Researchers have for some years been investigating the mechanisms by which salamanders can regenerate limbs and organs. The hope is that either this capacity still exists in mammals in some form, dormant but able to be reactivated, or otherwise that there is something to be learned from salamander biology that might be imported to mammals to create greater feats of regeneration.
This latest research might go some way to explaining some of the contradictory results that have emerged from past work on the biology of salamander regeneration, such as whether or not their regenerative capacity declines with age:
Scientists labelled different cell types in two species of salamander in order to ascertain what kinds of cell give rise to new muscle tissue in salamanders that had lost a front leg. Salamanders are known for their remarkable ability to regenerate not only lost tails and other extremities but also the tissue of internal organs, such as the heart and brain. The traditional view is that the new tissue is formed from a population of stem cells activated when body parts are damaged; what they found, however, was that even though the two species were relatively closely related, this was true only for one.
"We show that in one of the salamander species, muscle tissue is regenerated from specialised muscle cells that dedifferentiate and forget what type of cell they've been. This is an interesting cellular mechanism that destabilises cell specialisation and produces new stem cells, as opposed to the other species, in which the new muscles are created from existing stem cells."
In the dedifferentiating species, the capacity to regenerate tissue does not decline with age, which the scientists believe can be linked to their ability to make new stem cells from muscle cells on demand. "It's important to study the process by which the salamander's muscle cells forget their cellular identity and how its modulated. It's also important to examine why their ability to regenerate is independent of age and the number of times the same tissue and body part has been regenerated."