The story begins with the Aztec God of death and lightning, the Xolotl. As legends have it, he was a monstrous dog that guarded the sun god and ushered souls to the underworld every night. One day, as Gods began sacrificing each other for the newly created sun, Xolotl, a master transformer, managed to escape death by turning himself into a salamander. And that creature came to be known as the axolotl.
In ancient Aztec tongue, the name ‘Axolotl’ translates to “water monster,” and just as their name suggests, these creatures live their entire lives underwater using these adorable feather gills to breathe. After being driven to near extinction from their only natural habitats in Central Mexico, these creatures are now found more in labs than anywhere else. This is because the axolotl is one of nature’s scrappiest creatures with a unique ability that has baffled the scientific community for decades.
Dr. James Godwin: “They are pretty amazing actually. So I mean obviously, they are famous for their ability to regenerate extreme structures like limbs and we all know that it’s the only terrestrial animal that can regrow a limb and the only vertebrate that can regrow a limb. So if you amputate at the level of the wrist, you regenerate the hand. If you amputate at the upper arm, you can regenerate a full arm.”
But the axolotl’s regenerative ability doesn’t stop there.
Dr. James Godwin: “There is a whole laundry list of structures that they can regenerate. They can regenerate the front portion of their brain, called the telencephalon. You can crush the spinal cord and in about three weeks, all of the spinal cord machinery would reconnect and the tail and the legs will work again. They can regenerate impressively their testes. But most importantly, they can regenerate like a third of the heart ventricle. So if you amputate or injure a third of the heart, of the pumping machinery of the heart, it will regrow that in the course of about 30 days to 60 days. Comparative to humans, where a tiny, little blockage in our heart vessel will lead to extreme damage and eventually death, these guys are pretty amazing.”
Axolotls are able to achieve this sort of regeneration because they react to injuries in an entirely different way than humans. When we are injured, a wound from a severed limb simply gets covered with skin tissue. But not the axolotls. They transform nearby cells to stem cells, forming bones, skins, and veins in their exact original state. Scientists are still unable to explain why we react to injuries so differently.
Dr. James Godwin: “When humans or mice gets injured certain parts of the immune system participate in that in a different way that may lead to a scarring outcome or it may block the ability to activate or awaken that regenerative process. The other thing is that there may be some intricate difference in the salamander’s cell. Salamanders may have cells that are poised, ready to take place in reaction of regeneration and human cells could be locked down in their potential.”
Recently, researchers gained access to the full genome sequence of an axolotl allowing them to identify specific genes and proteins that could hold the key to regeneration.
Dr. James Godwin: “Now that we have a sequence genome and we have all the molecular tools, I think it’s going to be a very exciting future for this model. If we could learn from these regenerative organisms and use them as a template, we might be able to sort of unlock the natural way to regenerate.”