ErythRED, a hESC line enabling identification of erythroid cells

Long-term engrafting multilineage hematopoietic cells differentiated from human induced pluripotent stem cells

Hematopoietic stem cells (HSCs) derived from human induced pluripotent stem cells (iPS cells) have important biomedical applications. We identified differentiation conditions that generate HSCs defined by robust long-term multilineage engraftment in immune-deficient NOD,B6.Prkdcscid Il2rgtm1Wjl/SzJ KitW41/W41 mice. We guided differentiating iPS cells, as embryoid bodies in a defined culture medium supplemented with retinyl acetate, through HOXA-patterned mesoderm to hemogenic endothelium specified by bone morphogenetic protein 4 and vascular endothelial growth factor (VEGF). Removal of VEGF facilitated an efficient endothelial-to-hematopoietic transition, evidenced by release into the culture medium of CD34+ blood cells, which were cryopreserved. Intravenous transplantation of two million thawed CD34+ cells differentiated from four independent iPS cell lines produced multilineage bone marrow engraftment in 25-50% of immune-deficient recipient mice. These functionally defined, multipotent CD34+ hematopoietic cells, designated iPS cell-derived HSCs (iHSCs), produced levels of engraftment similar to those achieved following umbilical cord blood transplantation. Our study provides a step toward the goal of generating HSCs for clinical translation.

Definitive Erythropoiesis from Pluripotent Stem Cells: Recent Advances and Perspectives

Derivation of functional and mature red blood cells (RBCs) with adult globin expression from renewable source such as induced pluripotent stem cells (iPSCs) is of importance from the clinical point of view. Definitive RBC generation can only be succeeded through production of true hematopoietic stem cells (HSCs). There has been a great effort to obtain definitive engraftable HSCs from iPSCs but the results were mostly unsatisfactory due to low, short-term and linage-biased engraftment in mouse models. Moreover, ex vivo differentiation approaches ended up with RBCs with mostly embryonic and fetal globin expression. To establish reliable, standardized and effective laboratory protocols, we need to expand our knowledge about developmental hematopoiesis/erythropoiesis and identify critical regulatory signaling pathways and transcription factors. Once we meet these challenges, we could establish differentiation protocols for massive RBC production for transfusion purposes in the clinical setting, performing drug screening and disease modeling in ex vivo conditions, and investigating the embryological cascade of erythropoiesis. More interestingly, with the introduction of relatively efficient and facile genome editing tools, genetic correction for inherited RBC disorders such as sickle cell disease (SCD) would become possible through iPSCs that can subsequently generate definitive HSCs, which then give rise to definitive RBCs producing β-globin after transplantation.

Human haematopoietic stem cell development: from the embryo to the dish

Haematopoietic stem cells (HSCs) emerge during embryogenesis and give rise to the adult haematopoietic system. Understanding how early haematopoietic development occurs is of fundamental importance for basic biology and medical sciences, but our knowledge is still limited compared with what we know of adult HSCs and their microenvironment. This is particularly true for human haematopoiesis, and is reflected in our current inability to recapitulate the development of HSCs from pluripotent stem cells in vitro In this Review, we discuss what is known of human haematopoietic development: the anatomical sites at which it occurs, the different temporal waves of haematopoiesis, the emergence of the first HSCs and the signalling landscape of the haematopoietic niche. We also discuss the extent to which in vitro differentiation of human pluripotent stem cells recapitulates bona fide human developmental haematopoiesis, and outline some future directions in the field.

The RUNX1 +24 enhancer and P1 promoter identify a unique subpopulation of hematopoietic progenitor cells derived from human pluripotent stem cells

Derivation of hematopoietic stem cells (HSCs) from human pluripotent stem cells remains a key goal for the fields of developmental biology and regenerative medicine. Here, we use a novel genetic reporter system to prospectively identify and isolate early hematopoietic cells derived from human embryonic stem cells (hESCs) and human induced pluripotent cells (iPSCs). Cloning the human RUNX1c P1 promoter and +24 enhancer to drive expression of tdTomato (tdTom) in hESCs and iPSCs, we demonstrate that tdTom expression faithfully enriches for RUNX1c-expressing hematopoietic progenitor cells. Time-lapse microscopy demonstrated the tdTom(+) hematopoietic cells to emerge from adherent cells. Furthermore, inhibition of primitive hematopoiesis by blocking Activin/Nodal signaling promoted the expansion and/or survival of the tdTom(+) population. Notably, RUNX1c/tdTom(+) cells represent only a limited subpopulation of the CD34(+) CD45(+) and CD34(+) CD43(+) cells with a unique genetic signature. Using gene array analysis, we find significantly lower expression of Let-7 and mir181a microRNAs in the RUNX1c/tdTom(+) cell population. These phenotypic and genetic analyses comparing the RUNX1c/tdTom(+) population to CD34(+) CD45(+) umbilical cord blood and fetal liver demonstrate several key differences that likely impact the development of HSCs capable of long-term multilineage engraftment from hESCs and iPSCs.

Productive Infection of Human Embryonic Stem Cell-Derived NKX2.1+ Respiratory Progenitors with Human Rhinovirus

Airway epithelial cells generated from pluripotent stem cells (PSCs) represent a resource for research into a variety of human respiratory conditions, including those resulting from infection with common human pathogens. Using an NKX2.1-GFP reporter human embryonic stem cell line, we developed a serum-free protocol for the generation of NKX2.1(+) endoderm that, when transplanted into immunodeficient mice, matured into respiratory cell types identified by expression of CC10, MUC5AC, and surfactant proteins. Gene profiling experiments indicated that day 10 NKX2.1(+) endoderm expressed markers indicative of early foregut but lacked genes associated with later stages of respiratory epithelial cell differentiation. Nevertheless, NKX2.1(+) endoderm supported the infection and replication of the common respiratory pathogen human rhinovirus HRV1b. Moreover, NKX2.1(+) endoderm upregulated expression of IL-6, IL-8, and IL-1B in response to infection, a characteristic of human airway epithelial cells. Our experiments provide proof of principle for the use of PSC-derived respiratory epithelial cells in the study of cell-virus interactions.

SIGNIFICANCE

This report provides proof-of-principle experiments demonstrating, for the first time, that human respiratory progenitor cells derived from stem cells in the laboratory can be productively infected with human rhinovirus, the predominant cause of the common cold.

Utilization of the AAVS1 safe harbor locus for hematopoietic specific transgene expression and gene knockdown in human ES cells

Human pluripotent stem cells offer a powerful system to study human biology and disease. Here, we report a system to both express transgenes specifically in ES cell derived hematopoietic cells and knockdown gene expression stably throughout the differentiation of ES cells. We characterize a CD43 promoter construct that when inserted into the AAVS1 "safe harbor" locus utilizing a zinc finger nuclease specifically drives GFP expression in hematopoietic cells derived from a transgenic ES cell line and faithfully recapitulates endogenous CD43 expression. In addition, using the same gene targeting strategy we demonstrate that constitutive expression of short hairpin RNAs within a microRNA backbone can suppress expression of PU.1, an important regulator of myeloid cell development. We show that PU.1 knockdown cell lines display an inhibition in myeloid cell formation and skewing towards erythroid development. Overall, we have generated a powerful system to track hematopoietic development from pluripotent stem cells and study gene function through hematopoietic specific gene expression and constitutive gene knockdown.

Rapid determination of human globin chains using reversed-phase high-performance liquid chromatography

Reversed-phase high-performance liquid chromatography (RP-HPLC) of human globin chains is an important tool for detecting thalassemias and hemoglobin variants. The challenges of this method that limit its clinical application are a long analytical time and complex sample preparation. The aim of this study was to establish a simple, rapid and high-resolution RP-HPLC method for the separation of globin chains in human blood. Red blood cells from newborns and adults were diluted in deionized water and injected directly onto a micro-jupiter C18 reversed-phase column (250 mm × 4.6 mm) with UV detection at 280 nm. Under the conditions of varying pH or the HPLC gradient, the globin chains (pre-β, β, δ, α, (G)γ and (A)γ) were denatured and separated from the heme groups in 12 min with a retention time coefficient of variation (CV) ranging from 0.11 to 1.29% and a peak area CV between 0.32% and 4.86%. Significant differences (P<0.05) among three groups (normal, Hb H and β thalassemia) were found in the area ratio of α/pre-β+β applying the rapid elution procedure, while P≥0.05 was obtained between the normal and α thalassemia silent/trait group. Based on the ANOVA results, receiver operating characteristic (ROC) curve analysis of the δ/β and α/pre-β+β area ratios showed a sensitivity of 100.0%, and a specificity of 100.0% for indicating β thalassemia carriers, and a sensitivity of 96.6% and a specificity of 89.6% for the prediction of hemoglobin H (Hb H) disease. The proposed cut-off was 0.026 of δ/β for β thalassemia carriers and 0.626 of α/pre-β+β for Hb H disease. In addition, abnormal hemoglobin hemoglobin E (Hb E) and Hb Westmead (Hb WS) were successfully identified using this RP-HPLC method. Our experience in developing this RP-HPLC method for the rapid separation of human globin chains could be of use for similar work.

Brief report: efficient generation of hematopoietic precursors and progenitors from human pluripotent stem cell lines

By mimicking embryonic development of the hematopoietic system, we have developed an optimized in vitro differentiation protocol for the generation of precursors of hematopoietic lineages and primitive hematopoietic cells from human embryonic stem cells (ESC) and induced pluripotent stem cells (iPSCs). Factors such as cytokines, extra cellular matrix components, and small molecules as well as the temporal association and concentration of these factors were tested on seven different human ESC and iPSC lines. We report the differentiation of up to 84% human CD45+ cells (average 41% ± 16%, from seven pluripotent lines) from the differentiation culture, including significant numbers of primitive CD45+/CD34+ and CD45+/CD34+/CD38- hematopoietic progenitors. Moreover, the numbers of hematopoietic progenitor cells generated, as measured by colony forming unit assays, were comparable to numbers obtained from fresh umbilical cord blood mononuclear cell isolates on a per CD45+ cell basis. Our approach demonstrates highly efficient generation of multipotent hematopoietic progenitors with among the highest efficiencies reported to date (CD45+/CD34+) using a single standardized differentiation protocol on several human ESC and iPSC lines. Our data add to the cumulating evidence for the existence of an in vitro derived precursor to the hematopoietic stem cell (HSC) with limited engrafting ability in transplanted mice but with multipotent hematopoietic potential. Because this protocol efficiently expands the preblood precursors and hematopoietic progenitors, it is ideal for testing novel factors for the generation and expansion of definitive HSCs with long-term repopulating ability.

Generation of human female reproductive tract epithelium from human embryonic stem cells

Background

Recent studies have identified stem/progenitor cells in human and mouse uterine epithelium, which are postulated to be responsible for tissue regeneration and proliferative disorders of human endometrium. These progenitor cells are thought to be derived from Müllerian duct (MD), the primordial female reproductive tract (FRT).

Methodology/Principal Findings

We have developed a model of human reproductive tract development in which inductive neonatal mouse uterine mesenchyme (nMUM) is recombined with green fluorescent protein (GFP)-tagged human embryonic stem cells (hESCs); GFP-hESC (ENVY). We demonstrate for the first time that hESCs can be differentiated into cells with a human FRT epithelial cell phenotype. hESC derived FRT epithelial cells emerged from cultures containing MIXL1⁺ mesendodermal precursors, paralleling events occurring during normal organogenesis. Following transplantation, nMUM treated embryoid bodies (EBs) generated epithelial structures with a typical MD phenotype that expressed the MD markers PAX2, HOXA10. Functionally, the hESCs derived FRT epithelium responded to exogenous estrogen by proliferating and secreting uterine-specific glycodelin A (GdA).

Conclusions/Significance

These data show nMUM can induce differentiation of hESC to form the FRT epithelium. This may provide a model to study early developmental events of the human FRT.

Albumin and mammalian cell culture: implications for biotechnology applications

Albumin has a long historical involvement in design of media for the successful culture of mammalian cells, in both the research and commercial fields. The potential application of albumins, bovine or human serum albumin, for cell culture is a by-product of the physico-chemical, biochemical and cell-specific properties of the molecule. In this review an analysis of these features of albumin leads to a consideration of the extracellular and intracellular actions of the molecule, and importantly the role of its interactions with numerous ligands or bioactive factors that influence the growth of cells in culture: these include hormones, growth factors, lipids, amino acids, metal ions, reactive oxygen and nitrogen species to name a few. The interaction of albumin with the cell in relation to these co-factors has a potential impact on metabolic and biosynthetic activity, cell proliferation and survival. Application of this knowledge to improve the performance in manufacturing biotechnology and in the emerging uses of cell culture for tissue engineering and stem cell derived therapies is an important prospect.