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Cell replacement is a long-standing and realistic goal for the treatment of Parkinsonʼs disease (PD). Cells for transplantation can be obtained from fetal brain tissue or from stem cells. However, after transplantation, dopamine (DA) neurons are seen to be a minor component of grafts, and it has remained difficult to determine the identity of other cell types. Here, we report analysis by single-cell RNA sequencing (scRNA-seq) combined with comprehensive histological analyses to characterize intracerebral grafts from human embryonic stem cells (hESCs) and fetal tissue after functional maturation in a pre-clinical rat PD model. We show that neurons and astrocytes are major components in both fetal and stem cell-derived grafts. Additionally, we identify a cell type closely resembling a class of recently identified perivascular-like cells in stem cell-derived grafts. Thus, this study uncovers previously unknown cellular diversity in a clinically relevant cell replacement PD model. What happens to cells on engrafting into the brain in animal models to treat Parkinson’s disease is unclear. Here, the authors use scRNA-seq to examine ventral midbrain (VM)-patterned human embryonic stem cells after functional maturation in a pre-clinical rat model for Parkinson’s disease and identify perivascular-like cells.

Peer reviewed: True, Funder: New York Stem Cell Foundation; Id: http://dx.doi.org/10.13039/100003194, Funder: Parkinsonfonden; Id: http://dx.doi.org/10.13039/100008444, Funder: Lund University; Id: http://dx.doi.org/10.13039/501100003252, Funder: HORIZON EUROPE Marie Sklodowska-Curie Actions, Significant efforts are ongoing to develop refined differentiation protocols to generate midbrain dopamine (DA) neurons from pluripotent stem cells for application in disease modeling, diagnostics, drug screening and cell-based therapies for Parkinson's disease. An increased understanding of the timing and molecular mechanisms that promote the generation of distinct subtypes of human midbrain DA during development will be essential for guiding future efforts to generate molecularly defined and subtype-specific DA neurons from pluripotent stem cells. Here, we use droplet-based single-cell RNA sequencing to transcriptionally profile the developing human ventral midbrain (VM) when the DA neurons are generated (6-11 weeks post-conception) and their subsequent differentiation into functional mature DA neurons in primary fetal 3D organoid-like cultures. This approach reveals that 3D cultures are superior to monolayer conditions for their ability to generate and maintain mature DA neurons; hence, they have the potential to be used for studying human VM development. These results provide a unique transcriptional profile of the developing human fetal VM and functionally mature human DA neurons that can be used to guide stem cell-based therapies and disease modeling approaches in Parkinson's disease.

Parkinson's disease (PD) is the second most common neurodegenerative disorder worldwide and is caused by the degeneration and loss of dopamine (DA) neurons in the ventral midbrain (VM). The focal and progressive degeneration of DA neurons in the VM makes PD a particularly attractive target for cell-based therapies. Human pluripotent stem cells (hPSCs) offer unprecedented opportunities to model the development and functional properties of human DA neurons in a dish. The use of human in vitro models based on hPSCs has empowered studies of VM development and provided access to neurons expressing a particular disease-specific phenotype. Currently, hPSC differentiation is most routinely carried out in monolayer cultures, which do not properly recapitulate cell-cell interactions and the structural complexity of the brain. Moreover, 2D cultures are challenging to maintain long term, as the cells tend to detach from the plate and lose their functional characteristics. This precludes the possibility of mimicking later phases of DA neurogenesis and recreating the complexity of functional neural circuitries. Here, we describe protocols showing how to maintain hPSCs in an undifferentiated state and how to then drive these hPSCs into 3D regionalized VM organoids. After long-term culture, these VM organoids exhibit mature and post-mitotic molecular features, including neuromelanin pigments similar to those released in primate VMs. We also report a protocol describing how to efficiently perform immunohistochemistry and how to detect neuromelanin-containing DA neurons in VM organoids. Together, these protocols provide a 3D in vitro platform that can be used to better understand the molecular mechanisms underlying DA neuron function and disease and may serve as a powerful tool for designing more targeted disease-modifying therapies. © 2022 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Human pluripotent stem cell culture Basic Protocol 2: hPS cell differentiation for the generation of human ventral midbrain organoids Basic Protocol 3: Characterization of ventral midbrain organoids.

Midbrain dopamine (mDA) neurons constitute a heterogenous group of cells that have been intensely studied, not least because their degeneration causes major symptoms in Parkinson’s disease. Understanding the diversity of mDA neurons – previously well characterized anatomically – requires a systematic molecular classification at the genome-wide gene expression level. Here, we use single cell RNA sequencing of isolated mouse neurons expressing the transcription factor Pitx3, a marker for mDA neurons. Analyses include cells isolated during development up until adulthood and the results are validated by histological characterization of newly identified markers. This identifies seven neuron subgroups divided in two major branches of developing Pitx3-expressing neurons. Five of them express dopaminergic markers, while two express glutamatergic and GABAergic markers, respectively. Analysis also indicate evolutionary conservation of diversity in humans. This comprehensive molecular characterization will provide a valuable resource for elucidating mDA neuron subgroup development and function in the mammalian brain., Midbrain dopamine (mDA) neurons are significantly associated with Parkinson’s disease and yet there is no systematic molecular classification of these heterogenous group of cells. Here authors use single cell RNA sequencing of isolated mouse neurons expressing the transcription factor Pitx3 (broad mDA neuronal marker) to identify and characterize seven neuron subgroups divided in two major branches of developing Pitx3-expressing neurons.

LncRNAs have recently emerged as new and fundamental transcriptional and post-transcriptional regulators acting at multiple levels of gene expression. Indeed, lncRNAs participate in a wide variety of stem cell and developmental processes, acting in cis and/or in trans in the nuclear and/or in the cytoplasmic compartments, and generating an intricate network of interactions with RNAs, enhancers, and chromatin-modifier complexes. Given the versatility of these molecules to operate in different subcellular compartments, via different modes of action and with different target specificity, the interest in this research field is rapidly growing. Here, we review recent progress in defining the functional role of lncRNAs in stem cell biology with a specific focus on the underlying mechanisms. We also discuss recent findings on a new family of evolutionary conserved lncRNAs transcribed from ultraconserved elements, which show perfect conservation between human, mouse, and rat genomes, and that are emerging as new player in this complex scenario.

Background: Human induced pluripotent stem cells (hiPSCs) have been proposed as an alternative source for cell replacement therapy for Parkinson’s disease (PD) and they provide the option of using the patient’s own cells. A few studies have investigated transplantation of patient-derived dopaminergic (DA) neurons in preclinical models; however, little is known about the long-term integrity and function of grafts derived from patients with PD. Objective: To assess the viability and function of DA neuron grafts derived from a patient hiPSC line with an α-synuclein gene triplication (AST18), using a clinical grade human embryonic stem cell (hESC) line (RC17) as a reference control. Methods: Cells were differentiated into ventral mesencephalic (VM)-patterned DA progenitors using an established GMP protocol. The progenitors were then either terminally differentiated to mature DA neurons in vitro or transplanted into 6-hydroxydopamine (6-OHDA) lesioned rats and their survival, maturation, function, and propensity to develop α-synuclein related pathology, were assessed in vivo. Results: Both cell lines generated functional neurons with DA properties in vitro. AST18-derived VM progenitor cells survived transplantation and matured into neuron-rich grafts similar to the RC17 cells. After 24 weeks, both cell lines produced DA-rich grafts that mediated full functional recovery; however, pathological changes were only observed in grafts derived from the α-synuclein triplication patient line. Conclusion: This data shows proof-of-principle for survival and functional recovery with familial PD patient-derived cells in the 6-OHDA model of PD. However, signs of slowly developing pathology warrants further investigation before use of autologous grafts in patients.

Inherent limitations of the traditional approaches to study brain function and disease, such as rodent models and 2D cell culture platforms, have led to the development of 3D in vitro cell culture systems. These systems, products of multidisciplinary efforts encompassing stem cell biology, materials engineering, and biofabrication, have quickly shown great potential to mimic biochemical composition, structural properties, and cellular morphology and diversity found in the native brain tissue. Crucial to these developments have been the advancements in stem cell technology and cell reprogramming protocols that allow reproducible generation of human subtype-specific neurons and glia in laboratory conditions. At the same time, biomaterials have been designed to provide cells in 3D with a microenvironment that mimics functional and structural aspects of the native extracellular matrix with increasing fidelity. In this article, we review the use of biomaterials in 3D in vitro models of neurological disorders with focus on hydrogel technology and with biochemical composition and physical properties of the in vivo environment as reference.

SUMMARYTransplantation of midbrain dopamine (DA) neurons for the treatment of Parkinson’s disease (PD) is a strategy that has being extensively explored and clinical trials using fetal and stem cell-derived DA neurons are ongoing. An increased understanding of the mechanisms promoting the generation of distinct subtypes of midbrain DA during normal development will be essential for guiding future efforts to precisely generate molecularly defined and subtype specific DA neurons from pluripotent stem cells. In this study, we used droplet-based scRNA-seq to transcriptionally profile a large number of fetal cells from human embryos at different stages of ventral midbrain (VM) development (6, 8, and 11 weeks post conception). This revealed that the emergence of transcriptionally distinct cellular populations was evident already at these early timepoints. To study late events of human DA differentiation and functional maturation, we established a primary fetal 3D culture system that recapitulates key molecular aspects of late human DA neurogenesis and sustains differentiation and functional maturation of DA neurons in a physiologically relevant cellular context. This approach allowed us to define the molecular identities of distinct human DA progenitors and neurons at single cell resolution and construct developmental trajectories of cell types in the developing fetal VM.Overall these findings provide a unique transcriptional profile of developing fetal VM and functionally mature human DA neurons, which can be used to quality control stem cell-derived DA neurons and guide stem cell-based therapies and disease modeling approaches in PD.

The focal and progressive degeneration of dopaminergic (DA) neurons in ventral midbrain has made Parkinson’s disease (PD) a particularly interesting target of cell-based therapies. However, ethical issues and limited tissue availability have so far hindered the widespread use of human fetal tissue in cell-replacement therapy. DA neurons derived from human pluripotent stem cells (hPSCs) offer unprecedented opportunities to access a renewable source of cells suitable for PD therapeutic applications. To better understand the functional properties of stem-cell derived DA neurons, we generated targeted hPSC lines with the gene coding for Cre recombinase knocked into the TH locus. When combined with flexed GFP, they serve as reporter cell lines able to identify and isolate TH+ neurons in vitro and after transplantation in vivo. These TH-Cre lines provide a valuable genetic tool to manipulate DA neurons useful for the design of more precise DA differentiation protocols and the study of these cells after transplantation in pre-clinical animal models of PD.

Parkinson’s disease (PD),one ofthe most common neurodegenerative disorders, ischaracterized by a progressive loss of dopamine (DA)neurons in the ventral midbrain (VM). Theinability of two-dimensional (2D) in vitroculturesto recapitulate thecomplexity of the architecture and cell composition has made the study of human VMchallenging.Despite intensive research efforts, the molecular mechanisms controlling both the development and functional maturation of DA neuron subtypes remains largely unknown. In this study, we designed a new method forexpanding and differentiating human fetal cells dissociated from the VM of 7-9 weeks old human embryos. We developed a three-dimensional (3D) organoid culture system with the aim to better preserve authentic and functional DA neurons in vitro. Using fetal-derived organoids as valuable reference, we also conducted a comparison between fetal-derivedand human embryonic stem cell (hESC)-derived VM organoids. Using single cell RNA sequencing (scRNA-seq) we compared human fetal cells from 2D and 3D in vitro culture systems. Despite the analysis showing that both cell preparations initially gave rise the same culture composition, the 2D system promoted proliferation of glial and oligodendrocyte progenitors, with limited surviving neuronal populations. On the contrary, 3D organoids could sustain the maturation of the neuronal population, and importantly maintained the dopaminergic neuronal compartment. Intriguingly, we have also found clear differences between fetal and hESC-derived organoids at the single cell resolution. While both cell preparations gave rise to neurons, we found that astrocytes and oligodendrocytes were detected only in fetal organoids whereas a barrier forming fibroblast-like cell type normally present in the brain was identified as a unique component of hES-derived organoids during late stage differentiation. Taken together these results represent an important step in characterizing both fetal derived- and hESC-derived authentic dopaminergic neurons through the use of novel 3D-culture conditions which better recapitulates the features of human ventral midbrain. &nbsp

Cell replacement therapy in Parkinson’s disease (PD) has put emphasis on developing methods for efficient differentiation of human stem or progenitor cells into mesencephalic dopaminergic (mesDA) neurons. Previous clinical trials have indeed shown that using human fetal ventral midbrain (hVM) can restore DA release and provide long-term clinical improvement PD patients. There is now a need to move to large-scale clinical applications with the use of renewable cell sources such as human pluripotent stem cells (hPSCs). When optimizing protocols for human mesDA neuron differentiation in vitro from human stem cell, the accurate characterization of DA neuron progenitors and how they mature in vivo and in vitro is of highest interest. In this context, hVM tissue represent the gold standard and several studies have compared gene and protein expression of human fetal DA progenitors with that of stem cell derived DA progenitors. However, it is difficult to maintain the fetal DA neurons in primary cell culture to further study their subtype specificity and functional maturation and there is a need for better in vitro model system. In this study, we therefore developed a method for differentiating human fetal tissue into three-dimensional (3D) culture system providing an opportunity to understand hVM progenitors expansion and differentiation in a physiologically relevant cellular context and to better obtain functional maturity of fetal neurons. By combining single-cell RNAseq analysis at different timepoints we reconstructed human VM development in vitro and compared the molecular profiles of fetal organoids with conventional 2D culture. Immunocytochemistry analysis and electrophysiological measurements were performed to examine and compare functional maturation of the DA neurons in both culture conditions. We show that the 3D model better preserves the global neuronal composition, maintains higher expression of dopamine genes in the short and long-term period and limits the skewing toward non neuronal cells than traditional 2D culture. By measuring the electrophysiological activity of dopamine neurons over the time we confirm that 3D cultures recapitulates thecomplex environment andfunction of dopaminergic circuitries leading to long-term maturation of authentic and functional fetal hVM.

Summary Neural stem cell populations generate a wide spectrum of neuronal and glial cell types in a highly ordered fashion. MicroRNAs are essential regulators of this process. T-UCstem1 is a long non-coding RNA containing an ultraconserved element, and in vitro analyses in pluripotent stem cells provided evidence that it regulates the balance between proliferation and differentiation. Here we investigate the in vivo function of T-UCstem1. We show that T-UCstem1 is expressed in the forebrain neurogenic lineage that generates interneurons for the postnatal olfactory bulb. Gain of function in neural stem cells increased progenitor proliferation at the expense of neuron production, whereas knockdown had the opposite effect. This regulatory function is mediated by its interaction with miR-9-3p and miR-9-5p. Based thereon, we propose a mechanistic model for the role of T-UCstem1 in the dynamic regulation of neural progenitor proliferation during neurogenesis., Graphical Abstract, Highlights • T-UCstem1 is expressed in the SVZ-RMS-OB neurogenic system • T-UCstem1 controls proliferation of neuronal progenitors in the subventricular zone • T-UCstem1 regulates neuron addition to the olfactory bulb • T-UCstem1 acts through miR-9-3p and miR-9-5p, In this study, Fico, Beclin, and colleagues show that the long non-coding RNA T-UCstem1 is expressed in the forebrain neurogenic lineage generating interneurons for the postnatal olfactory bulb. Increased T-UCstem1 levels in neural stem cells induced progenitor proliferation at the expense of neuron production, whereas its downregulation caused the opposite effect. This regulatory function is mediated by its interaction with miR-9.

The human forebrain has expanded in size and complexity compared to chimpanzees despite limited changes in protein-coding genes, suggesting that gene expression regulation is an important driver of brain evolution. Here, we identify a KRAB-ZFP transcription factor, ZNF558, that is expressed in human but not chimpanzee forebrain neural progenitor cells. ZNF558 evolved as a suppressor of LINE-1 transposons but has been co-opted to regulate a single target, the mitophagy gene SPATA18. ZNF558 plays a role in mitochondrial homeostasis, and loss-of-function experiments in cerebral organoids suggests that ZNF558 influences developmental timing during early human brain development. Expression of ZNF558 is controlled by the size of a variable number tandem repeat that is longer in chimpanzees compared to humans, and variable in the human population. Thus, this work provides mechanistic insight into how a cis-acting structural variation establishes a regulatory network that affects human brain evolution.

Summary Ultraconserved elements (UCEs) show the peculiar feature to retain extended perfect sequence identity among human, mouse, and rat genomes. Most of them are transcribed and represent a new family of long non-coding RNAs (lncRNAs), the transcribed UCEs (T-UCEs). Despite their involvement in human cancer, the physiological role of T-UCEs is still unknown. Here, we identify a lncRNA containing the uc.170+, named T-UCstem1, and provide in vitro and in vivo evidence that it plays essential roles in embryonic stem cells (ESCs) by modulating cytoplasmic miRNA levels and preserving transcriptional dynamics. Specifically, while T-UCstem1::miR-9 cytoplasmic interplay regulates ESC proliferation by reducing miR-9 levels, nuclear T-UCstem1 maintains ESC self-renewal and transcriptional identity by stabilizing polycomb repressive complex 2 on bivalent domains. Altogether, our findings provide unprecedented evidence that T-UCEs regulate physiological cellular functions and point to an essential role of T-UCstem1 in preserving ESC identity., Graphical Abstract, Highlights • The transcribed ultraconserved element T-UCstem1 exerts a dual function in ESCs • T-UCstem1 controls ESC proliferation by regulating the miR-9/Lin28b molecular axis • T-UCstem1 maintains ESC self-renewal • T-UCstem1 preserves ESC transcriptional identity by stabilizing PRC2, In this article Fico, Minchiotti, and colleagues identify an ultraconserved element containing long non-coding RNA, named T-UCstem1, in embryonic stem cells (ESCs) and provide evidence that it regulates cell-cycle progression by modulating cytoplasmic miR-9 levels and preserves ESC identity and self-renewal by stabilizing polycomb repressive complex 2 (PRC2) on bivalent domains.

Since the pioneering studies using fetal cell transplants in Parkinson’s disease (PD), brain repair by cell replacement has remained a long-standing and realistic goal for the treatment of neurodegenerative disorders including PD. Authentic and functional midbrain dopamine (DA) neurons can now be generated from human pluripotent stem cells (hPSCs) via a floor plate intermediate1,2, and these cell preparations are both safe and functional when transplanted to animal models of PD3. However, although resulting grafts from fetal brain tissue and hPSCs contain large numbers of desired DA neurons, these therapeutic cells are a minor component of the grafts. Moreover, the cellular composition of the graft has remained difficult to assess due to limitations in histological methods that rely on pre-conceived notions concerning cell types. Here, we used single cell RNA sequencing (scRNA-seq) combined with comprehensive histological analyses to characterize intracerebral grafts from ventral midbrain (VM)-patterned human embryonic stem cells (hESCs) and VM fetal tissue after long-term survival and functional maturation in a pre-clinical rat model of PD. The analyses revealed that while both cell preparations gave rise to neurons and astrocytes, oligodendrocytes were only detected in grafts of fetal tissue. On the other hand, a cell type closely resembling a class of newly identified perivascular-like cells was identified as a unique component of hESC-derived grafts. The presence of these cells was confirmed in transplants from three different hESC lines, as well as from iPSCs. Thus, these experiments have addressed one of the major outstanding questions in the field of cell replacement in neurological disease by revealing graft composition and differences between hESC- and fetal cell-derived grafts, which can have important implications for clinical trials.

Parkinson disease (PD) is characterized by a loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc). The selective loss of this cell population makes PD a good candidate for cell-based therapies. Clinical trials using cells derived from human fetal ventral midbrain (hVM) have shown that dopamine release could be restored to normal levels and in some PD patients produced substantial long-term clinical improvement. The ethical issues related to the use of human fetal material as well as the low number of hVM tissue available have limited the spread of this approach and have lead researchers to find new sources of cells such as human embryonic stem cells (hESCs) and pluripotent stem cells (IPCs). This study was designed to provide a detailed molecular and functional of the fetal VM tissue in order to give a deeper understanding of its composition and characteristics. The characterization is based on the comparison of standard culture conditions (2D) versus organoids of hVM (3D). We used unbiased single cell RNA sequencing to transcriptionally compare fetal VM tissue in 2D and 3D conditions together with a functional analysis performed using whole cell patch clamp technique. Our analysis determined the molecular and functional properties of the tissue that originates dopaminergic neurons and also confirmed important differences between the culture conditions as well as it . The data can be used for quality assessment of new cell sources and provide new molecular targets for improved subtype specificity during stem cell differentiation.

The power of embryonic stem cells (ESCs) lies in their ability to self-renew and differentiate. Behind these two unique capabilities is a fine-tuned molecular network that shapes the genetic, epigenetic, and epitranscriptomic ESC plasticity. Although RNA has been shown to be functionally important in only a small minority of long non-coding RNA genes, a growing body of evidence has highlighted the pivotal and intricate role of lncRNAs in chromatin remodeling. Due to their multifaceted nature, lncRNAs interact with DNA, RNA, and proteins, and are emerging as new modulators of extensive gene expression programs through their participation in ESC-specific regulatory circuitries. Here, we review the tight cooperation between lncRNAs and Polycomb repressive complex 2 (PRC2), which is intimately involved in determining and maintaining the ESC epigenetic landscape. The lncRNA-PRC2 partnership is fundamental in securing the fully pluripotent state of ESCs, which must be primed to differentiate properly. We also reflect on the advantages brought to this field of research by the advent of single-cell analysis.

Cell replacement is a long-standing and realistic goal for the treatment of Parkinsonʼs disease (PD). Cells for transplantation can be obtained from fetal brain tissue or from stem cells. However, after transplantation, dopamine (DA) neurons are seen to be a minor component of grafts, and it has remained difficult to determine the identity of other cell types. Here, we report analysis by single-cell RNA sequencing (scRNA-seq) combined with comprehensive histological analyses to characterize intracerebral grafts from human embryonic stem cells (hESCs) and fetal tissue after functional maturation in a pre-clinical rat PD model. We show that neurons and astrocytes are major components in both fetal and stem cell-derived grafts. Additionally, we identify a cell type closely resembling a class of recently identified perivascular-like cells in stem cell-derived grafts. Thus, this study uncovers previously unknown cellular diversity in a clinically relevant cell replacement PD model., What happens to cells on engrafting into the brain in animal models to treat Parkinson’s disease is unclear. Here, the authors use scRNA-seq to examine ventral midbrain (VM)-patterned human embryonic stem cells after functional maturation in a pre-clinical rat model for Parkinson’s disease and identify perivascular-like cells.

Summary Metabolites and cofactors are emerging as key regulators of cell plasticity and reprogramming, and their role in the control of pluripotency is just being discovered. Here we provide unprecedented evidence that embryonic stem cell (ESC) pluripotency relies on the relative levels of two physiological metabolites, namely ascorbic acid (vitamin C, VitC) and l-proline (l-Pro), which affect global DNA methylation, transcriptional profile, and energy metabolism. Specifically, while a high VitC/l-Pro ratio drives ESCs toward a naive state, the opposite condition (l-Pro excess) captures a fully reversible early primed pluripotent state, which depends on autocrine fibroblast growth factor and transforming growth factor β signaling pathways. Our findings highlight the pivotal role of metabolites availability in controlling the pluripotency continuum from naive to primed states., Graphical Abstract, Highlights • Global DNA methylation is modulated by l-Pro and VitC availability in ESCs • l-Pro and VitC relative levels induce naive and reversible primed pluripotency • High l-Pro/low VitC levels induce metabolic reprogramming in ESCs • l-Pro induces and sustains autocrine FGF and TGF-β signaling in ESCs, In this article, Minchiotti, De Cesare, and colleagues show that the relative levels of two physiological metabolites, vitamin C and l-proline, direct ESCs toward naive or reversible primed states of pluripotency, placed between the naive/2i and FGF/activin states, and highlight a pivotal role of metabolic-epigenetic crosstalk in the developmental continuum.

Aims Mammalian cardiomyogenesis occurs through a multistep process that requires a complex network of tightly regulated extracellular signals, which integrate with the genetic and epigenetic machinery to maintain, expand, and regulate the differentiation of cardiac progenitor cells. Pluripotent embryonic stem cells (ESCs) recapitulate many aspects of development, and have provided an excellent opportunity to dissect the molecular mechanisms underlying cardiomyogenesis, which is still incompletely defined. Methods and results We provide new in vivo evidence that the G-protein-coupled receptor angiotensin receptor-like 1 ( Apj ) is expressed in the mesodermal cells of the second heart field, a population of cardiac progenitors that give rise to a major part of the definitive heart. By combining loss-and-gain of function studies in mouse ESCs, we show that Apj (i) controls the balance between proliferation and cardiovascular differentiation, (ii) regulates the Nodal/Bone Morphogenetic Protein antagonist Cerberus and the Baf60c/Smarcd3 subunit of the Brg1/Brm-associated factors (BAF) chromatin-remodelling complex. Conclusion We propose a model in which Apj controls a regulatory Cerberus–Baf60c pathway in pluripotent stem cell cardiomyogenesis, and speculate that this regulatory circuit may regulate cardiac progenitor cell behaviour.

Known molecular determinants of developmental plasticity are mainly transcription factors, while the extrinsic regulation of this process has been largely unexplored. Here we identify Cripto as one of the earliest epiblast markers and a key extracellular determinant of the naive and primed pluripotent states. We demonstrate that Cripto sustains mouse embryonic stem cell (ESC) self-renewal by modulating Wnt/β-catenin, whereas it maintains mouse epiblast stem cell (EpiSC) and human ESC pluripotency through Nodal/Smad2. Moreover, we provide unprecedented evidence that Cripto controls the metabolic reprogramming in ESCs to EpiSC transition. Remarkably, Cripto deficiency attenuates ESC lineage restriction in vitro and in vivo, and permits ESC transdifferentiation into trophectoderm lineage, suggesting that Cripto has earlier functions than previously recognized. All together, our studies provide novel insights into the current model of mammalian pluripotency and contribute to the understanding of the extrinsic regulation of the first cell lineage decision in the embryo., Stem cell plasticity is crucial for early embryo development and the differentiation of stem cells. Here, the authors show that the extracellular protein Cripto sustains mouse ESC self-renewal and maintains mouse EpiSC as well as human ESC pluripotency and controls the metabolic reprogramming in ESCs to EpiSC transition.

Stemness was recently depicted as a dynamic condition in normal and tumor cells. We found that the embryonic protein Cripto-1 (CR1) was expressed by normal stem cells at the bottom of colonic crypts and by cancer stem cells (CSCs) in colorectal tumor tissues. CR1-positive populations isolated from patient-derived tumor spheroids exhibited increased clonogenic capacity and expression of stem-cell-related genes. CR1 expression in tumor spheroids was variable over time, being subject to a complex regulation of the intracellular, surface and secreted protein, which was related to changes of the clonogenic capacity at the population level. CR1 silencing induced CSC growth arrest in vitro with a concomitant decrease of Src/Akt signaling, while in vivo it inhibited the growth of CSC-derived tumor xenografts and reduced CSC numbers. Importantly, CR1 silencing in established xenografts through an inducible expression system decreased CSC growth in both primary and metastatic tumors, indicating an essential role of CR1 in the regulation the CSC compartment. These results point to CR1 as a novel and dynamically regulated effector of stem cell functions in colorectal cancer.

Parkinson disease (PD) is characterized by a loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc). The selective loss of this cell population makes PD a good candidate for cell-based therapies. Clinical trials using cells derived from human fetal ventral midbrain (hVM) have shown that dopamine release could be restored to normal levels and in some PD patients produced substantial long-term clinical improvement. The ethical issues related to the use of human fetal material as well as the low number of hVM tissue available have limited the spread of this approach and have lead researchers to find new sources of cells such as human embryonic stem cells (hESCs) and pluripotent stem cells (IPCs). This study was designed to provide a detailed molecular and functional of the fetal VM tissue in order to give a deeper understanding of its composition and characteristics. The characterization is based on the comparison of standard culture conditions (2D) versus organoids of hVM (3D). We used unbiased single cell RNA sequencing to transcriptionally compare fetal VM tissue in 2D and 3D conditions together with a functional analysis performed using whole cell patch clamp technique. Our analysis determined the molecular and functional properties of the tissue that originates dopaminergic neurons and also confirmed important differences between the culture conditions as well as it . The data can be used for quality assessment of new cell sources and provide new molecular targets for improved subtype specificity during stem cell differentiation.

Parkinson disease (PD) is characterized by a loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc). The selective loss of this cell population makes PD a good candidate for cell-based therapies. Clinical trials using cells derived from human fetal ventral midbrain (hVM) have shown that dopamine release was restored to normal levels and in some PD patients produced substantial long-term clinical improvement. Although new sources of cells such as human embryonic stem cells (hESCs) and pluripotent stem cells (IPCs) are now been the focus of studies and new clinical trials, the hVM tissue represent the gold standard for cell based therapies and serve as important comparator for new cell sources. Therefore there is a need of an increased understanding and characterization of this tissue with new technologies such as organoid culture conditions and single cell sequencing. This study is designed to give a detailed characterization of human fetal VM tissue in standard culture conditions (2D) versus organoids (3D). We used immunocytochemistry to study the presence of ventral midbrain markers in 2D versus 3D condition together with single cell RNA sequencing to transcriptionally compare fetal VM tissue in standard or organoid cultures. Our analysis confirmed that the 3D condition preserve the neuronal composition of the tissue more than standard culture where instead, over a long period of time, the majority of the cells are non-neuronal. This suggest that 3D culture represent a better condition to maintain and study dopaminergic neurons in culture. &nbsp