Regeneration in animals:

Insights from the annelid Platynereis dumerilii

Regeneration is widespread across animals but varies significantly in scale. Some phyla, such as the annelids, display substantial regenerating abilities, though little is known about the cellular mechanisms underlying the process.
The annelid Platynereis dumerilii is promptly emerging as a strong and relevant model to study this process. Platynereis can stereotypically restore, upon amputation, the complex posterior part of its body including both differentiated structures and stem cells whose divisions allow the production of new segments and the growth of the worm.
To precisely determine the origin, plasticity and fate of the cells participating in blastema formation and posterior end regeneration following amputation in Platynereis, we developed specific tools to track different cell populations.
We find that regeneration is partly promoted by a population of proliferative gut cells whose regenerative potential varies as a function of their position along the worm’s antero-posterior axis. However, they are unable to regenerate the stem cells responsible for the growth of the worms. Those stem cells are of local origin, deriving from the cells present in the segment abutting the amputation plane, as are most of the blastema cells. Our results favour a hybrid and flexible cellular model for posterior regeneration in Platynereis relying on different degrees of cell plasticity.

Ève Gazave is CNRS researcher at the Institut Jacques Monod.

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