EphrinB2 regulates the emergence of a hemogenic endothelium from the aorta

Modulation of WNT, Activin/Nodal, and MAPK Signaling Pathways Increases Arterial Hemogenic Endothelium and Hematopoietic Stem/Progenitor Cell Formation During Human iPSC Differentiation

Several differentiation protocols enable the emergence of hematopoietic stem and progenitor cells (HSPCs) from human-induced pluripotent stem cells (iPSCs), yet optimized schemes to promote the development of HSPCs with self-renewal, multilineage differentiation, and engraftment potential are lacking. To improve human iPSC differentiation methods, we modulated WNT, Activin/Nodal, and MAPK signaling pathways by stage-specific addition of small-molecule regulators CHIR99021, SB431542, and LY294002, respectively, and measured the impact on hematoendothelial formation in culture. Manipulation of these pathways provided a synergy sufficient to enhance formation of arterial hemogenic endothelium (HE) relative to control culture conditions. Importantly, this approach significantly increased production of human HSPCs with self-renewal and multilineage differentiation properties, as well as phenotypic and molecular evidence of progressive maturation in culture. Together, these findings provide a stepwise improvement in human iPSC differentiation protocols and offer a framework for manipulating intrinsic cellular cues to enable de novo generation of human HSPCs with functionality in vivo.

Modulation of WNT, Activin/Nodal and MAPK Signaling Pathways Increases Arterial Hemogenic Endothelium and Hematopoietic Stem/Progenitor Cell Formation During Human iPSC Differentiation

Several differentiation protocols enable the emergence of hematopoietic stem and progenitor cells (HSPCs) from human induced pluripotent stem cells (iPSCs), yet optimized schemes to promote the development of HSPCs with self-renewal, multilineage differentiation and engraftment potential are lacking. To improve human iPSC differentiation methods, we modulated WNT, Activin/Nodal and MAPK signaling pathways by stage-specific addition of small molecule regulators CHIR99021, SB431542 and LY294002, respectively, and measured the impact on hematoendothelial formation in culture. Manipulation of these pathways provided a synergy sufficient to enhance formation of arterial hemogenic endothelium (HE) relative to control culture conditions. Importantly, this approach significantly increased production of human HSPCs with self-renewal and multilineage differentiation properties, as well as phenotypic and molecular evidence of progressive maturation in culture. Together, these findings provide a stepwise improvement in human iPSC differentiation protocols and offer a framework for manipulating intrinsic cellular cues to enable de novo generation of human HSPCs with functionality in vivo .

Significance Statement

The ability to produce functional HSPCs by differentiation of human iPSCs ex vivo holds enormous potential for cellular therapy of human blood disorders. However, obstacles still thwart translation of this approach to the clinic. In keeping with the prevailing arterial-specification model, we demonstrate that concurrent modulation of WNT, Activin/Nodal and MAPK signaling pathways by stage-specific addition of small molecules during human iPSC differentiation provides a synergy sufficient to promote arterialization of HE and production of HSPCs with features of definitive hematopoiesis. This simple differentiation scheme provides a unique tool for disease modeling, in vitro drug screening and eventual cell therapies.

Berberine as a potential agent for breast cancer therapy

Breast cancer (BC) is a common malignancy that mainly occurred in women and it has become the most diagnosed cancer annually since 2020. Berberine (BBR), an alkaloid extracted from the Berberidacea family, has been found with broad pharmacological bioactivities including anti-inflammatory, anti-diabetic, anti-hypertensive, anti-obesity, antidepressant, and anticancer effects. Mounting evidence shows that BBR is a safe and effective agent with good anticancer activity against BC. However, its detailed underlying mechanism in BC treatment remains unclear. Here, we will provide the evidence for BBR in BC therapy and summarize its potential mechanisms. This review briefly introduces the source, metabolism, and biological function of BBR and emphasizes the therapeutic effects of BBR against BC via directly interacting with effector proteins, transcriptional regulatory elements, miRNA, and several BBR-mediated signaling pathways. Moreover, the novel BBR-based therapeutic strategies against BC improve biocompatibility and water solubility, and the efficacies of BBR are also briefly discussed. Finally, the status of BBR in BC treatment and future research directions is also prospected.

Integrative epigenomic and transcriptomic analysis reveals the requirement of JUNB for hematopoietic fate induction

Human pluripotent stem cell differentiation towards hematopoietic progenitor cell can serve as an in vitro model for human embryonic hematopoiesis, but the dynamic change of epigenome and transcriptome remains elusive. Here, we systematically profile the chromatin accessibility, H3K4me3 and H3K27me3 modifications, and the transcriptome of intermediate progenitors during hematopoietic progenitor cell differentiation in vitro. The integrative analyses reveal sequential opening-up of regions for the binding of hematopoietic transcription factors and stepwise epigenetic reprogramming of bivalent genes. Single-cell analysis of cells undergoing the endothelial-to-hematopoietic transition and comparison with in vivo hemogenic endothelial cells reveal important features of in vitro and in vivo hematopoiesis. We find that JUNB is an essential regulator for hemogenic endothelium specialization and endothelial-to-hematopoietic transition. These studies depict an epigenomic roadmap from human pluripotent stem cells to hematopoietic progenitor cells, which may pave the way to generate hematopoietic progenitor cells with improved developmental potentials.

In the spotlight: the role of TGFβ signalling in haematopoietic stem and progenitor cell emergence

Haematopoietic stem and progenitor cells (HSPCs) sustain haematopoiesis by generating precise numbers of mature blood cells throughout the lifetime of an individual. In vertebrates, HSPCs arise during embryonic development from a specialised endothelial cell population, the haemogenic endothelium (HE). Signalling by the Transforming Growth Factor β (TGFβ) pathway is key to regulate haematopoiesis in the adult bone marrow, but evidence for a role in the formation of HSPCs has only recently started to emerge. In this review, we examine recent work in various model systems that demonstrate a key role for TGFβ signalling in HSPC emergence from the HE. The current evidence underpins two seemingly contradictory views of TGFβ function: as a negative regulator of HSPCs by limiting haematopoietic output from HE, and as a positive regulator, by programming the HE towards the haematopoietic fate. Understanding how to modulate the requirement for TGFβ signalling in HSC emergence may have critical implications for the generation of these cells in vitro for therapeutic use.

Engineering a niche supporting hematopoietic stem cell development using integrated single-cell transcriptomics

Hematopoietic stem cells (HSCs) develop from hemogenic endothelium within embryonic arterial vessels such as the aorta of the aorta-gonad-mesonephros region (AGM). To identify the signals responsible for HSC formation, here we use single cell RNA-sequencing to simultaneously analyze the transcriptional profiles of AGM-derived cells transitioning from hemogenic endothelium to HSCs, and AGM-derived endothelial cells which provide signals sufficient to support HSC maturation and self-renewal. Pseudotemporal ordering reveals dynamics of gene expression during the hemogenic endothelium to HSC transition, identifying surface receptors specifically expressed on developing HSCs. Transcriptional profiling of niche endothelial cells identifies corresponding ligands, including those signaling to Notch receptors, VLA-4 integrin, and CXCR4, which, when integrated in an engineered platform, are sufficient to support the generation of engrafting HSCs. These studies provide a transcriptional map of the signaling interactions necessary for the development of HSCs and advance the goal of engineering HSCs for therapeutic applications.

Notch Signaling in HSC Emergence: When, Why and How

The hematopoietic stem cell (HSC) sustains blood homeostasis throughout life in vertebrates. During embryonic development, HSCs emerge from the aorta-gonads and mesonephros (AGM) region along with hematopoietic progenitors within hematopoietic clusters which are found in the dorsal aorta, the main arterial vessel. Notch signaling, which is essential for arterial specification of the aorta, is also crucial in hematopoietic development and HSC activity. In this review, we will present and discuss the evidence that we have for Notch activity in hematopoietic cell fate specification and the crosstalk with the endothelial and arterial lineage. The core hematopoietic program is conserved across vertebrates and here we review studies conducted using different models of vertebrate hematopoiesis, including zebrafish, mouse and in vitro differentiated Embryonic stem cells. To fulfill the goal of engineering HSCs in vitro, we need to understand the molecular processes that modulate Notch signaling during HSC emergence in a temporal and spatial context. Here, we review relevant contributions from different model systems that are required to specify precursors of HSC and HSC activity through Notch interactions at different stages of development.

Current Advances in Coptidis Rhizoma for Gastrointestinal and Other Cancers

Cancer is a serious disease with an increasing number of reported cases and high mortality worldwide. Gastrointestinal cancer defines a group of cancers in the digestive system, e.g., liver cancer, colorectal cancer, and gastric cancer. Coptidis Rhizoma (C. Rhizoma; Huanglian, in Chinese) is a classical Chinese medicinal botanical drug for the treatment of gastrointestinal disorders and has been shown to have a wide variety of pharmacological activity, including antifungal, antivirus, anticancer, antidiabetic, hypoglycemic, and cardioprotective effects. Recent studies on C. Rhizoma present significant progress on its anticancer effects and the corresponding mechanisms as well as its clinical applications. Herein, keywords related to C. Rhizoma, cancer, gastrointestinal cancer, and omics were searched in PubMed and the Web of Science databases, and more than three hundred recent publications were reviewed and discussed. C. Rhizoma extract along with its main components, berberine, palmatine, coptisine, magnoflorine, jatrorrhizine, epiberberine, oxyepiberberine, oxyberberine, dihydroberberine, columbamine, limonin, and derivatives, are reviewed. We describe novel and classic anticancer mechanisms from various perspectives of pharmacology, pharmaceutical chemistry, and pharmaceutics. Researchers have transformed the chemical structures and drug delivery systems of these components to obtain better efficacy and bioavailability of C. Rhizoma. Furthermore, C. Rhizoma in combination with other drugs and their clinical application are also summarized. Taken together, C. Rhizoma has broad prospects as a potential adjuvant candidate against cancers, making it reasonable to conduct additional preclinical studies and clinical trials in gastrointestinal cancer in the future.

Biomechanical cues as master regulators of hematopoietic stem cell fate

Hematopoietic stem cells (HSCs) perceive both soluble signals and biomechanical inputs from their microenvironment and cells themselves. Emerging as critical regulators of the blood program, biomechanical cues such as extracellular matrix stiffness, fluid mechanical stress, confined adhesiveness, and cell-intrinsic forces modulate multiple capacities of HSCs through mechanotransduction. In recent years, research has furthered the scientific community's perception of mechano-based signaling networks in the regulation of several cellular processes. However, the underlying molecular details of the biomechanical regulatory paradigm in HSCs remain poorly elucidated and researchers are still lacking in the ability to produce bona fide HSCs ex vivo for clinical use. This review presents an overview of the mechanical control of both embryonic and adult HSCs, discusses some recent insights into the mechanisms of mechanosensing and mechanotransduction, and highlights the application of mechanical cues aiming at HSC expansion or differentiation.

Sequential regulation of hemogenic fate and hematopoietic stem and progenitor cell formation from arterial endothelium by Ezh1/2

Across species, hematopoietic stem and progenitor cells (HSPCs) arise during embryogenesis from a specialized arterial population, termed hemogenic endothelium. Here, we describe a mechanistic role for the epigenetic regulator, Enhancer of zeste homolog-1 (Ezh1), in vertebrate HSPC production via regulation of hemogenic commitment. Loss of ezh1 in zebrafish embryos favored acquisition of hemogenic (gata2b) and HSPC (runx1) fate at the expense of the arterial program (ephrinb2a, dll4). In contrast, ezh1 overexpression blocked hematopoietic progression via maintenance of arterial gene expression. The related Polycomb group subunit, Ezh2, functioned in a non-redundant, sequential manner, whereby inhibition had no impact on arterial identity, but was capable of blocking ezh1-knockdown-associated HSPC expansion. Single-cell RNA sequencing across ezh1 genotypes revealed a dropout of ezh1^+/− cells among arterial endothelium associated with positive regulation of gene transcription. Exploitation of Ezh1/2 modulation has potential functional relevance for improving in vitro HSPC differentiation from induced pluripotent stem cell sources.

•

ezh1 loss increases HSPC and lymphoid progenitor formation during embryogenesis

•

ezh1 loss promotes a developmental shift from arterial to hemogenic fate in the DA

•

Ezh2 functions downstream of Ezh1-regulated arterial identity in HSPC commitment

•

scRNA-seq confirms ezh1 loss modifies distinct arterial associated gene programs

Activation of the Arterial Program Drives Development of Definitive Hemogenic Endothelium with Lymphoid Potential

Understanding the pathways guiding the development of definitive hematopoiesis with lymphoid potential is essential for advancing human pluripotent stem cell (hPSC) technologies for the treatment of blood diseases and immunotherapies. In the embryo, lymphoid progenitors and hematopoietic stem cells (HSCs) arise from hemogenic endothelium (HE) lining arteries but not veins. Here, we show that activation of the arterial program through ETS1 overexpression or by modulating MAPK/ERK signaling pathways at the mesodermal stage of development dramatically enhanced the formation of arterial-type HE expressing DLL4 and CXCR4. Blood cells generated from arterial HE were more than 100-fold enriched in T cell precursor frequency and possessed the capacity to produce B lymphocytes and red blood cells expressing high levels of BCL11a and β-globin. Together, these findings provide an innovative strategy to aid in the generation of definitive lymphomyeloid progenitors and lymphoid cells from hPSCs for immunotherapy through enhancing arterial programming of HE.

Robust generation of erythroid and multilineage hematopoietic progenitors from human iPSCs using a scalable monolayer culture system

One of the most promising objectives of clinical hematology is to derive engraftable autologous hematopoietic stem cells (HSCs) from human induced pluripotent stem cells (iPSCs). Progress in translating iPSC technologies to the clinic relies on the availability of scalable differentiation methodologies. In this study, human iPSCs were differentiated for 21 days using STEMdiff™, a monolayer-based approach for hematopoietic differentiation of human iPSCs that requires no replating, co-culture or embryoid body formation. Both hematopoietic and non-hematopoietic cells were functionally characterized throughout differentiation. In the hematopoietic fraction, an early transient population of primitive CD235a⁺ erythroid progenitor cells first emerged, followed by hematopoietic progenitors with multilineage differentiation activity in vitro but no long-term engraftment potential in vivo. In later stages of differentiation, a nearly exclusive production of definitive erythroid progenitors was observed. In the non-hematopoietic fraction, we identified a prevalent population of mesenchymal stromal cells and limited arterial vascular endothelium (VE), suggesting that the cellular constitution of the monolayer may be inadequate to support the generation of HSCs with durable repopulating potential. Quantitative modulation of WNT/β-catenin and activin/nodal/TGFβ signaling pathways with CHIR/SB molecules during differentiation enhanced formation of arterial VE, definitive multilineage and erythroid progenitors, but was insufficient to orchestrate the generation of engrafting HSCs. Overall, STEMdiff™ provides a clinically-relevant and readily adaptable platform for the generation of erythroid and multilineage hematopoietic progenitors from human pluripotent stem cells.

Blood stem cell-forming haemogenic endothelium in zebrafish derives from arterial endothelium

Haematopoietic stem cells are generated from the haemogenic endothelium (HE) located in the floor of the dorsal aorta (DA). Despite being integral to arteries, it is controversial whether HE and arterial endothelium share a common lineage. Here, we present a transgenic zebrafish runx1 reporter line to isolate HE and aortic roof endothelium (ARE)s, excluding non-aortic endothelium. Transcriptomic analysis of these populations identifies Runx1-regulated genes and shows that HE initially expresses arterial markers at similar levels to ARE. Furthermore, runx1 expression depends on prior arterial programming by the Notch ligand dll4. Runx1^−/− mutants fail to downregulate arterial genes in the HE, which remains integrated within the DA, suggesting that Runx1 represses the pre-existing arterial programme in HE to allow progression towards the haematopoietic fate. These findings strongly suggest that, in zebrafish, aortic endothelium is a precursor to HE, with potential implications for pluripotent stem cell differentiation protocols for the generation of transplantable HSCs.

HSCs emerge from haemogenic endothelium (HE) in the dorsal aorta but whether these tissues share a common lineage is unclear. Here, the authors use a zebrafish runx1 reporter to show that HE maintains an arterial gene expression profile in the absence of Runx1, suggesting the aortic endothelium as a precursor of HE.

Endothelial Cell Development and Its Application to Regenerative Medicine

The formation and remodeling of a functional circulatory system is critical for sustaining prenatal and postnatal life. During embryogenesis, newly differentiated endothelial cells require further specification to create the unique features of distinct vessel subtypes needed to support tissue morphogenesis. In this review, we explore signaling pathways and transcriptional regulators that modulate endothelial cell differentiation and specification, as well as applications of these processes to stem cell biology and regenerative medicine. We also summarize recent technical advances, including the growing utilization of single-cell sequencing to study vascular heterogeneity and development.

Arterial identity of hemogenic endothelium: a key to unlock definitive hematopoietic commitment in human pluripotent stem cell cultures

Human pluripotent stem cells (hPSCs) have been suggested as a potential source for the de novo production of blood cells for transfusion, immunotherapies, and transplantation. However, even with advanced hematopoietic differentiation methods, the primitive and myeloid-restricted waves of hematopoiesis dominate in hPSC differentiation cultures, whereas cell surface markers to distinguish these waves of hematopoiesis from lympho-myeloid hematopoiesis remain unknown. In the embryo, hematopoietic stem cells (HSCs) arise from hemogenic endothelium (HE) lining arteries, but not veins. This observation led to a long-standing hypothesis that arterial specification is an essential prerequisite to initiate the HSC program. It has also been established that lymphoid potential in the yolk sac and extraembryonic vasculature is mostly confined to arteries, whereas myeloid-restricted hematopoiesis is not specific to arterial vessels. Here, we review how the link between arterialization and the subsequent definitive multilineage hematopoietic program can be exploited to identify HE enriched in lymphoid progenitors and aid in in vitro approaches to enhance the production of lymphoid cells and potentially HSCs from hPSCs. We also discuss alternative models of hematopoietic specification at arterial sites and recent advances in our understanding of hematopoietic development and the production of engraftable hematopoietic cells from hPSCs.

Dissecting BMP signaling input into the gene regulatory networks driving specification of the blood stem cell lineage

Hematopoietic stem cells (HSCs) that sustain lifelong blood production are created during embryogenesis. They emerge from a specialized endothelial population, termed hemogenic endothelium (HE), located in the ventral wall of the dorsal aorta (DA). In Xenopus, we have been studying the gene regulatory networks (GRNs) required for the formation of HSCs, and critically found that the hemogenic potential is defined at an earlier time point when precursors to the DA express hematopoietic as well as endothelial genes, in the definitive hemangioblasts (DHs). The GRN for DH programming has been constructed and, here, we show that bone morphogenetic protein (BMP) signaling is essential for the initiation of this GRN. BMP2, -4, and -7 are the principal ligands expressed in the lineage forming the HE. To investigate the requirement and timing of all BMP signaling in HSC ontogeny, we have used a transgenic line, which inducibly expresses an inhibitor of BMP signaling, Noggin, as well as a chemical inhibitor of BMP receptors, DMH1, and described the inputs from BMP signaling into the DH GRN and the HE, as well as into primitive hematopoiesis. BMP signaling is required in at least three points in DH programming: first to initiate the DH GRN through gata2 expression, then for kdr expression to enable the DH to respond to vascular endothelial growth factor A (VEGFA) ligand from the somites, and finally for gata2 expression in the DA, but is dispensable for HE specification after hemangioblasts have been formed.

NOTCH signaling specifies arterial-type definitive hemogenic endothelium from human pluripotent stem cells

NOTCH signaling is required for the arterial specification and formation of hematopoietic stem cells (HSCs) and lympho-myeloid progenitors in the embryonic aorta-gonad-mesonephros region and extraembryonic vasculature from a distinct lineage of vascular endothelial cells with hemogenic potential. However, the role of NOTCH signaling in hemogenic endothelium (HE) specification from human pluripotent stem cell (hPSC) has not been studied. Here, using a chemically defined hPSC differentiation system combined with the use of DLL1-Fc and DAPT to manipulate NOTCH, we discover that NOTCH activation in hPSC-derived immature HE progenitors leads to formation of CD144⁺CD43⁻CD73⁻DLL4⁺Runx1 + 23-GFP⁺ arterial-type HE, which requires NOTCH signaling to undergo endothelial-to-hematopoietic transition and produce definitive lympho-myeloid and erythroid cells. These findings demonstrate that NOTCH-mediated arterialization of HE is an essential prerequisite for establishing definitive lympho-myeloid program and suggest that exploring molecular pathways that lead to arterial specification may aid in vitro approaches to enhance definitive hematopoiesis from hPSCs.

It is unclear whether arterial specification is required for hematopoietic stem cell formation. Here, the authors use a chemically defined human pluripotent stem cell (hPSC) differentiation system to show the role of NOTCH signaling in forming arterial-type hemogenic endothelial cells.

Ephrin ligands and Eph receptors contribution to hematopoiesis

Hematopoietic stem and progenitor cells reside predominantly in the bone marrow. They supply billions of mature blood cells every day during life through maturation into multilineage progenitors and self-renewal. Newly produced mature cells serve to replenish the pool of circulating blood cells at the end of their life-span. These mature blood cells and a few hematopoietic progenitors normally exit the bone marrow through the sinusoidal vessels, a specialized venous vascular system that spreads throughout the bone marrow. Many signals regulate the coordinated mobilization of hematopoietic cells from the bone marrow to the circulation. In this review, we present recent advances on hematopoiesis and hematopoietic cell mobilization with a focus on the role of Ephrin ligands and their Eph receptors. These constitute a large family of transmembrane ligands and receptors that play critical roles in development and postnatally. New insights point to distinct roles of ephrin and Eph in different aspects of hematopoiesis.

Berberine inhibits the proliferation and migration of breast cancer ZR-75-30 cells by targeting Ephrin-B2

BACKGROUND

Berberine, a plant-derived compound isolated from Coptis chinensis used in traditional Chinese medicine, has been shown to possess anti-cancer properties. However, no study has shown that berberine could target ephrin-B2, which plays a critical role in cell proliferation and migration.

PURPOSE

The aim of this study is to investigate the effect of berberine on cancer cell growth and migration, through the regulation of ephrin-B2 and downstream signaling molecules.

METHODS

In this study, a high ephrin-B2-expressing cell membrane chromatography method was developed to investigate 48 crude extracts from traditional Chinese medicine that could act on ephrin-B2. Cell proliferative and wound-healing assays were used to study the effect of berberine on cancer cell growth and migration. The mechanism of berberine was investigated using western blot.

RESULTS

Berberine was isolated from C. chinensis extracts and showed activity on the HEK293/ephrin-B2 cell membrane chromatography column. Berberine showed a greater inhibitory effect in high-expressing ephrin-B2 cells (HEK293/ephrin-B2 cells) than in normal HEK293 cells, and decreased the expression of ephrin-B2 and its PDZ binding proteins, which indicates that ephrin-B2 is a target of berberine. Furthermore, berberine downregulates the phosphorylation of VEGFR2 and downstream signaling members (AKT and Erk1/2), which in turn downregulates the expression of MMP2 and MMP9.

CONCLUSION

The above data confirm the inhibitory effects of berberine on ZR-75-30 cell proliferation and cell migration. Overall, our studies demonstrate that berberine inhibits cell growth and migration by targeting ephrin-B2.