Showing papers on "Cellular differentiation published in 2012"
TL;DR: It is argued that altered metabolism has attained the status of a core hallmark of cancer.
2,623 citations
TL;DR: Cellular and molecular mechanisms in the differentiation and function of regulatory T cells and their role in autoimmune and autoinflammatory disorders, allergy, acute and chronic infections, cancer, and metabolic inflammation are discussed.
Abstract: The immune system has evolved to mount an effective defense against pathogens and to minimize deleterious immune-mediated inflammation caused by commensal microorganisms, immune responses against self and environmental antigens, and metabolic inflammatory disorders. Regulatory T (Treg) cell–mediated suppression serves as a vital mechanism of negative regulation of immune-mediated inflammation and features prominently in autoimmune and autoinflammatory disorders, allergy, acute and chronic infections, cancer, and metabolic inflammation. The discovery that Foxp3 is the transcription factor that specifies the Treg cell lineage facilitated recent progress in understanding the biology of regulatory T cells. In this review, we discuss cellular and molecular mechanisms in the differentiation and function of these cells.
2,356 citations
TL;DR: It is identified how well-characterized surface markers, including MerTK and FcγR1 (CD64), along with a cluster of previously unidentified transcripts, were distinctly and universally associated with mature tissue macrophages and how these transcripts and the proteins they encode facilitated distinguishing macrophage from dendritic cells.
Abstract: We assessed gene expression in tissue macrophages from various mouse organs The diversity in gene expression among different populations of macrophages was considerable Only a few hundred mRNA transcripts were selectively expressed by macrophages rather than dendritic cells, and many of these were not present in all macrophages Nonetheless, well-characterized surface markers, including MerTK and FcγR1 (CD64), along with a cluster of previously unidentified transcripts, were distinctly and universally associated with mature tissue macrophages TCEF3, C/EBP-α, Bach1 and CREG-1 were among the transcriptional regulators predicted to regulate these core macrophage-associated genes The mRNA encoding other transcription factors, such as Gata6, was associated with single macrophage populations We further identified how these transcripts and the proteins they encode facilitated distinguishing macrophages from dendritic cells
1,675 citations
TL;DR: It is reported that 2HG-producing IDH mutants can prevent the histone demethylation that is required for lineage-specific progenitor cells to differentiate into terminally differentiated cells, and that inhibition of histone methylation can be sufficient to block the differentiation of non-transformed cells.
Abstract: Recurrent mutations in isocitrate dehydrogenase 1 (IDH1) and IDH2 have been identified in gliomas, acute myeloid leukaemias (AML) and chondrosarcomas, and share a novel enzymatic property of producing 2-hydroxyglutarate (2HG) from α-ketoglutarate. Here we report that 2HG-producing IDH mutants can prevent the histone demethylation that is required for lineage-specific progenitor cells to differentiate into terminally differentiated cells. In tumour samples from glioma patients, IDH mutations were associated with a distinct gene expression profile enriched for genes expressed in neural progenitor cells, and this was associated with increased histone methylation. To test whether the ability of IDH mutants to promote histone methylation contributes to a block in cell differentiation in non-transformed cells, we tested the effect of neomorphic IDH mutants on adipocyte differentiation in vitro. Introduction of either mutant IDH or cell-permeable 2HG was associated with repression of the inducible expression of lineage-specific differentiation genes and a block to differentiation. This correlated with a significant increase in repressive histone methylation marks without observable changes in promoter DNA methylation. Gliomas were found to have elevated levels of similar histone repressive marks. Stable transfection of a 2HG-producing mutant IDH into immortalized astrocytes resulted in progressive accumulation of histone methylation. Of the marks examined, increased H3K9 methylation reproducibly preceded a rise in DNA methylation as cells were passaged in culture. Furthermore, we found that the 2HG-inhibitable H3K9 demethylase KDM4C was induced during adipocyte differentiation, and that RNA-interference suppression of KDM4C was sufficient to block differentiation. Together these data demonstrate that 2HG can inhibit histone demethylation and that inhibition of histone demethylation can be sufficient to block the differentiation of non-transformed cells.
1,651 citations
TL;DR: It is shown that temporal modulation of Wnt signaling is both essential and sufficient for efficient cardiac induction in hPSCs under defined, growth factor-free conditions.
Abstract: Human pluripotent stem cells (hPSCs) offer the potential to generate large numbers of functional cardiomyocytes from clonal and patient-specific cell sources. Here we show that temporal modulation of Wnt signaling is both essential and sufficient for efficient cardiac induction in hPSCs under defined, growth factor-free conditions. shRNA knockdown of β-catenin during the initial stage of hPSC differentiation fully blocked cardiomyocyte specification, whereas glycogen synthase kinase 3 inhibition at this point enhanced cardiomyocyte generation. Furthermore, sequential treatment of hPSCs with glycogen synthase kinase 3 inhibitors followed by inducible expression of β-catenin shRNA or chemical inhibitors of Wnt signaling produced a high yield of virtually (up to 98%) pure functional human cardiomyocytes from multiple hPSC lines. The robust ability to generate functional cardiomyocytes under defined, growth factor-free conditions solely by genetic or chemically mediated manipulation of a single developmental pathway should facilitate scalable production of cardiac cells suitable for research and regenerative applications.
1,398 citations
TL;DR: Recent advances in molecular and genetic studies using gene targeting in mice enable a better understanding of TGF-β/BMP signaling in bone and in the signaling networks underlying osteoblast differentiation and bone formation.
Abstract: Transforming growth factor-beta (TGF-β)/bone morphogenic protein (BMP) signaling is involved in a vast majority of cellular processes and is fundamentally important throughout life. TGF-β/BMPs have widely recognized roles in bone formation during mammalian development and exhibit versatile regulatory functions in the body. Signaling transduction by TGF-β/BMPs is specifically through both canonical Smad-dependent pathways (TGF-β/BMP ligands, receptors and Smads) and non-canonical Smad-independent signaling pathway (e.g. p38 mitogen-activated protein kinase pathway, MAPK). Following TGF-β/BMP induction, both the Smad and p38 MAPK pathways converge at the Runx2 gene to control mesenchymal precursor cell differentiation. The coordinated activity of Runx2 and TGF-β/BMP-activated Smads is critical for formation of the skeleton. Recent advances in molecular and genetic studies using gene targeting in mice enable a better understanding of TGF-β/BMP signaling in bone and in the signaling networks underlying osteoblast differentiation and bone formation. This review summarizes the recent advances in our understanding of TGF-β/BMP signaling in bone from studies of genetic mouse models and human diseases caused by the disruption of TGF-β/BMP signaling. This review also highlights the different modes of cross-talk between TGF-β/BMP signaling and the signaling pathways of MAPK, Wnt, Hedgehog, Notch, and FGF in osteoblast differentiation and bone formation.
1,308 citations
TL;DR: It remains uncertain whether the stem cell model applies to many, or few, cancers due to questions about the robustness of cancer stem cell markers and the extent to which existing assays underestimate the frequency of tumorigenic cells.
1,043 citations
TL;DR: It is found that the production of TGF-β3 by developing Th17 cells was dependent on IL-23, which together with IL-6 induced very pathogenic TH17 cells, which had a molecular signature that defined pathogenic effector TH 17 cells in autoimmune disease.
Abstract: Interleukin 17 (IL-17)-producing helper T cells (T(H)17 cells) are often present at the sites of tissue inflammation in autoimmune diseases, which has led to the conclusion that T(H)17 cells are main drivers of autoimmune tissue injury. However, not all T(H)17 cells are pathogenic; in fact, T(H)17 cells generated with transforming growth factor-β1 (TGF-β1) and IL-6 produce IL-17 but do not readily induce autoimmune disease without further exposure to IL-23. Here we found that the production of TGF-β3 by developing T(H)17 cells was dependent on IL-23, which together with IL-6 induced very pathogenic T(H)17 cells. Moreover, TGF-β3-induced T(H)17 cells were functionally and molecularly distinct from TGF-β1-induced T(H)17 cells and had a molecular signature that defined pathogenic effector T(H)17 cells in autoimmune disease.
980 citations
TL;DR: The past 15 years have witnessed tremendous progress in the molecular understanding of osteoblasts, the main bone-forming cells in the vertebrate skeleton, and evidence indicates that osteoblast may also regulate the behaviour of other cell types.
Abstract: The past 15 years have witnessed tremendous progress in the molecular understanding of osteoblasts, the main bone-forming cells in the vertebrate skeleton In particular, all of the major developmental signals (including WNT and Notch signalling), along with an increasing number of transcription factors (such as RUNX2 and osterix), have been shown to regulate the differentiation and/or function of osteoblasts As evidence indicates that osteoblasts may also regulate the behaviour of other cell types, a clear understanding of the molecular identity and regulation of osteoblasts is important beyond the field of bone biology
919 citations
TL;DR: Using conditional ablation, it is shown that Dnmt3a loss progressively impairs hematopoietic stem cell differentiation over serial transplantation, while simultaneously expanding HSC numbers in the bone marrow.
Abstract: Margaret Goodell, Wei Li and colleagues report conditional ablation of the Dnmt3a DNA methyltransferase in hematopoietic stem cells (HSCs) in mice. They show that Dnmt3a is critical for epigenetic silencing of HSC regulatory genes and for HSC differentiation.
909 citations
TL;DR: It is demonstrated that exosomes carry Wnts on their surface to induce Wnt signalling activity in target cells and an evolutionarily conserved functional role of extracellular vesicular transport of Wnt proteins is demonstrated.
Abstract: Wnt signalling has important roles during development and in many diseases As morphogens, hydrophobic Wnt proteins exert their function over a distance to induce patterning and cell differentiation decisions Recent studies have identified several factors that are required for the secretion of Wnt proteins; however, how Wnts travel in the extracellular space remains a largely unresolved question Here we show that Wnts are secreted on exosomes both during Drosophila development and in human cells We demonstrate that exosomes carry Wnts on their surface to induce Wnt signalling activity in target cells Together with the cargo receptor Evi/WIs, Wnts are transported through endosomal compartments onto exosomes, a process that requires the R-SNARE Ykt6 Our study demonstrates an evolutionarily conserved functional role of extracellular vesicular transport of Wnt proteins
TL;DR: It is suggested that transcriptional potentiation and a permissive chromatin context characterize the ground state and that exit from it may not require a metastable intermediate or multilineage priming.
TL;DR: It is found that keratinocytes and neurons were the main sources of IL-34, which specifically directs the differentiation of myeloid cells in the skin epidermis and CNS.
Abstract: The differentiation of bone marrow-derived progenitor cells into monocytes, tissue macrophages and some dendritic cell (DC) subtypes requires the growth factor CSF1 and its receptor, CSF1R. Langerhans cells (LCs) and microglia develop from embryonic myeloid precursor cells that populate the epidermis and central nervous system (CNS) before birth. Notably, LCs and microglia are present in CSF1-deficient mice but absent from CSF1R-deficient mice. Here we investigated whether an alternative CSF1R ligand, interleukin 34 (IL-34), is responsible for this discrepancy. Through the use of IL-34-deficient (Il34(LacZ/LacZ)) reporter mice, we found that keratinocytes and neurons were the main sources of IL-34. Il34(LacZ/LacZ) mice selectively lacked LCs and microglia and responded poorly to skin antigens and viral infection of the CNS. Thus, IL-34 specifically directs the differentiation of myeloid cells in the skin epidermis and CNS.
TL;DR: Cues from the extracellular matrix, cell adhesion sites, cell shape and the actomyosin cytoskeleton were found to converge on the regulation of the downstream effectors of the Hippo pathway YAP and TAZ in vertebrates and Yorkie in flies, which may explain how mechanical signals can direct normal and pathological cell behaviour.
Abstract: The physical and mechanical properties of the cellular microenvironment regulate cell shape and can strongly influence cell fate. How mechanical cues are sensed and transduced to regulate gene expression has long remained elusive. Recently, cues from the extracellular matrix, cell adhesion sites, cell shape and the actomyosin cytoskeleton were found to converge on the regulation of the downstream effectors of the Hippo pathway YAP (Yes-associated protein) and TAZ (transcriptional co-activator with PDZ-binding motif) in vertebrates and Yorkie in flies. This convergence may explain how mechanical signals can direct normal and pathological cell behaviour.
TL;DR: Whereas Treg cells generated in the thymus appear sufficient for control of systemic and tissue-specific autoimmunity, extrathymic differentiation of Treg Cells affects commensal microbiota composition and serves a distinct, essential function in restraint of allergic-type inflammation at mucosal interfaces.
Abstract: A balance between pro- and anti-inflammatory mechanisms at mucosal interfaces, which are sites of constitutive exposure to microbes and non-microbial foreign substances, allows for efficient protection against pathogens yet prevents adverse inflammatory responses associated with allergy, asthma and intestinal inflammation 1 . Regulatory T (Treg) cells prevent systemic and tissuespecific autoimmunity and inflammatory lesions at mucosal interfaces. These cells are generated in the thymus (tTreg cells) and in the periphery (induced (i)Treg cells), and their dual origin implies a division of labour between tTreg and iTreg cells in immune homeostasis. Here we show that a highly selective blockage in differentiation of iTreg cells in mice did not lead to unprovoked multiorgan autoimmunity, exacerbation of induced tissue-specific autoimmune pathology, or increased pro-inflammatory responses of T helper 1 (TH1) and TH17 cells. However, mice deficient in iTreg cells spontaneously developed pronounced TH2-type pathologies at mucosal sites—in the gastrointestinal tract and lungs—with hallmarks of allergic inflammation and asthma. Furthermore, iTreg-cell deficiency altered gut microbial communities. These results suggest that whereas Treg cells generated in the thymus appear sufficient for control of systemic and tissue-specific autoimmunity, extrathymic differentiation of Treg cells affects commensal microbiota composition and serves a distinct, essential function in restraint of allergic-type inflammation at mucosal interfaces. Exquisitely balanced control mechanisms operating at mucosal sites are able to accommodate potent immune defences and the need to prevent tissue damage resulting from inflammatory responses caused by commensal microorganisms, food and environmental antigens, allergens, and noxious substances 1 .
TL;DR: It is demonstrated that the aged muscle stem cell niche, the muscle fibre, expresses Fgf2 under homeostatic conditions, driving a subset of satellite cells to break quiescence and lose their self-renewing capacity.
Abstract: The niche is a conserved regulator of stem cell quiescence and function. During ageing, stem cell function declines. To what extent and by what means age-related changes within the niche contribute to this phenomenon are unknown. Here we demonstrate that the aged muscle stem cell niche, the muscle fibre, expresses Fgf2 under homeostatic conditions, driving a subset of satellite cells to break quiescence and lose their self-renewing capacity. We show in mice that relatively dormant aged satellite cells robustly express sprouty 1 (Spry1), an inhibitor of fibroblast growth factor (FGF) signalling. Increasing FGF signalling in aged satellite cells under homeostatic conditions by removing Spry1 results in the loss of quiescence, satellite cell depletion and diminished regenerative capacity. Conversely, reducing niche-derived FGF activity through inhibition of Fgfr1 signalling or overexpression of Spry1 in satellite cells prevents their depletion. These experiments identify an age-dependent change in the stem cell niche that directly influences stem cell quiescence and function. The expression of fibroblast growth factor in aged muscle fibre, the muscle stem cell niche, is shown to cause satellite cells to lose the capacity for self-renewal, and is thus an age-dependent change that directly influences stem cell quiescence and function. The efficiency of stem-cell maintenance declines with age, but it is not clear whether the stem-cell niche itself plays a part in this decline. Here, Andrew Brack and colleagues report that as mice age, the skeletal-muscle niche becomes more mitogenic — meaning more cells undergo mitosis and differentiation — and less capable of maintaining the quiescence of the skeletal-muscle stem cells. This results in the loss of capacity for stem-cell self-renewal. The protein FGF2 is a key mitogenic factor in the aged niche, although a small number of muscle stem cells express SPRY1, an inhibitor of FGF signalling, and maintain some quiescence in aged skeletal-muscle fibres.
TL;DR: Lineage tracing in Dll1GFP–ires–CreERT2 knock-in mice reveals that single Dll 1high cells generate small, short-lived clones containing all four secretory cell types, which exhibit plasticity by regaining stemness on damage.
Abstract: Lgr5+ intestinal stem cells generate enterocytes and secretory cells. Secretory lineage commitment requires Notch silencing. The Notch ligand Dll1 is expressed by a subset of immediate stem cell daughters. Lineage tracing in Dll1(GFP-ires-CreERT2) knock-in mice reveals that single Dll1(high) cells generate small, short-lived clones containing all four secretory cell types. Lineage specification thus occurs in immediate stem cell daughters through Notch lateral inhibition. Cultured Dll1(high) cells form long-lived organoids (mini-guts) on brief Wnt3A exposure. When Dll1(high) cells are genetically marked before tissue damage, stem cell tracing events occur. Thus, secretory progenitors exhibit plasticity by regaining stemness on damage.
TL;DR: An 80-d, three-stage process that recapitulates cortical development is demonstrated, in which human PSCs (hPSCs) first differentiate to cortical stem and progenitor cells that then generate cortical projection neurons in a stereotypical temporal order before maturing to actively fire action potentials, undergo synaptogenesis and form neural circuits in vitro.
Abstract: Efficient derivation of human cerebral neocortical neural stem cells (NSCs) and functional neurons from pluripotent stem cells (PSCs) facilitates functional studies of human cerebral cortex development, disease modeling and drug discovery. Here we provide a detailed protocol for directing the differentiation of human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs) to all classes of cortical projection neurons. We demonstrate an 80-d, three-stage process that recapitulates cortical development, in which human PSCs (hPSCs) first differentiate to cortical stem and progenitor cells that then generate cortical projection neurons in a stereotypical temporal order before maturing to actively fire action potentials, undergo synaptogenesis and form neural circuits in vitro. Methods to characterize cortical neuron identity and synapse formation are described.
TL;DR: Characterization of MSCs containing skin substitutes is described, demonstrating the presence of key growth factors and cytokines uniquely suited to aid in wound repair.
Abstract: Wound healing requires a coordinated interplay among cells, growth factors, and extracellular matrix proteins. Central to this process is the endogenous mesenchymal stem cell (MSC), which coordinates the repair response by recruiting other host cells and secreting growth factors and matrix proteins. MSCs are self-renewing multipotent stem cells that can differentiate into various lineages of mesenchymal origin such as bone, cartilage, tendon, and fat. In addition to multilineage differentiation capacity, MSCs regulate immune response and inflammation and possess powerful tissue protective and reparative mechanisms, making these cells attractive for treatment of different diseases. The beneficial effect of exogenous MSCs on wound healing was observed in a variety of animal models and in reported clinical cases. Specifically, they have been successfully used to treat chronic wounds and stimulate stalled healing processes. Recent studies revealed that human placental membranes are a rich source of MSCs for tissue regeneration and repair. This review provides a concise summary of current knowledge of biological properties of MSCs and describes the use of MSCs for wound healing. In particular, the scope of this review focuses on the role MSCs have in each phase of the wound-healing process. In addition, characterization of MSCs containing skin substitutes is described, demonstrating the presence of key growth factors and cytokines uniquely suited to aid in wound repair.
TL;DR: It is found that during biliary regeneration, expression of Jagged 1 by myofibroblasts promoted Notch signaling in HPCs and thus their biliary specification to cholangiocytes and thus the promotion of their specification to hepatocytes.
Abstract: During chronic injury a population of bipotent hepatic progenitor cells (HPCs) become activated to regenerate both cholangiocytes and hepatocytes. Here we show in human diseased liver and mouse models of the ductular reaction that Notch and Wnt signaling direct specification of HPCs via their interactions with activated myofibroblasts or macrophages. In particular, we found that during biliary regeneration, expression of Jagged 1 (a Notch ligand) by myofibroblasts promoted Notch signaling in HPCs and thus their biliary specification to cholangiocytes. Alternatively, during hepatocyte regeneration, macrophage engulfment of hepatocyte debris induced Wnt3a expression. This resulted in canonical Wnt signaling in nearby HPCs, thus maintaining expression of Numb (a cell fate determinant) within these cells and the promotion of their specification to hepatocytes. By these two pathways adult parenchymal regeneration during chronic liver injury is promoted.
TL;DR: Two sequential, genetically separable checkpoints of NK cell maturation are revealed, the progression of which is metered largely by the anatomic localization of hematopoiesis.
TL;DR: It is established that epithelial KrasG12D influences multiple cell types to drive pancreatic tumorigenesis and is essential for tumor maintenance, and strongly support the notion that inhibiting Krasg12D, or its downstream effectors, could provide a new approach for the treatment of pancreatic cancer.
Abstract: Pancreatic cancer is almost invariably associated with mutations in the KRAS gene, most commonly KRASG12D, that result in a dominant-active form of the KRAS GTPase However, how KRAS mutations promote pancreatic carcinogenesis is not fully understood, and whether oncogenic KRAS is required for the maintenance of pancreatic cancer has not been established To address these questions, we generated two mouse models of pancreatic tumorigenesis: mice transgenic for inducible KrasG12D, which allows for inducible, pancreas-specific, and reversible expression of the oncogenic KrasG12D, with or without inactivation of one allele of the tumor suppressor gene p53 Here, we report that, early in tumorigenesis, induction of oncogenic KrasG12D reversibly altered normal epithelial differentiation following tissue damage, leading to precancerous lesions Inactivation of KrasG12D in established precursor lesions and during progression to cancer led to regression of the lesions, indicating that KrasG12D was required for tumor cell survival Strikingly, during all stages of carcinogenesis, KrasG12D upregulated Hedgehog signaling, inflammatory pathways, and several pathways known to mediate paracrine interactions between epithelial cells and their surrounding microenvironment, thus promoting formation and maintenance of the fibroinflammatory stroma that plays a pivotal role in pancreatic cancer Our data establish that epithelial KrasG12D influences multiple cell types to drive pancreatic tumorigenesis and is essential for tumor maintenance They also strongly support the notion that inhibiting KrasG12D, or its downstream effectors, could provide a new approach for the treatment of pancreatic cancer
TL;DR: A review of the basic biology underlying the differentiation of human pluripotent cells to cardiac lineages can be found in this paper, where the authors describe current state-of-the-art protocols, as well as ongoing refinements.
Abstract: Since human embryonic stem cells were first differentiated to beating cardiomyocytes a decade ago, interest in their potential applications has increased exponentially. This has been further enhanced over recent years by the discovery of methods to induce pluripotency in somatic cells, including those derived from patients with hereditary cardiac diseases. Human pluripotent stem cells have been among the most challenging cell types to grow stably in culture, but advances in reagent development now mean that most laboratories can expand both embryonic and induced pluripotent stem cells robustly using commercially available products. However, differentiation protocols have lagged behind and in many cases only produce the cell types required with low efficiency. Cardiomyocyte differentiation techniques were also initially inefficient and not readily transferable across cell lines, but there are now a number of more robust protocols available. Here, we review the basic biology underlying the differentiation of pluripotent cells to cardiac lineages and describe current state-of-the-art protocols, as well as ongoing refinements. This should provide a useful entry for laboratories new to this area to start their research. Ultimately, efficient and reliable differentiation methodologies are essential to generate desired cardiac lineages to realize the full promise of human pluripotent stem cells for biomedical research, drug development, and clinical applications.
TL;DR: It is shown that female (XX) embryonic stem cells and induced pluripotent stem cells in mice are induced into primordial germ cell–like cells (PGCLCs), which, when aggregated with female gonadal somatic cells as reconstituted ovaries, undergo X-reactivation, imprint erasure, and cyst formation, and exhibit meiotic potential.
Abstract: In mice, male embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) have been shown to differentiate into primordial germ cell–like cells (PGCLCs) in vitro. Upon transplantation into testes, these PGCLCs can form fully functional sperm. Again working in mice, Hayashi et al. (p. [971][1], published online 4 October) found that female ESCs and iPSCs can also differentiate into PGCLCs, which, when aggregated in reconstituted ovaries, exhibited epigenetic reprogramming and meiotic potential in vitro. Upon transplantation of the reconstituted ovaries under ovarian bursa, female PGCLCs developed into fully grown oocytes that contributed to healthy offspring upon in vitro maturation and fertilization.
[1]: /lookup/volpage/338/971
TL;DR: In this article, state-of-the-art methods for generating de novo cardiomyocytes from human pluripotent stem cells (hPSCs) and reprogrammed fibroblasts are discussed.
TL;DR: A novel preactivation chromatin pattern at the promoters of genes associated with heart development and cardiac function is discovered and forms a basis for understanding developmentally regulated chromatin transitions during lineage commitment and the molecular etiology of congenital heart disease.
TL;DR: Recent progress is covered establishing an emerging relationship between stem cell metabolism and cell fate control, which offers a potential target for controlling tissue homeostasis and regeneration in aging and disease.
TL;DR: A protocol to efficiently differentiate commercially available human embryonic stem cells in vitro into a highly enriched PDX1+ pancreatic progenitor cell population that further develops in vivo to mature pancreatic endocrine cells supports the feasibility of using differentiated hESCs as an alternative to cadaveric islets for treating patients with diabetes.
Abstract: Diabetes is a chronic debilitating disease that results from insufficient production of insulin from pancreatic β-cells. Islet cell replacement can effectively treat diabetes but is currently severely limited by the reliance upon cadaveric donor tissue. We have developed a protocol to efficiently differentiate commercially available human embryonic stem cells (hESCs) in vitro into a highly enriched PDX1+ pancreatic progenitor cell population that further develops in vivo to mature pancreatic endocrine cells. Immature pancreatic precursor cells were transplanted into immunodeficient mice with streptozotocin-induced diabetes, and glycemia was initially controlled with exogenous insulin. As graft-derived insulin levels increased over time, diabetic mice were weaned from exogenous insulin and human C-peptide secretion was eventually regulated by meal and glucose challenges. Similar differentiation of pancreatic precursor cells was observed after transplant in immunodeficient rats. Throughout the in vivo maturation period hESC-derived endocrine cells exhibited gene and protein expression profiles that were remarkably similar to the developing human fetal pancreas. Our findings support the feasibility of using differentiated hESCs as an alternative to cadaveric islets for treating patients with diabetes.
TL;DR: It is shown that endothelial cells derived from human pluripotent stem cells (hPSCs) acquire BBB properties when co-differentiated with neural cells that provide relevant cues, including those involved in Wnt/β-catenin signaling.
Abstract: The blood-brain barrier (BBB) is crucial to the health of the brain and is often compromised in neurological disease. Moreover, because of its barrier properties, this endothelial interface restricts uptake of neurotherapeutics. Thus, a renewable source of human BBB endothelium could spur brain research and pharmaceutical development. Here we show that endothelial cells derived from human pluripotent stem cells (hPSCs) acquire BBB properties when co-differentiated with neural cells that provide relevant cues, including those involved in Wnt/β-catenin signaling. The resulting endothelial cells have many BBB attributes, including well-organized tight junctions, appropriate expression of nutrient transporters and polarized efflux transporter activity. Notably, they respond to astrocytes, acquiring substantial barrier properties as measured by transendothelial electrical resistance (1,450 ± 140 Ω cm2), and they possess molecular permeability that correlates well with in vivo rodent blood-brain transfer coefficients.
TL;DR: Wnt is part of a signaling loop that affects homeostasis of intestinal stem and Paneth cells in mice, and Wnt3 signaling is required for growth and development of organoid cultures, whereas nonepithelial Wnt signals could provide a secondary physiological source of Wnt.