A Northeastern University researcher has made a breakthrough discovery in the regenerative abilities of axolotls, shedding light on how these salamanders can regrow entire limbs and organs. James Monaghan, biology chair and professor at Northeastern University, has been studying the axolotl’s superpower to unlock its secrets for human medical treatment.
According to Monaghan, axolotls possess a unique positional memory that allows them to know which body part to grow back when injured. This is made possible by a molecule called retinoic acid, which serves as a cue for regenerative cells to determine what to grow and how much to grow it back.
In the arm, axolotls have higher levels of retinoic acid in their shoulders and lower levels in their hands, with specific enzymes present in different parts of the body. Monaghan has found that this gradient of retinoic acid signaling allows the salamander’s cells to interpret the cue and grow back the correct limb.
To test the limits of this system, Monaghan added extra retinoic acid to an axolotl’s hand, resulting in a duplicated limb growing instead of just a hand. This breakthrough has significant implications for human regenerative medicine, with potential applications ranging from scar-free wound healing to growing back entire fingers and limbs.
However, there is still much work to be done before humans can harness the axolotl’s regenerative abilities. Monaghan emphasizes that understanding the signals in an axolotl’s system is only the first step, and that further research is needed to understand the mechanics of the cells themselves and how retinoic acid targets inside them.
Notably, Monaghan has already identified a key target: the short homeobox gene, or shox. When retinoic acid signaling increased, shox activated, and removing it from the axolotl’s genome resulted in short arms with normal-sized hands. This discovery highlights the importance of shox in regeneration and may provide new insights for human regenerative biology.
Monaghan’s research has significant implications for the field of regenerative medicine, emphasizing the need to understand positional memory and how to manipulate it. By unlocking the secrets of axolotls’ regenerative abilities, researchers may be able to develop new treatments for injuries and diseases that currently have no cure.
Source: https://news.northeastern.edu/2025/06/10/axolotl-limb-regeneration