Some animals grow back lost body parts. clawed frogs (Xenopus laevis) are not included. At least not in nature. In one laboratory experiment, however, the frogs developed new, fully functional, almost complete limbs. The animals could feel and move their hind legs, as researchers reported in the journal Science Advances.
For their experiment, the team administered a five-drug cocktail, or MDT for short, to adult clawed frogs using a portable silicone mini-bioreactor. Each compound served a different purpose: one inhibited inflammation, another inhibited collagen production, which would cause scarring, and the rest allowed nerve fibers, blood vessels, and muscles to grow. For 24 hours, the device pumped the mix of active ingredients into the respective residual limb. A functioning leg was restored within 18 months.
“The regenerated tissues, consisting of skin, bone, vessels and nerves, clearly exceeded the complexity and the sensorimotor abilities of the untreated animals and the control animals,” writes the team. The data would show that even in vertebrates, regeneration processes can be set in motion in a targeted manner.
For limbs to regrow, they hypothesize, two components are needed at a very early stage of the process: first, a closed environment that allows wound cells to control the post-injury biochemical milieu, and second, a set of signals that trigger the growth process in a targeted manner.
For years, teams have been working on limb regeneration in mammals. The researchers hope that their experiments will help to develop similar therapies for people who have lost an arm or a leg as a result of diabetes or an accident.