be encouraged to repair itself better.
"We believe that this is a fundamental repair mechanism that can be applied to many tissues, not just cartilage." says Kraus.
The studies were published in E.g. of Science .