Drug Cocktail Spurs Frogs To Regrow Amputated Limbs, Research Finds

Some unusual creatures have an innate ability to regrow a limb: salamanders, starfish, crabs, lizards, and newts.

Photo Insert: The African Clawed Frog

Such extraordinary powers elude most animals, including humans, although scientists have long sought to understand and replicate them in a quest to regenerate limbs for millions of patient amputees, including diabetics and victims of trauma, Katie Hunt reported for CNN.

Now, researchers in the United States said Wednesday they were able to trigger the regrowth of an amputated leg in a type of African clawed frog (Xenopus laevis), in what they described as a "step closer to the goal of regenerative medicine."

The technique used by the team of scientists, based at Harvard University's Wyss Institute and Tufts University, involved applying a mix of five drugs to the test frogs' spike-like stump, sealed in with a small silicone dome. The cocktail was only applied for 24 hours, but after 18 months, the limb was almost fully functional.

The frogs, which live in water, were able to swim and respond to touch. They also grew several toes but not the webbing between them. The research was published in the journal Science Advances on Wednesday.

The results were "impressive" and "exciting," said James Monaghan, an associate professor in the department of biology at Northeastern University. He wasn't involved in the research.

"Xenopus frogs are somewhere in between a salamander that regrows a limb nearly perfectly and a mammal that generates a scar after amputation. Adult Xenopus frogs regenerate a spike after amputation, but the spike lacks any pattern like a limb," Monaghan explained.

"This study is significant because it shows that patterning, albeit not perfect, can be induced in a limb that typically regenerates only a spike," Monaghan said via email.

The team said that the fact that only a brief exposure to the drugs set in motion a months-long regeneration suggested that frogs -- and perhaps other animals -- have dormant regenerative capabilities that can be triggered into action.

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