Live cell pool and rare cell isolation using Enrich TROVO system

Although several technologies have been developed to isolate cells of interest from a heterogenous sample, clogging and impaired cell viability limit such isolation. We have developed the Enrich TROVO system as a novel, nonfluidic technology to sort live cells. The TROVO system combines imaging-based cell selection and photo-crosslinking of (gelatin methacrylate) gelMA-hydrogel to capture cells. After capture, cells are released by enzymatic digestion of the hydrogel and then retrieved for downstream analysis or further cell culturing. The system can capture cells with a recovery rate of 48% while maintaining 90% viability. Moreover, TROVO can enrich rare cells 506-fold with 93% efficiency using single step isolation from a 1:104 cell mixture, and can also capture one target cell from 1 million cells, reaching an enrichment ratio of 9128. In addition, 100% purity and 49% recovery rate can be achieved by a following negative isolation process. Compared to existing technologies, the TROVO system is clog-resistant, highly biocompatible, and can process a wide range of sample sizes.

In a century from agitated cells to human organoids

Reaching back more than a century, suspension cultures have provided major insights into processes of histogenesis; e.g., cell communication, distinction of self/nonself, cell sorting and cell adhesion. Besides studies on lower animals, the vertebrate retina served as excellent reaggregate model to analyze 3D reconstruction of a complex neural laminar tissue. Methodologically, keeping cells under suspension is essential to achieve tissue organisation in vitro; thereby, the environmental conditions direct the emergent histotypic particulars. Recent progress in regenerative medicine is based to a large extent on human induced pluripotent stem cells (hiPSCs), which are cultured under suspension. Following their genetically directed differentiation into various histologic 3D structures, organoids provide excellent multipurpose in vitro assay models, as well as tissues for repair transplantations. Historically, a nearly fully laminated retinal spheroid from avian embryos was achieved already in 1984, foreshadowing the potential of culturing stem cells under suspension for tissue reconstruction purposes.

IL-33-ST2 signaling in fibro-adipogenic progenitors alleviates immobilization-induced muscle atrophy in mice

BACKGROUND

The regenerative and adaptive capacity of skeletal muscles reduces with age, leading to severe disability and frailty in the elderly. Therefore, development of effective therapeutic interventions for muscle wasting is important both medically and socioeconomically. In the present study, we aimed to elucidate the potential contribution of fibro-adipogenic progenitors (FAPs), which are mesenchymal stem cells in skeletal muscles, to immobilization-induced muscle atrophy.

METHODS

Young (2-3 months), adult (12-14 months), and aged (20-22 months) mice were used for analysis. Muscle atrophy was induced by immobilizing the hind limbs with a steel wire. FAPs were isolated from the hind limbs on days 0, 3, and 14 after immobilization for transcriptome analysis. The expression of ST2 and IL-33 in FAPs was evaluated by flow cytometry and immunostaining, respectively. To examine the role of IL-33-ST2 signaling in vivo, we intraperitoneally administered recombinant IL-33 or soluble ST2 (sST2) twice a week throughout the 2-week immobilization period. After 2-week immobilization, the tibialis anterior muscles were harvested and the cross-sectional area of muscle fibers was evaluated.

RESULTS

The number of FAPs increased with the progression of muscle atrophy after immobilization in all age-groups. Transcriptome analysis of FAPs collected before and after immobilization revealed that Il33 and Il1rl1 transcripts, which encode the IL-33 receptor ST2, were transiently induced in young mice and, to a lesser extent, in aged mice. The number of FAPs positive for ST2 increased after immobilization in young mice. The number of ST2-positive FAPs also increased after immobilization in aged mice, but the difference from the baseline was not statistically significant. Immunostaining for IL-33 in the muscle sections revealed a significant increase in the number of FAPs expressing IL-33 after immobilization. Administration of recombinant IL-33 suppressed immobilization-induced muscle atrophy in aged mice but not in young mice.

CONCLUSIONS

Our data reveal a previously unknown protective role of IL-33-ST2 signaling against immobilization-induced muscle atrophy in FAPs and suggest that IL-33-ST2 signaling is a potential new therapeutic target for alleviating disuse muscle atrophy, particularly in older adults.

Microfluidic technology for cell biology-related applications: a review

Fluid flow at the microscale level exhibits a unique phenomenon that can be explored to fabricate microfluidic devices integrated with components that can perform various biological functions. In this manuscript, the importance of physics for microscale fluid dynamics using microfluidic devices has been reviewed. Microfluidic devices provide new opportunities with regard to spatial and temporal control over cell growth. Furthermore, the manuscript presents an overview of cellular stimuli observed by combining surfaces that mimic the complex biochemistries and different geometries of the extracellular matrix, with microfluidic channels regulating the transport of fluids, soluble factors, etc. We have also explained the concept of mechanotransduction, which defines the relation between mechanical force and biological response. Furthermore, the manipulation of cellular microenvironments by the use of microfluidic systems has been highlighted as a useful device for basic cell biology research activities. Finally, the article focuses on highly integrated microfluidic platforms that exhibit immense potential for biomedical and pharmaceutical research as robust and portable point-of-care diagnostic devices for the assessment of clinical samples.

Sorting Technology for Mesenchymal Stem Cells from a Single Tissue Source

Mesenchymal stem cells (MSCs) are adult stem cells that can be obtained, enriched and proliferated in vitro. They owned enormous potential in fields like regenerative medicine, tissue engineering and immunomodulation. However, though isolated from the same origin, MSCs are still essentially heterogeneous cell populations with different phenotypes and functions. This heterogeneity of MSCs significantly affects their therapeutic efficacy and brings obstacles to scientific research. Thus, reliable sorting technology which can isolate or purify MSC subpopulations with various potential and differentiation pathways is urgently needed. This review summarized principles, application status and clinical implications for these sorting methods, aiming at improving the understanding of MSC heterogeneity as well as providing fresh perspectives for subsequent clinical applications.

Co-staining with Fluorescent Antibodies and Antibody-Derived Tags for Cell Sorting Prior to CITE-Seq

The paired detection of the transcriptome and proteome at single-cell resolution provides exquisite insight to immune mechanisms in health and disease. Here, we describe a detailed protocol wherein we combine cellular indexing of transcriptomes and epitopes by sequencing (CITE-Seq), a technique utilizing antibody-derived tags (ADTs) to profile mRNA and proteins simultaneously via sequencing, with fluorescence-activated cell sorting to enrich cell populations. Our protocol provides step-by-step guidance on co-staining cells with both fluorescent antibodies and ADTs simultaneously, instructions on cell sorting and an overview of the single-cell capture workflow using the BD Rhapsody™ system. This method is useful for in-depth single-cell characterization on sorted rare cell populations.

Isolation and Immunophenotyping of Leukocytes from the Human Maternal-Fetal Interface

During human pregnancy, leukocytes that infiltrate the maternal-fetal interface play a major role in establishing a delicate balance between immune tolerance and functional response and setting the inflammatory process that leads to labor. Here we describe two methods for isolating immune cells from the chorioamniotic membranes (decidua parietalis) and placental blood (decidua basalis) that combine gentle enzymatic digestion, magnetic cell sorting, and density gradient. Isolated leukocytes can be immunophenotypified by flow cytometry, and both isolation methods are compatible with downstream cellular and molecular applications, such as cell culture, transcriptome, and proteome analyses.

Practicalities of Cell Sorting

Cell sorting is a technique commonly used in academic and biotechnology laboratories in order to separate out cells or particles of interest from heterogeneous populations. Cell sorters use the same principles as flow cytometry analyzers, but instead of cell populations passing to the waste of the instrument, they can be collected for further studies including DNA sequencing as well as other genomic, in vitro and in vivo experiments. This chapter aims to give an overview of cell sorting, the different types of cell sorters, details on how a cell sorter works, as well as protocols that are useful when embarking on a journey with cell sorting.

Cytometry in High-Containment Laboratories

The emergence of new pathogens continues to fuel the need for advanced high-containment laboratories across the globe. Here we explore challenges and opportunities for integration of cytometry, a central technology for cell analysis, within high-containment laboratories. We review current applications in infectious disease, vaccine research, and biosafety. Considerations specific to cytometry within high-containment laboratories, such as biosafety requirements, and sample containment strategies are also addressed. We further tour the landscape of emerging technologies, including combination of cytometry with other omics, the application of automation, and artificial intelligence. Finally, we propose a framework to fast track the immersion of advanced technologies into the high-containment research setting to improve global preparedness for new emerging diseases.

Multistage microfluidic cell sorting method and chip based on size and stiffness

High performance sorting of circulating tumor cells (CTCs) from peripheral blood is key to liquid biopsies. Size-based deterministic lateral displacement (DLD) technique is widely used in cell sorting. But conventional microcolumns have poor fluid regulation ability, which limits the sorting performance of DLD. When the size difference between CTCs and leukocytes is small (e.g., less than 3 μm), not only DLD, many size-based separation techniques fail due to low specificity. CTCs have been confirmed to be softer than leukocytes, which could serve as a basis for sorting. In this study, we presented a multistage microfluidic CTCs sorting method, first sorting CTCs using a size-based two-array DLD chip, then purifying CTCs mixed by leukocytes using a stiffness-based cone channel chip, and finally identifying cell types using Raman techniques. The entire CTCs sorting and analysis process was label free, highly pure, high-throughput and efficient. The two-array DLD chip employed a droplet-shaped microcolumn (DMC) developed by optimization design rather than empirical design. Attributed to the excellent fluid regulation capability of DMC, the CTCs sorter system developed by parallelizing four DMC two-array DLD chips was able to process a sample of 2.5 mL per minute with a recovery efficiency of 96.30 ± 2.10% and a purity of 98.25 ± 2.48%. To isolate CTCs mixed dimensionally by leukocytes, a cone channel sorting method and chip were developed based on solid and hydrodynamic coupled analysis. The cone channel chip allowed CTCs to pass through the channel and entrap leukocytes, improving the purity of CTCs mixed by leukocytes by 1.8-fold.

Development of a mammalian cell-based ZZ display system for IgG quantification

BACKGROUND

Biological laboratories and companies involved in antibody development need convenient and versatile methods to detect highly active antibodies.

METHODS

To develop a mammalian cell-based ZZ display system for antibody quantification, the eukaryotic ZZ-displayed plasmid was constructed and transfected into CHO cells. After screening by flow cytometric sorting, the stable ZZ display cells were incubated with reference IgG and samples with unknown IgG content for 40 min at 4℃, the relative fluorescence intensity of cells was analyzed and the concentration of IgG was calculated.

RESULTS

By investigating the effects of different display-associated genetic elements, a eukaryotic ZZ-displaying plasmid with the highest display efficiency were constructed. After transfection and screening, almost 100% of the cells were able to display the ZZ peptide (designated CHO-ZZ cells). These stable CHO-ZZ cells were able to capture a variety of IgG, including human, rabbit, donkey and even mouse and goat. CHO-ZZ cells could be used to quantify human IgG in the range of approximately 12.5-1000 ng/mL, and to identify high-yielding engineered monoclonal cell lines.

CONCLUSIONS

We have established a highly efficient CHO-ZZ display system in this study, which enables the quantification of IgG from various species under physiological conditions. This system offers the advantage of eliminating the need for antibody purification and will contribute to antibody development.

Configurational entropy is an intrinsic driver of tissue structural heterogeneity

Tissues comprise ordered arrangements of cells that can be surprisingly disordered in their details. How the properties of single cells and their microenvironment contribute to the balance between order and disorder at the tissue-scale remains poorly understood. Here, we address this question using the self-organization of human mammary organoids as a model. We find that organoids behave like a dynamic structural ensemble at the steady state. We apply a maximum entropy formalism to derive the ensemble distribution from three measurable parameters - the degeneracy of structural states, interfacial energy, and tissue activity (the energy associated with positional fluctuations). We link these parameters with the molecular and microenvironmental factors that control them to precisely engineer the ensemble across multiple conditions. Our analysis reveals that the entropy associated with structural degeneracy sets a theoretical limit to tissue order and provides new insight for tissue engineering, development, and our understanding of disease progression.

Experimental datasets on the immunohistological assessment of δ-cells in the islet organs of the endocrine pancreas of Japanese medaka (Oryzias latipes) fish exposed to graphene oxide

The datasets of this article present the experimental parameters resulting from the assessment of δ-cells in the islet organs of the endocrine pancreas as a potential biomarker of endocrine disruption (ED) mediated by graphene oxide (GO), using Japanese medaka fish as the model. These datasets support the article "Evaluation of pancreatic δ-cells as a potential target site of graphene oxide toxicity in Japanese medaka (Oryzias latipes) fish". GO used in the experiments was either obtained from a commercial source or synthesized in the laboratory by us. GO was sonicated for 5 min in ice temperature before application. The experiments were conducted on reproductively active adult fish maintained as a breeding pair (one male and one female) in 500 ml balanced salt solution (BSS) either by immersion (IMR) in GO (20 mg/L) continuously for 96 h with the refreshing of media once in every 24 h, or by a single intraperitoneal (IP) administration of GO (100 µg/g) to both male and female partners. Control fish were maintained in BSS only (IMR experiment), or nanopure water (vehicle) was injected into the peritoneal cavity (IP experiment). The IP experimental fish were anesthetized in MS-222 (100 mg/L in BSS); the injected volume (0.5 µL/10 mg fish) never exceeds 50 µl/fish. After injection, the injected fish were allowed for recovery in clean BSS and after recovery both partners were transferred to 1 L glass jars with 500 mL BSS. During depuration, the media of the breeders refreshed once every 24 h and the eggs were collected. After 21 days, the survived fish were anaesthetized, and the trunk region was preserved in 4% paraformaldehyde in PBS (20 mM) containing 0.05% Tween 20. The phenotypic sex of adult fish was assessed externally by secondary sex characters (fin features) and internally by gonad (testis and ovary) histology. Once the location of pancreas was determined after HE stains, immunohistochemical technique was applied on next few slides using rabbit derived polyclonal antisomatostatin antibody as primary antibody and a commercial kit for colorimetric determination of δ-cells in the islet organs was used. Images were captured using an Olympus CKX53 inverted microscope with DP22 camera and CellSens software. Using imagej software, a minimum 3 images of principal islets and one image of secondary islets were assessed. The immunoreactivity of δ-cells, due to neuron-like appearance and filopodia like processes, enabled us to separate them from other cell types found in the pancreatic islets of medaka. Based on immunoreactivity, we have classified islet cells into three categories; noncommunicating delta cells (NCDC), communicating cells (CC), and non-delta cells (NDC), and expressed as number of cells (NCDC/CC/NDC)/mm² of islet organs. The nuclear area (µm²) and the linear length of filopodia of NCDCs were also considered for evaluation. Numerical data were analysed by Kruskal-Wallis test followed by Mann-Whitney's test as post hoc test and presented as means  ±  SEM. Statistically significant differences were considered for p ≤ 0.05.

Self-organized collective cell behaviors as design principles for synthetic developmental biology

Over the past two decades, molecular cell biology has graduated from a mostly analytic science to one with substantial synthetic capability. This success is built on a deep understanding of the structure and function of biomolecules and molecular mechanisms. For synthetic biology to achieve similar success at the scale of tissues and organs, an equally deep understanding of the principles of development is required. Here, we review some of the central concepts and recent progress in tissue patterning, morphogenesis and collective cell migration and discuss their value for synthetic developmental biology, emphasizing in particular the power of (guided) self-organization and the role of theoretical advances in making developmental insights applicable in synthesis.

spSeudoMap: cell type mapping of spatial transcriptomics using unmatched single-cell RNA-seq data

Since many single-cell RNA-seq (scRNA-seq) data are obtained after cell sorting, such as when investigating immune cells, tracking cellular landscape by integrating single-cell data with spatial transcriptomic data is limited due to cell type and cell composition mismatch between the two datasets. We developed a method, spSeudoMap, which utilizes sorted scRNA-seq data to create virtual cell mixtures that closely mimic the gene expression of spatial data and trains a domain adaptation model for predicting spatial cell compositions. The method was applied in brain and breast cancer tissues and accurately predicted the topography of cell subpopulations. spSeudoMap may help clarify the roles of a few, but crucial cell types.

Evaluation of pancreatic δ- cells as a potential target site of graphene oxide toxicity in Japanese medaka (Oryzias latipes) fish

In continuation to our previous investigations on graphene oxide (GO) as an endocrine disrupting chemical (EDC), in the present experiment, we have investigated endocrine pancreas of Japanese medaka adults focusing on δ-cells in the islet organs as an endpoint. Breeding pairs of adult male and female fish were exposed to 0 mg/L (control) or 20 mg/L GO by continuous immersion (IMR) for 96 h, or to 0 µg/g or 100 µg/g GO by a single intraperitoneal (IP) administration and depurated 21 days in a GO-free environment. Histological investigations indicated that the endocrine cells are concentrated in one large principal islet, and several small secondary islets scattered within the mesentery near the liver and intestine. The cells of the islet organ are in various shapes with basophilic nuclei and eosinophilic cytoplasm. Immunohistochemical evaluation using rabbit polyclonal antisomatostatin antibody indicated that immunoreactivity is localized either at the periphery or at the central region in principal islets, and throughout the secondary islets, and found to be enhanced in fish exposed to GO than controls. The soma of δ-cells exhibits neuron-like morphology and have filopodia like processes. Cell sorting as non-communicating δ-cells (NCDC), communicating cells (CC), and non- δ-cells (NDC) indicated that within an islet organ, the population of NDCC is found to be the least and NDC is the highest. Our data further indicated that GO-induced impairments in the islet organs of medaka pancreas are inconsistent and could be affected by the exposure roots as well as the sex of the fish.

Isobaric labeling-based quantitative proteomics of FACS-purified immune cells and epithelial cells from the intestine of Crohn's disease patients reveals proteome changes of potential importance in disease pathogenesis

Crohn's disease (CD) is a chronic condition characterized by recurrent flares of inflammation in the gastrointestinal tract. Disease etiology is poorly understood and is characterized by dysregulated immune activation that progressively destroys intestinal tissue. Key cellular compartments in disease pathogenesis are the intestinal epithelial layer and its underlying lamina propria. While the epithelium contains predominantly epithelial cells, the lamina propria is enriched in immune cells. Deciphering proteome changes in different cell populations is important to understand CD pathogenesis. Here, using isobaric labeling-based quantitative proteomics, we perform an exploratory study to analyze in-depth proteome changes in epithelial cells, immune cells and stromal cells in CD patients compared to controls using cells purified by FACS. Our study revealed increased proteins associated with neutrophil degranulation and mitochondrial metabolism in immune cells of CD intestinal mucosa. We also found upregulation of proteins involved in glycosylation and secretory pathways in epithelial cells of CD patients, while proteins involved in mitochondrial metabolism were reduced. The distinct alterations in protein levels in immune- versus epithelial cells underscores the utility of proteome analysis of defined cell types. Moreover, our workflow allowing concomitant assessment of cell-type specific changes on an individual basis enables deeper insight into disease pathogenesis.

High performance isolation of circulating tumor cells by acoustofluidic chip coupled with ultrasonic concentrated energy transducer

The isolation of circulating tumor cells (CTCs) from whole blood is a challenging task. Although various studies on the separation of CTCs by acoustofluidic devices have been reported, difficulties still persist, such as the complicated equipment, high cost, and difficult operation. Those problems should be resolved urgently. Herein, we developed an acoustofluidic chip separation system coupled with an ultrasonic concentrated energy transducer (UCET) system for efficient separation of CTCs. In the separation system, the acoustically sensitive particles were pre-focused by inertial forces of the PDMS chip channel structure. Then, the particles with different sizes were separated by acoustic radiation forces (ARF). In this study, the circulating tumor cells was simulated (CTCs-like particles) by aminated mesoporous acoustically sensitive particles (MSN@AM) encapsulated carboxylate polystyrene microspheres (PS-COOH). Subsequently, efficient CTCs-like particles separation was achieved by the acoustofluidic chip coupling system. This study effectively separated polystyrene microspheres carrying acoustically sensitive particles (MSN@AM@PS-COOH). However, the MSNs agglomerates and PS microspheres without acoustically sensitive particles did not show phenomenon of separation. This method allows to efficiently separate 2 µm MSNs agglomerates，8.0-8.9 µm PS microspheres and 10-10.5 µm MSN@AM@PS-COOH particles. It is demonstrated that the CTCs-like particles show more sensitive response, longer moving distance, and more obvious separation effect at the condition of the low frequency traveling wave sound field (20 kHz from UCET). This system can maintain the same separation with reduced amount of reagents used for cancer detection. It may provide a reliable basis for sorting out CTCs efficiently from the whole blood of cancer patients.

Analyzing the Tumor-Immune Microenvironment by Flow Cytometry

Flow cytometry is an essential tool for studying the tumor-immune microenvironment. It allows us to quickly quantify and identify multiple cell types in a heterogeneous sample. This chapter provides an overview of the flow cytometry instrumentation and a discussion of the appropriate considerations and steps in building a reproducible flow cytometry staining panel. We present an updated lymphoid tissue and solid tumor-infiltrating leucocyte flow cytometry staining protocol and an example of flow cytometry data analysis.

Isolation and Functional Characterization of Regulatory CD4+ T Cells from the Inflamed Joints of Patients with Rheumatoid Arthritis

Regulatory T cells play a critical role in maintaining immune homeostasis and in preventing and controlling unwanted immune activation. These cells are often studied in the context of human peripheral blood, but can also be isolated from other biofluids. Here we describe methods for the isolation and functional characterization of human CD4⁺ CD25^hi CD127^low regulatory T cells from the synovial fluid of patients with inflammatory arthritis.

Large-Scale Isolation of Mouse Thymic Epithelial Cells

The thymus is compartmentalized into the cortex and the medulla. Cortical and medullary thymic epithelial cells (TECs) characterize T cell-producing and T cell-selecting functions of cortical and medullary microenvironments in the thymus. Enzymatic digestion of the thymus and flow cytometric isolation of TECs and their subpopulations are useful for molecular and cellular characterization of TECs. However, the cellularity of cTECs and mTECs isolated from mouse thymus is limited. In this chapter, we describe the method for isolation of a large number of TECs using enlarged mouse thymus, which enables biochemical and proteomic analysis of TEC subpopulations.

Antibody Selection on Cells Targeting Membrane Proteins

Antibody phage display selection on cells is a powerful tool to generate highly specific antibodies recognizing a target in its cell bound conformation. Unlike phage display selections on immobilized proteins, it is not hampered by difficulties caused by recombinant protein expression of target proteins like altered folding or loss of epitopes. It also allows the generation of antibodies against proteins that are commercially unavailable, due to high production costs or lack of production. It is also a promising approach for single and especially multi-pass membrane proteins for which the complex secondary and tertiary structures can often not be retained upon recombinant protein expression. The selected antibodies are not only tools for in vivo studies but also used for the development of diagnostic assays and for therapeutical applications. Here, we describe a straightforward protocol for generation and screening of scFv binders by phage display selections on cells.

Design and Analysis of Massively Parallel Reporter Assays Using FORECAST

Machine learning is revolutionizing molecular biology and bioengineering by providing powerful insights and predictions. Massively parallel reporter assays (MPRAs) have emerged as a particularly valuable class of high-throughput technique to support such algorithms. MPRAs enable the simultaneous characterization of thousands or even millions of genetic constructs and provide the large amounts of data needed to train models. However, while the scale of this approach is impressive, the design of effective MPRA experiments is challenging due to the many factors that can be varied and the difficulty in predicting how these will impact the quality and quantity of data obtained. Here, we present a computational tool called FORECAST, which can simulate MPRA experiments based on fluorescence-activated cell sorting and subsequent sequencing (commonly referred to as Flow-seq or Sort-seq experiments), as well as carry out rigorous statistical estimation of construct performance from this type of experimental data. FORECAST can be used to develop workflows to aid the design of MPRA experiments and reanalyze existing MPRA data sets.

Ensuring Quality Cell Input for Single Cell Sequencing Experiments by Viability and Singlet Enrichment Using Cell Sorting

As with every sensitive analysis technology, the golden principle of "input quality rules output quality" also applies to single cell sequencing methods. Given the sensitivity of the current methods in single cell sequencing and the minuscule amounts of RNA present within a single cell, any extrinsic source of variability should be reduced by ensuring a homogenous input right at the start. Not every tissue is as readily handled as a single cell suspension like blood and most tissues will have to undergo digestions to free the cells from their spatial organization to undergo single cell transcriptomics workflows. This chapter provides working protocols for two simple, but very precise and powerful methods to ensure only the most viable cells are introduced into single cell assays.

Laser-assisted bioprinting of microorganisms with hydrogel microdroplets: peculiarities of Ascomycota and Basidiomycota yeast transfer

Laser-assisted bioprinting of microbial cells by hydrogel microdroplets is a rapidly developing and promising field that can contribute to solving a number of issues in microbiology and biotechnology. To date, most research on the use of laser bioprinting for microorganism manipulation and sorting has focused on prokaryotes; the bioprinting of eukaryotic microorganisms is much less understood. The use of hydrogel allows solving two fundamental problems: creating comfortable environments for living microorganisms and imparting the necessary rheological properties of the gel for the stable transfer of microdroplets of a preset size. Two main problems were solved in this article. First, the parameters of the hydrogel based on hyaluronic acid and laser fluence to ensure stable transfer of single drops are selected. Second, possible differences in the bioprinting by hyaluronic acid hydrogel microdroplets with yeasts of various taxonomy (Ascomycota vs Basidiomycota), which form and do not form polysaccharide capsules and evaluated. We have performed laser induced forward transfer of 8 yeast species (Goffeauzyma gilvescens, Lipomyces lipofer, Lipomyces starkey, Pichia manshurica, Saitozyma podzolica, Schwanniomyces occidentalis var. occidentalis, Sterigmatosporidium polymorphum, Vanrija humicola) and assessed its viability based on colony formation on the nutrient medium. It is shown that after laser-induced transfer in hydrogel microdroplets the mean viability rate was 77% with some strains showing relatively high viability rates exceeding 90%. Effect of capsules presence on colony formation after laser bioprinting was not revealed. Differences in laser transfer of the yeast of various phyla were found-basidiomycetes formed a greater number of colonies than ascomycetes. The causes and mechanisms of these effects require detailed studies. The data obtained contributes to the knowledge about the bioprinting of eukaryotic microorganisms and can be useful in the studies of single microbial cells and inter-organism interactions.

Comparison of swab types & elution buffers for collection and analysis of intact cells to aid in deconvolution of complex DNA mixtures

Heightened sensitivity of forensic DNA techniques has led to an increased variety of samples tested, often yielding complex DNA mixtures, in turn making the interpretation of profiling results more complicated. Currently, there is no prescribed upstream laboratory method to separate complex DNA mixtures by their contributors; therefore, a method is needed that could reduce mixtures into their component parts. Various cell sorting applications have the potential to be this method, if intact cells can be reliably obtained from forensic samples. Here, the effects of elution buffer and swab substrate on the recovery of intact, human, white blood cells from dried blood samples were evaluated. Approximately 328,000 cells per swab were deposited onto cotton, flocked, and dissolvable swabs. The whole-cell elution of the dried samples was evaluated with water, phosphate buffered saline, and AutoMACS® elution buffers. We demonstrate that AutoMACS® buffer is superior for the elution of intact cells, compared to phosphate buffered saline and water. When swab type was considered, the highest yield of intact cells resulted from flocked swabs, as opposed to cotton or dissolvable swabs.

Marangoni effect and cell spreading

Cells are very sensitive to the shear stress (SS). However, undesirable SS is generated during physiological process such as collective cell migration (CCM) and influences the biological processes such as morphogenesis, wound healing and cancer invasion. Despite extensive research devoted to study the SS generation caused by CCM, we still do not fully understand the main cause of SS appearance. An attempt is made here to offer some answers to these questions by considering the rearrangement of cell monolayers. The SS generation represents a consequence of natural and forced convection. While forced convection is dependent on cell speed, the natural convection is induced by the gradient of tissue surface tension. The phenomenon is known as the Marangoni effect. The gradient of tissue surface tension induces directed cell spreading from the regions of lower tissue surface tension to the regions of higher tissue surface tension and leads to the cell sorting. This directional cell migration is described by the Marangoni flux. The phenomenon has been recognized during the rearrangement of (1) epithelial cell monolayers and (2) mixed cell monolayers made by epithelial and mesenchymal cells. The consequence of the Marangoni effect is an intensive spreading of cancer cells through an epithelium. In this work, a review of existing literature about SS generation caused by CCM is given along with the assortment of published experimental findings, to invite experimentalists to test given theoretical considerations in multicellular systems.

Cellular and molecular mechanisms of EPH/EPHRIN signaling in evolution and development

The EPH receptor tyrosine kinases and their signaling partners, the EPHRINS, comprise a large class of cell signaling molecules that plays diverse roles in development. As cell membrane-anchored signaling molecules, they regulate cellular organization by modulating the strength of cellular contacts, usually by impacting the actin cytoskeleton or cell adhesion programs. Through these cellular functions, EPH/EPHRIN signaling often regulates tissue shape. Indeed, recent evidence indicates that this signaling family is ancient and associated with the origin of multicellularity. Though extensively studied, our understanding of the signaling mechanisms employed by this large family of signaling proteins remains patchwork, and a truly "canonical" EPH/EPHRIN signal transduction pathway is not known and may not exist. Instead, several foundational evolutionarily conserved mechanisms are overlaid by a myriad of tissue -specific functions, though common themes emerge from these as well. Here, I review recent advances and the related contexts that have provided new understanding of the conserved and varied molecular and cellular mechanisms employed by EPH/EPHRIN signaling during development.

Tight association of autophagy and cell cycle in leukemia cells

Background

Autophagy plays an essential role in maintaining cellular homeostasis and in the response to cellular stress. Autophagy is also involved in cell cycle progression, yet the relationship between these processes is not clearly defined.

Results

In exploring this relationship, we observed that the inhibition of autophagy impaired the G2/M phase-arresting activity of etoposide but enhanced the G1 phase-arresting activity of palbociclib. We further investigated the connection of basal autophagy and cell cycle by utilizing the autophagosome tracer dye Cyto-ID in two ways. First, we established a double-labeling flow-cytometric procedure with Cyto-ID and the DNA probe DRAQ5, permitting the cell cycle phase-specific determination of autophagy in live cells. This approach demonstrated that different cell cycle phases were associated with different autophagy levels: G1-phase cells had the lowest level, and G2/M-phase cells had the highest one. Second, we developed a flow-cytometric cell-sorting procedure based on Cyto-ID that separates cell populations into fractions with low, medium, and high autophagy. Cell cycle analysis of Cyto-ID-sorted cells confirmed that the high-autophagy fraction contained a much higher percentage of G2/M-phase cells than the low-autophagy fraction. In addition, Cyto-ID-based cell sorting also proved to be useful for assessing other autophagy-related processes: extracellular flux analysis revealed metabolic differences between the cell populations, with higher autophagy being associated with higher respiration, higher mitochondrial ATP production, and higher glycolysis.

Conclusion

This work provides clear evidence of high autophagy in G2/M-phase cells by establishing a novel cell sorting technique based on Cyto-ID.

Supplementary Information

The online version contains supplementary material available at 10.1186/s11658-022-00334-8.

Xylanase production by Thermobacillus xylanilyticus is impaired by population diversification but can be mitigated based on the management of cheating behavior

Background

The microbial production of hemicellulasic cocktails is still a challenge for the biorefineries sector and agro-waste valorization. In this work, the production of hemicellulolytic enzymes by Thermobacillus xylanilyticus has been considered. This microorganism is of interest since it is able to produce an original set of thermostable hemicellulolytic enzymes, notably a xylanase GH11, Tx-xyn11. However, cell-to-cell heterogeneity impairs the production capability of the whole microbial population.

Results

Sequential cultivations of the strain on xylan as a carbon source has been considered in order to highlight and better understand this cell-to-cell heterogeneity. Successive cultivations pointed out a fast decrease of xylanase activity (loss of ~ 75%) and Tx-xyn11 gene expression after 23.5 generations. During serial cultivations on xylan, flow cytometry analyses pointed out that two subpopulations, differing at their light-scattering properties, were present. An increase of the recurrence of the subpopulation exhibiting low forward scatter (FSC) signal was correlated with a progressive loss of xylanase activity over several generations. Cell sorting and direct observation of the sorted subpopulations revealed that the low-FSC subpopulation was not sporulating, whereas the high-FSC subpopulation contained cells at the onset of the sporulation stage. The subpopulation differences (growth and xylanase activity) were assessed during independent growth. The low-FSC subpopulation exhibited a lag phase of 10 h of cultivation (and xylanase activities from 0.15 ± 0.21 to 3.89 ± 0.14 IU/mL along the cultivation) and the high-FSC subpopulation exhibited a lag phase of 5 h (and xylanase activities from 0.52 ± 0.00 to 4.43 ± 0.61 over subcultivations). Serial cultivations on glucose, followed by a switch to xylan led to a ~ 1.5-fold to ~ 15-fold improvement of xylanase activity, suggesting that alternating cultivation conditions could lead to an efficient population management strategy for the production of xylanase.

Conclusions

Taken altogether, the data from this study point out that a cheating behavior is responsible for the progressive reduction in xylanase activity during serial cultivations of T. xylanilyticus. Alternating cultivation conditions between glucose and xylan could be used as an efficient strategy for promoting population stability and higher enzymatic productivity from this bacterium.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12934-022-01762-z.

Yeast Display Guided Selection of pH-Dependent Binders

pH-dependent antigen binding has proven useful in engineering next-generation therapeutics specifically via antibody recycling technology. This technology allows for half-life extension, thereby lowering the amount and frequency of dosing of therapeutics. Cell sorting, coupled with display techniques, has been used extensively for the selection of high-affinity binders. Herein, we describe a cell sorting methodology utilizing yeast surface display for selection of binding proteins with strong binding at physiological pH and weak to no binding at acidic pH. This methodology can be readily applied to engineer proteins and/or antibodies that do not have pH-dependent binding or for selection of de novo pH-dependent binders using library-based methods.

Engineering Binders with Exceptional Selectivity

Molecular display technologies have enabled the generation of synthetic binders with high affinities against a variety of antigens. However, engineering binders with high selectivity is still a challenging task. Here, we illustrate points to consider in developing highly selective binders against antigens of interest. We describe a systematic strategy for sorting selective binders using the yeast display technology. Using the approach described, our group has overcome molecular recognition challenges and developed a series of synthetic binders with exceptional selectivity against diverse antigens.

Measurement of canine Th17 cells by flow cytometry

Th17 cells are T helper cells which play an important role during inflammation and autoimmune disease. To investigate the role of these cells in diseases in dogs in a clinical setting, methods for fast identification had to be established. Th17 cells are a rare cell population, for their measurement stimulation is recommended. To examine more samples simultaneously and to receive a relatively high purity of cell population of CD3 + CD4+ cells, different methods on various levels of preselection of cells as well as the possibility of storing blood overnight for measuring Th17 cells by flow cytometry were investigated. Firstly, to receive a high number of mononuclear cells, two different density gradients were compared and analysed. Furthermore, the enrichment of CD3 + CD4+ cells via depletion of CD8alpha+, CD11b + and CD21+ cells by cell sorting (autoMACS Pro Separator) was tested. It was also investigated whether stimulation processes led to better interpretation of results and whether there was a significant difference in measurement of directly processed blood samples and samples that had been stored overnight. In conclusion, the use of the density gradient (Lymph24+ Spin Medium) resulted in a purer cell population through a significant decrease in polymorphonuclear cells (*p = 0.01). After cell sorting, a significant difference in cell population purity was detected. Within the target fraction (containing mainly CD3 + CD4+ cells), CD8alpha+, CD21+, CD11b + cell percentages were significantly lower (***p < 0.001, *p < 0.02, ***p < .0001, respectively), and CD3 + CD4+ cell percentage was significantly higher (***p < .0001). There was a significant difference in Th17 cell percentage between unstimulated and stimulated cell populations (***p < .0001), but no significant difference in the percentage of unstimulated Th17 cells (p = 0.29) or stimulated Th17 cells (p = 0.71) in stored blood in comparison to directly processed EDTA blood samples. Finally, a modified protocol that offers an efficient way to investigate samples that were stored overnight by means of flow cytometry was evolved to research the role of Th17 cells in dogs with different diseases or in healthy populations.

Bio-conjugation of anti-human CD3 monoclonal antibodies to magnetic nanoparticles by using cyanogen bromide: A potential for cell sorting and noninvasive diagnosis

The conjugation of monoclonal antibodies with superparamagnetic iron oxide nanoparticles (SPIONs) has appeared as a potential multifunctional clinical tool, which can effectively diagnose cancers and monitor their treatment, specifically. Despite the presence of different methods for conjugating antibodies to iron oxide nanoparticles, novel cost-effective and simpler conjugation techniques should be performed in this regard. In current study, an anti-CD3 monoclonal antibody was conjugated to the Fe3O4 coated by carboxymethyl dextran (CMD) using cyanogen bromide (CNBr). Moreover, EDC/NHS techniques were applied as a positive control. The experimental results showed that the Conjugation was performed and the presence of the antibody conjugated to the MNPs in human xenograft tumors was confirmed using Prussian blue (PB) staining, following magnetic resonance imaging (MRI), 30 min after injection. This conjugation method was shown to be able to separate CD3+ T lymphocytes efficiently from whole blood with high purity. Accordingly, this type of bio-conjugation method can be utilized in the future for cell sorting, and can be applied for adopted cell therapies such as CAR-T cell (Chimeric antigen receptor T cell) therapy, as well as targeted MRI imaging.

Two-photon fluorescence lifetime for label-free microfluidic droplet sorting

Microfluidic droplet sorting systems facilitate automated selective micromanipulation of compartmentalized micro- and nano-entities in a fluidic stream. Current state-of-the-art droplet sorting systems mainly rely on fluorescence detection in the visible range with the drawback that pre-labeling steps are required. This limits the application range significantly, and there is a high demand for alternative, label-free methods. Therefore, we introduce time-resolved two-photon excitation (TPE) fluorescence detection with excitation at 532 nm as a detection technique in droplet microfluidics. This enables label-free in-droplet detection of small aromatic compounds that only absorb in a deep-UV spectral region. Applying time-correlated single-photon counting, compounds with similar emission spectra can be distinguished due to their fluorescence lifetimes. This information is then used to trigger downstream dielectrophoretic droplet sorting. In this proof-of-concept study, we developed a polydimethylsiloxane-fused silica (FS) hybrid chip that simultaneously provides a very high optical transparency in the deep-UV range and suitable surface properties for droplet microfluidics. The herein developed system incorporating a 532-nm picosecond laser, time-correlated single-photon counting (TCSPC), and a chip-integrated dielectrophoretic pulsed actuator was exemplarily applied to sort droplets containing serotonin or propranolol. Furthermore, yeast cells were screened using the presented platform to show its applicability to study cells based on their protein autofluorescence via TPE fluorescence lifetime at 532 nm.

Detecting Persister Awakening Determinants

For long, persistence research has focused primarily on disentangling mechanisms of persister state entry. Due to the rapid advances in the field of single-cell techniques and newly obtained insights in the persister phenotype, studying persister awakening has been unlocked and it has gained much interest in the scientific community. However, a framework on how this research should be conducted is currently lacking. Therefore, we here present a method to detect and validate genes important for persister awakening.

A multivariate analysis of Multiple Myeloma subtype plasma cells

Trusted methods for identifying different Multiple Myeloma (MM) cells and their biological diversity due to their immunophenotypic variety are often little detailed and difficult to find in literature. In this work, we show that micro-Raman spectroscopy can be used to highlight if there is a certain degree of distinction or correlation between the MM subtype plasmacells in relation to the cluster of differentiation (CD45+/CD38+/CD138-) and (CD45-/CD38+/CD138+). After taking samples from the bone marrow of patients with Multiple Myeloma, the PCs were sorted by flow cytometry, selecting the most common CD of the disease, i.e. CD 45, CD38 and CD138. Some spectral differences are observed comparing the Raman spectra of the two set of samples investigated. To better define in which spectral regions there are greater differences and, therefore, to which biological contributions the changes refers, we also explored the principal component analysis (PCA) of the collected Raman data. The spectral variations between the different sorted cells have been highlighted by plotting loading vectors PC1 and PC2, which shows a net differentiation between the two set of cells. Ultimately, the differences shown by PCA have been associated with the spectral variations observed and explained in terms of changes of proteins and lipid contributions. Thus, the differentiation of Multiple Myeloma subtype plasma cells by confocal micro-Raman spectroscopy can be proposed as a diagnostic tool in the speeding up of cell identification, assessing the intracellular biochemical changes that take place in cancer cells.

Mechanics and self-organization in tissue development

Self-organization is an all-important feature of living systems that provides the means to achieve specialization and functionality at distinct spatio-temporal scales. Herein, we review this concept by addressing the packing organization of cells, the sorting/compartmentalization phenomenon of cell populations, and the propagation of organizing cues at the tissue level through traveling waves. We elaborate on how different theoretical models and tools from Topology, Physics, and Dynamical Systems have improved the understanding of self-organization by shedding light on the role played by mechanics as a driver of morphogenesis. Altogether, by providing a historical perspective, we show how ideas and hypotheses in the field have been revisited, developed, and/or rejected and what are the open questions that need to be tackled by future research.

Flow Cytometry Instrument Setting as a Crucial Checkpoint for Optimal T-Cell Analysis and Sorting

Although flow cytometry and cell sorting are widely used by immunologists both for basic and translation research, many aspects of these techniques should be optimized to obtain reproducible and meaningful data. In this chapter we provide some protocols and tips on instrument setting, multicolor panel design and T-cell immunophenotyping and proliferation assay.

Purification of Specific Cell Populations Differentiated from Stem Cells Using MicroRNA-Responsive Synthetic Messenger RNAs

Pluripotent stem cells have the potential to differentiate into various cell types that can be used for basic biological studies, drug discovery, and regenerative medicine. To obtain reliable results using the differentiated cells, the contamination of nontarget cells should be avoided. microRNAs (miRNAs) can serve as indicators to distinguish target and nontarget cells, because the activities of miRNAs are different among cell types.In this chapter, we introduce a method to purify target cells using synthetic messenger RNAs (mRNAs) that respond to cell-specific miRNAs. The method is composed of five steps: mRNA sequence design, template DNA preparation by PCR, in vitro mRNA transcription, mRNA transfection into cells, and fluorescence-activated cell sorting. This synthetic mRNA-based cell purification method will advance various applications of pluripotent stem cells.

Intrafemoral Delivery of Hematopoietic Progenitors

Hematopoiesis is a central process and is essential for the replenishment of short-lived leukocytes such as neutrophils. However, the molecular events underlining the developmental transition of quiescent hematopoietic stem cells into downstream progenitors and mature blood cells are not completely understood. Here, we describe the intrafemoral delivery of hematopoietic progenitors as a method to trace their development and differentiation lineage patterns within the bone marrow (BM) niche. Unlike other approaches, the direct adoptive transfer of progenitors into the BM cavity does not require prior irradiation preconditioning of recipient mice, and enables the delivery of lower cell numbers into the marrow space in a minimally perturbed environment. As a demonstrative example, we provide a protocol for the isolation of granulocyte-monocyte progenitors (GMP) by cell sorting, the delivery of these cells into recipient animals by intrafemoral transfer, and finally, the analysis of GMP-derived progenies by flow cytometry.

Potential applications of BPFP1 in Bcl-2 protein quantification, carcinoma cell visualization, cell sorting and early cancer diagnosis

Overexpression of the Bcl-2 protein has emerged as a hallmark of carcinoma cells and can be employed as a biochemical biomarker of these cells. Therefore, some Bcl-2 protein fluorescence probes (BPFPs) were designed for Bcl-2 protein quantification and carcinoma cells labeling. The high Bcl-2 protein binding affinity (K_i < 1 nM) and selectivity (over 50,000-fold Bcl-2 protein selectivity against Mcl-1 protein) of BPFP1 endow it with the ability to detect trace amounts of Bcl-2 protein. After being incubated with a range of concentrations of Bcl-2 protein, BPFP1 exhibited the desired fluorescence properties and its fluorescence intensity is proportional to Bcl-2 protein concentration. Therefore, BPFP1 provides a convenient approach for Bcl-2 protein quantification and we could determine the concentration of Bcl-2 protein based on the BPFP1's fluorescence intensity. Subsequent studies revealed that BPFP1 can fluorescently label carcinoma cells by binding to overexpressed Bcl-2 protein in living cells, and can distinguish carcinoma cells (HL-60 cells and ACHN cells) from normal-tissue cells (HUVECs) according to the different Bcl-2 protein expression levels between carcinoma cells and normal tissue cells. In the present study, BPFP1 represents a new tool for Bcl-2 protein quantification, carcinoma cell visualization and cell sorting. Moreover, BPFP1 can be used in the future for early cancer diagnosis by detecting carcinoma cells in patient tissues.

Isolation of GFP-expressing Malarial Hypnozoites by Flow Cytometry Cell Sorting

Hypnozoites are dormant liver-stage parasites unique to relapsing malarial species, including the important human pathogen Plasmodium vivax, and pose a barrier to the elimination of malaria. Little is known regarding the biology of these stages, largely due to their inaccessible location. Hypnozoites can be cultured in vitro but these cultures always consist of a mixture of hepatocytes, developing forms, and hypnozoites. Here, using a GFP-expressing line of the hypnozoite model parasite Plasmodium cynomolgi, we describe a protocol for the FACS-based isolation of malarial hypnozoites. The purified hypnozoites can be used for a range of '-omics' studies to dissect the biology of this cryptic stage of the malarial life cycle.

GARP transcription factors repress Arabidopsis nitrogen starvation response via ROS-dependent and -independent pathways

Plants need to cope with strong variations of nitrogen availability in the soil. Although many molecular players are being discovered concerning how plants perceive NO3- provision, it is less clear how plants recognize a lack of nitrogen. Following nitrogen removal, plants activate their nitrogen starvation response (NSR), which is characterized by the activation of very high-affinity nitrate transport systems (NRT2.4 and NRT2.5) and other sentinel genes involved in N remobilization such as GDH3. Using a combination of functional genomics via transcription factor perturbation and molecular physiology studies, we show that the transcription factors belonging to the HHO subfamily are important regulators of NSR through two potential mechanisms. First, HHOs directly repress the high-affinity nitrate transporters, NRT2.4 and NRT2.5. hho mutants display increased high-affinity nitrate transport activity, opening up promising perspectives for biotechnological applications. Second, we show that reactive oxygen species (ROS) are important to control NSR in wild-type plants and that HRS1 and HHO1 overexpressors and mutants are affected in their ROS content, defining a potential feed-forward branch of the signaling pathway. Taken together, our results define the relationships of two types of molecular players controlling the NSR, namely ROS and the HHO transcription factors. This work (i) up opens perspectives on a poorly understood nutrient-related signaling pathway and (ii) defines targets for molecular breeding of plants with enhanced NO3- uptake.

Identifying the functions of two biomarkers in human oligodendrocyte progenitor cell development

BACKGROUND

Human oligodendrocyte precursor cells (hOPCs) are an important source of myelinating cells for cell transplantation to treat demyelinating diseases. Myelin oligodendrocytes develop from migratory and proliferative hOPCs. It is well known that NG2 and A2B5 are important biological markers of hOPCs. However, the functional differences between the cell populations represented by these two biomarkers have not been well studied in depth.

OBJECTIVE

To study the difference between NG2 and A2B5 cells in the development of human oligodendrocyte progenitor cells.

METHODS

Using cell sorting technology, we obtained NG2+/-, A2B5+/- cells. Further research was then conducted via in vitro cell proliferation and migration assays, single-cell sequencing, mRNA sequencing, and cell transplantation into shiverer mice.

RESULTS

The proportion of PDGFR-α + cells in the negative cell population was higher than that in the positive cell population. The migration ability of the NG2+/-, A2B5+/- cells was inversely proportional to their myelination ability. The migration, proliferation, and myelination capacities of the negative cell population were stronger than those of the positive cell population. The ability of cell migration and proliferation of the four groups of cells from high to low was: A2B5- > NG2- > NG2+ > A2B5+. The content of PDGFR-α+ cells and the ability of cell differentiation from high to low was: NG2- > A2B5- > A2B5+ > NG2+.

CONCLUSION

In summary, NG2+  and A2B5+ cells have poor myelination ability due to low levels of PDGFR-α+ cells. Therefore, hOPCs with a higher content of PDGFR-α+ cells may have a better effect in the cell transplantation treatment of demyelinating diseases.

Flow cytometry in the analysis of hematological parameters of tilapias: applications in environmental aquatic toxicology

Blood tissue has been used to assess animal health and the environment in which they live. This tissue is easily acquired and has the ability to respond to various adverse conditions. Several techniques have been employed in the detection of xenobiotic-induced cell damage in blood cells. In general, traditionally used technologies, such as cellular analysis in blood smears, are time-consuming and require great analytical capacity. The present study proposes flow cytometry as a method to detect changes in blood cell populations. Tilapia (Oreochromis niloticus) was selected as a model for plotting the profile of fish blood cell populations after exposure to xenobiotics without euthanizing animals or using cell markers. Populations of erythrocytes and lymphocytes were detected only by combining the techniques of FACSAria cell sorting and light microscopy. Systemic deleterious effects were found through blood analysis, such as an increased lymphocyte-rich population at 48 h of exposure followed by a subsequent decrease. Moreover, the time-dependent expression of Nrf2 suggests its participation in increased membrane disruption, indicating it has a central role in erythrocyte lifespan. The present results shed light on the viability of using flow cytometry for blood analysis of living fish.

Dynamic conversion of cell sorting patterns in aggregates of embryonic stem cells with differential adhesive affinity

BACKGROUND

Mammalian early development comprises the proliferation, differentiation, and self-assembly of the embryonic cells. The classic experiment undertaken by Townes and Holtfreter demonstrated the ability of dissociated embryonic cells to sort and self-organize spontaneously into the original tissue patterns. Here, we further explored the principles and mechanisms underlying the phenomenon of spontaneous tissue organization by studying aggregation and sorting of mouse embryonic stem (ES) cells with differential adhesive affinity in culture.

RESULTS

As observed previously, in aggregates of wild-type and E-cadherin-deficient ES cells, the cell assemblies exhibited an initial sorting pattern showing wild-type cells engulfed by less adhesive E-cadherin-deficient ES cells, which fits the pattern predicted by the differential adhesive hypothesis proposed by Malcom Steinberg. However, in further study of more mature cell aggregates, the initial sorting pattern reversed, with the highly adhesive wild-type ES cells forming an outer shell enveloping the less adhesive E-cadherin-deficient cells, contradicting Steinberg's sorting principle. The outer wild-type cells of the more mature aggregates did not differentiate into endoderm, which is known to be able to sort to the exterior from previous studies. In contrast to the naive aggregates, the mature aggregates presented polarized, highly adhesive cells at the outer layer. The surface polarity was observed as an actin cap contiguously spanning across the apical surface of multiple adjacent cells, though independent of the formation of tight junctions.

CONCLUSIONS

Our experimental findings suggest that the force of differential adhesive affinity can be overcome by even subtle polarity generated from strong bilateral ligation of highly adhesive cells in determining cell sorting patterns.

Phenotypical Characterization and Isolation of Tumor-Derived Mouse Myeloid-Derived Suppressor Cells

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous cell population composed of mature and immature cells of myeloid origin that play a major role in tumor progression by inhibiting the antitumor immune responses mediated by T cells. In this chapter, we describe protocols for isolation, phenotypical and functional evaluation of MDSCs isolated from mouse tumors, with the aim at unifying and standardizing protocols set up by different laboratories.

Isolation of Bovine Neutrophils by Fluorescence- and Magnetic-Activated Cell Sorting

Flow cytometry and magnetic bead technology enable the separation of cell populations with the highest degree of purity. Here, we describe protocols to sort bovine neutrophils from blood, the labeling and sorting, including gating strategies. We also provide advice to preserve neutrophil viability and detail a protocol to measure phagocytosis and oxidative species production.

iNKT Cel Transfer: The Use of Cell Sorting Combined with Flow Cytometry Validation Approach

Natural killer T (NKT) cells are an innate-like T cell subset that recognize lipid antigens presented by CD1d-expressing antigen presenting cells (APCs), such as dendritic cells, macrophages, and B cells. They can be subdivided into two different subsets according to the variation in αβ TCR chains: type I and type II NKT cells. Type I, also called invariant NKT cells (iNKT), express restricted TCRs with an invariant α-chain (Vα24-Jα18 in humans and Vα14-Jα18 in mice) and limited β-chains. Here we have established a protocol in which iNKT cells are isolated from a donor wild-type mouse and transferred into iNKT KO (Jα18^-/-) mouse. Below we will explore the methods for cell sorting of splenic iNKTs, iNKT cells transfer, and detection of transferred cells into the liver using flow cytometry technique.