The Axolotl looks like a Pokémon (and in fact has several clearly designed in its image). It’s almost too cute to be able to also do something as astounding as regrowing entire limbs, part of its heart, spinal cord, and even parts of its brain, whenever it wants. For years, we’ve been studying this Wolverine-like regeneration ability to see if maybe we can borrow some of it for ourselves. And it looks like we might be getting close.
As Wired’s Ana Lagos reported, James Monaghan’s lab at Northeastern University has been probing the axolotl’s freakish regenerative talents, hoping to uncover secrets that could revolutionize human medicine and maybe even one day become walking, talking Ships of Theseus.
Publishing their findings in Nature Communications, the team may have figured out how a severed limb knows what part of the limb to regrow, a vital bit of information necessary to figure out the larger puzzle of regrowth.
Turns out, it’s all centered around a kind of chemically-based GPS inside the axolotl, specifically centered around a molecule called retinoic acid, or RA, a derivative of vitamin A. RA barks out orders at cells, demanding that they rebuild a hand or shoulder or whatever, and make it snappy! But the researchers noticed a weird thing about RA: it dies way faster in certain parts of the body than others.
They found that this is due to an enzyme called CYP26B1 that shreds RA apart. They didn’t find much of it in the shoulder, which allowed an entire arm to regrow, but they found a lot of it in the wrist, where it was destroying RA. In fact, that’s literally the only thing it does. It does nothing but destroy the thing responsible for rapid regeneration. Monaghan’s team discovered that cells near the wrist pump out tons of this enzyme, killing RA before it can build anything more than a hand.
To test their theory, the team dosed wrist-stump axolotls with a drug that blocks CYP26B1. This caused the wrist cells to think and behave like shoulder cells, so they went to work building entire extra limbs, effectively overclocking an already overpowered ability.
The researchers also found that high RA levels switched on a gene called Shox, which is crucial for forming upper limbs. CRISPR’d (aka, gene-edited) axolotls without Shox ended up with tiny, malformed arms but normal hands, proving that the gene did, in fact, play a vital role in telling cells to rebuild the entire missing limb, from the ground up.
All very fascinating, all very cool. Here’s the frustrating part for us humans: we all have these exact same genes inside our bodies, but none of them do any of that cool superhuman stuff. Instead of regenerating, we scar. BOOO. That sucks. Maybe one day we’ll be able to flip some switches inside of us that tell our cells to regrow a limb.
We’re still a long way away from that. But we are a little bit closer than we’ve ever been, and it’s all thanks to the axolotl, a little miracle of a creature that might also be one of the cutest things in existence.
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