Humans naturally regenerate certain tissues, such as the top layer of skin, gut lining, and liver tissue.
Fingertips have even been known to re-grow, with bone, nail and skin restored.
But, crucially, we can’t yet re-grow entire limbs — even with medical interference.
Now scientists have found a way to stimulate leg regeneration in frogs — which do not normally re-grow limbs — bringing humans one step closer to unlocking the superpower.
“A very brief application of bioreactor and its payload triggered months of tissue growth and patterning”
“At best, adult frogs normally grow back only a featureless, thin, cartilaginous spike,” said senior author Michael Levin, developmental biologist at the Allen Discovery Center, Tufts University.
He added their method resulted in “bigger, more structured appendages”.
The frogs could even swim almost as well as ones which hadn’t been subjected to the chop.
The scientists used a 3D printer to make a tiny device which they filled with silk protein — to hydrate the wound — and the hormone progesterone.
Progesterone — known as the pregnancy hormone — has been shown to help repair nerves, blood vessels and bones.
The tiny “bioreactor” device was sutured into the wounds of the frogs, then removed after 24 hours.
The frogs were then observed for nine months.
The bioreactor triggered a degree of leg re-growth not seen in frogs which had no device inserted and frogs which had the device but no progesterone.
Professor Levin said: “A very brief application of bioreactor and its payload triggered months of tissue growth and patterning.”
The treated frogs had thicker leg bones and had better nerve and blood vessel growth.
The team will now look at spinal cord regeneration and how to “re-program” tumours.
“Brief Local Application of Progesterone via a Wearable Bioreactor Induces Long-Term Regenerative Response in Adult Xenopus Hindlimb” was published in Cell Press.