The axolotl, a pink-gilled salamander from Mexican lakes, has an amazing ability: it can regrow lost limbs, hearts, and even parts of its brain. Scientists have long wondered why humans cannot do the same. Now, researchers from Wake Forest University, Duke University, and the University of Wisconsin-Madison believe they have found the answer. Remarkably, humans already have the necessary genes. We simply stopped using them after we were born.
The team discovered two genes called SP6 and SP8 that act like master switches for regrowing bones. These genes work in axolotls, zebrafish, and mice, despite these animals being separated by hundreds of millions of years of evolution. When scientists removed these genes from axolotls using CRISPR technology, the salamanders could no longer regrow their limbs properly. The same happened in mice.
The researchers then designed a gene therapy using a virus to deliver instructions that could restart the regeneration process. In mice without these genes, the therapy partially restored their ability to regrow fingertip tips. In healthy mice, it even sped up the natural regeneration process.
While these results are exciting, scientists warn that much more research is needed before this could help human patients. Currently, over one million people worldwide lose limbs each year due to disease, diabetes, injury, or cancer. If this research continues successfully, it could one day offer a completely new way to treat limb loss.