Could we one day regrow amputated limbs? We have taken a small step down this road with partial regeneration of the hind legs of frogs.
Scientists have invented a device that kick-starts legs to grow back after they’ve been chopped off, with hopes it will lead to human limb regeneration.
Several kinds of animals can regenerate damaged body parts to some extent, including flatworms, fish and some amphibians. With just a few exceptions mammals seem to have lost this ability in their evolutionary past but there’s hope it could be reawakened with the right chemical nudges.
A species of African frog has relatively weak limb regenerating powers. If they lose a leg they normally regrow a thin spike of rubbery cartilage. But now Michael Levin at Tufts University, Massachusetts, and his colleagues have coaxed the animals into re-growing a wider, paddle-like structure complete with bones, nerves and blood vessels – although it lacked a foot.
The team achieved their results with progesterone, which is best known as a female sex hormone, but which also plays a role in wound repair. It was delivered with a bioreactor, a small box containing progesterone-loaded gel that was sewn over the wound straight after amputation.
Leaving the bioreactor in place for 24 hours triggered a cascade of tissue regrowth that lasted 9 months. The animals were able to use their resulting paddle-like limbs in a rudimentary swimming motion. Those that had a bioreactor sewn on without progesterone in the gel, for comparison, grew a spike.
Levin says his team has recently begun using more complex cocktails in the bioreactor, and found that this triggers regrowth of better-formed limbs with partial toes, although that work isn’t yet published. “A very short stimulation can deliver a very complex set of instructions,” he says.
Levin says human limbs may also be made to regenerate if we find the right chemicals to put in a scaled-up bioreactor. “Your body knows how to make a limb – it did that during embryonic development.”
Source: News Scientist