A thymic epithelial stem cell pool persists throughout ontogeny andiIs modulated by TGF-β.
Ucar O, Li K, Dvornikov D, Kreutz C, Timmer J, Matt S, Brenner L, Smedley C, Travis MA, Hofmann TG, Klingmüller U, Kyewski B.
Adult tissue-specific stem cells (SCs) mediate tissue homeostasis and regeneration and can give rise to all lineages in the corresponding tissue, similar to theearly progenitors that generate organs in the first place. However, the developmental origins of adult SCs are largely unknown. We recently identified thymosphereforming stem cells (TSFCs) in the adult mouse thymus, which display genuine stemness features and can generate the two major thymic epithelial cell lineages. Here, we show that embryonic TSFCs possess stemness features but differ from adult TSFCs in surface marker profile. Our findings support the model of a continuous thymic SC lineage that is maintained throughout ontogeny. TGF-b signaling differentially affects embryonic versus adult thymosphere formation, suggesting that thymic epithelial SC potency depends on both developmental stage and environmental signals. Collectively, our findings suggest that embryonic TSFCs contributeto an adult SC pool and that TSFC plasticity is controlled by TGF-b signaling.
