Different from mammals, several salamanders called newts their can repeatedly regenerate their limbs at any age. Base on a new Nature Communications study, adult newts were able to secure their amazing regenerative capabilities, however they make use of a diverse system compared to the young larval newts before metamorphosis. The scientists hope that these results will give you hints for tissue regeneration and wound repair in other species, including ours.
When a leg or tail is amputated, the newt generates a cell mass called the blastema at the stump, and from this a new, fully-functional limb will eventually be regenerated, regardless of the age. Not all amphibians can do this: While several larval salamanders and tadpoles may regenerate their limbs, they usually shed that capability once they metamorphose into adult salamanders and frogs.
It’s uncertain just how newts have the ability to do this throughout their lives. Prior reports claim that possibly skeletal muscle-fiber cells (SMFCs) or muscle base/progenitor cells (MPCs) subscribe to fresh muscle in the regenerated newt limbs. SMFCs make up skeletal muscles – among three main kinds of muscle as well as cardiac and smooth muscles. MPCs (such as satellite cells) are predecessors that can differentiate into SMFCs.
So, in order to observe these cells during limb regeneration in larval and adult newts, an international team led by University of Dayton’s Panagiotis Tsonis and Chikafumi Chiba from the University of Tsukuba amputated the limbs of Japanese fire-bellied newts (Cynops pyrrhogaster) aged 3 months, 16 months, and 3 years or more. These newts are transgenic: They have a gene for SMFCs that fluoresces and can be turned on and off.
The team discovered that these newts switch the cellular mechanism for limb regeneration as they metamorphose from larvae to adults: from a stem/progenitor-based mechanism to one that’s based on “dedifferentiation.” That means for adult newts to regenerate their amputated limbs, SMFCs that have been recruited to the stump regress (or dedifferentiate) to a more primitive state. In contrast, larval newts don’t need muscle fiber cells for regeneration; instead, they use satellite cells for new muscle.