Direct development of functionally mature tryptase/chymase double-positive connective tissue-type mast cells from primate embryonic stem cells

Overexpression of HOXA9 upregulates NF-κB signaling to promote human hematopoiesis and alter the hematopoietic differentiation potentials

Background

The HOX genes are master regulators of embryogenesis that are also involved in hematopoiesis. HOXA9 belongs to a cluster of HOX genes that play extensively studied roles in hematopoiesis and leukemogenesis.

Methods

We established HOXA9-inducible human embryonic stem cells (HOXA9/hESCs) with normal pluripotency and potential for hematopoiesis, which could be used to analyze gene function with high accuracy. HOXA9/hESCs co-cultured with aorta–gonad–mesonephros-derived stromal cells (AGM-S3) were induced to overexpress HOXA9 with doxycycline (DOX) at various times after hematopoiesis started and then subjected to flow cytometry.

Results

Induction of HOXA9 from Day 4 (D4) or later notably promoted hematopoiesis and also increased the production of CD34+ cells and derived populations. The potential for myelogenesis was significantly elevated while the potential for erythrogenesis was significantly reduced. At D14, a significant promotion of S phase was observed in green fluorescent protein positive (GFP+) cells overexpressing HOXA9. NF-κB signaling was also up-regulated at D14 following induction of HOXA9 on D4. All of these effects could be counteracted by addition of an NF-κB inhibitor or siRNA against NFKB1 along with DOX.

Conclusions

Overexpression of HOXA9 starting at D4 or later during hematopoiesis significantly promoted hematopoiesis and the production of myeloid progenitors while reduced the production of erythroid progenitors, indicating that HOXA9 plays a key role in hematopoiesis and differentiation of hematopoietic lineages.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13619-020-00066-0.

Early development and functional properties of tryptase/chymase double-positive mast cells from human pluripotent stem cells

Mast cells (MCs) play a pivotal role in the hypersensitivity reaction by regulating the innate and adaptive immune responses. Humans have two types of MCs. The first type, termed MC_TC, is found in the skin and other connective tissues and expresses both tryptase and chymase, while the second, termed MC_T, which only expresses tryptase, is found primarily in the mucosa. MCs induced from human adult-type CD34⁺ cells are reported to be of the MC_T type, but the development of MCs during embryonic/fetal stages is largely unknown. Using an efficient coculture system, we identified that a CD34⁺c-kit⁺ cell population, which appeared prior to the emergence of CD34⁺CD45⁺ hematopoietic stem and progenitor cells (HSPCs), stimulated robust production of pure Tryptase⁺Chymase⁺ MCs (MC_TCs). Single-cell analysis revealed dual development directions of CD34⁺c-kit⁺ progenitors, with one lineage developing into erythro-myeloid progenitors (EMP) and the other lineage developing into HSPC. Interestingly, MC_TCs derived from early CD34⁺c-kit⁺ cells exhibited strong histamine release and immune response functions. Particularly, robust release of IL-17 suggested that these early developing tissue-type MC_TCs could play a central role in tumor immunity. These findings could help elucidate the mechanisms controlling early development of MC_TCs and have significant therapeutic implications.

Progenitor mast cells and tryptase in Q fever

Q fever is an infectious disease due to Coxiella burnetii. Following a primary-infection, C. burnetii may persist in some patients, leading to endocarditis and vascular infections. Mast cells (MCs), known for their role in allergic diseases, innate immunity and cardiac function, are produced by bone marrow, circulate as progenitors in the bloodstream and reach tissues for their maturation and activation. The latter may be estimated by measuring serum tryptase levels. We wondered if MC progenitors and tryptase were affected in Q fever. We showed a decrease in MC progenitor count in Q fever patients whereas serum tryptase levels were increased. Taken together, our results show alterations of MC numbers and activity in Q fever patients, suggesting that MC are involved in Q fever pathophysiology.

Mast cells derived from human induced pluripotent stem cells are useful for allergen tests

BACKGROUND

Several methods have been developed to detect allergen-specific IgE in sera. The passive IgE sensitization assay using human IgE receptor-expressing rat cell line RBL-2H3 is a powerful tool to detect biologically active allergen-specific IgE in serum samples. However, one disadvantage is that RBL-2H3 cells are vulnerable to high concentrations of human sera. Only a few human cultured cell lines are easily applicable to the passive IgE sensitization assay. However, the use of human induced pluripotent stem cells (iPSCs) to generate human mast cells (MCs) has not yet been reported.

METHODS

The nuclear factor-kappa B (NF-κB)-responsive luciferase reporter gene was stably introduced into a human iPSC line 201B7, and the transfectants were induced to differentiate into MCs (iPSC-MCs). The iPSC-MCs were sensitized overnight with sera from subjects who were allergic to cedar pollen, ragweed pollen, mites, or house dust, and then stimulated with an extract of corresponding allergens. Activation of iPSC-MCs was evaluated by β-hexosaminidase release, histamine release, or luciferase intensity.

RESULTS

iPSCs-MCs stably expressed high-affinity IgE receptor and functionally responded to various allergens when sensitized with human sera from relevant allergic subjects. This passive IgE sensitization system, which we termed the induced mast cell activation test (iMAT), worked well even with undiluted human sera.

CONCLUSIONS

iMAT may serve as a novel determining system for IgE/allergens in the clinical and research settings.

Purinergic Signaling in Mast Cell Degranulation and Asthma

Mast cells are responsible for the majority of allergic conditions. It was originally thought that almost all allergic events were mediated directly only via the high-affinity immunoglobulin E receptors. However, recent evidence showed that many other receptors, such as G protein-coupled receptors and ligand-gated ion channels, are also directly involved in mast cell degranulation, the release of inflammatory mediators such as histamine, serine proteases, leukotrienes, heparin, and serotonin. These mediators are responsible for the symptoms in allergic conditions such as allergic asthma. In recent years, it has been realized that purinergic signaling, induced via the activation of G protein-coupled adenosine receptors and P2Y nucleotide receptors, as well as by ATP-gated P2X receptors, plays a significant role in mast cell degranulation. Both adenosine and ATP can induce degranulation and bronchoconstriction on their own and synergistically with allergens. All three classes of receptors, adenosine, P2X and P2Y are involved in tracheal mucus secretion. This review will summarize the currently available knowledge on the role of purinergic signaling in mast cell degranulation and its most relevant disease, asthma.

Heterogeneity of mast cells and expression of Annexin A1 protein in a second degree burn model with silver sulfadiazine treatment

Mast cells (MCs) participate in all stages of skin healing and one of their mediators is the Annexin A1 protein (AnxA1), linked to inflammation, proliferation, migration and apoptosis processes, but not studied in thermal burns yet. Therefore, our objectives were to evaluate the behavior of MCs and AnxA1 in a second degree burn model, treated or not with silver sulfadiazine 1% (SDP 1%) and associated to macrophages quantification and cytokines dosages. MCs counts showed few cells in the early stages of repair but increased MCs in the final phases in the untreated group. The normal skin presented numerous tryptase-positive MCs that were reduced after burning in all analyzed periods. Differently, few chymase-positive MCs were observed in the early stages of healing, however, increased chymase-positive MCs were found at the final phase in the untreated group. MCs also showed high immunoreactivity for AnxA1 on day 3 in both groups. In the tissue there was a strong protein expression in the early stages of healing, but in the final phases only in the SDP treated animals. TNF-α, IL-1β, IL-6, IL-10 and MCP-1 levels and macrophages quantification were increased in inflammation and reepithelialization phases. Reduced IL-1β, IL-6 and IL-10 levels and numerous macrophages occurred in the treated animals during tissue repair. Our results indicate modulation in the profile of MCs and AnxA1expression during healing by the treatment with SDP 1%, pointing them as targets for therapeutic interventions on skin burns.

Diagnosis and treatment of juvenile myelomonocytic leukemia

Juvenile myelomonocytic leukemia (JMML) is a rare myelodysplastic/myeloproliferative disorder that occurs during infancy and early childhood; this disorder is characterized by hypersensitivity of the myeloid progenitor cells to granulocyte-macrophage colony-stimulating factor in vitro. JMML usually involves somatic and/or germline mutations in the genes of the RAS pathway, including PTPN11, NRAS, KRAS, NF1, and CBL, in the leukemic cells. Almost all patients with JMML experience an aggressive clinical course, and hematopoietic stem cell transplantation (HSCT) is the only curative treatment. A certain proportion of patients with somatic NRAS and germline mutations in CBL, however, have spontaneous resolution. A suitable treatment after diagnosis and conditioning regimen prior to HSCT are yet to be determined, but several clinical trials have been initiated throughout the world to develop suitable pre- or post-allogeneic HSCT treatments and new targeted therapies that are less toxic, to improve patient outcome.

Development of a Xeno-Free Feeder-Layer System from Human Umbilical Cord Mesenchymal Stem Cells for Prolonged Expansion of Human Induced Pluripotent Stem Cells in Culture

Various feeder layers have been extensively applied to support the prolonged growth of human pluripotent stem cells (hPSCs) for in vitro cultures. Among them, mouse embryonic fibroblast (MEF) and mouse fibroblast cell line (SNL) are most commonly used feeder cells for hPSCs culture. However, these feeder layers from animal usually cause immunogenic contaminations, which compromises the potential of hPSCs in clinical applications. In the present study, we tested human umbilical cord mesenchymal stem cells (hUC-MSCs) as a potent xeno-free feeder system for maintaining human induced pluripotent stem cells (hiPSCs). The hUC-MSCs showed characteristics of MSCs in xeno-free culture condition. On the mitomycin-treated hUC-MSCs feeder, hiPSCs maintained the features of undifferentiated human embryonic stem cells (hESCs), such as low efficiency of spontaneous differentiation, stable expression of stemness markers, maintenance of normal karyotypes, in vitro pluripotency and in vivo ability to form teratomas, even after a prolonged culture of more than 30 passages. Our study indicates that the xeno-free culture system may be a good candidate for growth and expansion of hiPSCs as the stepping stone for stem cell research to further develop better and safer stem cells.

In vitro expansion of CD34(+)CD38(-) cells under stimulation with hematopoietic growth factors on AGM-S3 cells in juvenile myelomonocytic leukemia

Using serum-containing culture, we examined whether AGM-S3 stromal cells, alone or in combination with hematopoietic growth factor(s), stimulated the proliferation of CD34(+) cells from patients with juvenile myelomonocytic leukemia (JMML). AGM-S3 cells in concert with stem cell factor plus thrombopoietin increased the numbers of peripheral blood CD34(+) cells to approximately 20-fold of the input value after 2 weeks in nine JMML patients with either PTPN11 mutations or RAS mutations, who received allogeneic hematopoietic transplantation. Granulocyte-macrophage colony-stimulating factor (GM-CSF) also augmented the proliferation of JMML CD34(+) cells on AGM-S3 cells. The expansion potential of CD34(+) cells was markedly low in four patients who achieved spontaneous hematological improvement. A large proportion of day-14-cultured CD34(+) cells were negative for CD38 and cryopreservable. Cultured JMML CD34(+)CD38(-) cells expressed CD117, CD116, c-mpl, CD123, CD90, but not CXCR4, and formed GM and erythroid colonies. Day-7-cultured CD34(+) cells from two of three JMML patients injected intrafemorally into immunodeficient mice stimulated with human GM-CSF after transplantation displayed significant hematopoietic reconstitution. The abilities of OP9 cells and MS-5 cells were one-third and one-tenth, respectively, of the value obtained with AGM-S3 cells. Our culture system may provide a useful tool for elucidating leukemogenesis and for therapeutic approaches in JMML.

Two-step differentiation of mast cells from induced pluripotent stem cells

Mast cells play important roles in the pathogenesis of allergic diseases. They are generally classified into 2 phenotypically distinct populations: connective tissue-type mast cells (CTMCs) and mucosal-type mast cells (MMCs). The number of mast cells that can be obtained from tissues is limited, making it difficult to study the function of mast cells. Here, we report the generation and characterization of CTMC-like mast cells derived from mouse induced pluripotent stem (iPS) cells. iPS cell-derived mast cells (iPSMCs) were generated by the OP9 coculture method or embryoid body formation method. The number of Safranin O-positive cells, expression levels of CD81 protein and histidine decarboxylase mRNA, and protease activities were elevated in the iPSMCs differentiated by both methods as compared with those in bone marrow-derived mast cells (BMMCs). Electron microscopic analysis revealed that iPSMCs contained more granules than BMMCs. Degranulation was induced in iPSMCs after stimulation with cationic secretagogues or vancomycin. In addition, iPSMCs had the ability to respond to stimulation with the IgE/antigen complex in vitro and in vivo. Moreover, when iPSMCs generated on OP9 cells were cocultured with Swiss 3T3 fibroblasts, protease activities as maturation index were more elevated, demonstrating that mature mast cells were differentiated from iPS cells. iPSMCs can be used as an in vitro model of CTMCs to investigate their functions.

Differentiation of mast cells from embryonic stem cells

In this unit, we describe a simple coculture-free method for obtaining mast cells from mouse and human embryonic stem (ES) cells. Much of our knowledge regarding the mechanisms by which mast cells are activated comes from studies of mouse bone marrow-derived mast cells. Studies of human mast cells have been hampered by the limited sources from which they can be cultured, the difficulty in introducing specific genetic changes into these cells, and differences between established cultures that reflect the unique genetic makeup of the tissue donor. Derivation of mast cells from embryonic stem cells addresses these limitations. ES-derived mast cells can be generated in numbers sufficient for studies of the pathways involved in mast cell effector functions. These ES cell-derived mast cells respond to antigens and other stimuli by releasing histamine, cytokines, lipids, and other bioactive mediators. The derivation of human mast cells from ES cells carrying mutations introduced by homologous recombination should provide a novel means of testing the function of genes in both the development and the effector functions of mast cells.

Generation of red blood cells from human embryonic/induced pluripotent stem cells for blood transfusion

Red blood cell (RBC) transfusion is necessary for many patients with emergency or hematological disorders. However, to date the supply of RBCs remains labile and dependent on voluntary donations. In addition, the transmission of infectious disease via blood transfusion from unspecified donors remains a risk. Establishing a large quantity of safe RBCs would help to address this issue. Human embryonic stem (hES) cells and the recently established human induced pluripotent stem (hiPS) cells represent potentially unlimited sources of donor-free RBCs for blood transfusion, as they can proliferate indefinitely in vitro. Extensive research has been done to efficiently generate transfusable RBCs from hES/iPS cells. Nevertheless, a number of challenges must be overcome before the clinical usage of hES/iPS cell-derived RBCs can become a reality.

Influence of FAS on murine mast cell maturation

BACKGROUND

FAS has been shown to be involved in the regulation of many immune processes by induction of cellular apoptosis. However, accumulated evidence shows that FAS signaling also exhibits nonapoptotic functions, such as induction of cell proliferation and differentiation. FAS is the only death receptor known to be expressed on murine mast cells (MCs).

OBJECTIVE

To evaluate the role of FAS on murine MC maturation.

METHODS

Mouse bone marrow-derived MCs (BMMCs) or peritoneal MCs were derived from FAS-deficient, FASlpr/lpr, and congenic wild-type strains. The MC degranulation and cytokine release after IgE activation was assessed by measuring β-hexosaminidase, interleukin 13, and tumor necrosis factor α release. Transmission electron microscopy analysis was performed to evaluate the level of BMMC maturation. The surface markers and intracellular preformed mediators were measured as well.

RESULTS

Our data reveal that FAS deficiency has an impact on IgE-dependent activation of BMMCs, resulting in a significant decrease in β-hexosaminidase, interleukin 13, and tumor necrosis factor α release. The total content of preformed mediators (eg, tryptase and β-hexosaminidase) was reduced in BMMCs derived from FAS-deficient mice. We also found that the level of FcεRI in peritoneal mast cells from FAS-deficient mice was significantly diminished. FAS deficiency also influenced the kinetics of BMMC maturation as was revealed by transmission electron microscopy analysis.

CONCLUSION

Our data show that FAS has an impact on the regulation of mouse MC maturation in vitro.

Human embryonic stem cells: a source of mast cells for the study of allergic and inflammatory diseases

Human mast cells are tissue resident cells with a principal role in allergic disorders. Cross-linking of the high-affinity receptor for immunoglobulin E (FcepsilonRI) results in release of inflammatory mediators initiating the clinical symptoms of allergy and anaphylaxis. Much of our knowledge regarding the mechanisms of mast cell activation comes from studies of mouse bone marrow-derived mast cells. However, clear differences have been identified between human and mouse mast cells. Studies of human mast cells are hampered by the limited sources available for their isolation, the resistance of these cells to genetic manipulation, and differences between cultures established from different persons. To address this limitation, we developed a simple coculture-free method for obtaining mast cells from human embryonic stem cells (hES). These hES-derived mast cells respond to antigen by releasing mast cell mediators. Moreover, the cells can be generated in numbers sufficient for studies of the pathways involved in their effector functions. Genetically modified mast cells, such as GFP-expressing cells, can be obtained by introduction and selection for modification in hES cells before differentiation. This direct coculture-free differentiation of hES cells represents a new and unique model to analyze the function and development of human mast cells.

Generation of functional erythrocytes from human embryonic stem cell-derived definitive hematopoiesis

A critical issue for clinical utilization of human ES cells (hESCs) is whether they can generate terminally mature progenies with normal function. We recently developed a method for efficient production of hematopoietic progenitors from hESCs by coculture with murine fetal liver-derived stromal cells. Large numbers of hESCs-derived erythroid progenitors generated by the coculture enabled us to analyze the development of erythropoiesis at a clone level and investigate their function. The results showed that the globin expression in the erythroid cells in individual clones changed in a time-dependent manner. In particular, embryonic epsilon-globin-expressing erythroid cells from individual clones decreased, whereas adult-type beta-globin-expressing cells increased to approximately 100% in all clones we examined, indicating that the cells undergo definitive hematopoiesis. Enucleated erythrocytes also appeared among the clonal progeny. A comparison analysis showed that hESC-derived erythroid cells took a similar differentiation pathway to human cord blood CD34(+) progenitor-derived cells when examined for the expression of glycophorin A, CD71 and CD81. Furthermore, these hESC-derived erythroid cells could function as oxygen carriers and had a sufficient glucose-6-phosphate dehydrogenase activity. The present study should provide an experimental model for exploring early development of human erythropoiesis and hemoglobin switching and may help in the discovery of drugs for hereditary diseases in erythrocyte development.