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: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:The aim of this experiment was to investigate the role of TGFβ signalling pathway in human pluripotency, through ChIP-seq analysis of its main downstream effector SMAD2/3 in naïve and primed human pluripotent stem cells (hPSCs).
Project description:The embryonic stem cell (ESC) transition from naive to primed pluripotency is marked by major changes in cellular properties and developmental potential. ISY1 is implicated in miRNA biogenesis yet its widespread role and relevance to ESC biology remain unknown. Here we find that highly dynamic ISY1 expression during the naïve to primed ESC transition defines a unique phase of ‘poised’ pluripotency characterized by distinct miRNA and mRNA transcriptomes and widespread poised cell contribution to mouse chimeras. Loss- and gain-of-function experiments reveal that ISY1 promotes exit from the naïve state, is necessary and sufficient to induce and maintain poised pluripotency, and that persistent ISY1 overexpression inhibits the transition from the naïve to the primed state. We identify a large subset of ISY1-dependent miRNAs that can rescue the inability of miRNA-deficient ESCs to establish the poised state and transition to the primed state. Thus, dynamic ISY1 regulates poised pluripotency through miRNAs to control ESC fate.