Search

Summary MYSM1 deficiency causes inherited bone marrow failure syndrome (IBMFS). We have previously identified an IBMFS patient with a homozygous pathogenic variant in MYSM1 who recovered from cytopenia due to spontaneous correction of one MYSM1 variant in the haematopoietic compartment, an event called somatic genetic rescue (SGR). The study of the genetic and biological aspects of the patient's haematopoietic/lymphopoietic system over a decade after SGR shows that one genetically corrected haematopoietic stem cell (HSC) can restore a healthy and stable haematopoietic system. This supports in vivo gene correction of HSCs as a promising treatment for IBMFS, including MYSM1 deficiency. [ABSTRACT FROM AUTHOR]

Sialic acid is a unique sugar moiety that resides in the distal and most accessible position of the glycans on mammalian cell surface and extracellular glycoproteins and glycolipids. The potential for sialic acid to obscure underlying structures has long been postulated, but the means by which such structural changes directly affect biological processes continues to be elucidated. Here, we appraise the growing body of literature detailing the importance of sialic acid for the generation, differentiation, function and death of haematopoietic cells. We conclude that sialylation is a critical post‐translational modification utilized in haematopoiesis to meet the dynamic needs of the organism by enforcing rapid changes in availability of lineage‐specific cell types. Though long thought to be generated only cell‐autonomously within the intracellular ER‐Golgi secretory apparatus, emerging data also demonstrate previously unexpected diversity in the mechanisms of sialylation. Emphasis is afforded to the mechanism of extrinsic sialylation, whereby extracellular enzymes remodel cell surface and extracellular glycans, supported by charged sugar donor molecules from activated platelets. [ABSTRACT FROM AUTHOR]

Protein tyrosine phosphatase 1B (PTP1B) is a non-receptor tyrosine phosphatase best known for its role in regulating insulin and leptin signalling. Recently, knowledge on the role of PTP1B as a major regulator of multiple signalling pathways involved in cell growth, proliferation, viability and metabolism has expanded, and PTP1B is recognised as a therapeutic target in several human disorders, including diabetes, obesity, cardiovascular diseases and hematopoietic malignancies. The function of PTP1B in the immune system was largely overlooked until it was discovered that PTP1B negatively regulates the Janus kinase—a signal transducer and activator of the transcription (JAK/STAT) signalling pathway, which plays a significant role in modulating immune responses. PTP1B is now known to determine the magnitude of many signalling pathways that drive immune cell activation and function. As such, PTP1B inhibitors are being developed and tested in the context of inflammation and autoimmune diseases. Here, we provide an up-to-date summary of the molecular role of PTP1B in regulating immune cell function and how targeting its expression and/or activity has the potential to change the outcomes of immune-mediated and inflammatory disorders. [ABSTRACT FROM AUTHOR]

Summary: Background: The ubiquitin regulatory X (UBX) domain-containing proteins (UBXNs) are putative adaptors for ubiquitin ligases and valosin-containing protein; however, their in vivo physiological functions remain poorly characterised. We recently showed that UBXN3B is essential for activating innate immunity to DNA viruses and controlling DNA/RNA virus infection. Herein, we investigate its role in adaptive immunity. Methods: We evaluated the antibody responses to multiple viruses and pathogenesis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and influenza in tamoxifen-inducible global and constitutive B cell-specific Ubxn3b knockout mice; quantified various immune populations, B lineage progenitors/precursors, B cell receptor (BCR) signalling and apoptosis by flow cytometry, immunoblotting and immunofluorescence microscopy. We also performed bone marrow transfer, single-cell and bulk RNA sequencing. Findings: Both global and B cell-specific Ubxn3b knockout mice present a marked reduction in small precursor B-II (>60%), immature (>70%) and mature B (>95%) cell numbers. Transfer of wildtype bone marrow to irradiated global Ubxn3b knockouts restores normal B lymphopoiesis, while reverse transplantation does not. The mature B population shrinks rapidly with apoptosis and higher pro and activated caspase-3 protein levels were observed following induction of Ubxn3b knockout. Mechanistically, Ubxn3b deficiency leads to impaired pre-BCR signalling and cell cycle arrest. Ubxn3b knockout mice are highly vulnerable to respiratory viruses, with increased viral loads and prolonged immunopathology in the lung, and reduced production of virus-specific IgM/IgG. Interpretation: UBXN3B is essential for B lymphopoiesis by maintaining constitutive pre-BCR signalling and cell survival in a cell-intrinsic manner. Funding: United States National Institutes of Health grants, R01AI132526 and R21AI155820.

Platelet-derived growth factor receptor β (PDGFRβ) plays a crucial role in murine haematopoiesis. Baicalein (BAI), a naturally occurring flavonoid, can alleviate disease damage through anti-oxidative, anti-apoptotic, and anti-inflammatory mechanisms. However, whether BAI attenuates oxidative damage in murine haematopoietic cells by PDGFRβ remains unexplored. In this study, we utilized a tert-butyl hydroperoxide (TBHP)-induced BaF3 cell injury model and an ionising radiation (IR)-induced mice injury model to investigate the impact of the presence or absence of PDGFRβ on the pharmacological effects of BAI. In addition, the BAI-PDGFRβ interaction was characterized by molecular docking and dynamics simulations. The results show that a specific concentration of BAI led to increased cell viability, reduced reactive oxygen species (ROS) content, upregulated nuclear factor erythroid 2-related factor 2 (NRF2) expression, and its downstream target genes heme oxygenase 1 (HO-1) and NAD(P)H Quinone Dehydrogenase 1 (NQO1), and activated protein kinase B (AKT) pathway in cells expressing PDGFRβ plasmid and experiencing damage. Similarly, BAI elevated lineage−Sca1+cKIT+ (LSK) cell proportion, promoted haematopoietic restoration, enhanced NRF2-mediated antioxidant response in PDGFRβ+/+ mice. However, despite BAI usage, PDGFRβ knockout mice (PDGFRβ−/−) showed lower LSK proportion and less antioxidant capacity than the total body irradiation (TBI) group. Furthermore, we demonstrated an interaction between BAI and PDGFRβ at the molecular level. Collectively, our results indicate that BAI attenuates oxidative stress injury and helps promote haematopoietic cell recovery through regulation of PDGFRβ.

Early organogenesis represents a key step in animal development, during which pluripotent cells diversify to initiate organ formation. Here, we sampled 300,000 single-cell transcriptomes from mouse embryos between E8.5 and E9.5 in 6-h intervals and combined this new dataset with our previous atlas (E6.5-E8.5) to produce a densely sampled timecourse of >400,000 cells from early gastrulation to organogenesis. Computational lineage reconstruction identified complex waves of blood and endothelial development, including a new programme for somite-derived endothelium. We also dissected the E7.5 primitive streak into four adjacent regions, performed scRNA-seq and predicted cell fates computationally. Finally, we defined developmental state/fate relationships by combining orthotopic grafting, microscopic analysis and scRNA-seq to transcriptionally determine cell fates of grafted primitive streak regions after 24 h of in vitro embryo culture. Experimentally determined fate outcomes were in good agreement with computationally predicted fates, demonstrating how classical grafting experiments can be revisited to establish high-resolution cell state/fate relationships. Such interdisciplinary approaches will benefit future studies in developmental biology and guide the in vitro production of cells for organ regeneration and repair. [ABSTRACT FROM AUTHOR]

In vertebrates, the central nervous system (CNS) harbours various immune cells, including parenchymal microglia, perivascular macrophages and dendritic cells, which act in coordination to establish an immune network to regulate neurogenesis and neural function, and to maintain the homeostasis of the CNS. Recent single cell transcriptomic profiling has revealed that the adult zebrafish CNS contains microglia, plasmacytoid dendritic cells (pDCs) and two conventional dendritic cells (cDCs), ccl35+ cDCs and cnn3a+cDCs. However, how these distinct myeloid cells are established in the adult zebrafish CNS remains incompletely defined. Here, we show that the Inhibitor of DNA binding 2a (Id2a) is essential for the development of pDCs and cDCs but is dispensable for the formation of microglia, whereas the Basic leucine zipper transcription factor ATF-like 3 (Batf3) acts downstream of id2a and is required exclusively for the formation of the cnn3a+ cDC subset. In contrast, the Zinc finger E-box-binding homeobox 2a (Zeb2a) promotes the expansion of microglia and inhibits the DC specification, possibly through repressing id2a expression. Our study unravels the genetic networks that govern the development of microglia and brainassociated DCs in the zebrafish CNS. [ABSTRACT FROM AUTHOR]

The micro‐environment plays a critical role in haematopoietic stem cell (HSC) development, self‐renewal, differentiation and maintenance by providing a supportive cellular framework and essential molecular cues to sustain homeostasis. In ageing and development of age‐related clonal haematopoiesis, the combined contribution of intrinsic alterations in haematopoietic stem cells and their surrounding micro‐environment can promote myeloid skewing and release of pro‐inflammatory cytokines. A pro‐inflammatory micro‐environment is a common feature in the initiation and sustenance of several myeloid malignancies. Furthermore, remodelling of the micro‐environment is recognized to potentiate the survival of malignant over normal cells. This review explores micro‐environmental interactions in the haematopoietic system of adults, especially how the bone marrow micro‐environment is impacted by ageing, the onset of age‐related clonal haematopoiesis and the development of myeloid malignancies. In addition, we also discuss the possible role age‐related clonal haematopoiesis and chronic inflammatory conditions play in altering the bone marrow micro‐environment dynamics. Finally, we explore the importance of in vitro models that accurately mimic different aspects of the bone marrow micro‐environment in order to study normal and malignant haematopoiesis. LINKED ARTICLES: This article is part of a themed issue on Cancer Microenvironment and Pharmacological Interventions. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v181.2/issuetoc [ABSTRACT FROM AUTHOR]

The emergence of definitive human haematopoietic stem cells (HSCs) from Carnegie Stage (CS) 14 to CS17 in the aorta-gonad-mesonephros (AGM) region is a tightly regulated process. Previously, we conducted spatial transcriptomic analysis of the human AGM region at the end of this period (CS16/CS17) and identified secreted factors involved in HSC development. Here, we extend ouranalysis to investigate the progression of dorso-ventral polarised signalling around the dorsal aorta over the entire period of HSC emergence. Our results reveal a dramatic increase in ventral signalling complexity from the CS13-CS14 transition, coinciding with the first appearance of definitive HSCs. We further observe stage-specific changes in signalling up to CS17, which may underpin the step-wise maturation of HSCs described in the mouse model. The data-rich resource is also presented in an online interface enabling in silico analysis of molecular interactions between spatially defined domains of the AGM region. This resource will be of particular interest for researchers studying mechanisms underlying human HSC development as well as those developing in vitro methods for the generation of clinically relevant HSCs from pluripotent stem cells. [ABSTRACT FROM AUTHOR]

During inflammation, haematopoietic stem cells (HSCs) in the bone marrow (BM) and periphery rapidly expand and preferentially differentiate into myeloid cells that mediate innate immune responses. HSCs can be directed into quiescence or differentiation by sensing alterations to the haematopoietic niche, including cytokines, chemokines, and pathogen‐derived products. Most studies attempting to identify the mechanisms of haematopoiesis have focused on bacterial and viral infections. From intracellular protozoan infections to large multicellular worms, parasites are a global health burden and represent major immunological challenges that remain poorly defined in the context of haematopoiesis. Immune responses to parasites vary drastically, and parasites have developed sophisticated immunomodulatory mechanisms that allow development of chronic infections. Recent advances in imaging, genomic sequencing, and mouse models have shed new light on how parasites induce unique forms of emergency haematopoiesis. In addition, parasites can modify the haematopoiesis in the BM and periphery to improve their survival in the host. Parasites can also induce long‐lasting modifications to HSCs, altering future immune responses to infection, inflammation or transplantation, a term sometimes referred to as central trained immunity. In this review, we highlight the current understanding of parasite‐induced haematopoiesis and how parasites target this process to promote chronic infections. [ABSTRACT FROM AUTHOR]

The importance of metabolism to cancer has increasingly been recognised and this is particularly the case for leukaemia. This has opened the possibility of targeting dysregulated metabolism with the aim of increasing the effectiveness of current therapies, some of which are anti-metabolites. One key challenge to be addressed is avoiding negative side effects due to shared metabolic dependencies between leukaemic and normal cells. This Mini Review will discuss how our understanding of wide-ranging effects of metabolism is continuing to evolve thanks to recent discoveries, as well as how metabolism can both directly and indirectly affect leukaemia cell functions. This includes introducing how metabolism is compartmentalised at levels ranging from organelle to whole body as well as how the metabolome can modify other ‘Omes.’ This Mini Review also places a focus on the overlay in metabolic demands of normal haematopoietic and immune cells. Finally, how therapies targeting metabolic processes have already delivered success, as well as the promise of new therapies targeting metabolism that are currently being investigated in clinical trials, will also be discussed.

The parasitic worm-derived immunomodulator, ES-62 rescues defective levels of IL-10-producing regulatory B cells (Bregs) and suppresses chronic Th1/Th17-driven inflammation to protect against joint destruction in the mouse collagen-induced arthritis (CIA) model of rheumatoid arthritis. Such autoimmune arthritis is also associated with dysbiosis of the gut microbiota and disruption of intestinal barrier integrity. We recently further exploited the CIA model to show that ES-62’s prevention of joint destruction is associated with protection of intestinal barrier integrity and normalization of the gut microbiota, thereby suppressing the gut pathology that precedes the onset of autoimmunity and joint damage in CIA-mice. As the status of the gut microbiota impacts on immune responses by influencing haematopoiesis, we have therefore investigated whether ES-62 harnesses the homeostatic mechanisms regulating this gut-bone marrow (BM) axis to resolve the chronic inflammation promoting autoimmunity and joint destruction in CIA. Reflecting this, ES-62 was found to counteract the BM myeloid/lymphoid bias typically associated with chronic inflammation and infection. This was achieved primarily by ES-62 acting to maintain the levels of lymphoid lineages (B220+ and CD3+ cells) observed in naïve, healthy mice but lost from the BM of CIA-mice. Moreover, ES-62’s ability to prevent bone-destroying osteoclastogenesis was found to be associated with its suppression of CIA-induced upregulation of osteoclast progenitors (OCPs) in the BM. Critically, and supporting ES-62’s targeting of the gut-BM axis, this rewiring of inflammatory haematopoiesis was lost in mice with a depleted microbiome. Underlining the importance of ES-62’s actions in restoring steady-state haematopoiesis, the BM levels of B and T lymphoid cells were shown to be inversely correlated, whilst the levels of OCPs positively correlated, with the severity of joint damage in CIA-mice.

Protein tyrosine phosphatase 1B (PTP1B) is a non-receptor tyrosine phosphatase best known for its role in regulating insulin and leptin signalling. Recently, knowledge on the role of PTP1B as a major regulator of multiple signalling pathways involved in cell growth, proliferation, viability and metabolism has expanded, and PTP1B is recognised as a therapeutic target in several human disorders, including diabetes, obesity, cardiovascular diseases and hematopoietic malignancies. The function of PTP1B in the immune system was largely overlooked until it was discovered that PTP1B negatively regulates the Janus kinase—a signal transducer and activator of the transcription (JAK/STAT) signalling pathway, which plays a significant role in modulating immune responses. PTP1B is now known to determine the magnitude of many signalling pathways that drive immune cell activation and function. As such, PTP1B inhibitors are being developed and tested in the context of inflammation and autoimmune diseases. Here, we provide an up-to-date summary of the molecular role of PTP1B in regulating immune cell function and how targeting its expression and/or activity has the potential to change the outcomes of immune-mediated and inflammatory disorders.

The formation of blood cells, haematopoiesis, is regulated by a family of extracellular glycosylated proteins called haematopoietic growth factors. Over the past four decades their identification, purification and cloning has led to the development of recombinant haematopoietic growth factors for medicinal use. These growth factors play a valuable role in treatment of a variety of childhood conditions, ranging from anaemia of chronic kidney disease through to rare congenital bone marrow failure syndromes. Erythropoietin and granulocyte-colony stimulating factor are the two recombinant haematopoietic growth factors in most widespread use in paediatrics and paediatricians should be aware of their indications and their side effects when managing patients. This review articles gives an overview of the major recombinant haematopoietic growth factors used in children, their indications, and their toxicities. [ABSTRACT FROM AUTHOR]

Over the last decade, the concept of Clonal haematopoiesis of undetermined potential (CHIP) has emerged. Low frequency somatic mutations in hematopoietic cells can occur with age and might allow formation of clones in individuals with no characterized haematological pathology. These CHIP mutations are associated with an increased risk of cancer or atherothrombosis, and their prevalence are more and more studied in pathologies with an inflammatory component. In our study, we analysed, by next generation sequencing, the prevalence of CHIP mutation in 94 patients with deep venous thrombosis (DVT), distinguishing two clinical phenotypes: provoked distal and non-provoked proximal DVTs. We show that there is no difference in CHIP prevalence between these two groups, nor with a matched-aged control group. The number of mutation per patients and the affected genes remain also the same between the three groups. Consequently and despite the relative small number of patients in each cohort, it seems that CHIP is not a strong concern in venous thromboembolism. [ABSTRACT FROM AUTHOR]

Dysregulation of the bone marrow niche resulting from the direct and indirect effects of HIV infection contributes to haematological abnormalities observed in HIV patients. The bone marrow niche is a complex, multicellular environment which functions primarily in the maintenance of haematopoietic stem/progenitor cells (HSPCs). These adult stem cells are responsible for replacing blood and immune cells over the course of a lifetime. Cells of the bone marrow niche support HSPCs and help to orchestrate the quiescence, self-renewal and differentiation of HSPCs through chemical and molecular signals and cell-cell interactions. This narrative review discusses the HIV-associated dysregulation of the bone marrow niche, as well as the susceptibility of HSPCs to infection by HIV. [ABSTRACT FROM AUTHOR]

The haematopoietic system has a highly regulated and complex structure in which cells are organized to successfully create and maintain new blood cells. It is known that feedback regulation is crucial to tightly control this system, but the specific mechanisms by which control is exerted are not completely understood. In this work, we aim to uncover the underlying mechanisms in haematopoiesis by conducting perturbation experiments, where animal subjects are exposed to an external agent in order to observe the system response and evolution. We have developed a novel Bayesian hierarchical framework for optimal design of perturbation experiments and proper analysis of the data collected. We use a deterministic model that accounts for feedback and feedforward regulation on cell division rates and self-renewal probabilities. A significant obstacle is that the experimental data are not longitudinal, rather each data point corresponds to a different animal. We overcome this difficulty by modelling the unobserved cellular levels as latent variables. We then use principles of Bayesian experimental design to optimally distribute time points at which the haematopoietic cells are quantified. We evaluate our approach using synthetic and real experimental data and show that an optimal design can lead to better estimates of model parameters.

PurposeRepairing the irradiation-induced osteogenic differentiation injury of bone marrow mesenchymal stem cells (BM-MSCs) is beneficial to recovering haematopoiesis injury in radiotherapy; however, its mechanism is elusive. Our study aimed to help meet the needs of understanding the effects of radiotherapy on BM-MSC osteogenic potential.Methods and materialsBalb/c mice and the BM-MSCs were used to evaluate the irradiation-induced osteogenic differentiation injury in vivo. The cellular and molecular characterization were applied to determine the mechanism for recovery of irradiation-derived haematopoiesis injuries.ResultsWe report a functional role of IL-12 in acute irradiation hematopoietic injury recovery and intend to dissect the possible mechanisms through BM-MSC, other than the direct effect of IL-12 on hematopoietic stem and progenitor cells (HSPCs). Specifically, we show that early use of IL-12 enhanced the osteogenic differentiation of BM-MSCs through IL-12Rβ1/TYK2/STAT3 signaling; furthermore, IL-12 induced osteogenesis facilitated bone formation and irradiation hematopoiesis recovery when transplanted BM-MSCs in the femur of Balb/c mice. For the mechanism of action, we found that IL-12 receptor beta 1 (IL-12Rβ1) expression of irradiated BM-MSCs was upregulated rapidly, coincidentally consistent with early use of IL-12 induced osteogenic differentiation enhancement. IL-12Rβ1 and tyrosine kinase 2 gene (Tyk2) silencing experiments and phosphotyrosine of signal transducer and activator of transcription 3 (p-STAT3) suppression experiments indicated the IL-12Rβ1/TYK2/STAT3 signaling was essential in IL-12-induced osteogenic differentiation enhancement of BM-MSCs.ConclusionThese findings suggested that IL-12 may exert BM-MSCs-based hematopoietic recovery by repairing osteogenic differentiation abilities damages through IL-12Rβ1/TYK2/STAT3 signaling pathway post-irradiation.

Summary: The concept of cell fate relates to the future identity of a cell, and its daughters, which is obtained via cell differentiation and division. Understanding, predicting, and manipulating cell fate has been a long-sought goal of developmental and regenerative biology. Recent insights obtained from single-cell genomic and integrative lineage-tracing approaches have further aided to identify molecular features predictive of cell fate. In this perspective, we discuss these approaches with a focus on theoretical concepts and future directions of the field to dissect molecular mechanisms underlying cell fate.

Monocytes are heterogeneous innate effector leukocytes generated in the bone marrow and released into circulation in a CCR2-dependent manner. During infection or inflammation, myelopoiesis is modulated to rapidly meet the demand for more effector cells. Danger signals from peripheral tissues can influence this process. Herein we demonstrate that repetitive TLR7 stimulation via the epithelial barriers drove a potent emergency bone marrow monocyte response in mice. This process was unique to TLR7 activation and occurred independently of the canonical CCR2 and CX3CR1 axes or prototypical cytokines. The monocytes egressing the bone marrow had an immature Ly6C-high profile and differentiated into vascular Ly6C-low monocytes and tissue macrophages in multiple organs. They displayed a blunted cytokine response to further TLR7 stimulation and reduced lung viral load after RSV and influenza virus infection. These data provide insights into the emergency myelopoiesis likely to occur in response to the encounter of single-stranded RNA viruses at barrier sites.

Dysregulation of the bone marrow niche resulting from the direct and indirect effects of HIV infection contributes to haematological abnormalities observed in HIV patients. The bone marrow niche is a complex, multicellular environment which functions primarily in the maintenance of haematopoietic stem/progenitor cells (HSPCs). These adult stem cells are responsible for replacing blood and immune cells over the course of a lifetime. Cells of the bone marrow niche support HSPCs and help to orchestrate the quiescence, self-renewal and differentiation of HSPCs through chemical and molecular signals and cell-cell interactions. This narrative review discusses the HIV-associated dysregulation of the bone marrow niche, as well as the susceptibility of HSPCs to infection by HIV.

Cytotoxic cancer therapy often results in dose-limiting haematotoxic side effects. Predicting an individual's risk is a major objective in precision medicine of cancer treatment. In this regard, patient heterogeneity presents a significant challenge. In this paper, we explore the use of hypothesis-free machine learning models based on recurrent nonlinear auto-regressive networks with exogenous inputs (NARX) as an approach to achieve this goal. Also, we propose a knowledge transfer approach to ameliorate the issue of sparse individual data, which typically hampers learning of individual networks. We demonstrate the feasibility of our approach based on a virtual patient population generated using a semi-mechanistic model of haematopoiesis and imposing different cytotoxic therapy scenarios on it. Employing different techniques of model optimisation, we derive robust and parsimonious individual networks with good generalisation performances. Moreover, we analyse in detail possible factors influencing the generalisation performance. Results suggest that our transfer learning approach using NARX networks can provide robust predictions of individual patient's response to treatment. As a practical perspective, we apply our approach to individual time series data of two patients with non-Hodgkin's lymphoma.

The Haematopoietically expressed homeobox transcription factor (Hhex) is a transcriptional repressor that is of fundamental importance across species, as evident by its evolutionary conservation spanning fish, amphibians, birds, mice and humans. Indeed, Hhex maintains its vital functions throughout the lifespan of the organism, beginning in the oocyte, through fundamental stages of embryogenesis in the foregut endoderm. The endodermal development driven by Hhex gives rise to endocrine organs such as the pancreas in a process which is likely linked to its role as a risk factor in diabetes and pancreatic disorders. Hhex is also required for the normal development of the bile duct and liver, the latter also importantly being the initial site of haematopoiesis. These haematopoietic origins are governed by Hhex, leading to its crucial later roles in definitive haematopoietic stem cell (HSC) self-renewal, lymphopoiesis and haematological malignancy. Hhex is also necessary for the developing forebrain and thyroid gland, with this reliance on Hhex evident in its role in endocrine disorders later in life including a potential role in Alzheimer's disease. Thus, the roles of Hhex in embryological development throughout evolution appear to be linked to its later roles in a variety of disease processes. [ABSTRACT FROM AUTHOR]

The haematopoietic system plays an essential role in our health and survival. It is comprised of a range of mature blood and immune cell types, including oxygen-carrying erythrocytes, platelet-producing megakaryocytes and infection-fighting myeloid and lymphoid cells. Self-renewing multipotent haematopoietic stem cells (HSCs) and a range of intermediate haematopoietic progenitor cell types differentiate into these mature cell types to continuously support haematopoietic system homeostasis throughout life. This process of haematopoiesis is tightly regulated in vivo and primarily takes place in the bone marrow. Over the years, a range of in vitro culture systems have been developed, either to expand haematopoietic stem and progenitor cells or to differentiate them into the various haematopoietic lineages, based on the use of recombinant cytokines, co-culture systems and/or small molecules. These approaches provide important tractable models to study human haematopoiesis in vitro. Additionally, haematopoietic cell culture systems are being developed and clinical tested as a source of cell products for transplantation and transfusion medicine. This review discusses the in vitro culture protocols for human HSC expansion and differentiation, and summarises the key factors involved in these biological processes. [ABSTRACT FROM AUTHOR]

The Haematopoietically expressed homeobox transcription factor (Hhex) is a transcriptional repressor that is of fundamental importance across species, as evident by its evolutionary conservation spanning fish, amphibians, birds, mice and humans. Indeed, Hhex maintains its vital functions throughout the lifespan of the organism, beginning in the oocyte, through fundamental stages of embryogenesis in the foregut endoderm. The endodermal development driven by Hhex gives rise to endocrine organs such as the pancreas in a process which is likely linked to its role as a risk factor in diabetes and pancreatic disorders. Hhex is also required for the normal development of the bile duct and liver, the latter also importantly being the initial site of haematopoiesis. These haematopoietic origins are governed by Hhex, leading to its crucial later roles in definitive haematopoietic stem cell (HSC) self-renewal, lymphopoiesis and haematological malignancy. Hhex is also necessary for the developing forebrain and thyroid gland, with this reliance on Hhex evident in its role in endocrine disorders later in life including a potential role in Alzheimer’s disease. Thus, the roles of Hhex in embryological development throughout evolution appear to be linked to its later roles in a variety of disease processes.

All-trans retinoic acid (ATRA) activation of retinoic acid receptors (RARs) is crucial to an organism’s proper development as established by findings for mouse foetuses from dams fed a vitamin A-deficient diet. ATRA influences decision-making by embryonic stem (ES) cells for differentiation including lineage fate. From studies of knockout mice, RARα and RARγ regulate haematopoiesis whereby active RARα modulates the frequency of decision-making for myeloid differentiation, but is not essential for myelopoiesis, and active RARγ supports stem cell self-renewal and maintenance. From studies of zebrafish embryo development, active RARγ plays a negative role in stem cell decision-making for differentiation whereby, in the absence of exogenous ATRA, selective agonism of RARγ disrupted stem cell decision-making for differentiation patterning for development. From transactivation studies, 0.24 nM ATRA transactivated RARγ and 19.3 nM (80-fold more) was needed to transactivate RARα. Therefore, the dose of ATRA that cells are exposed to in vivo, from gradients created by cells that synthesize and metabolize, is important to RARγ versus RARα and RARγ activation and balancing of the involvements in modulating stem cell maintenance versus decision-making for differentiation. RARγ activation favours stemness whereas concomitant or temporal activation of RARγ and RARα favours differentiation. Crosstalk with signalling events that are provoked by membrane receptors is also important.

Studies over the past decade have shown how stem cells representing embryonic and extra-embryonic tissues of the mouse can self-assemble in the culture dish to recapitulate an astonishing part of early embryonic development. A systematic analysis has demonstrated how pluripotent embryonic stem cells can be induced to behave like the implanting epiblast; how they can interact with trophectoderm stem cells to form a patterned structure resembling the implanting embryo prior to gastrulation; and how the third stem cell type—extra-embryonic endoderm cells—can be incorporated to generate structures that undergo the cell movements and gene expression patterns of gastrulation. Moreover, such stem cell-derived embryo models can proceed to neurulation and establish progenitors for all parts of the brain and neural tube, somites, beating heart structures and gut tube. They develop within extra-embryonic yolk sacs that initiate haematopoiesis. Here we trace this journey of discovery.

DEAD‐box Helicase 41 (DDX41) is a member of the DExD/H‐box helicase family that has a variety of cellular functions. Of note, germline and somatic mutations in the DDX41 gene are prevalently found in myeloid malignancies. Here, we present a comprehensive and analytic review covering relevant clinical, translational and basic science findings on DDX41. We first describe the initial characterisation of DDX41 mutations in patients affected by myelodysplastic syndromes, their associated clinical characteristics, and current treatment modalities. We then cover the known cellular functions of DDX41, spanning from its discovery in Drosophila as a neuroregulator through its more recently described roles in inflammatory signalling, R‐loop metabolism and snoRNA processing. We end with a summary of the identified basic functions of DDX41 that when perturbed may contribute to the underlying pathology of haematologic neoplasms. [ABSTRACT FROM AUTHOR]

Haematopoietic stem cell (HSC) self-renewal is a process that is essential for the development and homeostasis of the blood system. Self-renewal expansion divisions, which create two daughter HSCs from a single parent HSC, can be harnessed to create large numbers of HSCs for a wide range of cell and gene therapies, but the same process is also a driver of the abnormal expansion of HSCs in diseases such as cancer. Although HSCs are first produced during early embryonic development, the key stage and location where they undergo maximal expansion is in the foetal liver, making this tissue a rich source of data for deciphering the molecules driving HSC self-renewal. Another equally interesting stage occurs post-birth, several weeks after HSCs have migrated to the bone marrow, when HSCs undergo a developmental switch and adopt a more dormant state. Characterising these transition points during development is key, both for understanding the evolution of haematological malignancies and for developing methods to promote HSC expansion. In this Spotlight article, we provide an overview of some of the key insights that studying HSC development have brought to the fields of HSC expansion and translational medicine, many of which set the stage for the next big breakthroughs in the field. [ABSTRACT FROM AUTHOR]

Budi Santosa,1 Ali Rosidi,2 Herlisa Anggraini,3 Zahra Maharani Latrobdiba,2 Fitriani Nur Damayanti,4 Heru Santoso Wahito Nugroho5 1Department of Medical Laboratory Science, Universitas Muhammadiyah Semarang, Semarang, Indonesia; 2Department of Nutrition, Faculty of Nursing and Health Science, Universitas Muhammadiyah Semarang, Semarang, Indonesia; 3Department of Medical Laboratory Technology, Faculty of Nursing and Health Science, Universitas Muhammadiyah Semarang, Semarang, Indonesia; 4Department of Midwifery, Faculty of Nursing and Health Science, Universitas Muhammadiyah Semarang, Semarang, Indonesia; 5Department of Health, Poltekkes Kemenkes Surabaya, Surabaya, IndonesiaCorrespondence: Budi Santosa, Department of Medical Laboratory Science, Universitas Muhammadiyah Semarang, Jl. Kedungmundu Raya 18, Semarang, 50273, Central Java, Indonesia Email budisantosa@unimus.ac.idIntroduction: Automotive body painters are at risk of excessive lead exposure that may compromise their health. This study examined the protective effects of masks against lead exposure and its correlation with blood profile of automotive body painters at Ligu district, Semarang, Indonesia.Material and Methods: This cross-sectional study included 61 painters at Ligu district, Semarang, Indonesia (mean age 45 years, 100% male). Mask use was categorized into “frequent” and “infrequent”. Blood samples were taken to measure lead exposure and haematological parameters (haemoglobin/HGB, erythrocytes/RBC, haematocrit/HCT, mean corpuscular haemoglobin/MCH, mean corpuscular volume/MCV, mean corpuscular haemoglobin concentration/MCHC). Effectivity of mask use against lead exposure was analysed with Fisher’s exact test, while lead exposure and haematopoietic parameters were evaluated with Pearson’s correlation tests.Results: There were 26 automotive painters (42.6%) classified as unfrequent mask users, and all of them had high blood lead levels. Most haematopoiesis parameters were in normal range. Workers with infrequent mask use were 1.269 more likely to be exposed to lead compared to those with frequent mask use (CI 95%, 1.082– 1.552). Significant associations were found between lead exposure and RBC (p=0.0, r=− 0.53), HGB (p=0, r=− 0.61), and HCT (p=0.00, r=− 0.61). No significant correlations were observed between lead exposure and MCV, MCH, MCHC.Conclusion: Lead exposure was significantly associated with haematological parameters RBC, HGB, and HCT, confirming the effects of prolonged exposure on blood profile. However, mask use provided significant protection against lead exposure in automotive body painters and should be an obligatory gear for workers.Keywords: mask, lead, haematopoiesis, automotive painters

Abstract Background Myelodysplastic syndromes (MDS) are a group of heterogeneous myeloid clonal disorders characterized by ineffective haematopoiesis and immune deregulation. Emerging evidence has shown the effect of bone marrow (BM) endothelial progenitor cells (EPCs) in regulating haematopoiesis and immune balance. However, the number and functions of BM EPCs in patients with different stages of MDS remain largely unknown. Methods Patients with MDS (N = 30), de novo acute myeloid leukaemia (AML) (N = 15), and healthy donors (HDs) (N = 15) were enrolled. MDS patients were divided into lower-risk MDS (N = 15) and higher-risk MDS (N = 15) groups according to the dichotomization of the Revised International Prognostic Scoring System. Flow cytometry was performed to analyse the number of BM EPCs. Tube formation and migration assays were performed to evaluate the functions of BM EPCs. In order to assess the gene expression profiles of BM EPCs, RNA sequencing (RNA-seq) were performed. BM EPC supporting abilities of haematopoietic stem cells (HSCs), leukaemia cells and T cells were assessed by in vitro coculture experiments. Results Increased but dysfunctional BM EPCs were found in MDS patients compared with HDs, especially in patients with higher-risk MDS. RNA-seq indicated the progressive change and differences of haematopoiesis- and immune-related pathways and genes in MDS BM EPCs. In vitro coculture experiments verified that BM EPCs from HDs, lower-risk MDS, and higher-risk MDS to AML exhibited a progressively decreased ability to support HSCs, manifested as elevated apoptosis rates and intracellular reactive oxygen species (ROS) levels and decreased colony-forming unit plating efficiencies of HSCs. Moreover, BM EPCs from higher-risk MDS patients demonstrated an increased ability to support leukaemia cells, characterized by increased proliferation, leukaemia colony-forming unit plating efficiencies, decreased apoptosis rates and apoptosis-related genes. Furthermore, BM EPCs induced T cell differentiation towards more immune-tolerant cells in higher-risk MDS patients in vitro. In addition, the levels of intracellular ROS and the apoptosis ratios were increased in BM EPCs from MDS patients, especially in higher-risk MDS patients, which may be therapeutic candidates for MDS patients. Conclusion Our results suggest that dysfunctional BM EPCs are involved in MDS patients, which indicates that improving haematopoiesis supporting ability and immuneregulation ability of BM EPCs may represent a promising therapeutic approach for MDS patients.

Platelet-derived growth factor receptor β (PDGFRβ) plays a crucial role in murine haematopoiesis. Baicalein (BAI), a naturally occurring flavonoid, can alleviate disease damage through anti-oxidative, anti-apoptotic, and anti-inflammatory mechanisms. However, whether BAI attenuates oxidative damage in murine haematopoietic cells by PDGFRβ remains unexplored. In this study, we utilized a tert -butyl hydroperoxide (TBHP)-induced BaF3 cell injury model and an ionising radiation (IR)-induced mice injury model to investigate the impact of the presence or absence of PDGFRβ on the pharmacological effects of BAI. In addition, the BAI-PDGFRβ interaction was characterized by molecular docking and dynamics simulations. The results show that a specific concentration of BAI led to increased cell viability, reduced reactive oxygen species (ROS) content, upregulated nuclear factor erythroid 2-related factor 2 (NRF2) expression, and its downstream target genes heme oxygenase 1 (HO-1) and NAD(P)H Quinone Dehydrogenase 1 (NQO1), and activated protein kinase B (AKT) pathway in cells expressing PDGFRβ plasmid and experiencing damage. Similarly, BAI elevated lineage−Sca1+cKIT+ (LSK) cell proportion, promoted haematopoietic restoration, enhanced NRF2-mediated antioxidant response in PDGFRβ+/+ mice. However, despite BAI usage, PDGFRβ knockout mice (PDGFRβ−/−) showed lower LSK proportion and less antioxidant capacity than the total body irradiation (TBI) group. Furthermore, we demonstrated an interaction between BAI and PDGFRβ at the molecular level. Collectively, our results indicate that BAI attenuates oxidative stress injury and helps promote haematopoietic cell recovery through regulation of PDGFRβ. • Baicalein attenuates haematopoietic harm caused by oxidative stress. • Baicalein enhances the NRF2 antioxidant pathway through PDGFRβ. • Baicalein interacts with PDGFRβ. [ABSTRACT FROM AUTHOR]