Axolotls amaze scientists by regenerating this complex organ
Axolotls can completely rebuild their thymus, a key immune organ
By Taylor Mitchell Brown edited by Sarah Lewin Frasier
Paul Starosta/Getty Images
Axolotls are famous for their ability to regrow significant parts of their bodies. But according to recent research, these frilly salamanders, which are native to lakes and wetlands around Mexico Citycan achieve an even more extraordinary biological feat: they can completely regrow their thymus, a complex organ instrumental to the immune system in most vertebrates.
Previous work suggested that some animals could partially regrow the thymuses, but the co-authors of the new paper, published In Scientific immunologywere surprised to see axolotls completely reconstruct this organ with its complex structure from scratch.
“Axolotls are legendary for regenerating limbs and parts of the central nervous system,” says study co-author Maximina H. Yun, a biologist at the China Medical Research Institutes in Beijing. “The realization that these animals can regenerate their entire thymus from scratch is a watershed moment.”
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The thymus is responsible for producing the body’s T cells, which help target and destroy invading pathogens. “In humans and most other vertebrates, the thymus is famous for being one of the first organs to degenerate,” says Turan Demircan, a biologist and regeneration expert at Muğla Sıtkı Koçman University in Turkey, who was not involved in the new research. “Until now, it was thought that once this tissue was lost or removed, it could not be completely reconstructed. »
For the new study, Yun and his colleagues removed the thymus glands of several juvenile axolotls. After seven days, many animals already had new budding thymuses. After 35 days, more than 60 percent of them had completely regenerated their organ. “I was truly surprised,” says study co-author René Maehr, a biologist at the University of Massachusetts Chan Medical School. “I didn’t expect complete and functional regeneration of a complex immune organ.”
The team then tested the function of the regenerated thymuses by transplanting them into other axolotls. “Remarkably, the transplanted organs integrated perfectly,” says Demircan.
Further analysis identified two key characteristics essential to the regeneration process: Foxn1 gene, which scientists already knew was involved in thymus development, and a signaling molecule called midkine, which Demircan said appears in human embryos but is largely inactive in adults. The results indicate that there may be a biological pathway involving these components that could be useful in treating thymus-related conditions in humans.
“Axolotls are essentially nature’s master key to regeneration research,” says Demircan. “If we could awaken this specific pathway in humans, we might be able to stimulate thymus regrowth, potentially reverse immune aging or help thymectomy patients.”
According to Yun, researchers may one day modify human stem cells to mimic the axolotl and restore thymus function. “We are laying the foundation for transformative therapies that could redefine our approach to immune restoration. »
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