Single-cell analysis reveals functionally distinct classes within the planarian stem cell compartment
van Wolfswinkel, J.C., Wagner, D.E., Reddien, P.W.
Planarians are flatworms capable of regenerating any missing body region. This capacity is mediated by neoblasts, a proliferative cell population that contains pluripotent stem cells. Although population-based studies have revealed many neoblast characteristics, whether functionally distinct classes exist within this population is unclear. Here, we used high-dimensional single-cell transcriptional profiling from over a thousand individual neoblasts to directly compare gene expression fingerprints during homeostasis and regeneration. We identified two prominent neoblast classes that we named ζ (zeta) and σ (sigma). Zeta-neoblasts encompass specified cells that give rise to an abundant postmitotic lineage including epidermal cells, and are not required for regeneration. By contrast, sigma-neoblasts proliferate in response to injury, possess broad lineage capacity, and can give rise to zeta-neoblasts. These findings present a new view of planarian neoblasts, in which the population is comprised of two major and functionally distinct cellular compartments.
van Wolfswinkel, J.C., Wagner, D.E., Reddien, P.W. "Single-cell analysis reveals functionally distinct classes within the planarian stem cell compartment" Cell Stem Cell (2014): 326–39