Pluripotent embryonic stem cells (ESCs) can develop into any cell type in the body. Yet, the regulatory mechanisms that govern cell fate decisions during embryogenesis remain largely unknown. We now demonstrate that mouse ESCs (mESCs) display large natural variations in mitochondrial reactive oxygen species (mitoROS) levels that individualize their nuclear redox state, H3K4me3 landscape, and cell fate. While mESCs with high mitoROS levels (mitoROSHIGH) differentiate toward mesendoderm and form the primitive streak during gastrulation, mESCs, which generate less ROS, choose the alternative neuroectodermal fate. Temporal studies demonstrated that mesendodermal (ME) specification of mitoROSHIGH mESCs is mediated by a Nrf2-controlled switch in the nuclear redox state, triggered by the accumulation of redox-sensitive H3K4me3 marks, and executed by a hitherto unknown ROS-dependent activation process of the Wnt signaling pathway. In summary, our study explains how ESC heterogeneity is generated and used by individual cells to decide between distinct cellular fates.

Human pluripotent stem cell (hPSC) cultures are prone to genetic drift, because cells that have acquired specific genetic abnormalities experience a selective advantage in vitro. These abnormalities are highly recurrent in hPSC lines worldwide, but their functional consequences in differentiating cells are scarcely described. In this work, we show that the loss of chromosome 18q impairs neuroectoderm commitment and that downregulation of SALL3, a gene located in the common 18q loss region, is responsible for this failed neuroectodermal differentiation. Knockdown of SALL3 in control lines impaired differentiation in a manner similar to the loss of 18q, and transgenic overexpression of SALL3 in hESCs with 18q loss rescued the differentiation capacity of the cells. Finally, we show that loss of 18q and downregulation of SALL3 leads to changes in the expression of genes involved in pathways regulating pluripotency and differentiation, suggesting that these cells are in an altered state of pluripotency.

Linking phenotypes to genetic components has been an essential part of novel drug discovery, and screening methods have been widely employed to achieve such a goal. Screens can be conducted in either pooled or arrayed formats. Although arrayed screenings provide a better and cheaper alternative in small scale, the larger-scale screenings are conducted in pooled manner. With its adaptability to various models and conditions, CRISPR/Cas9 technology provides an invaluable alternative to classical and RNAi-based screening methods. Combined with high-throughput sequencing and bioinformatics, CRISPR-/Cas9-based pooled screening methods provide unbiased and robust data. In this protocol, we employed CRISPR-/Cas9-based pooled screening for a non-binary and non-immediate readout.

Epidermoid cysts are infrequent lesions occupying the intracranial space, comprising approximately 1-2% of all intracranial tumors. Brainstem epidermoids are exceptionally uncommon in children; up until now, only a few scattered case reports have been documented in the literature regarding this unique location. These cysts commonly arise from the inclusion of ectodermal elements during neural tube closure. Complete excision of these cysts is challenging due to their close proximity and adherence to the brainstem, which makes it difficult to achieve. As a result, recurrence of the cysts is not uncommon. We have reported a rare case of a 3-year-old with a 5-month history of progressive headache, imbalance while walking and progressive weakness in his right upper limb and lower limb along with difficulty in swallowing. On MRI Brain imaging study he had a pre-pontine epidermoid with intra-axial extension in the pons. The patient underwent retro-sigmoid/suboccipital craniotomy and microsurgical excision of the tumor, including the tumor capsule. After completing the surgery, the cavity was irrigated using a solution containing hydrocortisone and Ringer lactate to prevent the occurrence of aseptic meningitis. In the postoperative, the patient recovered without any complications, as all symptoms showed immediate improvement, and the lower cranial nerves returned to normal functioning.

Acetylcholine, a vital neurotransmitter, plays a multifarious role in the brain and peripheral nervous system of various organisms. Previous research has demonstrated the proximity of cholinergic neurons to serotonergic neurons in the apical organ of sea urchin embryos. While several transcription factors have been identified as playing a role in the development of serotonergic neurons in this region of a sea urchin, Hemicentrotus pulcherrimus, comparatively little is known about the specific transcription factors and their spatiotemporal expression patterns that regulate the development of cholinergic neurons. In this study, we establish the requirement of the transcription factor Rx for the development of cholinergic neurons in the apical organ of the species. Furthermore, we investigate the role of the RNA-binding protein Musashi1, known to be involved in neurogenesis, including cholinergic neurons in other organisms, and demonstrate that it is a downstream factor of Rx, and that choline acetyltransferase expression is suppressed in Musashi1 downregulated embryos. Our research also highlights the intricate network formed by neurons and other cells in and around the apical organ of sea urchin larvae through axons and dendrites, providing possibility for a systematic and complexed neural pattern like those of the brain in other organisms.

Three-dimensional (3D) human brain spheroids are instrumental to study central nervous system (CNS) development and (dys)function. Yet, in current brain spheroid models the limited variety of cell types hampers an integrated exploration of CNS (disease) mechanisms.
Here we report a 5-month culture protocol that reproducibly generates H9 embryonic stem cell-derived human cortical spheroids (hCSs) with a large cell-type variety.
We established the presence of not only neuroectoderm-derived neural progenitor populations, mature excitatory and inhibitory neurons, astrocytes and oligodendrocyte (precursor) cells, but also mesoderm-derived microglia and endothelial cell populations in the hCSs via RNA-sequencing, qPCR, immunocytochemistry and transmission electron microscopy. Transcriptomic analysis revealed resemblance between the 5-months-old hCSs and dorsal frontal rather than inferior regions of human fetal brains of 19-26 weeks of gestational age. Pro-inflammatory stimulation of the generated hCSs induced a neuroinflammatory response, offering a proof-of-principle of the applicability of the spheroids.
Our protocol provides a 3D human brain cell model containing a wide variety of innately developing neuroectoderm- as well as mesoderm-derived cell types, furnishing a versatile platform for comprehensive examination of intercellular CNS communication and neurological disease mechanisms.

Differentiated cells can be reprogrammed to embryonic stem cell-like cells called induced pluripotent stem cells (iPSCs), in which the natural developmental differentiation process is reversed. It is unclear whether the multi-lineage cells can be isolated and identified during reprogramming. In the current study, we detected the expression of lineage markers, isolated neural lineages, and identified the related microRNAs during iPSC formation. Our results demonstrated that a neuroectoderm appeared earlier than mesoderm and definitive endoderm before forming colonies when mouse embryonic fibroblasts were subjected to iPSC formation using transcription factors (TFs). On day 3, the cells expressed Sox1 and Nestin and had ultrastructure consistent with the transition to identity neural germ layer lineage. Fluorescence-activated cell sorting analysis revealed a peak (40%) in neural progenitor marker-positive cells. When subsequently cultured in a neural precursor cell medium, these cells proliferated slowly, became round and aggregated, generating into neurons and glia. Genome-wide microRNA (miRNA) analysis identified 45 differentially regulated miRNAs. Molecular network analysis demonstrated that these miRNAs validated 6,047 experimental mRNA targets. The GO functional annotation analysis of mRNA targets revealed that most genes were related to neurogenesis, such as growth cone, neuronal cell body, neuron projection, and cell junction synapse. The network of protein-protein interactions was observed, which demonstrated that key nodes of neural lineage reprogramming-associated targets were Sall1, Foxa2, Nf2, Ctnnb1, Shh, and Bmpr1a. Therefore, these data suggested that TFs can drive the reprogramming of somatic cells towards a pluripotent state via neuroectoderm. Moreover, the neural lineage reprogramming system can address how miRNAs influence their target sites.

Ovarian immature teratoma is a rare subtype of germ cell tumour that can be pure or associated with non-teratomatous germ cell tumour elements and is graded based on extent of the immature neuroectodermal component. Immature teratoma (IT) can also be associated with somatic differentiation in the form of sarcoma, carcinoma, or extensive immature neuroectodermal elements and may produce low levels of serum alpha-fetoprotein. Variable interpretation of these issues underlies diagnostic and management dilemmas, resulting in substantial practice differences between paediatric and adult women with IT. The Malignant Germ Cell International Consortium (MaGIC) convened oncologists, surgeons, and pathologists to address the following crucial clinicopathologic issues related to IT: (1) grading of IT, (2) definition and significance of \'microscopic\' yolk sac tumour, (3) transformation to a somatic malignancy, and (4) interpretation of serum tumour biomarkers. This review highlights the discussion, conclusions, and suggested next steps from this clinicopathologic conference.

The development of the vertebrate eyes is a complex process starting from anterior-posterior and dorso-ventral patterning of the anterior neural tube, resulting in the formation of the eye field. Symmetrical separation of the eye field at the anterior neural plate is followed by two symmetrical evaginations to generate a pair of optic vesicles. Next, reciprocal invagination of the optic vesicles with surface ectoderm-derived lens placodes generates double-layered optic cups. The inner and outer layers of the optic cups develop into the neural retina and retinal pigment epithelium (RPE), respectively. In vitro produced retinal tissues, called retinal organoids, are formed from human pluripotent stem cells, mimicking major steps of retinal differentiation in vivo. This review article summarizes recent progress in our understanding of early eye development, focusing on the formation the eye field, optic vesicles, and early optic cups. Recent single-cell transcriptomic studies are integrated with classical in vivo genetic and functional studies to uncover a range of cellular mechanisms underlying early eye development. The functions of signal transduction pathways and lineage-specific DNA-binding transcription factors are dissected to explain cell-specific regulatory mechanisms underlying cell fate determination during early eye development. The functions of homeodomain (HD) transcription factors Otx2, Pax6, Lhx2, Six3 and Six6, which are required for early eye development, are discussed in detail. Comprehensive understanding of the mechanisms of early eye development provides insight into the molecular and cellular basis of developmental ocular anomalies, such as optic cup coloboma. Lastly, modeling human development and inherited retinal diseases using stem cell-derived retinal organoids generates opportunities to discover novel therapies for retinal diseases.

Retinal organoids (ROs) derived from human pluripotent stem cells (hPSCs) recapitulate key features of retinogenesis and provide a promising platform to study retinal development and disease in a human context. Although multiple protocols are currently in use, hPSCs exhibit tremendous variability in differentiation efficiency, with some cell lines consistently yielding few or even no ROs, limiting their utility in research. We report here that early nicotinamide (NAM) treatment significantly improves RO yield across 8 hPSC lines from different donors, including some that would otherwise fail to generate a meaningful number of ROs. NAM treatment promotes neural commitment of hPSCs at the expense of non-neural ectodermal cell fate, which in turn increases eye field progenitor generation. Further analysis suggests that this effect is partially mediated through inhibition of BMP signaling. Our data encourage a broader use of human ROs for disease modeling applications that require the use of multiple patient-specific cell lines.