Project description:Although cell therapies require large numbers of quality-controlled hPSCs, existing technologies are limited in their ability to efficiently grow and scale stem cells. We report here that cell-state conversion from primed-to-naïve pluripotency enhances the biomanufacturing of hPSCs. Naïve hPSCs exhibit superior growth kinetics and aggregate formation characteristics in stirred suspension bioreactors compared to their primed counterparts. Moreover, we demonstrate the role of the bioreactor mechanical environment in the maintenance of naïve pluripotency, through transcriptomic enrichment of mechano-sensing signaling for cells in the bioreactor along with a decrease in expression of lineage-specific and primed pluripotency hallmarks. Bioreactor-cultured, naïve hPSCs express epigenetic regulatory transcripts associated with naïve pluripotency, and display hallmarks of X-chromosome reactivation. They exhibit robust production of naïve pluripotency metabolites and display reduced expression of primed pluripotency cell surface markers. We also show that these cells retain the ability to undergo targeted differentiation into beating cardiomyocytes, hepatocytes, and neural rosettes. They additionally display faster kinetics of teratoma formation compared to their primed counterparts. Naïve bioreactor hPSCs also retain structurally stable chromosomes. Our research corroborates that converting hPSCs to the naïve state enhances hPSC manufacturing and indicates a potentially important role for the bioreactor’s mechanical environment in maintaining naïve pluripotency.
Project description:In this study we identify Mettl3, an m6A RNA modification writer, as a critical regulator for terminating naïve pluripotency and a positive maintainer of primed pluripotency in vitro and in vivo. Remarkably, Mettl3 knockout pre-implantation epiblasts and naïve ES cells, entirely lack m6A on coding mRNAs and are viable. Yet, they fail to adequately terminate the naïve pluripotent state, and subsequently undergo aberrant priming and early lineage commitment at the post-implantation stage. A comprehensive functional and genomic analysis involving profiling of m6A, RNA transcription and translation in Mettl3 wild-type and knockout pluripotent and differentiated cells, identified m6A as a critical determinant that destabilizes secondary naïve specific pluripotency genes Esrrb, Klf4 and Nanog, and restrains their transcript stability and translation efficiency. In summary, our findings provide for the first time evidence for a critical role for an mRNA epigenetic modification in early mammalian development in vivo, and identify a mechanism that functionally regulates mouse naïve and primed pluripotency in an opposing manner. Ribosome footprint (Ribo-Seq) was measured from mouse embryonic stem cells and mouse embriod bodies, in WT and Mettl3-KO cell lines.
Project description:In this study we identify Mettl3, an m6A RNA modification writer, as a critical regulator for terminating naïve pluripotency and a positive maintainer of primed pluripotency in vitro and in vivo. Remarkably, Mettl3 knockout pre-implantation epiblasts and naïve ES cells, entirely lack m6A on coding mRNAs and are viable. Yet, they fail to adequately terminate the naïve pluripotent state, and subsequently undergo aberrant priming and early lineage commitment at the post-implantation stage. A comprehensive functional and genomic analysis involving profiling of m6A, RNA transcription and translation in Mettl3 wild-type and knockout pluripotent and differentiated cells, identified m6A as a critical determinant that destabilizes secondary naïve specific pluripotency genes Esrrb, Klf4 and Nanog, and restrains their transcript stability and translation efficiency. In summary, our findings provide for the first time evidence for a critical role for an mRNA epigenetic modification in early mammalian development in vivo, and identify a mechanism that functionally regulates mouse naïve and primed pluripotency in an opposing manner. polyA RNA-seq was measured in mouse embryonic stem cells (ESCs) and embroid bodies (EBs), each in WT and in Mettl3-KO cell lines. RNA-seq was measured also from WT mouse embronic fibroblasts (MEF). 3 biological replicates are available from ESCs and 2 from EBs. Replicate C in ESCs was measured alongside protein levels (SILAC) and was used for the analysis of that assay.
Project description:Pluripotency is highly dynamic and progresses through a continuum of pluripotent stem-cell states. The two states that bookend the pluripotency continuum, naïve and primed, are well characterized, but our understanding of the intermediate states and transitions between them remain incomplete. Here, we dissect the dynamics of pluripotent state transitions underlying pre- to post-implantation epiblast differentiation. Through comprehensive mapping of the proteome, phosphoproteome, transcriptome, and epigenome of embryonic stem cells transitioning from naïve to primed pluripotency, we find that rapid, acute, and widespread changes to the phosphoproteome precede ordered changes to the epigenome, transcriptome, and proteome. Reconstruction of kinase-substrate networks reveals signaling cascades, dynamics, and crosstalk. Distinct waves of global proteomic changes mark discrete phases of pluripotency, with cell state-specific surface markers tracking pluripotent state transitions. Our data provide new insights into the multi-layered control of the phased progression of pluripotency and a foundation for modeling mechanisms regulating pluripotent state transitions (www.stemcellatlasorg).
Project description:The role of mitochondria dynamics and its molecular regulators remains largely unknown during naïve-to-primed pluripotent cell interconversion. Here we report that mitochondrial MTCH2 is a regulator of mitochondrial fusion, essential for the naïve-to-primed interconversion of murine embryonic stem cells (ESCs). During this interconversion, wild-type ESCs elongate their mitochondria and slightly alter their glutamine utilization. In contrast, MTCH2-/- ESCs fail to elongate their mitochondria and to alter their metabolism, maintaining high levels of histone acetylation and expression of naïve pluripotency markers. Importantly, enforced mitochondria elongation by the pro-fusion protein Mitofusin (MFN) 2 or by a dominant negative form of the pro-fission protein dynamin-related protein (DRP) 1 is sufficient to drive the exit from naïve pluripotency of both MTCH2-/- and wild-type ESCs. Taken together, our data indicate that mitochondria elongation, governed by MTCH2, plays a critical role and constitutes an early driving force in the naïve-to-primed pluripotency interconversion of murine ESCs.
Project description:It is now well recognized that human embryonic stem cells (hESCs)1 closely resemble mouse epiblast stem cells (mEpiSCs)2-5 exhibiting primed pluripotency unlike mouse ESCs (mESCs) which acquire a naïve pluripotent state4-8. Efforts have been made to trigger naïve pluripotency in hESCs9-11 for subsequent unbiased lineage-specific differentiation, a common conundrum faced by primed pluripotent hESCs due to heterogeneity in gene expression existing within and between hESC lines12. We report here a novel culture medium facilitating rapid induction of naïve pluripotency in established hESCs. Our medium also allows derivation of naïve mESCs from blastocyst stage which has not been shown earlier. The established naïve hESCs could survive long-term single cell passaging, maintain a normal karyotype, exhibit upregulation of naïve pluripotency genes and were dependent on signaling pathways similar to naïve mESCs. Also, they undergo global DNA demethylation, cluster together with previously described naïve hESCs13 and show a distinctive long non-coding RNA profile. Collectively, we demonstrate an alternate route to capture naïve pluripotency in hESCs which is fast, reproducible, can be employed to derive naïve mESCs and can induce efficient differentiation. Three primed and matching naive human embryonic stem cell lines were profiled in duplo.