[Circulating populations of CD4+ CD25+ CD127- regulatory t lymphocytes in peripheral blood of allergic asthmatic children]

OBJECTIVE

To carry out a preliminary analysis on the Treg lymphocyte counts present in the peripheral blood of allergic asthmatic children from the city of Cartagena, Colombia, compared to healthy controls.

METHODS

We compared cytometry counts of ten asthmatic patients (age 7-16 years) and seven healthy controls (6-12 years), recruited in the city of Cartagena. Peripheral blood samples were stained using Cytek's 14-color cFluor Immunoprofiling kit (Cytek® cFluor® Immunoprofiling Kit 14 Color RUO kit), and analyzed on a Northern Lights™ spectral cytometer (Cytek® Biosciences, Fremont, CA, USA), to read 50.000 events per sample. The data obtained were analyzed in SpectroFlo® and FlowJo. The study was approved by the ethics committee of the University of Cartagena (SGR, Grant BPIN2020000100405).

RESULTS

The frequency of CD3+, CD4+, CD25+, CD127- Tregs was 11% of all CD4+ T cells, with a range of minimum 8,1% and maximum 17,7%. There was no significant difference in the proportion of Tregs between allergic asthmatic patients and healthy controls (P = 0,2).

CONCLUSIONS

With this preliminary sample size, no significant differences were found in the Treg lymphocyte population between allergic asthmatic patients and healthy controls. The 14-color multiplexed panel is a useful tool not only to count CD3+ and CD4+ populations, but also to obtain the percentage of regulatory T cells using cell surface markers.

Phenotypic and Functional Characterization of Memory CD4+ and CD8+ T Cells After Antigenic Stimulation

The encounter of T cells with the antigen through the interaction of T cell receptors with peptides and major histocompatibility complex (MHC) molecules on the surface of antigen-presenting cells (APCs) can generate effector response and memory T cells. Memory T cells developed following infections or vaccination may persist, leading to the generation of a specific immune response upon reexposure to the same pathogen through rapid clonal proliferation and activation of effector functions. T cell memory subsets can be identified based on the expression of several membrane markers such as CCR7, CD27, and CD45RA. Using fluorescent antibodies against these markers and a flow cytometer, it is possible to perform immunophenotyping via the analysis of cell surface expression of proteins by different subpopulations such as the subsets of naïve, effector, and memory T cells as well as via the analysis of functional markers that further characterize each sample. Intracellular cytokine staining allows for the evaluation of intracellular proteins expressed in T cells in response to antigenic stimulation. This chapter presents the phenotypic and functional characterization of memory T cells after antigenic stimulation, detailing the procedures for identifying intracellular and surface protein markers. Herein, we review and present a reproducible standardized protocol using antibodies for specific markers and applying flow cytometry.

Spatially Characterizing the Immune Contexture in Mouse Tissue Using Multiplex Immunohistochemistry

Multiplex immunohistochemistry (mIHC) facilitates the simultaneous detection of various immune cell markers on a single tissue section. Here, we describe a protocol for an mIHC staining workflow using specific antibodies against CD4, CD8α, FOXP3, and B220 to identify distinct lymphocyte populations including T and B cells. This staining strategy can be adapted to include other cell markers to evaluate the immune contexture in murine tissues.

The Promise of CAR T-Cell Therapy for the treatment of cancer stem cells: A Short Review

Chimeric antigen receptor (CAR) T-cell therapy is a type of sophisticated tailored immunotherapy used to treat a variety of tumors. Immunotherapy works by utilizing the body's own immune system to discover and destroy malignant cells. In CAR-T therapy, a patient's own immune cells are genetically engineered to recognize and attack cancer. Treatments employing CAR T-cells are currently showing promising therapeutic results in patients with hematologic malignancies, and their safety and feasibility in solid tumors has been verified. In this review, we will discuss in detail the likelihood that CAR T-cells inhibit cancer stem cells (CSCs) by selectively targeting their cell surface markers will ultimately improve the therapeutic response for patients with various forms of cancer. This review addresses the major components of cancer stem cell (CSC)-targeted CAR T-cells against malignancies, from bench to bedside.

Multiparameter Fluorescence-Activated Cell Sorting of Human Lymphatic Endothelial Cells

Multiparameter fluorescence-activated cell sorting (FACS) procedure separates target cells from a total population of cells by using specific signatures that the target cell expresses on their cell surface. For human lymphatic endothelial cells (LECs) this relates to cell surface expression of the CD34^LowCD31^HighVEGFR-3^HighPodoplanin^High profile that permits their separation from blood vascular endothelial cells and other cells likely to be present in the digested tissue sample. In addition, FACS allows the evaluation of LEC size, volume, granularity, and purity at the time of sorting.

Evaluation of the effect of donor weight on adipose stromal/stem cell characteristics by using weight-discordant monozygotic twin pairs

Background

Adipose stromal/stem cells (ASCs) are promising candidates for future clinical applications. ASCs have regenerative capacity, low immunogenicity, and immunomodulatory ability. The success of future cell-based therapies depends on the appropriate selection of donors. Several factors, including age, sex, and body mass index (BMI), may influence ASC characteristics. Our aim was to investigate the effect of acquired weight on ASC characteristics under the same genetic background using ASCs derived from monozygotic (MZ) twin pairs.

Methods

ASCs were isolated from subcutaneous adipose tissue from five weight-discordant (WD, within-pair difference in BMI > 3 kg/m²) MZ twin pairs, with measured BMI and metabolic status. The ASC immunophenotype, proliferation and osteogenic and adipogenic differentiation capacity were studied. ASC immunogenicity, immunosuppression capacity and the expression of inflammation markers were investigated. ASC angiogenic potential was assessed in cocultures with endothelial cells.

Results

ASCs showed low immunogenicity, proliferation, and osteogenic differentiation capacity independent of weight among all donors. ASCs showed a mesenchymal stem cell-like immunophenotype; however, the expression of CD146 was significantly higher in leaner WD twins than in heavier cotwins. ASCs from heavier twins from WD pairs showed significantly greater adipogenic differentiation capacity and higher expression of TNF and lower angiogenic potential compared with their leaner cotwins. ASCs showed immunosuppressive capacity in direct cocultures; however, heavier WD twins showed stronger immunosuppressive capacity than leaner cotwins.

Conclusions

Our genetically matched data suggest that a higher weight of the donor may have some effect on ASC characteristics, especially on angiogenic and adipogenic potential, which should be considered when ASCs are used clinically.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02587-0.

Comparison of similar cells: Mesenchymal stromal cells and fibroblasts

Almost from all organs, both mesenchymal stromal cells and fibroblasts can be isolated. Mesenchymal stromal cells (MSCs) are the most preferred cellular therapeutic agents with the regenerative potential, and fibroblasts are one of the most abundant cell types with the ability to maintain homeostasis. Because of the promising properties of MSCs, they have been well studied and their differentiation potentials, immunomodulatory potentials, gene expression profiles are identified. It has been observed that fibroblasts and mesenchymal stromal cells have similar morphology, gene expression patterns, surface markers, proliferation, differentiation, and immunomodulatory capacities. Thus, it is hard to distinguish these two cell types. Epigenetic signatures, i.e., methylation patterns of cells, are the only usable promising difference between them. Such significant similarities show that these two cells may be related to each other.

Differences and similarities between cancer and somatic stem cells: therapeutic implications

Over the last decades, the cancer survival rate has increased due to personalized therapies, the discovery of targeted therapeutics and novel biological agents, and the application of palliative treatments. Despite these advances, tumor resistance to chemotherapy and radiation and rapid progression to metastatic disease are still seen in many patients. Evidence has shown that cancer stem cells (CSCs), a sub-population of cells that share many common characteristics with somatic stem cells (SSCs), contribute to this therapeutic failure. The most critical properties of CSCs are their self-renewal ability and their capacity for differentiation into heterogeneous populations of cancer cells. Although CSCs only constitute a low percentage of the total tumor mass, these cells can regrow the tumor mass on their own. Initially identified in leukemia, CSCs have subsequently been found in cancers of the breast, the colon, the pancreas, and the brain. Common genetic and phenotypic features found in both SSCs and CSCs, including upregulated signaling pathways such as Notch, Wnt, Hedgehog, and TGF-β. These pathways play fundamental roles in the development as well as in the control of cell survival and cell fate and are relevant to therapeutic targeting of CSCs. The differences in the expression of membrane proteins and exosome-delivered microRNAs between SSCs and CSCs are also important to specifically target the stem cells of the cancer. Further research efforts should be directed toward elucidation of the fundamental differences between SSCs and CSCs to improve existing therapies and generate new clinically relevant cancer treatments.

Exposure of cigarette smoke condensate activates NLRP3 inflammasome in vitro and in vivo: A connotation of innate immunity and atherosclerosis

OBJECTIVE

Smoking is known to have detrimental effects on cardiovascular system. However, the potential molecular basis of smoking-induced atherosclerosis remains unclear. NLRP3 inflammasome is implicated in perpetuation of inflammatory response in atherosclerosis. Therefore, we aimed to explore the cytotoxic effects of cigarette smoke condensate (CSC) on the activation of NLRP3 inflammasome in vitro and in vivo.

METHODS

For in vitro study, the pro-atherogenic effects of CSC were evaluated in THP-1 monocytes with different dose concentrations (0.1, 1, 5, 10 and 20 µg/ml) for varied time periods (6, 12, 24 and 48 h). For in vivo study, 30 male C57BL/6J mice were employed. 6 mice were sacrificed for baseline investigations. 24 mice were randomly divided into four groups: Group-I:Control mice, Group-II:CSC model, Group-III:High-fat diet(HFD) model, and Group-IV:HFD + CSC model for 14 weeks (n = 6/group). The group-II and IV mice were injected with 720 µg CSC/20 g body weight intraperitoneally (6 days/week).

RESULTS

In vitro, higher dosage of CSC (20 µg/ml) was toxic to cells as significant decline in cell viability and proliferation was observed. Furthermore, the mRNA expression of NLRP3 inflammasome and its pro-cytokine levels were significantly augmented on CSC exposure in a dose-dependent manner but impeded in time-dependent manner. In vivo, CSC and HFD independently augmented the expression of NLRP3 inflammasome (~4-10 fold-change) along with pro-cytokine levels in Group-II and III vs Group-I mice whereas, HFD + CSC treatment demonstrated synergistic effects in Group-IV.

CONCLUSION

Our data suggest that CSC activates NLRP3 inflammasome in vitro and in vivo and collectively with HFD has synergistic effects in vivo that may promote atherosclerosis.

Stabilization of blood for long-term storage can affect antibody-based recognition of cell surface markers

Whole-blood fixation provides a rapid and simplified method for cell preservation compared to isolation of peripheral blood mononuclear cells (PBMCs). This can be especially important for sample acquisition and storage in resource-limited settings. However, some caveats have been reported, such as reduced cell marker recognition. Here, we evaluated the whole-blood proteomic stabilizer PROT1 and compared recognition of 53 common cell markers in fixed buffy coats and cryopreserved PBMCs isolated from the same donor. Several antibodies completely lost their binding to the cells, while others presented with partial loss of marker recognition or no effect at all. Based on the screened antibodies, we designed two antibody panels allowing phenotyping of B cells, monocytes, and dendritic cells and also T cells and NK cells in both fixed and non-fixed material. Taken together, our observations suggest that antibodies intended to be used with fixed blood first need to be evaluated for marker recognition and staining intensity, in comparison with fresh samples or cryopreserved PBMCs.

The application of cell surface markers to demarcate distinct human pluripotent states

Recent advances in human pluripotent stem cell (hPSC) research have uncovered different subpopulations within stem cell cultures and have captured a range of pluripotent states that hold distinct molecular and functional properties. At the two ends of the pluripotency spectrum are naïve and primed hPSC, whereby naïve hPSC grown in stringent conditions recapitulate features of the preimplantation human embryo, and the conventionally grown primed hPSC align closer to the early postimplantation embryo. Investigating these cell types will help to define the mechanisms that control early development and should provide new insights into stem cell properties such as cell identity, differentiation and reprogramming. Monitoring cell surface marker expression provides a valuable approach to resolve complex cell populations, to directly compare between cell types, and to isolate viable cells for functional experiments. This review discusses the discovery and applications of cell surface markers to study human pluripotent cell types with a particular focus on the transitions between naïve and primed states. Highlighted areas for future study include the potential functions for the identified cell surface proteins in pluripotency, the production of new high-quality monoclonal antibodies to naïve-specific protein epitopes and the use of cell surface markers to characterise subpopulations within pluripotent states.

Differential transcriptional profiles identify microglial- and macrophage-specific gene markers expressed during virus-induced neuroinflammation

Background

In the healthy central nervous system (CNS), microglia are found in a homeostatic state and peripheral macrophages are absent from the brain. Microglia play key roles in maintaining CNS homeostasis and acting as first responders to infection and inflammation, and peripheral macrophages infiltrate the CNS during neuroinflammation. Due to their distinct origins and functions, discrimination between these cell populations is essential to the comprehension of neuroinflammatory disorders. Studies comparing the gene profiles of microglia and peripheral macrophages, or macrophages in vitro-derived from bone marrow, under non-infectious conditions of the CNS, have revealed valuable microglial-specific genes. However, studies comparing gene profiles between CNS-infiltrating macrophages and microglia, when both are isolated from the CNS during viral-induced neuroinflammation, are lacking.

Methods

We isolated, via flow cytometry, microglia and infiltrating macrophages from the brains of Theiler’s murine encephalomyelitis virus-infected C57BL/6 J mice and used RNA-Seq, followed by validation with qPCR, to examine the differential transcriptional profiles of these cells. We utilized primary literature defining subcellular localization to determine whether or not particular proteins extracted from the transcriptional profiles were expressed at the cell surface. The surface expression and cellular specificity of triggering receptor expressed on myeloid cells 1 (TREM-1) protein were examined via flow cytometry. We also examined the immune response gene profile within the transcriptional profiles of these isolated microglia and infiltrating macrophages.

Results

We have identified and validated new microglial- and macrophage-specific genes, encoding cell surface proteins, expressed at the peak of neuroinflammation. TREM-1 protein was confirmed to be expressed by infiltrating macrophages, not microglia, at the peak of neuroinflammation. We also identified both unique and redundant immune functions, through examination of the immune response gene profiles, of microglia and infiltrating macrophages during neurotropic viral infection.

Conclusions

The differential expression of cell surface-specific genes during neuroinflammation can potentially be used to discriminate between microglia and macrophages as well as provide a resource that can be further utilized to target and manipulate specific cell responses during neuroinflammation.

Electronic supplementary material

The online version of this article (10.1186/s12974-019-1545-x) contains supplementary material, which is available to authorized users.

Newly Defined ATP-Binding Cassette Subfamily B Member 5 Positive Dermal Mesenchymal Stem Cells Promote Healing of Chronic Iron-Overload Wounds via Secretion of Interleukin-1 Receptor Antagonist

In this study, we report the beneficial effects of a newly identified dermal cell subpopulation expressing the ATP-binding cassette subfamily B member 5 (ABCB5) for the therapy of nonhealing wounds. Local administration of dermal ABCB5⁺ -derived mesenchymal stem cells (MSCs) attenuated macrophage-dominated inflammation and thereby accelerated healing of full-thickness excisional wounds in the iron-overload mouse model mimicking the nonhealing state of human venous leg ulcers. The observed beneficial effects were due to interleukin-1 receptor antagonist (IL-1RA) secreted by ABCB5⁺ -derived MSCs, which dampened inflammation and shifted the prevalence of unrestrained proinflammatory M1 macrophages toward repair promoting anti-inflammatory M2 macrophages at the wound site. The beneficial anti-inflammatory effect of IL-1RA released from ABCB5⁺ -derived MSCs on human wound macrophages was conserved in humanized NOD-scid IL2rγ ^null mice. In conclusion, human dermal ABCB5⁺ cells represent a novel, easily accessible, and marker-enriched source of MSCs, which holds substantial promise to successfully treat chronic nonhealing wounds in humans. Stem Cells 2019;37:1057-1074.

CD200 Expression Marks a Population of Quiescent Limbal Epithelial Stem Cells with Holoclone Forming Ability

One of the main challenges in limbal stem cell (LSC) biology and transplantation is the lack of definitive cell surface markers which can be used to identify and enrich viable LSCs. In this study, expression of 361 cell surface proteins was assessed in ex vivo expanded limbal epithelial cells. One marker, CD200 was selected for further characterization based on expression in a small subset of limbal epithelial cells (2.25% ± 0.69%) and reduced expression through consecutive passaging and calcium induced differentiation. CD200 was localized to a small population of cells at the basal layer of the human and mouse limbal epithelium. CD200⁺ cells were slow cycling and contained the majority of side population (SP) and all the holoclone forming progenitors. CD200⁺ cells displayed higher expression of LSCs markers including PAX6, WNT7A, CDH3, CK14, CK15, and ABCB5 and lower expression of Ki67 when compared to CD200^- . Downregulation of CD200 abrogated the ability of limbal epithelial cells to form holoclones, suggesting an important function for CD200 in the maintenance and/or self-renewal of LSCs. A second marker, CD109, which was expressed in 56.29% ± 13.96% of limbal epithelial cells, was also found to co-localize with ΔNp63 in both human and mouse cornea, albeit more abundantly than CD200. CD109 expression decreased slowly through calcium induced cell differentiation and CD109⁺ cells were characterized by higher expression of Ki67, when compared to CD109^- subpopulation. Together our data suggest that CD200 expression marks a quiescent population of LSCs with holoclone forming potential, while CD109 expression is associated with a proliferative progenitor phenotype. Stem Cells 2018;36:1723-1735.

c-MPL Is a Candidate Surface Marker and Confers Self-Renewal, Quiescence, Chemotherapy Resistance, and Leukemia Initiation Potential in Leukemia Stem Cells

Acute myeloid leukemia (AML) is initiated and maintained by a unique, small subset of leukemia cells known as leukemia stem cells (LSCs). Self-renewal, quiescence, and chemotherapy resistance are key stemness properties of LSCs that are essential for poor clinical responses to conventional therapies. Identifying LSC surface markers and targeting LSCs are important for the development of potential therapies. In this study, application of chemotherapy treatment in AML-ETO9a (AE9a) leukemia mice led to the enrichment of a chemotherapy-resistant cell population identified as Lin^- c-Kit⁺ c-MPL⁺ . In addition, this c-MPL-positive cell population within Lin^- c-Kit⁺ leukemia cells included a high percentage of cells in a quiescent state, enhanced colony formation ability, and increased homing efficiency. Serial transplantation demonstrated that Lin^- c-Kit⁺ c-MPL⁺ cells displayed a significantly high potential for leukemia initiation. Furthermore, it was demonstrated that in AML patients, c-MPL was expressed on the majority of CD34⁺ leukemia cells and that the proportion of c-MPL⁺ cells in CD34⁺ leukemia cells is associated with poor prognosis. Finally, AMM2, an inhibitor of c-MPL, was shown to significantly enhance the survival of AE9a leukemia mice when combined with chemotherapeutic agent. These results indicate that c-MPL is a candidate LSC surface marker that may serve as a therapeutic target for the elimination of LSCs. Stem Cells 2018;36:1685-1696.

Concise Review: Stem/Progenitor Cell Proteoglycans Decorated with 7-D-4, 4-C-3, and 3-B-3(-) Chondroitin Sulfate Motifs Are Morphogenetic Markers of Tissue Development

This study reviewed the occurrence of chondroitin sulfate (CS) motifs 4-C-3, 7-D-4, and 3-B-3(-), which are expressed by progenitor cells in tissues undergoing morphogenesis. These motifs have a transient early expression pattern during tissue development and also appear in mature tissues during pathological remodeling and attempted repair processes by activated adult stem cells. The CS motifs are information and recognition modules, which may regulate cellular behavior and delineate stem cell niches in developmental tissues. One of the difficulties in determining the precise role of stem cells in tissue development and repair processes is their short engraftment period and the lack of specific markers, which differentiate the activated stem cell lineages from the resident cells. The CS sulfation motifs 7-D-4, 4-C-3, and 3-B-3 (-) decorate cell surface proteoglycans on activated stem/progenitor cells and appear to identify these cells in transitional areas of tissue development and in tissue repair and may be applicable to determining a more precise role for stem cells in tissue morphogenesis. Stem Cells 2018;36:1475-1486.

The CD11a and Endothelial Protein C Receptor Marker Combination Simplifies and Improves the Purification of Mouse Hematopoietic Stem Cells

Hematopoietic stem cells (HSCs) are the self‐renewing multipotent progenitors to all blood cell types. Identification and isolation of HSCs for study has depended on the expression of combinations of surface markers on HSCs that reliably distinguish them from other cell types. However, the increasing number of markers required to isolate HSCs has made it tedious, expensive, and difficult for newcomers, suggesting the need for a simpler panel of HSC markers. We previously showed that phenotypic HSCs could be separated based on expression of CD11a and that only the CD11a negative fraction contained true HSCs. Here, we show that CD11a and another HSC marker, endothelial protein C receptor (EPCR), can be used to effectively identify and purify HSCs. We introduce a new two‐color HSC sorting method that can highly enrich for HSCs with efficiencies comparable to the gold standard combination of CD150 and CD48. Our results demonstrate that adding CD11a and EPCR to the HSC biologist's toolkit improves the purity of and simplifies isolation of HSCs. stemcellstranslationalmedicine2018;7:468–476

Isolation of Human Photoreceptor Precursors via a Cell Surface Marker Panel from Stem Cell-Derived Retinal Organoids and Fetal Retinae

Loss of photoreceptor cells due to retinal degeneration is one of the main causes of blindness in the developed world. Although there is currently no effective treatment, cell replacement therapy using stem‐cell‐derived photoreceptor cells may be a feasible future treatment option. In order to ensure safety and efficacy of this approach, robust cell isolation and purification protocols must be developed. To this end, we previously developed a biomarker panel for the isolation of mouse photoreceptor precursors from the developing mouse retina and mouse embryonic stem cell cultures. In the current study we applied this approach to the human pluripotent stem cell (hPSC) system, and identified novel biomarker combinations that can be leveraged for the isolation of human photoreceptors. Human retinal samples and hPSC‐derived retinal organoid cultures were screened against 242 human monoclonal antibodies using a high through‐put flow cytometry approach. We identified 46 biomarkers with significant expression levels in the human retina and hPSC differentiation cultures. Human retinal cell samples, either from fetal tissue or derived from embryonic and induced pluripotent stem cell cultures, were fluorescence‐activated cell sorted (FACS) using selected candidate biomarkers that showed expression in discrete cell populations. Enrichment for photoreceptors and exclusion of mitotically active cells was demonstrated by immunocytochemical analysis with photoreceptor‐specific antibodies and Ki‐67. We established a biomarker combination, which enables the robust purification of viable human photoreceptors from both human retinae and hPSC‐derived organoid cultures. Stem Cells2018;36:709–722

High Throughput Flow Cytometry for Cell Surface Profiling

Cell surface proteins are widely studied in the search for new biomarkers and therapeutic targets, but there is little information available about the surfaceome of individual cells, and this is difficult to obtain experimentally, especially in heterogeneous samples. Flow cytometry is a simple and robust tool for assessing cell surface protein expression on a single-cell level in a wide variety of cell types. However, due to the cost and relative scarcity of reagents, it is typically limited to interrogating known markers, screening small curated subsets of likely candidates, or validating targets obtained via other high throughput methods such as transcriptional profiling. Given recent advances in our understanding of stem cells, tumor-initiating cells, and other rare populations in seemingly homogenous samples, and the relative lack of correlation between the transcriptome and the surfaceome, large-scale flow cytometry screens have become an appealing option. A relatively exhaustive microarray-like flow cytometry screening platform can reveal unexpected markers or sub-populations that are not readily detected by other methods. The single-cell resolution, reliability, and simplicity of flow cytometry and the additional benefit of sub-population/heterogeneity discrimination with the addition of functional and/or phenotypic co-stains allow for the rapid generation of very reliable data from a wide variety of samples at a low cost per sample. These larger datasets can be used for more elaborate bioinformatics, such as hierarchical clustering. Here we describe a method for high throughput cell surface profiling using conventional single or multicolor flow cytometry, which can be adapted to an antibody panel of any size.

Proteome and Secretome Characterization of Glioblastoma-Derived Neural Stem Cells

Glioblastoma multiforme (GBM) (grade IV astrocytoma) is the most common and aggressive primary brain tumor. GBM consists of heterogeneous cell types including a subset of stem cell-like cells thought to sustain tumor growth. These tumor-initiating glioblastoma multiforme-derived neural stem (GNS) cells as well as their genetically normal neural stem (NS) counterparts can be propagated in culture as relatively pure populations. Here, we perform quantitative proteomics to globally characterize and compare total proteome plus the secreted proteome (secretome) between GNS cells and NS cells. Proteins and pathways that distinguish malignant cancer (GNS) stem cells from their genetically normal counterparts (NS cells) might have value as new biomarkers or therapeutic targets. Our analysis identified and quantified ∼7,500 proteins in the proteome and ∼2,000 in the secretome, 447 and 138 of which were differentially expressed, respectively. Notable tumor-associated processes identified using gene set enrichment analysis included: extracellular matrix interactions, focal adhesion, cell motility, and cell signaling. We focused on differentially expressed surface proteins, and identified 26 that participate in ligand-receptor pairs that play a prominent role in tumorigenesis. Immunocytochemistry and immunoblotting confirmed that CD9, a recently identified marker of adult subventricular zone NS cells, was consistently enriched across a larger set of primary GNS cell lines. CD9 may, therefore, have value as a GNS-specific surface marker and a candidate therapeutic target. Altogether, these findings support the notion that increased cell-matrix and cell-cell adhesion molecules play a crucial role in promoting the tumor initiating and infiltrative properties of GNS cells. Stem Cells 2017;35:967-980.

New Monoclonal Antibodies to Defined Cell Surface Proteins on Human Pluripotent Stem Cells

The study and application of human pluripotent stem cells (hPSCs) will be enhanced by the availability of well‐characterized monoclonal antibodies (mAbs) detecting cell‐surface epitopes. Here, we report generation of seven new mAbs that detect cell surface proteins present on live and fixed human ES cells (hESCs) and human iPS cells (hiPSCs), confirming our previous prediction that these proteins were present on the cell surface of hPSCs. The mAbs all show a high correlation with POU5F1 (OCT4) expression and other hPSC surface markers (TRA‐160 and SSEA‐4) in hPSC cultures and detect rare OCT4 positive cells in differentiated cell cultures. These mAbs are immunoreactive to cell surface protein epitopes on both primed and naive state hPSCs, providing useful research tools to investigate the cellular mechanisms underlying human pluripotency and states of cellular reprogramming. In addition, we report that subsets of the seven new mAbs are also immunoreactive to human bone marrow‐derived mesenchymal stem cells (MSCs), normal human breast subsets and both normal and tumorigenic colorectal cell populations. The mAbs reported here should accelerate the investigation of the nature of pluripotency, and enable development of robust cell separation and tracing technologies to enrich or deplete for hPSCs and other human stem and somatic cell types. Stem Cells2017;35:626–640

Developmental Exposure to Endocrine Disruptors Expands Murine Myometrial Stem Cell Compartment as a Prerequisite to Leiomyoma Tumorigenesis

Despite the high prevalence and major negative impact of uterine fibroids (UFs) on women's health, their pathogenesis remains largely unknown. While tumor-initiating cells have been previously isolated from UFs, the cell of origin for these tumors in normal myometrium has not been identified. We isolated cells with Stro1/CD44 surface markers from normal myometrium expressing stem cell markers Oct-4/c-kit/nanog that exhibited the properties of myometrial stem/progenitor-like cells (MSCs). Using a murine model for UFs, we showed that the cervix was a hypoxic "niche" and primary site (96%) for fibroid development in these animals. The pool size of these MSCs also responded to environmental cues, contracting with age and expanding in response to developmental environmental exposures that promote fibroid development. Translating these findings to women, the number of MSCs in unaffected human myometrium correlated with risk for developing UFs. Caucasian (CC) women with fibroids had increased numbers of MSCs relative to CC women without fibroids, and African-American (AA) women at highest risk for these tumors had the highest number of MSCs: AA-with fibroids > CC-with fibroids > AA-without fibroids > CC-without fibroids. These data identify Stro1⁺ /CD44⁺ MSCs as MSC/progenitor cell for UFs, and a target for ethnic and environmental factors that increase UF risk. Stem Cells 2017;35:666-678.

Identification, expansion and characterization of cancer cells with stem cell properties from head and neck squamous cell carcinomas

Head and neck squamous cell carcinoma (HNSCC) is a major public health concern. Recent data indicate the presence of cancer stem cells (CSC) in many solid tumors, including HNSCC. Here, we assessed the stem cell (SC) characteristics, including cell surface markers, radioresistance, chromosomal instability, and in vivo tumorigenic capacity of CSC isolated from HNSCC patient specimens. We show that spheroid enrichment of CSC from early and short-term HNSCC cell cultures was associated with increased expression of CD44, CD133, SOX2 and BMI1 compared with normal oral epithelial cells. On immunophenotyping, five of 12 SC/CSC markers were homogenously expressed in all tumor cultures, while one of 12 was negative, four of 12 showed variable expression, and two of the 12 were expressed heterogeneously. We showed that irradiated CSCs survived and retained their self-renewal capacity across different ionizing radiation (IR) regimens. Fluorescence in situ hybridization (FISH) analyses of parental and clonally-derived tumor cells revealed different chromosome copy numbers from cell to cell, suggesting the presence of chromosomal instability in HNSCC CSC. Further, our in vitro and in vivo mouse engraftment studies suggest that CD44+/CD66- is a promising, consistent biomarker combination for HNSCC CSC. Overall, our findings add further evidence to the proposed role of HNSCC CSCs in therapeutic resistance.

A strategy to ensure safety of stem cell-derived retinal pigment epithelium cells

Cell replacement and regenerative therapy using embryonic stem cell-derived material holds promise for the treatment of several pathologies. However, the safety of this approach is of prime importance given the teratogenic potential of residual stem cells, if present in the differentiated cell product. Using the example of embryonic stem cell-derived retinal pigment epithelium (RPE) for the treatment of age-related macular degeneration, we present a novel strategy for ensuring the absence of stem cells in the RPE population. Based on an unbiased screening approach, we identify and validate the expression of CD59, a cell surface marker expressed on RPE but absent on stem cells. We further demonstrate that flow sorting on the basis of CD59 expression can effectively purify RPE and deplete stem cells, resulting in a population free from stem cell impurity. This purification helps to ensure removal of stem cells and hence increases the safety of cells that may be used for clinical transplantation. This strategy can potentially be applied to other pluripotent stem cell-derived material and help mitigate concerns of using such cells for therapy.

Mesenchymal stem cell subpopulations: phenotype, property and therapeutic potential

Mesenchymal stem cells (MSC) are capable of differentiating into cells of multiple cell lineages and have potent paracrine effects. Due to their easy preparation and low immunogenicity, MSC have emerged as an extremely promising therapeutic agent in regenerative medicine for diverse diseases. However, MSC are heterogeneous with respect to phenotype and function in current isolation and cultivation regimes, which often lead to incomparable experimental results. In addition, there may be specific stem cell subpopulations with definite differentiation capacity toward certain lineages in addition to stem cells with multi-differentiation potential. Recent studies have identified several subsets of MSC which exhibit distinct features and biological activities, and enhanced therapeutic potentials for certain diseases. In this review, we give an overview of these subsets for their phenotypic, biological and functional properties.

Lacrimal Gland Repair Using Progenitor Cells

In humans, the lacrimal gland (LG) is the primary contributor to the aqueous layer of the tear film. Production of tears in insufficient quantity or of inadequate quality may lead to aqueous‐deficiency dry eye (ADDE). Currently there is no cure for ADDE. The development of strategies to reliably isolate LG stem/progenitor cells from the LG tissue brings great promise for the design of cell replacement therapies for patients with ADDE. We analyzed the therapeutic potential of epithelial progenitor cells (EPCPs) isolated from adult wild‐type mouse LGs by transplanting them into the LGs of TSP‐1^−/− mice, which represent a novel mouse model for ADDE. TSP‐1^−/− mice are normal at birth but progressively develop a chronic form of ocular surface disease, characterized by deterioration, inflammation, and secretory dysfunction of the lacrimal gland. Our study shows that, among c‐kit‐positive epithelial cell adhesion molecule (EpCAM⁺) populations sorted from mouse LGs, the c‐kit⁺dim/EpCAM⁺/Sca1⁻/CD34⁻/CD45⁻ cells have the hallmarks of an epithelial cell progenitor population. Isolated EPCPs express pluripotency factors and markers of the epithelial cell lineage Runx1 and EpCAM, and they form acini and ducts when grown in reaggregated three‐dimensional cultures. Moreover, when transplanted into injured or “diseased” LGs, they engraft into acinar and ductal compartments. EPCP‐injected TSP‐1^−/− LGs showed reduction of cell infiltration, differentiation of the donor EPCPs within secretory acini, and substantial improvement in LG structural integrity and function. This study provides the first evidence for the effective use of adult EPCP cell transplantation to rescue LG dysfunction in a model system. Stem Cells Translational Medicine2017;6:88–98

Enforced Expression of HOXB4 in Human Embryonic Stem Cells Enhances the Production of Hematopoietic Progenitors but Has No Effect on the Maturation of Red Blood Cells

: We have developed a robust, Good Manufacturing Practice-compatible differentiation protocol capable of producing scalable quantities of red blood cells (RBCs) from human pluripotent stem cells (hPSCs). However, translation of this protocol to the clinic has been compromised because the RBCs produced are not fully mature; thus, they express embryonic and fetal, rather than adult globins, and they do not enucleate efficiently. Based on previous studies, we predicted that activation of exogenous HOXB4 would increase the production of hematopoietic progenitor cells (HPCs) from hPSCs and hypothesized that it might also promote the production of more mature, definitive RBCs. Using a tamoxifen-inducible HOXB4-ER(T2) expression system, we first demonstrated that activation of HOXB4 does increase the production of HPCs from hPSCs as determined by colony-forming unit culture activity and the presence of CD43(+)CD34(+) progenitors. Activation of HOXB4 caused a modest, but significant, increase in the proportion of immature CD235a(+)/CD71(+) erythroid cells. However, this did not result in a significant increase in more mature CD235a(+)/CD71(-) cells. RBCs produced in the presence of enhanced HOXB4 activity expressed embryonic (ε) and fetal (γ) but not adult (β) globins, and the proportion of enucleated cells was comparable to that of the control cultures. We conclude that programming with the transcription factor HOXB4 increases the production of hematopoietic progenitors and immature erythroid cells but does not resolve the inherent challenges associated with the production of mature adult-like enucleated RBCs.

SIGNIFICANCE

As worldwide blood donations decrease and transfusable transmitted infections increase, intense interest has ensued in deriving red blood cells (RBCs) in vitro from alternative sources such as pluripotent stem cells. A translatable protocol was developed to generate RBCs; however, these RBCs have an immature phenotype. It was hypothesized that the transcription factor HOXB4 could enhance their production and maturation. Although HOXB4 increased the production of erythroid progenitors, it did not promote their maturation. Despite the remaining challenges, a robust system has been established to test other candidates and add to the knowledge base in this field.

Theory and Practice of Lineage Tracing

Lineage tracing is a method that delineates all progeny produced by a single cell or a group of cells. The possibility of performing lineage tracing initiated the field of Developmental Biology and continues to revolutionize Stem Cell Biology. Here, I introduce the principles behind a successful lineage-tracing experiment. In addition, I summarize and compare different methods for conducting lineage tracing and provide examples of how these strategies can be implemented to answer fundamental questions in development and regeneration. The advantages and limitations of each method are also discussed.

Recruited brain tumor-derived mesenchymal stem cells contribute to brain tumor progression

The identity of the cells that contribute to brain tumor structure and progression remains unclear. Mesenchymal stem cells (MSCs) have recently been isolated from normal mouse brain. Here, we report the infiltration of MSC-like cells into the GL261 murine glioma model. These brain tumor-derived mesenchymal stem cells (BT-MSCs) are defined with the phenotype (Lin-Sca-1+CD9+CD44+CD166+/-) and have multipotent differentiation capacity. We show that the infiltration of BT-MSCs correlates to tumor progression; furthermore, BT-MSCs increased the proliferation rate of GL261 cells in vitro. For the first time, we report that the majority of GL261 cells expressed mesenchymal phenotype under both adherent and sphere culture conditions in vitro and that the non-MSC population is nontumorigenic in vivo. Although the GL261 cell line expressed mesenchymal phenotype markers in vitro, most BT-MSCs are recruited cells from host origin in both wild-type GL261 inoculated into green fluorescent protein (GFP)-transgenic mice and GL261-GFP cells inoculated into wild-type mice. We show the expression of chemokine receptors CXCR4 and CXCR6 on different recruited cell populations. In vivo, the GL261 cells change marker profile and acquire a phenotype that is more similar to cells growing in sphere culture conditions. Finally, we identify a BT-MSC population in human glioblastoma that is CD44+CD9+CD166+ both in freshly isolated and culture-expanded cells. Our data indicate that cells with MSC-like phenotype infiltrate into the tumor stroma and play an important role in tumor cell growth in vitro and in vivo. Thus, we suggest that targeting BT-MSCs could be a possible strategy for treating glioblastoma patients.

Testicular niche required for human spermatogonial stem cell expansion

Prepubertal boys treated with high-dose chemotherapy do not have an established means of fertility preservation because no established in vitro technique exists to expand and mature purified spermatogonial stem cells (SSCs) to functional sperm in humans. In this study, we define and characterize the unique testicular cellular niche required for SSC expansion using testicular tissues from men with normal spermatogenesis. Highly purified SSCs and testicular somatic cells were isolated by fluorescence-activated cell sorting using SSEA-4 and THY1 as markers of SSCs and somatic cells. Cells were cultured on various established niches to assess their role in SSC expansion in a defined somatic cellular niche. Of all the niches examined, cells in the SSEA-4 population exclusively bound to adult testicular stromal cells, established colonies, and expanded. Further characterization of these testicular stromal cells revealed distinct mesenchymal markers and the ability to undergo differentiation along the mesenchymal lineage, supporting a testicular multipotent stromal cell origin. In vitro human SSC expansion requires a unique niche provided exclusively by testicular multipotent stromal cells with mesenchymal properties. These findings provide an important foundation for developing methods of inducing SSC growth and maturation in prepubertal testicular tissue, essential to enabling fertility preservation for these boys.

Brief report: CD24 and CD44 mark human intestinal epithelial cell populations with characteristics of active and facultative stem cells

Recent seminal studies have rapidly advanced the understanding of intestinal epithelial stem cell (IESC) biology in murine models. However, the lack of techniques suitable for isolation and subsequent downstream analysis of IESCs from human tissue has hindered the application of these findings toward the development of novel diagnostics and therapies with direct clinical relevance. This study demonstrates that the cluster of differentiation genes CD24 and CD44 are differentially expressed across LGR5 positive "active" stem cells as well as HOPX positive "facultative" stem cells. Fluorescence-activated cell sorting enables differential enrichment of LGR5 (CD24-/CD44+) and HOPX (CD24+/CD44+) cells for gene expression analysis and culture. These findings provide the fundamental methodology and basic cell surface signature necessary for isolating and studying intestinal stem cell populations in human physiology and disease.

Ex vivo expansion of hematopoietic stem and progenitor cells: Recent advances

Hematopoietic stem cells (HSCs) have become the most extensively studied stem cells and HSC-based cellular therapy is promising for hematopoietic cancers and hereditary blood disorders. Successful treatment of patients with HSC cells depends on sufficient number of highly purified HSCs and progenitor cells. However, stem cells are a very rare population no matter where they come from. Thus, ex vivo amplification of these HSCs is essential. The heavy demands from more and more patients for HSCs also require industrial-scale expansion of HSCs with lower production cost and higher efficiency. Two main ways to reach that goal: (1) to find clinically applicable, simple and efficient methods (or reagents) to enrich HSCs; (2) to find new developmental regulators and chemical compounds in order to replace the currently used cytokine cocktails for HSCs amplification. In this Editorial review, we would like to introduce the current status of ex vivo expansion of HSCs, particularly focusing on enrichment and culture supplements.

Transplantation of CD15-enriched murine neural stem cells increases total engraftment and shifts differentiation toward the oligodendrocyte lineage

Neural stem cell (NSC) transplantation is a promising therapeutic approach for neurological diseases. However, only a limited number of cells can be transplanted into the brain, resulting in relatively low levels of engraftment. This study investigated the potential of using a cell surface marker to enrich a primary NSC population to increase stable engraftment in the recipient brain. NSCs were enriched from the neonatal mouse forebrain using anti-CD15 (Lewis X antigen, or SSEA-1) in a "gentle" fluorescence-activated cell sorting protocol, which yielded >98% CD15-positive cells. The CD15-positive cells differentiated into neurons, astrocytes, and oligodendrocytes in vitro, after withdrawal of growth factors, demonstrating multipotentiality. CD15-positive cells were expanded in vitro and injected bilaterally into the ventricles of neonatal mice. Cells from enriched and unenriched donor populations were found throughout the neuraxis, in both neurogenic and non-neurogenic regions. Total engraftment was similar at 7 days postinjection, but by 28 days postinjection, after brain organogenesis was complete, the survival of donor cells was significantly increased in CD15-enriched grafts over the unenriched cell grafts. The engrafted cells were heterogeneous in morphology and differentiated into all three neural lineages. Furthermore, in the CD15-enriched grafts, there was a significant shift toward differentiation into oligodendrocytes. This strategy may allow better delivery of therapeutic cells to the developing central nervous system and may be particularly useful for treating diseases involving white matter lesions.

Flow cytometry and gene expression profiling of immune cells of the carotid plaque and peripheral blood

OBJECTIVES

The relative contribution of the local vs. peripheral inflammation to the atherothrombotic processes is unknown. We compared the inflammatory status of the immune cells of the carotid plaque with similar cells in peripheral circulation of patients with advanced carotid disease (PCDs).

METHODS

Mononuclear cells (MNCs) were extracted from carotid endarterectomy (CEA) samples by enzymatic digestion and subsequent magnetic cell sorting. The cell surface antigenic expressions, and mRNA expression levels were compared between CEA MNCs and peripheral MNCs, using flow cytometry and RT-PCR techniques.

RESULTS

The percentages of resting MNCs were lower, and activated MNCs, particularly monocytes, were higher in the CEAMNCs, as compared to the peripheral MNCs. The percentages of activated T cells and B cells were higher in the peripheral MNCs of PCDs, than in healthy controls (HCs), but the percentages of activated monocytes did not differ between the two groups. The expression levels of both pro-inflammatory/pro-thrombotic (P(38), JNKB-1, Egr-1 PAI-1, MCP-1, TF, MMP-9, HMGB-1, TNF-α, mTOR) and anti-inflammatory (PPAR-γ, TGF-β) mediators were significantly higher in the CEA MNCs as compared to the peripheral MNCs. Furthermore, MMP-9 and PPAR-γ expression levels were higher in the peripheral MNCs of PCDs than HCs.

CONCLUSION

The inflammatory status is higher in the immune cells of the carotid plaque, as compared to those cells in the peripheral blood. The altered expression levels of both pro-inflammatory/pro-thrombotic and anti-inflammatory mediators in the milieu of the plaque suggest that the balance between these various mediators may play a key role in carotid disease progression.