Scientists Just Hacked Axolotl Genes to Nudge Mice Toward Regrowing Limbs
Are humans next?
By Alex Tisdale
Wednesday, June 10, 2026
(Graphic via PNAS)
EARTH, Laniakea Supercluster—Axolotls, which can regrow entire limbs—bone, muscle, nerves, skin, the whole package—are one of biology’s stranger examples of self-repair. That weirdness might now lead scientists to a real breakthrough in human medicine.
Published in the Proceedings of the National Academy of Sciences (PNAS), the new study reports that three species—axolotls, zebrafish, and mice—share a set of SP genes that control appendage regrowth, and that an experimental gene therapy built around them can boost digit-tip regeneration in mice.
The findings are making people wonder: are humans next to regrow limbs?
At Wake Forest, assistant professor of biology Josh Currie discovered that regenerating skin tissue in axolotls, zebrafish, and mice can activate two genes, SP6 and SP8. His team investigated how the genes contribute to regeneration in each species.
“It showed us that there are universal, unifying genetic programs that are driving regeneration in very different types of organisms, salamanders, zebrafish and mice,” Currie said.
Using CRISPR gene-editing technology, Currie’s team removed the SP8 gene from the axolotl genome. Without it, axolotls couldn’t regenerate limb bones properly. Brown’s group saw similar problems in mice when SP6 and SP8 were knocked out in regenerating digits.
From there, Duke University plastic surgeon David A. Brown developed a viral gene therapy that promoted bone growth in damaged digits in mice.
This therapy delivered a signaling molecule, FGF8, which is normally activated by SP8. In mice, the treatment promoted bone growth and partially restored lost regenerative abilities in damaged digits when the SP genes were absent.
“Our results demonstrate a contextual gene therapy approach to address limb loss based on genes like SP transcription factors conserved across multiple contexts of appendage regeneration,” the authors wrote in PNAS.
Humans, by contrast, have never been able to regenerate their own limbs. According to the Global Burden of Disease statistics, more than 1 million amputations occur every year worldwide due to diabetes-related vascular disease, traumatic injuries, infections, and cancer. As populations age and diabetes becomes more common, researchers predict that the number of amputees will rise.
What makes these species so interesting is that zebrafish and axolotls can regenerate not only limbs but also important organs. Axolotls can regrow tails, spinal cord tissue, and parts of organs, including the heart, brain, lungs, liver, and jaw. Zebrafish can repair the heart, brain, spinal cord, kidneys, retinas, and pancreas.
When it comes to mice, they’re similar to humans because they’re both mammals. Humans can regrow fingertips (if their nail bed remains intact after injury); mice can regenerate the tips of their digits.
Researchers are optimistic that future therapies could potentially mimic some of the biological mechanisms controlled by SP genes.
“We can use this as a kind of proof of principle that we might be able to deliver therapies to substitute for this regenerative style of epidermis in regrowing tissue in humans,” Currie said.
This will take some time. The research is still in its early stages, and many more studies will be needed before these discoveries can be translated into humans.
“The gene therapy approach in this study is a new avenue that can complement and potentially augment what will surely be a multidisciplinary solution to one day regenerate human limbs,” Currie explained.
While the therapy itself is still years out (if ever), what this study really shows is a sort of blueprint we could follow. Maybe the instructions for regrowing a limb aren't gone from human DNA; we just haven't figured out which switch to flip.
About Alex Tisdale
Artistic journalist based in Florida, inspired by the sky.
You May Also Like
