Researchers looked at three very different animals—axolotls, zebrafish and mice—to see why they can grow back parts of their bodies. They found a small set of genes that act the same way in all three species.
Why It Matters
Every year more than a million people lose a limb because of disease, injury or cancer. Doctors hope one day to replace a missing arm or leg with the body’s own ability to regrow it, instead of using a prosthetic.
The new study points to two genes called SP6 and SP8. These genes turn on a special program in the skin that starts the rebuilding process.
What the Animals Teach Us
- Axolotls can rebuild whole limbs, spinal cord, parts of the heart, brain and many other organs.
- Zebrafish repeatedly grow back their tail fins and can also repair heart, brain, kidney and eye tissue.
- Mice are mammals like humans. They can regrow the tips of their fingers, and humans sometimes grow back a fingertip if the nail bed stays intact.
When scientists removed the SP8 gene from axolotls, the animals could not make new bone in a missing limb. The same problem appeared in mice that lacked both SP6 and SP8 during finger‑tip healing.
Testing a Gene‑Therapy Idea
Using a virus to deliver a signal called FGF8—normally turned on by SP8—researchers gave mice a boost that helped bone grow back in damaged fingers. The treatment only worked when the SP genes were missing, showing that the virus can replace their missing signal.
Looking Ahead
Human arms and legs cannot naturally regrow the way a salamander does, but the study gives scientists a proof that a gene‑based approach might someday help. Future work will need to test safety, dosage and how to deliver the therapy to people.
The research also highlights how sharing ideas across labs that study different animals can speed up discoveries. By comparing salamanders, fish and mammals, scientists uncovered a common genetic language for regeneration.