Wearable bioreactor stimulates limb regrowth in frogs

Whether it's the Mexican axolotl that can regrow its legs in weeks, the green anole lizard that sprouts new tails as needed, or the ability of newts to replace pretty whatever limb they happen to be missing, the regenerative abilities of certain creatures have much to teach the world of medical science.

A new breakthrough out of Tufts University has now resulted in partial limb regeneration in adult frogs that usually lack such capabilities, raising hopes the research could ultimately benefit human amputees.

The scientists enlisted an animal called the African clawed frog for their work, as a way of investigating what they see as an under-explored area of biomedical research. Regenerating limbs in humans would be a massive breakthrough for obvious reasons, and for a long time scientists have probed natural mechanisms in animals like those mentioned above in search of techniques that could ultimately be adapted to our species.

At the heart of the technique is a new kind of wearable bioreactor developed in-house at the Tufts' School of Engineering. The device is designed to be attached to the wound and uses a silk protein-based hydrogel to deliver small molecule compounds to the injury site. Future plans will look at additional enhancing factors, but the team's experiments so far have involved the delivery of the steroid hormone progesterone.

"We looked at progesterone because it showed promise for promoting nerve repair and regeneration," says Celia Herrera-Rincon, lead author of the study. "It also modulates the immune response to promote healing, and triggers the re-growth of blood vessels and bone.