How Salamanders Regrow Limbs

Like other salamanders, this North American newt can sprout new limbs in the place of those that have been amputated. Credit: Anoop Kumar/University College London

Salamanders regrow amputated limbs by producing tissue-specific progenitor cells, scientists have learned.

The find, reported in this week's Nature, challenges dogma and has important implications for our understanding of limb regeneration, which in turn has important implications for regenerative medicine and research into treatments that could restore adult body parts, according to a summary by the journal.

It had been thought that salamander limb amputation triggers remaining mature limb cells to generate "pluripotent" stem cells that can produce the many missing types of tissue.

But Elly Tanaka at the Center for Regenerative Therapies, Dresden, Germany and colleagues now show that blastema cells do not become pluripotent during limb regeneration and instead retain a strong memory of their tissue of embryonic origin. Each tissue, they conclude, produces a different set of progenitor cells with restricted potential for restoring a part of the limb — so cartilage cells cannot make muscle and muscle cells cannot make cartilage.

In 2007, scientist found that a protein called nAG helps to stimulate the proliferation of stem cells that ultimately form new limbs in red-spotted newts (Notophthalmus viridescens), a type of salamander.