Stem Cell Reports最新文献

Pigs are important for disease model generation, xenotransplantation, and interspecies organogenesis. Porcine induced pluripotent stem cells (piPSCs) should enable these efforts, but have not been generated to meet the attributes, such as feeder-free culture, robust development potential, and blastocyst generation through nuclear transfer. We report an improved strategy to generate such piPSCs. We show that chemically defined medium 3 promotes the formation of epithelium-like colonies in porcine reprogramming, which allows further reprogramming under the new medium cocktail LACID. The resulting piPSCs have key features, including flat morphology with feeder-free culture, generating robust teratoma and blastoids, forming chimeric blastocysts, and readily edited with CRISPR-Cas9. Lastly, nuclear transfer with piPSCs can develop into blastocysts. Despite maintaining a primed pluripotent state, our results suggest that the newly established LACID piPSCs may be ideal for applications in regenerative medicine. This method may be further improved to generate naive or totipotent stem cells.

Despite the central role of the nucleus in the cell, it remains unclear what determines nuclear size. Previous studies suggest a correlation between nuclear and cell size. However, many neurons have massive axon arbors, while maintaining a typical nuclear size. Here, we show a marked reduction of nuclear, but not cell, size during the direct conversion of human fibroblasts to induced neurons by ASCL1, miR124-9-9^∗, and p53 short hairpin RNA (shRNA) (AMp). Similar nuclear shrinkage was observed in the maturation of induced pluripotent stem cell-derived human cortical neurons. ASCL1 suppressed the transcription of the nucleoporin NUP37 by direct binding to its promoter. NUP37 knockdown enhanced AMp-mediated transdifferentiation and nuclear shrinkage, while NUP37 overexpression achieved the opposite. It appears that ASCL1 promotes nuclear shrinkage by suppressing NUP37 and reducing the nuclear pore complex (NPC), which gates nuclear transport. The study suggests a critical role of NPC in controlling nuclear size to match cell state.

It has long been hypothesized that DNA replication is important in reconfiguring the chromatin landscape during cell identity changes in development, disease, and reprogramming. There is now a large body of work showing that DNA replication indeed alters chromatin structure and composition, but a function for these changes has remained elusive. Using replication-coupled ATAC-seq in differentiating embryonic stem cells and reprogramming mouse embryonic fibroblasts, we profiled replicated and unreplicated chromatin and observed de novo chromatin opening specifically in the replicated fraction. These opening events created an accessibility landscape similar to that seen in later time points, and binding of lineage-specific transcription factors was enriched in these regions. Opening of these regions was impaired when replication was inhibited during early reprogramming. This work bridges the gap between replication-induced structural chromatin changes and functional consequences by demonstrating that replication facilitates a "window of opportunity" that advances the chromatin landscape during cell identity change.

The mammalian cornea is endowed with stem cells (SCs) that have lifelong regenerative activity. The niche for these cells is the limbus, and damage to it or its SCs results in limbal stem cell deficiency (LSCD). Despite the numerous studies that employ single-cell RNA sequencing, the identity of these cells remains an enigma principally because their spatial positioning is lost upon dissociation. These adversities were avoided via on-tissue spatial transcriptomics where Krt16 and Nkiras1 were differentially expressed. Krt16 was dynamically expressed in the developing limbus, correlated with slow-cycling label-retaining limbal epithelial SCs and was induced during corneal injury, observations consistent with marking functional SCs. Additionally, we established Nkiras1 as a novel maker of limbal neutrophils. Because current gold-standard treatments for LSCD include SC transplantation, our data will inform future studies in delivering a more reliable standard therapy that incorporates an identifiable SC population to improve clinical outcomes.

The International Society for Stem Cell Research (ISSCR) document "Standards For Human Stem Cell Use in Research" put forward a checklist for scientific journals to use in the assessment of compliance with its reporting standards. A trial implementation of this checklist at Stem Cell Reports revealed consistent gaps in the reporting of critical data relating to the cells and experimental methodologies employed in published manuscripts.

The STARD10 gene encodes for a lipid transfer protein and is associated with type 2 diabetes (T2D) risk and β cell function. However, the role of STARD10 in human β cell development and function are still unclear. Here, we deleted STARD10 in human embryonic stem cells and differentiated them into β-like cells. The deletion of STARD10 reduced the formation of INS⁺ β-like cells and proliferation. Lipidomics analyses revealed that STARD10-null β-like cells had higher triglyceride levels. Consistently, the expression levels of ETFB, which is involved in fatty acid β-oxidation, were severely reduced in STARD10-null β-like cells. STARD10-null β-like cells also had reduced glycolytic function, mitochondrial oxidative phosphorylation, and palmitate oxidation, which can likely contribute to slower proliferation and β cell dysfunction. Overall, our findings provided further insights into the role of STARD10 in human β cell development and function, and how its loss-of-function can contribute to increased T2D risk.

Human primordial germ cell-like cells (hPGCLCs) can be specified from human-induced pluripotent stem cells (hiPSCs), offering a valuable model for human germ cell development. However, further maturation steps of hPGCLCs rely on mouse feeders, or co-culture with mouse gonadal somatic cells. Exposure of hPGCLCs to human cellular niche has not been attempted. Here, we co-cultured female hPGCLCs in two distinct niche compartments. In reconstituted fetal ovary (rOv) culture, human fetal germ cells proliferated and initiated meiosis, while hPGCLCs upregulated gonadal germ cell markers such as DDX4. Additionally, hPGCLCs were supported and matured into migratory hPGCLCs in 3D co-culture with amnion-like cells (AMLCs). Compared to rOv, hPGCLCs in PGCLC/AMLC aggregates were less prone to dedifferentiate. In both niches, stem cell factor (SCF) was crucial for the survival of hPGCLCs. Together, this work underscores that a shift in niche is required for the further germ cell development of hPGCLCs.

Previous studies showed the polycomb repressive complex 2 (PRC2) co-factor Jarid2 represses self-renewal transcriptional networks in mouse multipotent progenitor cells (MPPs). But only a fraction of de-repressed HSC-specific genes were associated with loss of H3K27me3, implying Jarid2 may have non-canonical (PRC2-independent) functions in hematopoiesis. We sought to delineate these potential PRC2-independent functions by comparing stem and progenitor cells genetically deficient for either Jarid2 or Ezh2 (enzymatic component of PRC2). Loss of Ezh2 increased myeloid differentiation but with a defect in lymphopoiesis. In contrast, loss of Jarid2 enhanced multi-lineage differentiation proportionally. Single-cell transcriptomics showed loss of Jarid2 had minimal impact across progenitor populations, but loss of Ezh2 led to accumulation of lymphoid-biased MPP4 cells and B cell progenitors in the bone marrow. Functional assays confirmed a differentiation block at the pre-pro-B cell stage. These data suggest the major PRC2-dependent function of Jarid2 in hematopoietic progenitors is restriction of myeloid differentiation potential.

Cadherin-mediated adhesion of skeletal muscle stem cells within their niche is necessary for normal adult muscle maintenance and regeneration; however, the role of cadherins in regulating muscle development and growth has not yet been elucidated. Here, we show that M-cadherin protein is localized to adherens junctions in developing muscle and that deletion of Cdh15, the gene encoding M-cadherin, results in the loss of adherens junctions in fetal mouse muscle. This loss of adherens junctions is associated with reduced secondary myofiber formation, ultimately resulting in reduced adult myofiber number and muscle mass. Concordantly, via large-scale exome sequencing, we found that humans with predicted loss-of-function variants in the CDH15 gene had significantly reduced lean mass, indicating that M-cadherin functions to regulate muscle mass in both mice and humans. Overall, these data highlight a previously unrecognized role of M-cadherin in controlling fetal myofiber formation and establishment of adult muscle mass.

Embryonic oral epithelium is a multipotent, ectodermal tissue that gives rise to various organs, including salivary glands, tooth germs, taste buds, and anterior pituitary glands. Although oral epithelium is contiguous posteriorly with endodermal epithelium and anteriorly with surface ectoderm, it exhibits distinct gene expression profiles during development. However, the molecular mechanisms that govern fate specification between oral epithelium and surface ectoderm remain poorly understood. Here, we present a highly efficient protocol for the PITX2-positive oral epithelium induction from human induced pluripotent stem cells (hiPSCs) using a reporter system. Sonic Hedgehog (SHH) signaling activation is essential for the efficient PITX2-positive epithelial cell generation. The induced cells exhibited gene expression profiles resembling those of embryonic oral epithelium and formed epithelial spheres that replicated features of human oral epithelium. This study established a robust platform for investigating human oral epithelial development and provided a valuable foundation for organoid-based research on oral organs.