Regrowing Human Limbs, Scientists Think Salamanders Hold The Key

Scientists are peeling back the secret layers of the onion in the salamander, with the aim of regrowing human limbs for people who have suffered from devastating life-changing injuries as limb loss.

When the salamander loses its leg or tail, while unpleasant, it will heal eventually and grow back. It is not permanent. Furthermore, the axolotl can regenerate not just its limbs but any body part including the spine and even parts of its brain.

It can do this with such perfection as if the injury never happened. Also, it does not matter how many times this happens, the lost body part grows back correctly looking like the original. In fact, it is the original, similar to how we replace our cells completely every 7 years.

Scientists have always had the amphibious creature, as the perfect role model for regeneration, or the holy grail of regrowing human limbs. Salamanders are the only adult vertebrate that can fully regrow back its limbs with total perfection.

Now for the first time at the University College London, a study has been led by Dr. Maximina Yun, at the UCL Institute of Structural and Molecular Biology.

Dr. Yun specializes in regenerative biology and focuses on her research on how adult cells can be reprogrammed into less differentiated states during the regeneration process with certain species that are pioneers in regeneration. She also looks at the changes in the regeneration process with species as they age.

Her team has discovered an important signaling pathway that aids in the regeneration process. Allowing light to be cast on how the salamander’s natural healing abilities can be understood in regenerative medicine with a bid to apply it to injured humans.

 ERK Activation Pathway

The scientists discovered that the ERK Pathway (a set of proteins) must be constantly active for the cells in the salamander to be reprogrammed. Thus allowing the cells to divide and eventually turning into the biological structures that were lost.

More importantly, the researchers observed a key difference with the activity of this pathway in the salamander compared to humans, allowing a better understanding as to why humans don’t regenerate limbs when damaged or lost.

The scientist’s research was published in the Stem Cell Reports. The document reveals how the ERK pathway is not completely active in mammalian cells. However, when the scientists used a piece of DNA to force the pathway to be constantly active in mice, it gave the cells more potential for reprogramming of cells and regeneration.

The scientists believe this can help them better understand diseases and develop novel new treatments that will allow the patient to get more on a regenerative pathway.

With this understanding, they propose that in the future scientists could activate this ‘ERK pathway’ in humans who have lost their limbs, perhaps by a set of new DNA or molecules that would stimulate this process.

The lead Scientist, Dr. Max Yun mentions:

“We’re thrilled to have found a critical molecular pathway, the ERK pathway, that determines whether an adult cell is able to be reprogrammed and help the regeneration processes. Manipulating this mechanism could contribute to therapies directed at enhancing the regenerative potential of human cells.”

“While humans have limited regenerative abilities, other organisms, such as the salamander, are able to regenerate an impressive repertoire of complex structures including parts of their hearts, eyes, spinal cord, tails, and they are the only adult vertebrates able to regenerate full limbs.”

– Dr. Max Yun

If they can control this mechanism it could allow new therapies to enhance the regenerative potential of human cells the researchers point out.

Dr. Yun, who was interviewed by Fox News highlighted, “We can use this information and can try to apply it as we speak. In the longer term, if we were to try to induce humans to regrow their arms, [the ERK pathway] would be something we’d have in mind.”

The next step is to focus on discovering how this important pathway regulates limb regeneration and of course what other molecules are involved in the process since the ‘ERK pathway’ is only part of the story but important discovery.

I have discussed in a separate article on macrophages, over recent years, scientists have been studying intensely the regenerative feats of the salamander. They hope that the knowledge gained will contribute to understanding how to promote regeneration in humans.

If scientist is able to crack this puzzle then it could lead to methods to enhance the reprogramming of cells from patients and to further understand their diseases and develop suitable cures.

To Conclude

• The study shows a biological pathway that controls regeneration.
• This pathway called ‘ERK’ must always be active for salamander cells to be reprogrammed.
• This cellular activity is not known to occur in mammals.
• Such a discovery could unlock “regeneration abilities” in other animals.
• Continuing research will try to understand how this pathway is regulated during regeneration of a limb and what other processes are involved.

What are your thoughts on this article? Feel free to comment on your take about the research done by UCL contributing to limb regeneration research.