Retraction Note: Bidirectional developmental potential in reprogrammed cells with acquired pluripotency

Abstract

One of two papers describing a reprogramming phenomenon called stimulus-triggered acquisition of pluripotency (STAP) — in STAP, lineage-committed adult somatic cells are reprogrammed to pluripotency by transient exposure to low-pH treatment, and extensive analysis of the molecular features and developmental potential of STAP cells indicates that they represent a unique state of pluripotency. The fates of the somatic cells that form the bulk of the mammalian body are thought to be largely determined by the time the cellular differentiation processes of development have been completed. Reprogramming in response to environmental stress has been observed in plants but not so far in mammalian cells. Now two manuscripts by Haruko Obokata and colleagues describe an unexpected reprogramming phenomenon, which the authors call stimulus-triggered acquisition of pluripotency (STAP). In STAP, mouse somatic cells such as CD45+ haematopoietic cells are reprogrammed to pluripotency by transient exposure to low pH. Extensive analysis of the molecular features and developmental potential of STAP cells suggests that they represent a unique state of pluripotency — and provide an alternative source of pluripotent cells to the use of transcription factors, as has become routine for induced pluripotent stem cell production. We recently discovered an unexpected phenomenon of somatic cell reprogramming into pluripotent cells by exposure to sublethal stimuli, which we call stimulus-triggered acquisition of pluripotency (STAP)1. This reprogramming does not require nuclear transfer2,3 or genetic manipulation4. Here we report that reprogrammed STAP cells, unlike embryonic stem (ES) cells, can contribute to both embryonic and placental tissues, as seen in a blastocyst injection assay. Mouse STAP cells lose the ability to contribute to the placenta as well as trophoblast marker expression on converting into ES-like stem cells by treatment with adrenocorticotropic hormone (ACTH) and leukaemia inhibitory factor (LIF). In contrast, when cultured with Fgf4, STAP cells give rise to proliferative stem cells with enhanced trophoblastic characteristics. Notably, unlike conventional trophoblast stem cells, the Fgf4-induced stem cells from STAP cells contribute to both embryonic and placental tissues in vivo and transform into ES-like cells when cultured with LIF-containing medium. Taken together, the developmental potential of STAP cells, shown by chimaera formation and in vitro cell conversion, indicates that they represent a unique state of pluripotency.