An adorable, tiny, smiley-faced, and feathery-gilled Mexican salamander called an axolotl could be the answer to the future’s medical advancements. Contrary to its amicable appearance, these lizards don’t hesitate to bite off and eat away at their fellow lizard’s arms. Although it’s not all gruesome, they can grow whole new arms—bones, muscle, skin, nerves and all – over a few months.
“It’s pretty gruesome, but cannibalism is a possible reason why they grow their arms back,” says associate biology professor, James Monaghan at Northeastern University. His lab studies regeneration in axolotls, a peculiar species that can grow back limbs and other organs to various degrees.
“When an injury occurs, some cues are released in that animal that tells cells near the injury to go from a resting state into a regenerative state,” Monaghan says. “Humans are notoriously bad at regenerating. After we’re done growing, the genes that tell our cells to grow new organs are turned off. That’s a good thing because otherwise, it’d be chaos,” he says. No one wants to spontaneously grow an extra finger. “Axolotls can turn back on those genes that we turn off permanently.” Understanding the specific mechanisms that induce regenerative responses in axolotls could help them induce such mechanisms in humans too someday.
“When you think of the human condition, most of our issues with the disease are with internal organs,” Monaghan says. “Take retina regeneration, for example,” Monaghan says “we can either learn the process axolotls undergo that allows their specialised cells to return back to developmental cells and then mimic that process in human eyes. Or, we can learn which elements of the axolotl enable their cells to behave this way, and then add those elements to human stem cell therapy.”
The axolotl isn’t the only animal that can regrow organs. Starfish, worms, frogs, and other species of salamanders can also regenerate. However, axolotls are special because, unlike other animals, they can regrow organs that are just as robust as the originals, no matter how old they get. Monaghan says studying axolotls may not be the golden bullet for inducing regeneration in humans, too, but it could be part of the puzzle.