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| I mean, look at them. They're smiles with legs. Picture from Bing Images |
For those of you not in the know, these are axolotls, Ambystoma mexicanum. They're a type of salamander that don't exactly mature, so they stay in their aquatic juvenile state; they mature sexually, otherwise there would be no baby axolotls, but they don't metamorphose into what we think of as salamanders.
Axolotls are highly endangered in their native lake around Mexico City, but they're popular as pets because of their adorableness and in the scientific community because of their regenerative properties. In the same way that lizards can regrow a tail that was chopped off, axolotls can regrow pretty much any part of their body, so long as their central nervous system isn't damaged too badly. That being said, scientists have been looking to these amphibians for clues toward possible treatments for tissue and injury repair in humans.
Researchers in Australia and the UK found that the axolotl's ability to regrow so much of its body without scarring is largely due to its immune system, specifically the presence of macrophages. As their name suggests, these cells engulf bacteria and other foreign matter. They also secrete molecules that help trigger the healing process by eliminating dead cells, then promoting blood vessel and cell growth. Mammals have macrophages as well, but ours don't emit those molecules until a few days after the injury, whereas the researchers found them in the axolotls one day after the injury; when the macrophages were taken out, the injury sites scarred up like ours would.
Knowing this, scientists may seek macrophage-based treatments for injuries to the nervous system or other tissues. Of course, this doesn't mean we can go chopping off limbs and then be able to grow back new ones at the drop of a hat, but it's certainly a start. You can read the full study here.
