Stem Cell Reports最新文献

The adrenal glands are essential endocrine organs that secrete key hormones maintaining physiological homeostasis. Herein, we established expandable three-dimensional (3D) human adrenocortical organoid (ACO) cultures that preserved the characteristic of zona fasciculata cell lineages and retained their capacity to produce cortisol. The ACOs could secrete glucocorticoids in response to physiological stimuli and thus rescue adrenalectomized mice, indicating their potential for the treatment of primary adrenal insufficiency. Furthermore, by introducing a hotspot pathogenic variant (PRKACA L206R) identified in Cushing's syndrome, we achieved the organoid disease modeling of cortisol-producing adenomas. In summary, this study establishes a human organoid platform to explore homeostasis and dysfunction in adrenal glands, suggesting future applications in disease modeling and regenerative medicine.

In early blastocyst, inner cell mass (ICM) undergoes a second wave of lineage commitment to generate epiblast (Epi) and primitive endoderm (PrE), restricting the developmental potential of their progeny. However, the epigenetic mechanism underlying this lineage segregation remains unclear. Here, we reveal that enhancer of zeste homolog 2 (EZH2) inhibition with EPZ-6438 transdifferentiates murine embryonic stem cells (ESCs) into primitive endoderm stem cells (PrESCs). Genetic ablation of Ezh2 in ESCs reduces the trimethylation of lysine 27 on histone 3 (H3K27me3) deposition at the promoters of PrE-specific genes, derepressing their expression and facilitating the PrESC conversion. Reconstitution with wild-type EZH2, but not catalytically inactive or EED-binding-deficient mutants in EZH2-deficient ESCs, blocks this transition. Strikingly, EZH2 inhibition reduces epiblast cell numbers in blastocysts, with 45.9% of embryos exhibiting ICMs composed of no SOX2-positive cells. Furthermore, EPZ-6438 treatment in human naive ESCs upregulates hypoblast-associated genes. In sum, these results reveal an evolutionarily conserved role for EZH2-polycomb repressive complex 2 (PRC2) in safeguarding pluripotency from primitive endoderm cell fate.

In solid tissues, homeostasis and post-injury regeneration involve a complex interplay among various cell types. The mammalian liver harbors numerous epithelial and non-epithelial cells, and the global signaling networks governing their interactions are unknown. To unravel the hepatic cell network, we purified 10 different cell populations from normal and regenerative mouse livers. Analyzing their transcriptomes unveiled ligand-receptor interactions and over 50,000 potential cell-cell interactions in both ground state and after partial hepatectomy. Importantly, about half of these differed between the two states, indicating massive changes in the cell network during regeneration. Our study provides the first comprehensive database of potential cell-cell interactions in liver cell homeostasis and regeneration. Leveraging this predictive model, we identified and validated two previously unknown signaling interactions involved in accelerating and delaying liver regeneration. Overall, we provide a novel platform for investigating autocrine/paracrine pathways in tissue regeneration, with broader applications to other complex multicellular systems.

The mechanistic target of rapamycin complex 2 (mTORC2) is essential for embryonic development, but its underlying molecular mechanisms remain unclear. Here, we show that disruption of mTORC2 in human embryonic stem cells (hESCs) considerably alters the Rho/Rac signaling dynamics and reduces E-cadherin expression and cell adhesion. Despite this, mTORC2-deficient hESCs maintain self-renewal and expression of pluripotent markers when cultured in mouse embryonic fibroblast conditioned medium (MEF-CM) supplemented with bFGF. However, these hESCs exhibit significantly impaired mesoderm and endoderm differentiation in response to BMP4 and Activin treatment, respectively, possibly due to reduced WNT activation mediated by cell-cell interactions. Direct activation of the WNT pathway using a GSK3 inhibitor restores mesendoderm differentiation in mTORC2-deficient hESCs. Our study uncovers a novel mechanism by which mTORC2 regulates cell fate determination and highlights a critical link between the intercellular adhesion and the activation of canonical WNT genes.

The direct-to-consumer marketing of stem cell interventions now includes an emerging ecommerce marketplace of "stem cell" supplements. This research assessed the marketing of stem cell supplements on Amazon.com, evaluating how that marketing aligned or conflicted with regulatory frameworks in the United States and Canada. Given the results, new regulation strategies should be considered to offer greater transparency and consumer protection.

Direct reprogramming is a technique for elucidating the mechanisms that control cell-fate decisions and holds promise as a therapeutic strategy. We previously showed that a specific combination of three transcription factors (FOXA3, HNF1A, and HNF6) can induce direct reprogramming of human umbilical vein endothelial cells (HUVECs) into human induced hepatic progenitor cells (hiHepPCs). However, low reprogramming efficiency limits their application in research and therapy. Here, we show that activation of the canonical Wnt signaling pathway increases the reprogramming efficiency of HUVECs to hiHepPCs by rapidly inducing chromatin remodeling and gene expression changes in the transduced HUVECs. Moreover, endogenous Wnt activation, mainly mediated by WNT2B, is required for the initiation of direct reprogramming from HUVECs to hiHepPCs. Wnt activation that allows rapid induction of hiHepPCs enables efficient production of a large amount of hiHepPCs, which is an advantage in research and clinical applications using hiHepPCs and their descendants.

Cell replacement strategies utilizing stem cell-derived pancreatic β-cells (SCβ-cells) hold therapeutic potential for patients with diabetes. However, little is known about how endogenous (host) and exogenous (transplant) circadian systems interact to influence the engraftment and function of SCβ-cells. We report that differentiation of SCβ-cells in vitro is associated with the induction of key circadian clock genes known to regulate insulin secretion. Upon transplantation into severe combined immunodeficiency (SCID)-beige mice, SCβ-cells exhibit circadian rhythms in glucose-stimulated insulin secretion optimized to the host's active circadian phase. Furthermore, disrupting the host's circadian rhythms abolishes circadian regulation and the overall functional capacity of transplanted SCβ-cells. These observations suggest that the host's circadian system entrains SCβ-cell function to optimize the circadian control of insulin secretion.

Cell communication via signaling exchange plays a pivotal role in multicellular development for building up functional tissues and organs. In the Drosophila testis, a pair of somatic cyst cells (CCs) encapsulate the germline that differentiates through close-range EGFR signaling activation. The Dlg/Scrib/Lgl polarity complex and clathrin-mediated endocytosis attenuate EGFR signaling in CCs, and loss of their function leads to EGFR overactivation and death of the neighboring germ cells. Here, we show that EGFR overactivation leads to upregulation of JNK and p38 signaling in CCs and ROS levels in germ cells destined to die. Our data uncover a bidirectional-feedback mechanism between JNK signaling and ROS who regulate each other, while reducing the levels of either JNK or ROS restored germ cell survival. This study provides a framework of how polarity and cellular trafficking regulate the output of multiple signaling responses cell-intrinsically and across cells, to coordinate tissue-specific responses and maintain homeostasis.

Organ-on-chips (OoCs) are controlled microfluidic platforms that replicate specific organ-level functionalities and pathological processes using cultured cells. OoCs promise to enhance drug discovery, reduce dependence on animal models, and enable personalized treatments. However, OoCs also introduce ethical challenges. This article provides a mapping review of the philosophical and ethical issues associated with developing and using OoCs. Given the limited literature on OoC ethics, the review takes a comparative analytical approach, drawing on organoid, digital twin, and precision medicine literature. Ethical issues are categorized across three consecutive phases-research, clinical testing, and implementation. Nine key themes are identified: privacy and confidentiality, informed consent, evidence, ontology and moral status, animal experimentation, evidence standards, patient care, intellectual property and commercialization, and distributive justice. Overall, the review highlights several key challenges that require further normative inquiry and hold significance for both research and policy. These include underrepresented groups in OoC research, complexities and limitations related to different consent models, the need for clear criteria to determine evidence standards for replacing animal models, accountability in the standardization of OoC research, and sustainability.

The self-renewal and differentiation of spermatogonial stem cells (SSCs) play essential roles in spermatogenesis. Extracellular vesicle (EV) is a universal strategy for intercellular communications in stem cell niches. However, the involvement of EVs in regulating SSCs remains largely unknown. This study revealed that testis EVs from postnatal day 7 (PND7) neonatal mouse testis guided spermatogonia into a transit-amplifying state with increased proliferation while retaining their differentiation potential. We profiled the repertoires of proteins and small RNAs by proteomic and small RNA transcriptomic analyses, respectively. We further showed that the EVs secreted by undifferentiated spermatogonia and the Sertoli cell lines, but not from more differentiated germ cell lines, conveyed let-7b/7c microRNA (miRNA) cargoes to spermatogonia, which mediated the effect of EVs on spermatogonial transit amplification. Together, this study has deciphered crucial let-7b/7c cargoes of EV-mediated communication within the spermatogonial niche, providing a new insight into the regulation of SSCs and spermatogenesis.