Axolotls, the frilly-headed salamanders native to lakes and wetlands around Mexico City, have long been known for their incredible ability to regrow significant parts of their bodies. However, recent research has uncovered an even more astonishing biological feat: axolotls can completely regrow their thymus, a vital organ for the immune system in most vertebrates.
Published in Science Immunology, the study revealed that while some animals can partially regrow their thymuses, axolotls can rebuild the entire organ from scratch. This discovery marks a significant breakthrough in the field of regeneration biology.
Maximina H. Yun, a biologist at the Chinese Institutes for Medical Research in Beijing and co-author of the study, expressed her astonishment at this finding, stating, “Axolotls are legendary for regenerating limbs and parts of the central nervous system. The realization that these animals can regrow their full thymus from scratch is a breakthrough moment.”
The thymus plays a crucial role in producing T cells, which help the body target and destroy invading pathogens. Turan Demircan, a regeneration expert at Muğla Sıtkı Koçman University in Turkey, noted that in most vertebrates, including humans, the thymus degenerates over time and cannot be fully rebuilt once damaged or removed.
In the study, researchers removed the thymus from juvenile axolotls and observed the regeneration process. Within seven days, new thymuses began to form, and after 35 days, over 60 percent of the axolotls had fully regenerated the organ. René Maehr, a biologist at the University of Massachusetts Chan Medical School and co-author of the study, expressed his surprise at the full, functional regeneration of the complex immune organ.
Further analysis identified two key components essential to the regeneration process: the Foxn1 gene, known for its role in thymus development, and a signaling molecule called midkine. These findings suggest a potential biological pathway that could be harnessed for treating thymus-related conditions in humans.
Demircan emphasized the significance of axolotls in regeneration research, describing them as nature’s “master key” for understanding tissue regeneration. By reawakening the specific pathway involved in thymus regeneration, researchers may be able to stimulate thymus regrowth in humans, potentially reversing immune aging or aiding patients who have undergone thymectomies.
Yun proposed the idea of manipulating human stem cells to mimic the axolotl’s regenerative abilities and restore thymus function. This groundbreaking research lays the foundation for transformative therapies that could revolutionize immune restoration in humans.
As we continue to uncover the remarkable regenerative capabilities of axolotls, it becomes increasingly clear that these creatures hold valuable insights for advancing medical science. By supporting research in regeneration biology, we may unlock new possibilities for treating a wide range of health conditions and improving human health outcomes.

