Achieving a milestone, scientists regrow frog’s lost leg

For millions of patients who have lost limbs for reasons ranging from diabetes to trauma, the possibility of regaining function through natural regeneration remains out of reach. Regrowth of legs and arms remains the province of salamanders and superheroes.

But in a study published in the journal Science Advances, scientists at the Wyss Institute at Harvard University and Tufts University have brought us a step closer to the goal of regenerative medicine

On adult frogs, which are naturally unable to regenerate limbs, the researchers were able to trigger regrowth of a lost leg using a five-drug cocktail applied for just 24 hours in a silicone wearable bioreactor dome (BioDome) that seals in the elixir over the stump. That brief treatment sets in motion an 18-month period of regrowth that restores a functional leg.

The Tufts researchers triggered the regenerative process in African clawed frogs by enclosing the wound in a silicone cap, which they call a BioDome, containing a silk protein gel loaded with the five-drug cocktail

 Each drug fulfilled a different purpose, including tamping down inflammation, inhibiting the production of collagen which would lead to scarring, and encouraging the new growth of nerve fibers, blood vessels, and muscle.

The combination and the bioreactor provided a local environment and signals that tipped the scales away from the natural tendency to close off the stump, and toward the regenerative process. The researchers observed dramatic growth of tissue in many of the treated frogs, re-creating an almost fully functional leg.