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.

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.

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.

Recombinant human erythropoietin (EPO) is widely used to treat anemia. EPO has immunomodulatory effects extending beyond erythropoiesis, but its impact on lympho-hematopoiesis remains insufficiently explored. The objective of this study was to investigate B lymphopoiesis in the context of hyper-EPOemia-induced stress hematopoiesis. Using an EPO supplementation model in C57BL/6 mice, we found that EPO exerts contrasting effects on early B cell development. EPO supplementation promotes the transition from common lymphoid progenitors (CLPs) to pre-pro-B cells but impairs the pre-pro-B to pro-B transition, in part by downregulating interleukin-7 (IL-7) receptor expression. Remarkably, EPO promotes the emergence of atypical B cell precursors, including M-CSFR/CD115-expressing CLPs and CD11b and CD16/32-expressing pre-pro-B cells. Gene expression profiling revealed that EPO reprograms early B cell precursors, upregulating myeloid-type genes, while downregulating B lymphoid identity genes. In conclusion, our results show that hyper-EPOemia interferes with the earliest stages of B cell development, while promoting the emergence of mixed-lineage "myeloid-like" B cells.

Alternative promoters are critical for lineage-specific gene expression; however, their systematic roles in hematopoiesis remain unclear. Here, we analyze 532 RNA sequencing (RNA-seq) datasets to construct a high-resolution promoter activity landscape. We identify 1,074 high-impact promoters, including novel lineage-specific switches in Pou2f1 and Ikzf1. Pou2f1 P1 is active in T/NK cells/monocytes, while P2 is B-cell-/progenitor-specific. Ikzf1 P1 is active in B cells/monocytes, and P2 is T-cell-specific. CRISPRi-mediated repression validated their lineage-specific functions. We further pinpoint the following driving transcription factors: Spi1 (Ikzf1 P1), Foxo1 (Ikzf1 P2), Yy1 (Pou2f1 P1), and Pax5 (Pou2f1 P2). This study provides novel insights into promoter-mediated regulation in hematopoietic lineages and a foundation for targeting promoter-specific mechanisms in disease.

Hematopoietic stem cells (HSCs) self-renew to sustain stem cell pools and differentiate into all types of blood cells, whose properties are tightly regulated by epigenetic and transcriptional networks. Here, we identified DHX9 as a critical regulator of HSC maintenance. Dhx9 deletion caused bone marrow failure and impaired hematopoietic reconstitution in murine primary and secondary transplantation recipients due to loss of HSCs and defective self-renewal capacity. Further investigations revealed that Dhx9 deficiency led to aberrant cell cycle entry, increased apoptosis, and elevated ROS, which compromise HSC function. Mechanistically, DHX9 interacts with CBP/p300 acetyltransferase and maintains H3 acetylation at hematopoietic gene promoters to facilitate transcription activation. Inhibition of CBP/p300 disrupted their expression, whereas the enhancement of H3K27ac levels partially rescued hematopoietic defects caused by Dhx9 deficiency in both mouse models and human CD34⁺ cells. This study highlights DHX9 as a crucial factor linking epigenetic modifications with transcriptional programs in HSC biology.

Dynamic epigenetic changes guide retinal progenitor cells (RPCs) toward diverse neuronal subtypes and Müller glia during retinal development. However, the epigenetic mechanisms that maintain RPC proliferative and neurogenic potential throughout the final stages of retinal cell genesis remain poorly understood. Here, we integrate RNA sequencing and assay for transposase-accessible chromatin sequencing (ATAC-seq) to investigate how mouse RPC progenitor competence is regulated. Our analysis reveals conserved chromatin accessibility and gene expression profiles in mouse RPCs throughout retinal cell genesis. Notably, the histone methyltransferase Setd8, which catalyzes H4K20 monomethylation, remains persistently expressed in RPCs but is barely detectable in adult Müller glia. Setd8 deletion in developing RPCs reduces proliferation, triggers apoptosis, and disrupts retinal laminar organization and ocular axis length. Additionally, Setd8 deficiency impairs the chromatin accessibility that is normally preserved in RPCs, leading to a partial acquisition of a transcriptomic profile associated with terminally differentiated cells. Our study indicates that Setd8 safeguards mouse RPC identity by maintaining RPC-specific chromatin accessibility, thereby ensuring proper retinal development.

CACNA1A-related disorders constitute a diverse group of neurological conditions, including ataxia, migraine, and epilepsy. Despite extensive genetic studies, clear genotype-phenotype correlations remain elusive. Moreover, next-generation sequencing has identified many variants of uncertain significance (VUS). Here, we leveraged patient-derived and CRISPR-Cas9-engineered human neuronal networks to explore relationships between CACNA1A variants and neurophysiological activity. CACNA1A haploinsufficiency induced subtle alterations in glutamatergic network activity, whereas missense variants had a more pronounced effect on overall network function. Network fingerprints were most affected from patients where ataxia co-occurred with migraine or epilepsy. Furthermore, we analyzed the impact of CRISPR-Cas9-induced VUS on network developmental trajectories. Although functional changes could not be directly linked to clinical phenotypes, all tested variants induced measurable alterations in neuronal network function, supporting their classification as likely pathogenic. These findings highlight the potential of human neuronal networks as a translational model for evaluating CACNA1A variant effects and improving clinical variant interpretation.

The successful translation of a stem cell-derived product from the laboratory into an approved medicine requires specific scientific, technical, and regulatory understanding. Since this knowledge base is fragmented across websites and publications, the ISSCR has developed a new resource, The Best Practices for the Development of Pluripotent Stem Cell-Derived Therapies. This comprehensive, interactive document, designed for academia and industry, addresses critical areas of the translational pipeline and key decision points for the successful translation to a licensed therapy. Uniquely, it provides a global perspective of the regulatory landscape while providing resources for critical processes and links to jurisdictional regulatory information.