Ever wondered how Dr Who regenerates ? Well, ok, I know they just hire a different actor. But if and when the Doctor happens to get an arm amputated during his regeneration phase, it grows back, allegedly. Which is exactly what happens with a range of different animals, including salamanders.
Surprisingly, research in last week's issue of Nature shows that the axolotl does not use pluripotent stem cells to regenerate amputated limbs. Fluorescent labelling and tracking of cell fate reveals that the secret is in a sophisticated system of getting the right kinds of cells to the right places, and not in making cell pluripotent again.
Probably a disappointment for stem cell people, but intriguing nonetheless.
The original paper is here:
Cells keep a memory of their tissue origin during axolotl limb regeneration p60
By using an integrated GFP transgene to track the major limb tissues during limb regeneration in the salamander Ambystoma mexicanum (the axolotl), it has been possible to demonstrate that each limb tissue produces a different set of progenitors with restricted potential. Thus, the blastema—the collection of cells that regenerates the diverse tissues of the limb—is composed of a heterogeneous collection of restricted progenitor cells instead of dedifferentiated pluripotent cells, as previously thought.
Martin Kragl, Dunja Knapp, Eugen Nacu, Shahryar Khattak, Malcolm Maden, Hans Henning Epperlein & Elly M. Tanaka
there is also an excellent News & Views piece about this research:
Developmental biology: A cellular view of regeneration p39
How the salamander regrows an entire limb after injury has flummoxed the wisest of scientists. A closer look at the cells involved in limb regeneration shows that remembering past origins may be crucial for this feat.
Alejandro Sánchez Alvarado
I'm surprised they didn't mention Dr Who, though.