title: Embryonic origin of adult stem cells required for tissue homeostasis and regeneration.
abstract: Planarian neoblasts are pluripotent, adult somatic stem cells and lineage-primed progenitors that are required for the production and maintenance of all differentiated cell types, including the germline. Neoblasts, originally defined as undifferentiated cells residing in the adult parenchyma, are frequently compared to embryonic stem cells yet their developmental origin remains obscure. We investigated the provenance of neoblasts duringSchmidtea mediterraneaembryogenesis, and report that neoblasts arise from an anarchic, cyclingpiwi-1+population wholly responsible for production of all temporary and definitive organs during embryogenesis. Early embryonicpiwi-1+cells are molecularly and functionally distinct from neoblasts: they express unique cohorts of early embryo enriched transcripts and behave differently than neoblasts in cell transplantation assays. Neoblast lineages arise as organogenesis begins and are required for construction of all major organ systems during embryogenesis. These subpopulations are continuously generated during adulthood, where they act as agents of tissue homeostasis and regeneration.
authors.affiliation: Howard Hughes Medical Institute, Stowers Institute for Medical Research, Kansas City, United States.
authors.forename: Erin L
authors.initials: EL
authors.lastname: Davies
authors.affiliation: Howard Hughes Medical Institute, Stowers Institute for Medical Research, Kansas City, United States.
authors.forename: Kai
authors.initials: K
authors.lastname: Lei
authors.affiliation: Howard Hughes Medical Institute, Stowers Institute for Medical Research, Kansas City, United States.
authors.forename: Christopher W
authors.initials: CW
authors.lastname: Seidel
authors.affiliation: Howard Hughes Medical Institute, Stowers Institute for Medical Research, Kansas City, United States.
authors.forename: Amanda E
authors.initials: AE
authors.lastname: Kroesen
authors.affiliation: Howard Hughes Medical Institute, Stowers Institute for Medical Research, Kansas City, United States.
authors.forename: Sean A
authors.initials: SA
authors.lastname: McKinney
authors.affiliation: Howard Hughes Medical Institute, Stowers Institute for Medical Research, Kansas City, United States.
authors.forename: Longhua
authors.initials: L
authors.lastname: Guo
authors.affiliation: Howard Hughes Medical Institute, Stowers Institute for Medical Research, Kansas City, United States.
authors.forename: Sofia Mc
authors.initials: SM
authors.lastname: Robb
authors.affiliation: Howard Hughes Medical Institute, Stowers Institute for Medical Research, Kansas City, United States.
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Ross
authors.affiliation: Howard Hughes Medical Institute, Stowers Institute for Medical Research, Kansas City, United States.
authors.forename: Kirsten
authors.initials: K
authors.lastname: Gotting
authors.affiliation: Howard Hughes Medical Institute, Stowers Institute for Medical Research, Kansas City, United States.
authors.forename: Alejandro Sánchez
authors.identifier: 0000-0002-1966-6959
authors.initials: AS
authors.lastname: Alvarado
mesh_terms: D053687:Adult Stem Cells / Q000502:physiology*; D000818:Animals; D019070:Cell Lineage; D006706:Homeostasis; D010932:Planarians / Q000196:embryology*; D012038:Regeneration
keywords: Schmidtea mediterranea; anarchic cleavage; developmental biology; embryogenesis; planaria; stem cells