Short-term exposure of umbilical cord blood CD34+ cells to granulocyte–macrophage colony-stimulating factor early in culture improves ex vivo expansion of neutrophils

Neutrophil generation from hematopoietic progenitor cells and induced pluripotent stem cells (iPSCs): potential applications

Neutrophils are the most frequent immune cell type in peripheral blood, performing an essential role against pathogens. People with neutrophil deficiencies are susceptible to deadly infections, highlighting the importance of generating these cells in host immunity. Neutrophils can be generated from hematopoietic progenitor cells (HPCs) and embryonic stem cells (ESCs) using a cocktail of cytokines. In addition, induced pluripotent stem cells (iPSCs) can be differentiated into various functional cell types, including neutrophils. iPSCs can be derived from differentiated cells, such as skin and blood cells, by reprogramming them to a pluripotent state. Neutrophil generation from iPSCs involves a multistep process that can be performed through feeder cell-dependent and feeder cell-independent manners. Various cytokines and growth factors, in particular, stem cell facto, IL-3, thrombopoietin and granulocyte colony-stimulating factor (G-CSF), are used in both methods, especially, G-CSF which induces the final differentiation of neutrophils in the granulocyte lineage. iPSC-derived neutrophils have been used as a valuable tool for studying rare genetic disorders affecting neutrophils. The iPSC-derived neutrophils can also be used for disease modeling, infection research and drug discovery. However, several challenges must be overcome before iPSC-derived neutrophils can be used therapeutically in transplantation medicine. This review provides an overview of the commonly employed protocols for generating neutrophils from HPCs, ESCs and iPSCs and discusses the potential applications of the generated cells in research and medicine.

Molecular and Functional Characterization of Inhibitor of Apoptosis Proteins (IAP, BIRP) in Echinococcus granulosus

The larval stage of Echinococcus granulosus sensu lato, resulting in cystic echinococcosis, a parasitic zoonosis, causes huge economic losses to the livestock industry and poses a threat to public health. Inhibitor of apoptosis proteins (IAPs) is a class of endogenous anti-apoptotic family, which plays a significant functional role in the regulation of organism’s development. Herein, to explore potential functions of IAPs in E. granulosus, two members of IAPs from E. granulosus (Eg-IAP and Eg-BIRP) were cloned, expressed, and molecularly characterized. Eg-IAP and Eg-BIRP encoded putative 331 and 168 residue proteins, respectively. Bioinformatic analysis showed that both proteins contained a type II BIR domain-the essential functional domain of IAPs. Fluorescence immunohistochemistry revealed that both proteins were ubiquitously localized in all life-cycle stages of E. granulosus. Our fluorescent quantitative PCR (RT-qPCR) results revealed relatively higher transcription levels of two Eg-IAPs in protoscoleces (PSCs) compared to the 18-day strobilated worms. We further used different concentrations of LCL161, a Smac-mimetic pan-IAPs inhibitor, to induce the apoptosis in PSCs in vitro, and revealed that the survival rate of PSCs and transcription levels of both genes were negatively correlated with the concentration of LCL161. While the results of light microscopy, transmission electron microscopy (TEM), and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay also showed a higher apoptotic rate in PSCs with the increasing concentrations of LCL161. Taken together, our findings provide the reasonable evidence that both Eg-IAP and Eg-BIRP have potential implication in critical anti-apoptotic roles during the development of E. granulosus.

Spheroid Coculture of Hematopoietic Stem/Progenitor Cells and Monolayer Expanded Mesenchymal Stem/Stromal Cells in Polydimethylsiloxane Microwells Modestly Improves In Vitro Hematopoietic Stem/Progenitor Cell Expansion

While two-dimensional (2D) monolayers of mesenchymal stem/stromal cells (MSCs) have been shown to enhance hematopoietic stem/progenitor cell (HSPC) expansion in vitro, expanded cells do not engraft long term in human recipients. This outcome is attributed to the failure of 2D culture to recapitulate the bone marrow (BM) niche signal milieu. Herein, we evaluated the capacity of a novel three-dimensional (3D) coculture system to support HSPC expansion in vitro. A high-throughput polydimethylsiloxane (PDMS) microwell platform was used to manufacture thousands of uniform 3D multicellular coculture spheroids. Relative gene expression in 3D spheroid versus 2D adherent BM-derived MSC cultures was characterized and compared with literature reports. We evaluated coculture spheroids, each containing 25-400 MSCs and 10 umbilical cord blood (CB)-derived CD34⁺ progenitor cells. At low exogenous cytokine concentrations, 2D and 3D MSC coculture modestly improved overall hematopoietic cell and CD34⁺ cell expansion outcomes. By contrast, a substantial increase in CD34⁺CD38^- cell yield was observed in PDMS microwell cultures, regardless of the presence or absence of MSCs. This outcome indicated that CD34⁺CD38^- cell culture yield could be increased using the microwell platform alone, even without MSC coculture support. We found that the increase in CD34⁺CD38^- cell yield observed in PDMS microwell cultures did not translate to enhanced engraftment in NOD/SCID gamma (NSG) mice or a modification in the relative human hematopoietic lineages established in engrafted mice. In summary, there was no statistical difference in CD34⁺ cell yield from 2D or 3D cocultures, and MSC coculture support provided only modest benefit in either geometry. While the high-throughput 3D microwell platform may provide a useful model system for studying cells in coculture, further optimization will be required to generate HSPC yields suitable for use in clinical applications.

[Mononuclear cells of umbilical cord blood differentiation to granulocyte cell in vitro]

Objective: To explore an optimal method for granulocyte cell production from umbilical cord blood mononuclear cells. Methods: Erythrocytes were precipitated by hydroxyethyl starch. Mononuclear cells were isolated through Ficoll density gradient centrifugation. Different media, additives and cultivation model were chosen for granulocyte induction. Cell morphology was observed by microscopy, and cell phenotype was detected by flow cytometry. The CD18 expression of granulocytes was tested by immunofluorescence assay, and phagocytosis test was executed as well. Results: Compared to fetal bovine serum (FBS) treatment group, cell viability, counts and differentiation rate of granulocytes induced by X-VIVO(TM) 15 combined with TPO, SCF, G-CSF but without FBS were superior. And X-VIVO(TM)15 medium was better than SCGM medium at effectiveness and cost. Using two-stage mode of hematopoietic stem cell expansion followed by granulocyte induction with X-VIVO(TM)15 combining TPO, SCF and G-CSF, cell proliferation was nearly 132 times at day 21. Flow cytometry showed that the differentiation was lagged in 2-stage mode than in direct induction mode, CD15 expression was (69.60± 1.06) % vs (97.73±0.39) %; Wright-Giemsa staining demonstrated mature granulocytes; immunofluorescence showed the expression of lysosomal proteins CD18. A strong phagocytic function of mature granulocytes was demonstrated by phagotrophic efficiency of (51.43±0.05) %. And granulocyte had chemotaxis ability under the role of chemotactic factor IL-8. Conclusion: Optimized culture media and cultivation mode are achieved for functional granulocytes induction in vitro.

The heterogenic properties of monocytes/macrophages and neutrophils in inflammatory response in diabetes

Inflammation is a complicated biological process in response to harmful stimuli, which involves the cooperation of immune system and vascular system. Upon pathogen invasion or tissue injury, resident innate immune cells such as macrophages and dendritic cells are activated and release inflammatory mediators, which result in the vasodilation and recruitment of leukocytes, mainly monocytes and neutrophils. As two of the most important inflammation-mediating immune cells, macrophages and neutrophils have long been regarded to have a pro-inflammatory effect. However, increasing evidences suggest the role of macrophage and neutrophil in inflammation is more complicated and diversified than we thought. Differently activated macrophages and neutrophils lead to diverse even opposite activities. Precise understanding of the role of different subpopulations is critical to achieve the effective treatment for inflammatory diseases. In this review, we discuss the two potentially distinct activation routes of macrophages and neutrophils in obesity and diabetes.

Concise review: next-generation cell therapies to prevent infections in neutropenic patients

High-dose chemotherapy is accompanied by an obligate period of neutropenia. Resulting bacterial and fungal infections are the leading cause of morbidity and mortality in neutropenic patients despite prophylactic antimicrobials and hematopoietic growth factor supplements. Replacing neutrophils in the patient through transfusion of donor cells is a logical solution to prevent fulminant infections. In the past, this strategy has been hampered by poor yield, inability to store collected cells, and possible donor morbidity caused by granulocyte colony-stimulating factor injections and apheresis. Today, neutrophil-like cells can be manufactured in the laboratory at the clinical scale from hematopoietic stem and progenitor cells enriched from umbilical cord blood. This article reviews the rationale for focusing research efforts toward ex vivo neutrophil production and explores clinical settings for future trials.

The RNA binding protein RBM38 (RNPC1) regulates splicing during late erythroid differentiation

Alternative pre-mRNA splicing is a prevalent mechanism in mammals that promotes proteomic diversity, including expression of cell-type specific protein isoforms. We characterized a role for RBM38 (RNPC1) in regulation of alternative splicing during late erythroid differentiation. We used an Affymetrix human exon junction (HJAY) splicing microarray to identify a panel of RBM38-regulated alternatively spliced transcripts. Using microarray databases, we noted high RBM38 expression levels in CD71⁺ erythroid cells and thus chose to examine RBM38 expression during erythroid differentiation of human hematopoietic stem cells, detecting enhanced RBM38 expression during late erythroid differentiation. In differentiated erythroid cells, we validated a subset of RBM38-regulated splicing events and determined that RBM38 regulates activation of Protein 4.1R (EPB41) exon 16 during late erythroid differentiation. Using Epb41 minigenes, Rbm38 was found to be a robust activator of exon 16 splicing. To further address the mechanism of RBM38-regulated alternative splicing, a novel mammalian protein expression system, followed by SELEX-Seq, was used to identify a GU-rich RBM38 binding motif. Lastly, using a tethering assay, we determined that RBM38 can directly activate splicing when recruited to a downstream intron. Together, our data support the role of RBM38 in regulating alternative splicing during erythroid differentiation.

Granulocyte Transfusion Therapy

Bacterial and fungal infections continue to be a major cause of morbidity and mortality in severely neutropenic patients undergoing aggressive chemotherapy regimens or hematopoietic stem cell transplantation. Traditional granulocyte transfusion therapy, a logical approach in treating these infections, has been available for many years, and several controlled studies have shown this therapy to be useful. However, granulocyte transfusion therapy fell out of favor because the results were not clinically impressive, and adverse results were reported. These disappointing results were felt to be, in part, because of the low doses of granulocytes provided. More recent studies have attempted to increase the numbers of transfused cells by stimulating normal granulocyte donors with G-CSF (+/-corticosteroids). With these techniques, the number of granulocytes transfused can be increased 3-4 fold. The cells have been shown to circulate in recipients, and daily transfusions are capable of maintaining normal or near-normal blood neutrophil counts in previously severely neutropenic patients. The cells appear to function normally by a variety of in vitro and in vivo tests. Clinical benefit, as defined by survival or clearance of infection, has not been definitively determined. Results of an ongoing randomized controlled clinical trial should be available in the near future.

Alternative blood products and clinical needs in transfusion medicine

The primary focus of national blood programs is the provision of a safe and adequate blood supply. This goal is dependent on regular voluntary donations and a regulatory infrastructure that establishes and enforces standards for blood safety. Progress in ex vivo expansion of blood cells from cell sources including peripheral blood, cord blood, induced pluripotent stem cells, and human embryonic stem cell lines will likely make alternative transfusion products available for clinical use in the near future. Initially, alloimmunized patients and individuals with rare blood types are most likely to benefit from alternative products. However, in developed nations voluntary blood donations are projected to be inadequate in the future as blood usage by individuals 60 years and older increases. In developing nations economic and political challenges may impede progress in attaining self-sufficiency. Under these circumstances, ex vivo generated red cells may be needed to supplement the general blood supply.

AUF-1 and YB-1 are critical determinants of β-globin mRNA expression in erythroid cells

The normal accumulation of β-globin protein in terminally differentiating erythroid cells is critically dependent on the high stability of its encoding mRNA. The molecular basis for this property, though, is incompletely understood. Factors that regulate β-globin mRNA within the nucleus of early erythroid progenitors are unlikely to account for the constitutively high half-life of β-globin mRNA in the cytoplasm of their anucleate erythroid progeny. We conducted in vitro protein-RNA binding analyses that identified a cytoplasm-restricted β-globin messenger ribonucleoprotein (mRNP) complex in both cultured K562 cells and erythroid-differentiated human CD34(+) cells. This novel mRNP targets a specific guanine-rich pentanucleotide in a region of the β-globin 3'untranslated region that has recently been implicated as a determinant of β-globin mRNA stability. Subsequent affinity-enrichment analyses identified AUF-1 and YB-1, 2 cytoplasmic proteins with well-established roles in RNA biology, as trans-acting components of the mRNP. Factor-depletion studies conducted in vivo demonstrated the importance of the mRNP to normal steady-state levels of β-globin mRNA in erythroid precursors. These data define a previously unrecognized mechanism for the posttranscriptional regulation of β-globin mRNA during normal erythropoiesis, providing new therapeutic targets for disorders of β-globin gene expression.