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takyon [soylentnews.org] writes:

Scientists Got Adult Frogs to Regrow Limbs. It's a Step Toward Human 'Regeneration' [discovermagazine.com]

Millions of people live with amputated limbs that are gone forever. But that might not be the case in the future. For the first time, scientists have shown that adult frogs can regrow amputated legs. They say the approach can work in humans, too [discovermagazine.com]. "There is no reason that human bodies can't regenerate," said Tufts University biologist Michael Levin, who led the new research. "This is the first proof-of-principle of a roadmap for regenerative therapy in human medicine, well beyond limbs," he added. "Many problems — from birth defects to traumatic injury, aging and even cancer — could be solved if we understood how to induce organs to regrow in place."

Ultimately, that's what Levin and his research team at Tufts University in Medford, Massachusetts, want to figure out: how cells cooperate to build a complex three-dimensional organ and "stop exactly when it's done." But first, the scientists needed to try to reproduce organ growth in animals that don't regenerate. Adult African clawed frogs, a common laboratory animal known in scientific circles Xenopus laevis, fit the bill. The amphibians are not normally regenerative but have some tissue renewal capacity, just like humans. "We were hoping to show that adult Xenopus frogs are capable of limb regeneration, and to find a trigger that allows it to happen," Levin said.

The trigger the team found is progesterone, the sex hormone involved in the female menstrual cycle, pregnancy and breastfeeding. The scientists applied the compound to frogs' amputated back legs with a wearable bioreactor device for 24 hours. Then they watched as the limb regenerated.

See also: These Flatworms Can Regrow A Body From A Fragment. How Do They Do It And Could We? [npr.org]

Brief Local Application of Progesterone via a Wearable Bioreactor Induces Long-Term Regenerative Response in Adult Xenopus Hindlimb [cell.com] (open, DOI: 10.1016/j.celrep.2018.10.010) (DX [doi.org])

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