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Salamanders and a few odd fish are the lucky ones: they can regrow parts of damaged organs and even regenerate fins and entire limbs when the originals are cut off.
It seems reasonable to think other critters could do the same: we grew our limbs in the first place and the genetic information is probably still on board. But how do we activate those instructions?
Researchers at Harvard and Tufts University may have found the answer.
They anesthetized African clawed frogs—normally unable to regrow lost limbs—and amputated one of their hind legs.
The researchers then capped the stump with a silicone gel tip containing a silk protein gel laced with five drugs designed to mimic the in utero environment.
The drugs were chosen for their ability to reduce inflammation (a common occurrence at a wound), inhibit the formation of scar tissue, and stimulate the growth of blood vessels, nerve fibers, and muscle.
Leaving the wound capped with this mixture for just 24 hours was enough to spark the growth of a new, almost normal leg, complete with foot and toes, over the next 18 months.
The bone structure was not quite normal but the leg was functional enough to respond to touch and to allow the frogs to swim as well as walk or hop on land.
Next, the scientists will refine the drugs and process to see if the frogs can grow new legs that match the complete structure and functions of the original and will begin planning trials in larger creatures.
TRENDPOST: From legs to spinal cords (“Breakthroughs Restore Walking to Paralyzed Legs,” 15 Feb 2022, and “Protein Allows Paralyzed Mice to Walk Again,” 30 Mar 2021), the science of tissue regeneration is showing brisk progress. At the present pace, human trials of various techniques to regenerate human spinal cord neurons and tissue should be under way before mid-century.