Flow Cytometry-based Cell Sorting Research Articles

Genome-Wide Screening Approaches for Biochemical Reactions Independent of Cell Growth.

Genome-wide screening is a potent approach for comprehensively understanding the molecular mechanisms of biological phenomena. However, despite its widespread use in the past decades across various biological targets, its application to biochemical reactions with temporal and reversible biological outputs remains a formidable challenge. To uncover the molecular machinery underlying various biochemical reactions, we have recently developed the revival screening method, which combines flow cytometry-based cell sorting with library reconstruction from collected cells. Our refinements to the traditional genome-wide screening technique have proven successful in revealing the molecular machinery of biochemical reactions of interest. In this article, we elucidate the technical basis of revival screening, focusing on its application to CRISPR-Cas9 single guide RNA (sgRNA) library and complementary DNA (cDNA) library screening. Finally, we also discuss the future of genome-wide screening while describing recent achievements from in vitro and in vivo screening.

Stratifying macrophages based on their infectious burden identifies novel host targets for intervention during Crohn's disease associated adherent-invasive Escherichia coli infection.

Bacterial infection is a dynamic process resulting in a heterogenous population of infected and uninfected cells. These cells respond differently based on their bacterial load and duration of infection. In the case of infection of macrophages with Crohn's disease (CD) associated adherent-invasive Escherichia coli (AIEC), understanding the drivers of pathogen success may allow targeting of cells where AIEC replicate to high levels. Here we show that stratifying immune cells based on their bacterial load identifies novel pathways and therapeutic targets not previously associated with AIEC when using a traditional homogeneous infected population approach. Using flow cytometry-based cell sorting we stratified cells into those with low or high intracellular pathogen loads, or those which were bystanders to infection. Immune cells transcriptomics revealed a diverse response to the varying levels of infection while pathway analysis identified novel intervention targets that were directly related to increasing intracellular AIEC numbers. Chemical inhibition of identified targets reduced AIEC intracellular replication or inhibited secretion of tumour necrosis factor alpha (TNFα), a key cytokine associated with AIEC infection. Our results have identified new avenues of intervention in AIEC infection that may also be applicable to CD through the repurposing of already available inhibitors. Additionally, they highlight the applicability of immune cell stratification post-infection as an effective approach for the study of microbial pathogens.

Decorin suppresses stemness and migration potential of malignant peripheral nerve sheath tumor through inhibiting epidermal growth factor receptor signaling

Cancer stem cells (CSCs) play pivotal roles in the growth, invasion, metastasis, chemo-resistance in malignant peripheral nerve sheath tumor (MPNST). The current characterization of CSCs in MPNST is not complete. Decorin is a critical regulator of microenvironment, but its expression and function in CSCs of MPNST has not been studied. In the current study, Decorin levels and its relationship with lung and liver metastasis were determined in clinical specimens. Decorin expression in CD133-positive or CD44-positive CSCs was analyzed by RT-qPCR on cytospun MPNST cells after flow cytometry-based cell sorting. Decorin-positive cells were separated from Decorin-negative cells in transfected MPNST cell lines using a designed plasmid expressing red fluorescent protein (RFP) under a Decorin promoter. Tumor sphere formation, tumor growth, cell invasion, cell migration, and the resistance to chemotherapy-induced apoptosis were determined on Decorin-positive versus Decorin-negative MPNST cells. In vivo tumor growth was analyzed in mice receiving subcutaneous transplantation of Decorin-positive versus Decorin-negative MPNSTs. We found that Decorin levels were significantly downregulated in MPNST specimens, compared to non-tumorous adjacent tissue. Significantly lower Decorin levels were detected in MPNSTs with lung or liver metastasis compared to those without. Poorer patient survival was detected in Decorin-low MPNST, compared to Decorin-high subjects. More Decorin-negative cells were detected in CD133-positive MPNST cells than CD133-negative MPNST cells, and in CD44-positive MPNST cells than in CD44-negative MPNST cells. Compared to Decorin-positive MPNST cells, Decorin-negative MPNST cells generated significantly more tumor spheres in culture, were more invasive and migratory, and were more resistant to chemotherapy-induced apoptosis, likely due to the inhibition of epidermal growth factor receptor signaling by Decorin. Decorin-negative MPNST cells grew significantly larger tumor in vivo. Thus, depletion of Decorin may occur in CSCs in MPNSTs, serving possibly as a new therapeutic target.

Engineering of CD34+ progenitor-derived natural killer cells with higher-affinity CD16a for enhanced antibody-dependent cellular cytotoxicity

Background aimsNatural killer (NK) cell transfer is a promising cellular immunotherapy for cancer. Previously, we developed a robust method to generate large NK cell numbers from CD34+ hematopoietic stem and progenitor cells (HSPCs), which exhibit strong anti-tumor activity. However, since these cells express low levels of the Fc receptor CD16a in vitro, antibody-dependent cellular cytotoxicity (ADCC) by these cells is limited. To broaden clinical applicability of our HSPC-NK cells toward less NK-sensitive malignancies, we aimed to improve ADCC through CD16a transduction. MethodsUsing wildtype and S197P mutant greater-affinity (both with V158) CD16a retroviral transgenes (i.e., a cleavable and noncleavable CD16a upon stimulation), we generated CD16a HSPC-transduced NK cells, with CD34+ cells isolated from umbilical cord blood (UCB) or peripheral blood after G-CSF stem cell mobilization (MPB). CD16a expressing NK cells were enriched using flow cytometry–based cell sorting. Subsequently, phenotypic analyses and functional assays were performed to investigate natural cytotoxicity and ADCC activity. ResultsMean transduction efficiency was 34% for UCB-derived HSPCs and 20% for MPB-derived HSPCs, which was enriched by flow cytometry-based cell sorting to >90% for both conditions. Expression of the transgene remained stable during the entire NK expansion cell generation process. Proliferation and differentiation of HSPCs were not hampered by the transduction process, resulting in effectively differentiated CD56+ NK cells after 5 weeks. Activation of the HSPC-derived NK cells resulted in significant shedding of wildtype CD16a transcribed from the endogenous gene, but not of the noncleavable mutant CD16a protein expressed from the transduced construct. The mean increase of CD107+IFNγ+ expressing NK cells after inducing ADCC was tenfold in enriched noncleavable CD16a HSPC-NK cells. Killing capacity of CD16a-transduced NK cells was significantly improved after addition of a tumor-targeting antibody in tumor cell lines and primary B-cell leukemia and lymphoma cells compared to unmodified HSPC-NK cells. ConclusionsTogether, these data demonstrate that the applicability of adoptive NK cell immunotherapy may be broadened to less NK-sensitive malignancies by upregulation of CD16a expression in combination with the use of tumor-targeting monoclonal antibodies.

Targeted genome engineering based on CRISPR/Cas9 system to enhance FVIII expression in vitro

BackgroundHemophilia A is caused by a deficiency of coagulation factor VIII in the body due to a defect in the F8 gene. The emergence of CRISPR/Cas9 gene editing technology will make it possible to alter the expression of the F8 gene in hemophiliacs, while achieving a potential cure for the disease. MethodsInitially, we identified high-activity variants of FVIII and constructed donor plasmids using enzymatic digestion and ligation techniques. Subsequently, the donor plasmids were co-transfected with sgRNA-Cas9 protein into mouse Neuro-2a cells, followed by flow cytometry-based cell sorting and puromycin selection. Finally, BDD-hF8 targeted to knock-in the mROSA26 genomic locus was identified and validated for FVIII expression. ResultsWe identified the p18T-BDD-F8-V3 variant with high FVIII activity and detected the strongest pX458-mROSA26-int1-sgRNA1 targeted cleavage ability and no cleavage events were found at potential off-target sites. Targeted knock-in of BDD-hF8 cDNA at the mROSA26 locus was achieved based on both HDR/NHEJ gene repair approaches, and high level and stable FVIII expression was obtained, successfully realizing gene editing in vitro. ConclusionsKnock-in of exogenous genes based on the CRISPR/Cas9 system targeting genomic loci is promising for the research and treatment of a variety of single-gene diseases.

Flow Cytometry-Based Cell Sorting for Different Circulatory B Cell Populations

Flow Cytometry-Based Cell Sorting for Different Circulatory B Cell Populations

Flow Cytometry-Based Cell Sorting for Different Circulatory B Cell Populations

Flow Cytometry-Based Cell Sorting for Different Circulatory B Cell Populations

A Simplified Approach to Evaluating T Cell Development by Flow Cytometry.

T cell development is a complex multistep process that requires the coordinated activation of distinct signaling responses and the regulated progression of developing cells (thymocytes) through key stages of maturation. Although sophisticated techniques such as fetal thymus organ culture, in vitro thymocyte culture, and multiparameter flow cytometry-based cell sorting are now widely employed to evaluate thymocyte maturation by experienced laboratories, defects in T cell development can usually be identified with relatively simple flow cytometry screening methods. Here, we provide a basic protocol for assessment of T cell development that will enable laboratories with access to a multi-laser flow cytometer to screen mouse strains, including those generated from embryonic stem cells with targeted gene mutations, for thymocyte maturation defects.

A Candidate Therapeutic Monoclonal Antibody Inhibits Both HRSV and HMPV Replication in Mice.

Human metapneumovirus (HMPV) and human respiratory virus (HRSV) are two leading causes of acute respiratory tract infection in young children. While there is no licensed drug against HMPV, the monoclonal antibody (mAb) Palivizumab is approved against HRSV for prophylaxis use only. Novel therapeutics against both viruses are therefore needed. Here, we describe the identification of human mAbs targeting these viruses by using flow cytometry-based cell sorting. One hundred and two antibodies were initially identified from flow cytometry-based cell sorting as binding to the fusion protein from HRSV, HMPV or both. Of those, 95 were successfully produced in plants, purified and characterized for binding activity by ELISA and neutralization assays as well as by inhibition of virus replication in mice. Twenty-two highly reactive mAbs targeting either HRSV or HMPV were isolated. Of these, three mAbs inhibited replication in vivo of a single virus while one mAb could reduce both HRSV and HMPV titers in the lung. Overall, this study identifies several human mAbs with virus-specific therapeutic potential and a unique mAb with inhibitory activities against both HRSV and HMPV.

Gene expression in meningeal lymphatic endothelial cells following traumatic brain injury in mice.

Meningeal lymphatic vessels transport both the cerebrospinal fluid and interstitial fluid to the deep cervical lymph nodes. Traumatic brain injury (TBI) is accompanied by meningeal injury. We hypothesized that the TBI-induced meningeal injury would damage lymphatic vessels and affect brain function. We observed altered gene expression in meningeal lymphatic endothelial cells (LECs) in a mouse model of TBI. Through flow cytometry–based cell sorting, meningeal LECs were obtained from a mouse model of controlled cortical impact 3 days after TBI. Microarray analysis, real-time polymerase chain reaction assays, and enzyme-linked immunosorbent assays were performed to determine mRNA and protein expression levels in meningeal LECs. The number of meningeal LECs was significantly lower in the injury group than in the sham group 3 days after TBI. Additionally, the mRNA expression of lymphatic vessel endothelial hyaluronan receptor 1 (a specific marker of lymphatic vessels) in meningeal LECs was significantly lower in the injury group than in the sham group. The mRNA and protein expression of FMS-like tyrosine kinase 4 and neuropilin 2 (markers of lymphangiogenesis) in meningeal LECs was significantly higher in the injury group than in the sham group. Our findings indicate that TBI is associated with the impairment of meningeal LECs and meningeal lymphangiogenesis, which implicates lymphatic vessel injury in the pathogenesis of this condition.

GFAT1 is highly expressed in cancer stem cells of pancreatic cancer.

BackgroundCancer stem cells (CSCs) play pivotal roles in the growth, invasion, metastasis, and chemoresistance of pancreatic cancer (PC). The current characterization of CSCs in PC is not complete. Glutamine-fructose-6-phosphate transaminase 1 (GFAT1) is a key enzyme that regulates the hexosamine pathway (HP), in which it not only controls glucose influx but also catalyzes the reaction to form glucosamine 6-phosphate. Recently, it was reported that GFAT1 is highly expressed in PC. However, the relevance of this high expression of GFAT1, especially its association with cancer stemness, has not been well defined and is thus addressed in the current study.MethodsGFAT1 levels were determined in PC from a public database and assessed by bioinformatics tools. GFAT1 expression in CD133+ and CD44+ CSCs in PC was analyzed by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and immunostaining on cytospun cells after flow cytometry-based cell sorting. GFAT1+ cells were separated from GFAT1− cells by transfection of PC cell lines with a designed plasmid that expressed red fluorescent protein (RFP) under a GFAT1 promoter. Tumor sphere formation, tumor growth, tumor cell invasion, cell migration, and the resistance to gemcitabine-induced apoptosis were determined in GFAT1+ vs. GFAT1− PC cells.ResultsGFAT1 levels were significantly upregulated in PC compared to the adjacent non-PC tissue. There were significantly more GFAT1+ cells in the CD133+ population than in the CD133− population, and similarly, there were significantly more GFAT1+ cells in the CD44+ population than in the CD44− population. Compared to GFAT1− PC cells, GFAT1+ PC cells generated significantly more tumor spheres in culture, appeared to be more invasive and migratory, and were significantly more resistant to gemcitabine-induced cell apoptosis.ConclusionsGFAT1 is highly expressed in CSCs among PC cells and may be crucial for PC growth, metastasis, and chemoresistance.

Production of PfEMP1-Specific Human Monoclonal Antibodies from Naturally Immune Individuals.

Plasmodium falciparum parasites express variable surface antigens on the infected erythrocyte surface allowing adhesion to human host receptors on the blood and endothelial cells, which can result in immune evasion. One of the most studied and key antigens in adhesion is the highly polymorphic PfEMP1. However, despite the vast variation in the PfEMP1 antigens, they are the main targets of naturally acquired immunity and are therefore promising candidates for malaria vaccine development. Generating PfEMP1-specific human monoclonal antibodies from naturally immune individuals will help to determine the best targets of protection from clinical disease. Immortalization of human B cells is one of the oldest and most efficient techniques to generate human monoclonal antibodies. Nevertheless, most protocols require flow cytometry-based cell sorting, which can be a limiting factor for many laboratories. This chapter describes an efficient protocol for the generation of PfEMP1-specific human monoclonal antibodies from malaria immune individuals that can be performed without the use of advanced cell-sorting techniques.

Ex Vivo IL-2 Treatment Increases the Immunosuppressive Subset of T Lymphocytes to Suppress Allo-Immune Response

T lymphocytes are critical players in graft-versus-host disease (GVHD); however, their specific roles and mechanisms in GVHD have not been clearly defined. Co-inhibitory receptors including PD1, TIM3, TIGIT, and LAG3 play a key role in regulating T cell responses and maintaining immune homeostasis. TIM3 expression on lymphocytes was identified to induce immune tolerance in a mouse GVHD model; in addition, PD1 +TIM3 + double-positive T cells displayed more potent immunosuppression compared to PD1 + T cells. However, despite the strong immunosuppression exerted by PD1 +TIM3 + double-positive T cells, their clinical potential is greatly limited by their low cell number in peripheral blood. In this study, we introduce a novel method to isolate CD3 + cells from G-CSF mobilized peripheral blood stem cells (G-PBSCs), and culture CD3 +PD1 +TIM3 + lymphocytes to treat GVHD.Methods. The donors were subcutaneously injected with G-CSF (10μg/kg) for five days. G-PBSCs were collected from the donors using a COBE spectra cell separator. Then, the highly purified CD3 + cells were isolated by positive selection with magnetic-activated cell sorting (MACS) from G-PBSCs using CD3 Dynabeads™. Isolated CD3 + cells were cultured with a low concentration of IL-2 (50U/mL), and PD1, TIM3, LAG3, and TIGIT expressions were assessed using flow cytometry (FACS). CD3 +PD1 +TIM3 +, CD3 +PD1 +TIM3 +LAG3 +TIGIT - and CD3 +PD1 +TIM3 +LAG3 +TIGIT +cells are sorted and cultured with irradiated allo-MNCs for 4 days (Mixed Lymphocyte Reaction; MLR). We used 5,6-carboxyfluorescein diacetate succinimidyl ester (CFSE) as an intracellular fluorescent dye in MLR (CFSE-MLR) to measure of T cells proliferation.Results. In normal, untreated G-PBSCs, very low percentages of cells are CD3 +PD1 +TIM3 +, CD3 +PD1 +LAG3 + and CD3 +PD1 +TIGIT + (0.6±0.4, 0.3±0.2 and 1.3±0.5% in G-PBSC, respectively). However, after treating G-PBSC cells with a low concentration of IL-2 (50 U/mL), we discovered the percentages of CD3 +PD1 +TIM3 +, CD3 +PD1 +LAG3 +, and CD3 +PD1 +TIGT + lymphocytes in G-PBSCs markedly increased by 19.6±5.9, 18.5±4.3, 17.7±6.5%, respectively. Of note, there was a very small change (~1.2 fold increase) in the total number of CD3 + lymphocytes, which indicates that the low dose IL-2 therapy alters subpopulations of T lymphocytes, rather than increasing the proliferation rate. Next, we tested the immunosuppressive capacity of the cultured CD3 +PD1 +TIM3 +cells. To do this, we used CSFE-MLR to measure T cell proliferation. CD3 +PD1 +TIM3 + lymphocytes were depleted in CD3 + G-PBSCs by flow cytometry-based cell sorting. Then we cultured the CD3 + G-PBSCs with allo-MNCs and discovered that the CD3 + G-PBSCs that lacked CD3 +PD1 +TIM3 + lymphocytes demonstrated a significantly increased level of T-cell proliferation compared to CD3 + G-PBSCs, and thereby confirming the immunosuppressive function of CD3 +PD1 +TIM3 + lymphocytes in inhibiting T cell proliferation (% of unstimulated T cells in CD3 + G-PBSCs vs. in CD3 +PD1 +TIM3 + depleted G-PBSC CD3 + cells; 33.5±7.5% vs. 6.3±4.2%).After confirming the immunosuppressive function of the IL-2 treated CD3 +PD1 +TIM3 + lymphocytes, we investigated expressions of other co-inhibitory surface markers such as LAG3 and TIGIT. Amongst the cultured CD3 +PD1 +TIM3 + lymphocytes, 96.2±3.3% of the CD3 +PD1 +TIM3 + lymphocytes were LAG3 +, 28.9±5.4% of the CD3 +PD1 +TIM3 + lymphocytes were TIGIT +, and 63.7±7.8% of the cells were TIGIT -. Interestingly, CD3 +PD1 +TIM3 +LAG3 +TIGIT - lymphocytes demonstrated significantly enhanced levels of immunosuppression compared to CD3 +PD1 +TIM3 +LAG3 +TIGIT + lymphocytes (% of unstimulated T cells in CD3 +PD1 +TIM3 +LAG3 +TIGIT - lymphocytes vs. in CD3 +PD1 +TIM3 +LAG3 +TIGIT + lymphocytes, 53.8±5.5% vs. 23.2±7.4%).Conclusion.We demonstrate that treating CD3 + G-PBSCs with low-dose IL-2 markedly increases the percentage of CD3 +PD1 +TIM3 + lymphocytes, which is known to exert strong immunosuppression. Also, we suggest that CD3 +PD1 +TIM3 +LAG3 +TIGIT - lymphocytes are the subpopulation within CD3 +PD1 +TIM3 + cells that demonstrate the most potent immunosuppression compared to other subpopulations of CD3 +PD1 +TIM3 + lymphocytes. Taken together, such findings suggest that the low-dose IL-2 therapy has therapeutic potential to treat patients with GVHD. DisclosuresNo relevant conflicts of interest to declare.

Nanobody Activators of Von Willebrand Factor Via Targeting Its Autoinhibitory Module

Introduction: Von Willebrand factor (VWF) is a multimeric plasma glycoprotein responsible for platelet arrest during injury, especially at high shear. After immobilization to the vessel wall, a VWF multimer is unfurled and elongated. This leads to exposure of the A1 domain therein that in turn binds to platelet receptor GPIbα and starts the aggregation process. Recently, it was suggested that VWF activation involves force-dependent disruption of the autoinhibitory module (AIM) that flanks the A1 domain on both sides. In this scenario, the AIM could be targeted for both VWF inhibition (Caplacizumab) and activation (ristocetin), although the exact mechanism and binding site of ristocetin still remains murky. If the quasi-stable structure of the AIM is important to VWF autoinhibition, specific disruption of its confirmation may be able to activate VWF. To this end, we sought to identify AIM-targeting activators using yeast surface display of a llama nanobody library.Methods: One adult Lama glama was immunized with recombinant human VWF AIM-A1 protein produced from transfected Expi293F cells. VHH specific genes were amplified from cDNAs prepared from PBMCs of the animal and electroporated into EBY100 cells. The resulting yeast display library was screened for AIM-specific binders via selection against binding to recombinant A1 protein without an intact AIM, and then for binding to the complex of AIM-A1 with GPIbα. Positive hits were produced as His-tagged monomeric nanobodies in E. coli and purified with nickel-affinity and gel filtration chromatography. The affinity of nanobodies to AIM-A1 was determined using bio-layer interferometry. Platelet-rich plasma from healthy donors was used to assess the effect of nanobodies on platelet aggregation in a light transmission aggregometer with comparison to that of ristocetin.Results: An AIM-A1-specific nanobody yeast display library was established. Several rounds of flow cytometry-based cell sorting of yeast cells with aforementioned binding properties produced AIM-binding nanobodies. Nanobodies encoded in three single clones have been expressed from E. coli and they exhibited differential binding affinities towards AIM-A1. Clone 6C4 showed the lowest affinity (K D 120 ± 3 nM), 6D12 showed intermediate affinity (K D 31 ± 0.8 nM), and 6C11 showed the highest affinity (K D 13.5 ± 0.2 nM) as shown in Figure 1. These nanobodies showed no detectable affinity towards recombinant A1-CAIM protein (residues 1268-1493), indicating that their epitopes are located in the N-terminal portion of the AIM (residues 1238-1267).When added to human platelet-rich plasma, each nanobody dose-dependently activated platelets and rapidly induced full platelet aggregation at concentrations exceeding the affinity of the nanobody for VWF (Figure 2). The aggregation could be inhibited by the addition of antibodies that block the interaction between VWF and GPIbα. Plots of extents of aggregation as a function of nanobody concentration produced EC 50 values of ~100 nM for 6C11 and 6D12.Conclusion: By isolating nanobodies that can bind specifically to the AIM and activate plasma VWF, we add supporting evidence that the AIM protects the A1 domain from binding to platelets. Interestingly, these nanobodies bind to the NAIM, on the opposite side of the module compared to ristocetin, the only known AIM-activating agent until now. With higher VWF-binding affinities than ristocetin and a robust profile as stable monomers, these nanobodies may prove useful in VWF-related research and diagnostics. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Human Primary Airway Basal Cells Display a Continuum of Molecular Phases from Health to Disease in Chronic Obstructive Pulmonary Disease.

Airway basal cells are crucial for regeneration of the human lung airway epithelium and are believed to be important contributors to chronic obstructive pulmonary disease (COPD) and other lung disorders. To reveal how basal cells contribute to disease and to discover novel therapeutic targets, these basal cells need to be further characterized. In this study, we optimized a flow cytometry-based cell sorting protocol for primary human airway basal cells dependent on cell size and NGFR (nerve-growth factor receptor) expression. The basal cell population was found to be molecularly and functionally heterogeneous, in contrast to cultured basal cells. In addition, significant differences were found, such as KRT14 expression exclusively existing in cultured cells. Also, colony-forming capacity was significantly increased in cultured cells showing a clonal enrichment in vitro. Next, by single-cell RNA sequencing on primary basal cells from healthy donors and patients with Global Initiative for Chronic Obstructive Lung Disease stage IV COPD, the gene expression revealed a continuum ranging from healthy basal cell signatures to diseased basal cell phenotypes. We identified several upregulated genes that may indicate COPD, such as stress response-related genes GADD45B and AHSA1, together with with genes involved in the response to hypoxia, such as CITED2 and SOD1. Taken together, the presence of healthy basal cells in stage IV COPD demonstrates the potential for regeneration through the discovery of novel therapeutic targets. In addition, we show the importance of studying primary basal cells when investigating disease mechanisms as well as for developing future cell-based therapies in the human lung.

A method for high-purity isolation of neutrophil granulocytes for functional cell migration assays

Abstract Background Neutrophil-mediated killing of pathogens is one of the most significant functions of the primary defense of the host. Neutrophil activity and migration play a key role in inflammatory conditions. To gain insights into the interactions between neutrophils and neutrophil migration-related disorders, a large number of sophisticated methods have been developed. The technical limitations of isolating highly purified neutrophil populations, minimizing both cell death and activation during the isolation process, and the short lifespan of neutrophils present challenges for studying specific functions of neutrophils in vitro. In this study, we aimed to evaluate a separation medium-based density gradient method to obtain highly purified neutrophil populations and combined this protocol with a model for studying neutrophil migration in-vitro. Materials and methods Human granulocytes were isolated using Lympholyte-poly solution. The purity and viability of isolated neutrophils were assessed by flow cytometry and morphological analysis. Neutrophil activation was confirmed by immunocytochemistry. Lastly, filter assay was performed to measure neutrophil chemotaxis. Results and discussion All validation experiments revealed that this method was capable of generating a highly purified neutrophil population for further functional in-vitro assays. Consequently, this study demonstrates a quick, cost effective, and easy-to-follow model, and may be a significant alternative to isolation methods that need extra subsequent steps such as flow cytometry-based cell sorting for reaching highly purified neutrophil population. Conclusion The suggested combination of methods for the isolation and cell migration analysis of human neutrophils is highly recommended to use for disease models involving neutrophil migration such as autoinflammatory disorders.

Targeted in-vitro-stimulation reveals highly proliferative multi-virus-specific human central memory T cells as candidates for prophylactic T cell therapy.

Adoptive T cell therapy (ACT) has become a treatment option for viral reactivations in patients undergoing allogeneic hematopoietic stem cell transplantation (alloHSCT). Animal models have shown that pathogen-specific central memory T cells (TCM) are protective even at low numbers and show long-term survival, extensive proliferation and high plasticity after adoptive transfer. Concomitantly, our own recent clinical data demonstrate that minimal doses of purified (not in-vitro- expanded) human CMV epitope-specific T cells can be sufficient to clear viremia. However, it remains to be determined if human virus-specific TCM show the same promising features for ACT as their murine counterparts. Using a peptide specific proliferation assay (PSPA) we studied the human Adenovirus- (AdV), Cytomegalovirus- (CMV) and Epstein-Barr virus- (EBV) specific TCM repertoires and determined their functional and proliferative capacities in vitro. TCM products were generated from buffy coats, as well as from non-mobilized and mobilized apheresis products either by flow cytometry-based cell sorting or magnetic cell enrichment using reversible Fab-Streptamers. Adjusted to virus serology and human leukocyte antigen (HLA)-typing, donor samples were analyzed with MHC multimer- and intracellular cytokine staining (ICS) before and after PSPA. TCM cultures showed strong proliferation of a plethora of functional virus-specific T cells. Using PSPA, we could unveil tiniest virus epitope-specific TCM populations, which had remained undetectable in conventional ex-vivo-staining. Furthermore, we could confirm these characteristics for mobilized apheresis- and GMP-grade Fab-Streptamer-purified TCM products. Consequently, we conclude that TCM bare high potential for prophylactic low-dose ACT. In addition, use of Fab-Streptamer-purified TCM allows circumventing regulatory restrictions typically found in conventional ACT product generation. These GMP-compatible TCM can now be used as a broad-spectrum antiviral T cell prophylaxis in alloHSCT patients and PSPA is going to be an indispensable tool for advanced TCM characterization during concomitant immune monitoring.

Remission clone in acute myeloid leukemia shows growth advantage after chemotherapy but is distinct from leukemic clone

In a previously published case study of acute myeloid leukemia, we tracked the dynamics of somatic mutations over 9 years. Interestingly, we observed a group of mutations that expanded during remission, which we named the "remission clone." To determine the nature of the remission clones, we performed flow cytometry-based cell sorting followed by ultradeep sequencing. The remission clone repeatedly expanded after chemotherapeutic cycles and was suppressed during relapse in the myeloid lineage (multipotent hematopoietic stem, progenitor, and myeloid cells). On the other hand, the remission clone was consistently observed in lymphoid lineages (B and T cells) regardless of the disease state. When transfected into the HEK-293 cell line, the NR2C2(A93V) mutant exhibited a growth advantage (all p values < 0.05). The results indicate that the remission clone seems to be another form of clonal hematopoiesis, but without a clear association with leukemia. As the remission clone is present in both myeloid and lymphoid lineages, it likely originates from ancestral hematopoietic cell lineages. More importantly, the remission clone is distinct from the leukemic clone; therefore, mutations expanded during remission require special interpretation when performing next-generation sequencing-based measurable residual disease assessment.

Histone acetyltransferase CBP is critical for conventional effector and memory T-cell differentiation in mice

Compared with naïve T cells, memory CD8+ T cells have a transcriptional landscape and proteome that are optimized to generate a more rapid and robust response to secondary infection. Additionally, rewired kinase signal transduction pathways likely contribute to the superior recall response of memory CD8+ T cells, but this idea has not been experimentally confirmed. Herein, we utilized an MS approach to identify proteins that are phosphorylated on tyrosine residues in response to Listeria-induced T-cell receptor (TCR) stimulation in both naïve and memory CD8+ T cells from mice and separated by fluorescence- and flow cytometry-based cell sorting. This analysis identified substantial differences in tyrosine kinase signaling networks between naïve and memory CD8+ T cells. We also observed that an important axis in memory CD8+ T cells couples Janus kinase 2 (JAK2) hyperactivation to the phosphorylation of CREB-binding protein (CBP). Functionally, JAK2-catalyzed phosphorylation enabled CBP to bind with higher affinity to acetylated histone peptides, indicating a potential epigenetic mechanism that could contribute to rapid initiation of transcriptional programs in memory CD8+ T cells. Moreover, we found that CBP itself is essential for conventional effector and memory CD8+ T-cell formation. These results indicate how signaling pathways are altered to promote CD8+ memory cell formation and rapid responses to and protection from repeat infections.

Parts Characterization for Tunable Protein Expression.

Flow-seq combines flexible genome engineering methods with flow cytometry-based cell sorting and deep DNA sequencing to enable comprehensive interrogation of genotype to phenotype relationships. One application is to study the effect of specific regulatory elements on protein expression. Constructing targeted genomic variation around genomically integrated fluorescent marker genes enables rapid elucidation of the contribution of specific sequence variants to protein expression. Such an approach can be used to characterize the impact of modifications to the Shine-Dalgarno sequence in Escherichia coli.