Transcriptome sequencing wide functional analysis of human mesenchymal stem cells in response to TLR4 ligand

Translational potential of mesenchymal stem cells in regenerative therapies for human diseases: challenges and opportunities

Advances in stem cell technology offer new possibilities for patients with untreated diseases and disorders. Stem cell-based therapy, which includes multipotent mesenchymal stem cells (MSCs), has recently become important in regenerative therapies. MSCs are multipotent progenitor cells that possess the ability to undergo in vitro self-renewal and differentiate into various mesenchymal lineages. MSCs have demonstrated promise in several areas, such as tissue regeneration, immunological modulation, anti-inflammatory qualities, and wound healing. Additionally, the development of specific guidelines and quality control methods that ultimately result in the therapeutic application of MSCs has been made easier by recent advancements in the study of MSC biology. This review discusses the latest clinical uses of MSCs obtained from the umbilical cord (UC), bone marrow (BM), or adipose tissue (AT) in treating various human diseases such as pulmonary dysfunctions, neurological disorders, endocrine/metabolic diseases, skin burns, cardiovascular conditions, and reproductive disorders. Additionally, this review offers comprehensive information regarding the clinical application of targeted therapies utilizing MSCs. It also presents and examines the concept of MSC tissue origin and its potential impact on the function of MSCs in downstream applications. The ultimate aim of this research is to facilitate translational research into clinical applications in regenerative therapies.

Crosstalk between vault RNAs and innate immunity

PURPOSE

Vault (vt) RNAs are noncoding (nc) RNAs transcribed by RNA polymerase III (RNA Pol III) with 5'-triphosphate (5'-PPP) termini that play significant roles and are recognized by innate immune sensors, including retinoic acid-inducible protein 1 (RIG-I). In addition, vtRNAs adopt secondary structures that can be targets of interferon-inducible protein kinase R (PKR) and the oligoadenylate synthetase (OAS)/RNase L system, both of which are important for activating antiviral defenses. However, changes in the expression of vtRNAs have been associated with pathological processes that activate proinflammatory pathways, which influence cellular events such as differentiation, aging, autophagy, apoptosis, and drug resistance in cancer cells.

RESULTS

In this review, we summarized the biology of vtRNAs and focused on their interactions with the innate immune system. These findings provide insights into the diverse roles of vtRNAs and their correlation with various cellular processes to improve our understanding of their biological functions.

Mesodermal Derivatives of Pluripotent Stem Cells Route to Scarless Healing

Scar formation during normal tissue regeneration in adults may result in noticeable cosmetic and functional defects and have a significant impact on the quality of life. In contrast, fetal tissues in the mid-gestation period are known to be capable of complete regeneration with the restitution of the initial architecture, organization, and functional activity. Successful treatments that are targeted to minimize scarring can be realized by understanding the cellular and molecular mechanisms of fetal wound regeneration. However, such experiments are limited by the inaccessibility of fetal material for comparable studies. For this reason, the molecular mechanisms of fetal regeneration remain unknown. Mesenchymal stromal cells (MSCs) are central to tissue repair because the molecules they secrete are involved in the regulation of inflammation, angiogenesis, and remodeling of the extracellular matrix. The mesodermal differentiation of human pluripotent stem cells (hPSCs) recapitulates the sequential steps of embryogenesis in vitro and provides the opportunity to generate the isogenic cell models of MSCs corresponding to different stages of human development. Further investigation of the functional activity of cells from stromal differon in a pro-inflammatory microenvironment will procure the molecular tools to better understand the fundamental mechanisms of fetal tissue regeneration. Herein, we review recent advances in the generation of clonal precursors of primitive mesoderm cells and MSCs from hPSCs and discuss critical factors that determine the functional activity of MSCs-like cells in a pro-inflammatory microenvironment in order to identify therapeutic targets for minimizing scarring.

Strategy for RNA-Seq Experimental Design and Data Analysis

Ribonucleic acids (RNAs) are fundamental molecules that control regulation and expression of the genome and therefore the function of a cell. Robust analysis and quantification of RNA transcripts hold critical importance in understanding cell function, altered phenotypes in different biological context, for understanding and targeting diseases. The development of RNA-sequencing (RNA-Seq) now provides opportunities to analyze the expression and function of RNA molecules at an unprecedented scale. However, the strategy for RNA-Seq experimental design and data analysis can substantially differ depending on the biological application. The design choice could also have significant impact for downstream results and interpretation of data. Here we describe key critical considerations required for RNA-Seq experimental design and also describe a step-by-step bioinformatics workflow detailing the different steps required for RNA-Seq data analysis. We believe this article will be a valuable guide for designing and analyzing RNA-Seq data to address a wide range of different biological questions.

LncRNA MRF drives the regulatory function on monocyte recruitment and polarization through HNRNPD-MCP1 axis in mesenchymal stem cells

Background

Mesenchymal stem cells (MSCs) exhibit two bidirectional immunomodulatory abilities: proinflammatory and anti-inflammatory regulatory effects. Long noncoding RNAs (lncRNAs) have important functions in the immune system. Previously, we performed high-throughput sequencing comparing lncRNA expression profiles between MSCs cocultured with or without CD14+ monocytes and screened out a new lncRNA termed lncRNA MCP1 regulatory factor (MRF). However, the mechanism of MRF in MSCs is still unknown.

Methods

MRF expression was quantified via qRT–PCR. RNA interference and lentiviruses were used to regulate MRF expression. The immunomodulatory effects of MSCs on monocytes were evaluated via monocyte migration and macrophage polarization assays. RNA pull-down and mass spectrometry were utilized to identify downstream factors of MRF. A dual-luciferase reporter assay was applied to analyze the transcription factors regulating MRF. qRT–PCR, western blotting and ELISAs were used to assess MCP1 expression. A human monocyte adoptive transfer mouse model was applied to verify the function of MRF in vivo.

Results

MRF was upregulated in MSCs during coculture with CD14+ monocytes. MRF increased monocyte recruitment by upregulating the expression of monocyte chemotactic protein (MCP1). Knockdown of MRF enhanced the regulatory effect of MSCs on restraining M1 polarization and facilitating M2 polarization. Mechanistically, MRF bound to the downstream protein heterogeneous nuclear ribonucleoprotein D (HNRNPD) to upregulate MCP1 expression, and the transcription factor interferon regulatory factor 1 (IRF1) activated MRF transcription early during coculture. The human monocyte adoptive transfer model showed that MRF downregulation in MSCs inhibited monocyte chemotaxis and enhanced the effects of MSCs to inhibit M1 macrophage polarization and promote M2 polarization in vivo.

Conclusion

We identified the new lncRNA MRF, which exhibits proinflammatory characteristics. MRF regulates the ability of MSCs to accelerate monocyte recruitment and modulate macrophage polarization through the HNRNPD-MCP1 axis and initiates the proinflammatory regulatory process in MSCs, suggesting that MRF is a potential target to improve the clinical effect of MSC-based therapy or correct MSC-related immunomodulatory dysfunction under pathological conditions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12929-022-00858-3.

Cytokine Mixtures Mimicking the Local Milieu in Patients with Inflammatory Bowel Disease Impact Phenotype and Function of Mesenchymal Stromal Cells

Locally applied mesenchymal stromal cells (MSCs) have the capacity to promote the healing of perianal fistulas in Crohn’s disease (CD) and are under clinical development for the treatment of proctitis in ulcerative colitis (UC). Despite these clinical advances, the mechanism of action of local MSC therapy in inflammatory bowel disease (IBD) is largely unknown. We hypothesized that the local cytokine environment in IBD patients affects the immunomodulatory properties of MSCs. To evaluate this, 11 cytokines were analyzed in inflamed tissues obtained from CD and UC patients. Based on the identified cytokine profiles 4 distinct cytokine mixtures that mimic various inflammatory IBD environments were established. Next, MSCs were cultured in the presence of either of these 4 cytokine mixtures after which the expression of immunomodulatory and tissue regenerative molecules and the capacity of MSCs to modulate T-cell proliferation and dendritic cell (DC) differentiation were assessed. Our data show that MSCs respond, in a cytokine-specific manner, by upregulation of immunomodulatory and tissue regenerative molecules, including cyclooxygenase-2, indoleamine 2,3-dioxygenase, and transforming growth factor-β1. Functional studies indicate that MSCs exposed to a cytokine profile mimicking one of the 2 UC cytokine milieus were less effective in inhibition of DC differentiation. In conclusion, our data indicate that cytokine mixes mimicking the local cytokine milieus of inflamed UC colonic or CD fistulas tissues can differentially affect the immunomodulatory and tissue regenerative characteristics of MSCs. These data support the hypothesis that the local intestinal cytokine milieu serves as a critical factor in the efficacy of local MSC treatment.

The bromodomain inhibitor JQ1 up-regulates the long non-coding RNA MALAT1 in cultured human hepatic carcinoma cells

The epigenetic reader, bromodomain-containing 4 (BRD4), is overexpressed in hepatocellular carcinoma (HCC), and BRD4 inhibition is considered as a new therapeutic approach. The BRD inhibitor JQ1 is known to inhibit the enrichment of BRD4 at enhancer sites. Gene network analyses have implicated long non-coding RNAs (lncRNAs) in the effects of JQ1, but the precise molecular events remain unexplored. Here, we report that in HepG2 cells, JQ1 significantly reduced various proliferation-related lncRNAs, but up-regulated the known liver tumor marker, MALAT1. Using ChIP-sequencing data, ChIP-qPCR, luciferase reporter assays, and chromatin conformation capture (3C), we characterized the MALAT1 gene locus. We found that JQ1 elicited a rearrangement of its chromatin looping conformation, which involved the putative enhancers E1, E2, E3, the gene body, and the promoter. We further found that the forkhead box protein A2 (FOXA2) binds to E2 and the promoter; suppression of FOXA2 expression resulted in MALAT1 up-regulation and increased cell proliferation. These results suggest that the inhibition of MALAT1 may improve the effect of BET inhibitors as an anti-cancer therapy and that FOXA2 would be a suitable target for that approach.

Transcriptome analysis of umbilical cord mesenchymal stem cells revealed fetal programming due to chorioamnionitis

Although chorioamnionitis (CAM) has been demonstrated to be associated with numerous short- and long-term morbidities, the precise mechanisms remain unclear. One of the reasons for this is the lack of appropriate models for analyzing the relationship between the fetal environment and chorioamnionitis and fetal programming in humans. In this study, we aimed to clarify the fetal programming caused by CAM using the gene expression profiles of UCMSCs. From nine preterm neonates with CAM (n = 4) or without CAM (n = 5), we established UCMSCs. The gene expression profiles obtained by RNA-seq analysis revealed distinctive changes in the CAM group USMSCs. The UCMSCs in the CAM group had a myofibroblast-like phenotype with significantly increased expression levels of myofibroblast-related genes, including α-smooth muscle actin (p < 0.05). In the pathway analysis, the genes involved in DNA replication and G1 to S cell cycle control were remarkably decreased, suggesting that cellular proliferation was impaired, as confirmed by the cellular proliferation assay (p < 0.01–0.05). Pathway analysis revealed that genes related to white fat cell differentiation were significantly increased. Our results could explain the long-term outcomes of patients who were exposed to CAM and revealed that UCMSCs could be an in vitro model of fetal programming affected by CAM.

Upregulation of CD14 in mesenchymal stromal cells accelerates lipopolysaccharide-induced response and enhances antibacterial properties

Mesenchymal stromal cells (MSCs) have broad-ranging therapeutic properties, including the ability to inhibit bacterial growth and resolve infection. However, the genetic mechanisms regulating these antibacterial properties in MSCs are largely unknown. Here, we utilized a systems-based approach to compare MSCs from different genetic backgrounds that displayed differences in antibacterial activity. Although both MSCs satisfied traditional MSC-defining criteria, comparative transcriptomics and quantitative membrane proteomics revealed two unique molecular profiles. The antibacterial MSCs responded rapidly to bacterial lipopolysaccharide (LPS) and had elevated levels of the LPS co-receptor CD14. CRISPR-mediated overexpression of endogenous CD14 in MSCs resulted in faster LPS response and enhanced antibacterial activity. Single-cell RNA sequencing of CD14-upregulated MSCs revealed a shift in transcriptional ground state and a more uniform LPS-induced response. Our results highlight the impact of genetic background on MSC phenotypic diversity and demonstrate that overexpression of CD14 can prime these cells to be more responsive to bacterial challenge.

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MSCs from different genetic backgrounds have distinct responses to bacteria

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Upregulating CD14 in MSCs enhances LPS-induced response and antibacterial traits

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CD14 upregulation homogenizes MSC transcriptional profiles across individual cells

Unraveling molecular mechanism underlying biomaterial and stem cells interaction during cell fate commitment using high throughput data analysis

Stem cell differentiation towards various somatic cells and body organs has proven to be an effective technique in the understanding and progression of regenerative medicine. Despite the advances made, concerns regarding the low efficiency of differentiation and the remaining differences between stem cell products and their in vivo counterparts must be addressed. Biomaterials that mimic endogenous growth conditions represent one recent method used to improve the quality and efficiency of stem cell differentiation, though the mechanisms of this improvement remain to be completely understood. The effectiveness of various biomaterials can be analyzed through a multidisciplinary approach involving bioinformatics and systems biology tools. Here, we aim to use bioinformatics to accomplish two aims: 1) determine the effect of different biomaterials on stem cell growth and differentiation, and 2) understand the effect of cell of origin on the differentiation potential of multipotent stem cells. First, we demonstrate that the dimensionality (2D versus 3D) and the degradability of biomaterials affects the way that the cells are able to grow and differentiate at the transcriptional level. Additionally, according to transcriptional state of the cells, the particular cell of origin is an important factor in determining the response of stem cells to same biomaterial. Our data demonstrates the ability of bioinformatics to understand novel molecular mechanisms and context by which stem cells are most efficiently able to differentiate. These results and strategies can be used to suggest proper combinations of biomaterials and stem cells to achieve high differentiation efficiency and functionality of desired cell types.

The BET inhibitor attenuates the inflammatory response and cell migration in human microglial HMC3 cell line

Microglia, resident macrophages of the brain that act as primary immune cells, play essential roles in innate immunity and neuroinflammatory pathologies. Microglial cells are rapidly activated in response to infection and inflammation/injury, associated with the expression of proinflammatory genes and secretion of cytokines. The bromodomain and extra-terminal (BET) inhibitor JQ1 has been shown to be an epigenetic agent that reduces inflammation. In this study, we investigated the mechanisms underlying the anti-inflammatory and anti-migratory functions of JQ1 and the genes targeted by JQ1 in lipopolysaccharide (LPS)-activated human microglial clone 3 (HMC3) cells using RNA-sequencing (RNA-seq). We analyzed the pattern of inflammation-related genes (chemokines, cytokines, and interferon-stimulated genes) and migration-related genes with JQ1 treatment from differentially expressed genes analysis in HMC3 cells. We found that LPS-induced IRF1 directly regulated inflammation- and migration-related genes and that JQ1 significantly reduced IRF1 and its target genes. Additionally, IRF1 attenuation significantly downregulated target genes and inhibited microglial migration. Our data suggest that the BET inhibitor JQ1 can modulate the inflammatory response and migration through the regulation of LPS-induced IRF1 in human microglia.

Integrated Analysis of Transcriptome and Secretome From Umbilical Cord Mesenchymal Stromal Cells Reveal New Mechanisms for the Modulation of Inflammation and Immune Activation

Mesenchymal stromal cells (MSC) have been used in over 800 clinical trials with encouraging results in the field of transplant medicine and chronic inflammatory diseases. Today, Umbilical Cord (UC)-derived MSC are the second leading source used for clinical purposes, mainly due to its easy access and superior immune modulatory effects. Although the underlying molecular mechanisms of immune suppressive activities have not been fully understood, research over the last decade strongly suggests that MSC-mediated benefits are closely related to activation of secretome networks. Nevertheless, recent findings also point to cytokine-independent mechanisms as key players of MSC-mediated immune modulation. Here, we set up a robust in vitro immune assay using phytohemagglutinin- or anti-CD3/CD28-treated human peripheral blood mononuclear cells in cell-to-cell interaction or in cell-contact independent format with UC-MSC and conducted integrated transcriptome and secretome analyses to dissect molecular pathways driving UC-MSC-mediated immune modulation. Under inflammatory stimuli, multiparametric analyses of the secretome led us to identify cytokine/chemokine expression patterns associated with the induction of MSC-reprogrammed macrophages and T cell subsets ultimately leading to immune suppression. UC-MSC transcriptome analysis under inflammatory challenge allowed the identification of 47 differentially expressed genes, including chemokines, anti- and pro-inflammatory cytokines and adhesion molecules found also in UC-MSC-immunosupressive secretomes, including the novel candidate soluble IL-2R. This study enabled us to track functionally activated UC-MSC during immune suppression and opened an opportunity to explore new pathways involved in immunity control by UC-MSC. We propose that identified immunomodulatory molecules and pathways could potentially be translated into clinical settings in order to improve UC-MSC-therapy quality and efficacy.

Epigenetic regulation of IFITM1 expression in lipopolysaccharide-stimulated human mesenchymal stromal cells

Background

Toll-like receptor 4 (TLR4) ligands such as lipopolysaccharide (LPS) activate immunomodulatory functions and the migration of human mesenchymal stromal cells (hMSCs). Here, we study the migration-related gene expression of LPS-stimulated hMSCs and the role and regulation of one of the upregulated genes, encoding the interferon-induced transmembrane protein 1 (IFITM1).

Methods

Gene expression profiles were determined by whole-transcriptome analysis (RNA-seq) and quantitative real-time PCR (qRT-PCR). Bioinformatics approaches were used to perform network and pathway analyses. The cell migration-related genes were identified with an in vitro wound healing assay. RNA interference (RNAi) was used to suppress the IFITM1 gene expression. The IFITM1 gene enhancer was analyzed by chromatin immunoprecipitation (ChIP) sequencing, ChIP-to-PCR, luciferase reporter assays, and qRT-PCR for enhancer RNAs (eRNAs).

Results

RNA-seq confirmed IFITM1 as an LPS-stimulated gene, and RNAi demonstrated its importance for the LPS-stimulated migration. LPS treatment increased the eRNA expression in enhancer region R2 (2 kb upstream) of the IFITM1 gene and enriched R2 for H3K27ac. Bioinformatics implicated the transcription factors NF-κB and IRF1, ChIP assays revealed their binding to R2, and chemical inhibition of NF-κB and RNAi directed against IRF1 prevented R2 eRNA and IFITM1 gene expression.

Conclusions

Increased expression of the IFITM1 gene is required for LPS-stimulated hMSC migration. We described several underlying changes in the IFITM1 gene enhancer, most notably the NF-κB-mediated activation of enhancer region R2.

Mesenchymal stem cell perspective: cell biology to clinical progress

The terms MSC and MSCs have become the preferred acronym to describe a cell and a cell population of multipotential stem/progenitor cells commonly referred to as mesenchymal stem cells, multipotential stromal cells, mesenchymal stromal cells, and mesenchymal progenitor cells. The MSCs can differentiate to important lineages under defined conditions in vitro and in limited situations after implantation in vivo. MSCs were isolated and described about 30 years ago and now there are over 55,000 publications on MSCs readily available. Here, we have focused on human MSCs whenever possible. The MSCs have broad anti-inflammatory and immune-modulatory properties. At present, these provide the greatest focus of human MSCs in clinical testing; however, the properties of cultured MSCs in vitro suggest they can have broader applications. The medical utility of MSCs continues to be investigated in over 950 clinical trials. There has been much progress in understanding MSCs over the years, and there is a strong foundation for future scientific research and clinical applications, but also some important questions remain to be answered. Developing further methods to understand and unlock MSC potential through intracellular and intercellular signaling, biomedical engineering, delivery methods and patient selection should all provide substantial advancements in the coming years and greater clinical opportunities. The expansive and growing field of MSC research is teaching us basic human cell biology as well as how to use this type of cell for cellular therapy in a variety of clinical settings, and while much promise is evident, careful new work is still needed.

Basal-type lumenogenesis in extraembryonic endoderm stem cells models the early visceral endoderm

Cultured rat primitive extraembryonic endoderm (pXEN) cells easily form free-floating multicellular vesicles de novo, exemplifying a poorly studied type of morphogenesis. Here, we reveal the underlying mechanism and the identity of the vesicles. We resolve the morphogenesis into vacuolization, vesiculation and maturation, and define the molecular characteristics and requirements of each step. Vacuolization is fueled by macropinocytosis and occurs by default if not blocked by high cell density or matrix proteins. Fine-tuned cell-cell contact then forms nascent three-cell vesicles with vacuole-derived lumina. In maturation, the vesicles complete epithelialization, expand via mitosis and continued fluid uptake, and differentiate further. The mature vesicles consist of a simple squamous epithelium with an apical-outside/basal-inside polarity that we trace back to the single cell stage. The polarity and gene expression pattern of the vesicles are similar to those of the early visceral endoderm. pXEN cells provide a useful in vitro model for study of matrix-independent, basal-type lumenogenesis and the physiology of the visceral endoderm.This article has an associated First Person interview with the first author of the paper.

Effect of lipopolysaccharide addition on the gene transfection of spermine-introduced pullulan-plasmid DNA complexes for human mesenchymal stem cells

The objective of this study is to investigate the effect of lipopolysaccharide (LPS) addition on the gene transfection of human mesenchymal stem cells (hMSC). hMSC were treated with the LPS at different concentrations and the complex of spermine-introduced pullulan and luciferase plasmid DNA for 3 h. The maximum level of gene expression was observed for hMSC treated with a certain concentration range of LPS. In addition, the cytotoxicity, cellular internalization of complexes, and cell cycle after LPS treatment were investigated. The cytotoxicity increased with an increase in the LPS concentration treated. On the other hand, the cellular internalization of complexes increased with the increased LPS concentration, although the internalization was sharply reduced at the high concentration. The LPS treatment increased the actin polymerization of cells to allow to spread more. The enhanced cells spreading would enhance the cellular internalization of complexes. In addition, the LPS treatment increased the rate of cell cycle. It is possible that the balance of cytotoxicity, cellular internalization, and cell cycle caused by the LPS addition results in the enhanced gene transfection at a certain LPS concentration. It is concluded that LPS treatment positively modified the cellular internalization and the cell cycle, resulting in the enhanced gene transfection.

Forkhead box O1 (FOXO1) controls the migratory response of Toll-like receptor (TLR3)-stimulated human mesenchymal stromal cells

Mesenchymal stromal cells (MSCs) can potently regulate the functions of immune cells and are being investigated for the management of inflammatory diseases. Toll-like receptor 3 (TLR3)-stimulated human MSCs (hMSCs) exhibit increased migration and chemotaxis within and toward damaged tissues. However, the regulatory mechanisms underlying these migratory activities are unclear. Therefore, we analyzed the migration capability and gene expression profiles of TLR3-stimulated hMSCs using RNA-Seq, wound healing, and transwell cell migration assay. Along with increased cell migration, the TLR3 stimulation also increased the expression of cytokines, chemokines, and cell migration-related genes. The promoter regions of the latter showed an enrichment of putative motifs for binding the transcription factors forkhead box O1 (FOXO1), FOXO3, NF-κB (NF-κB1), and RELA proto-oncogene and NF-κB subunit. Of note, FOXO1 inhibition by the FOXO1-selective inhibitor AS1842856 significantly reduced both migration and the expression of migration-related genes. In summary, our results indicate that TLR3 stimulation induces hMSC migration through the expression of FOXO1-activated genes.

A Guide for Designing and Analyzing RNA-Seq Data

The identity of a cell or an organism is at least in part defined by its gene expression and therefore analyzing gene expression remains one of the most frequently performed experimental techniques in molecular biology. The development of the RNA-Sequencing (RNA-Seq) method allows an unprecedented opportunity to analyze expression of protein-coding, noncoding RNA and also de novo transcript assembly of a new species or organism. However, the planning and design of RNA-Seq experiments has important implications for addressing the desired biological question and maximizing the value of the data obtained. In addition, RNA-Seq generates a huge volume of data and accurate analysis of this data involves several different steps and choices of tools. This can be challenging and overwhelming, especially for bench scientists. In this chapter, we describe an entire workflow for performing RNA-Seq experiments. We describe critical aspects of wet lab experiments such as RNA isolation, library preparation and the initial design of an experiment. Further, we provide a step-by-step description of the bioinformatics workflow for different steps involved in RNA-Seq data analysis. This includes power calculations, setting up a computational environment, acquisition and processing of publicly available data if desired, quality control measures, preprocessing steps for the raw data, differential expression analysis, and data visualization. We particularly mention important considerations for each step to provide a guide for designing and analyzing RNA-Seq data.

Comparison of Antibacterial and Immunological Properties of Mesenchymal Stem/Stromal Cells from Equine Bone Marrow, Endometrium, and Adipose Tissue

Equine mesenchymal stem/stromal cells (MSCs) are multipotent cells that are widely used for treatment of musculoskeletal injuries, and there is significant interest in expanding their application to nonorthopedic conditions. MSCs possess antibacterial and immunomodulatory properties that may be relevant for combating infection; however, comparative studies using MSCs from different origins have not been carried out in the horse, and this was the focus of this study. Our results showed that MSC-conditioned media attenuated the growth of Escherichia coli, and that this effect was, on average, more pronounced for endometrium (EM)-derived and adipose tissue (AT)-derived MSCs than for bone marrow (BM)-derived MSCs. In addition, the antimicrobial lipocalin-2 was expressed at mean higher levels in EM-MSCs than in AT-MSCs and BM-MSCs, and the bacterial component lipopolysaccharide (LPS) stimulated its production by all three MSC types. We also showed that MSCs express interleukin-6 (IL-6), IL-8, monocyte chemoattractant protein-1, chemokine ligand-5, and Toll-like receptor 4, and that, in general, these cytokines were induced in all cell types by LPS. Low expression levels of the macrophage marker colony-stimulating factor 1 receptor were detected in BM-MSCs and EM-MSCs but not in AT-MSCs. Altogether, these findings suggest that equine MSCs from EM, AT, and BM have both direct and indirect antimicrobial properties that may vary between MSCs from different origins and could be exploited toward improvement of regenerative therapies for horses.

Isolation of primitive mouse extraembryonic endoderm (pXEN) stem cell lines

Mouse blastocysts contain the committed precursors of the extraembryonic endoderm (ExEn), which express the key transcription factor Oct4, depend on LIF/LIF-like factor-driven Jak/Stat signaling, and initially exhibit lineage plasticity. Previously described rat blastocyst-derived ExEn precursor-like cell lines (XENP cells/HypoSCs) also show these features, but equivalent mouse blastocyst-derived cell lines are lacking. We now present mouse blastocyst-derived cell lines, named primitive XEN (pXEN) cells, which share these and additional characteristics with the XENP cells/HypoSCs, but not with previously known mouse blastocyst-derived XEN cell lines. Otherwise, pXEN cells are highly similar to XEN cells by morphology, lineage-intrinsic differentiation potential, and multi-gene expression profile, although the pXEN cell profile correlates better with the blastocyst stage. Finally, we show that pXEN cells easily convert into XEN-like cells but not vice versa. The findings indicate that (i) pXEN cells are more representative than XEN cells of the blastocyst stage; (ii) mouse pXEN, rather than XEN, cells are homologs of rat XENP cells/HypoSCs, which we propose to call rat pXEN cells.

Repeated stimulation by LPS promotes the senescence of DPSCs via TLR4/MyD88-NF-κB-p53/p21 signaling

Dental pulp stem cells (DPSCs), one type of mesenchymal stem cells, are considered to be a type of tool cells for regenerative medicine and tissue engineering. Our previous studies found that the stimulation with lipopolysaccharide (LPS) might introduce senescence of DPSCs, and this senescence would have a positive correlation with the concentration of LPS. The β-galactosidase (SA-β-gal) staining was used to evaluate the senescence of DPSCs and immunofluorescence to show the morphology of DPSCs. Our findings suggested that the activity of SA-β-gal has increased after repeated stimulation with LPS and the morphology of DPSCs has changed with the stimulation with LPS. We also found that LPS bound to the Toll-like receptor 4 (TLR4)/myeloid differentiation factor (MyD) 88 signaling pathway. Protein and mRNA expression of TLR4, MyD88 were enhanced in DPSCs with LPS stimulation, resulting in the activation of nuclear factor-κB (NF-κB) signaling, which exhibited the expression of p65 improved in the nucleus while the decreasing of IκB-α. Simultaneously, the expression of p53 and p21, the downstream proteins of the NF-κB signaling, has increased. In summary, DPSCs tend to undergo senescence after repeated stimulation in an inflammatory microenvironment. Ultimately, these findings may lead to a new direction for cell-based therapy in oral diseases and other regenerative medicines.

Osteoimmunology and Beyond

Abstract: Objective

Osteoimmunology investigates interactions between skeleton and immune system. In the light of recent discoveries in this field, a new reading register of osteoporosis is actually emerging, in which bone and immune cells are strictly interconnected. Osteoporosis could therefore be considered a chronic immune mediated disease which shares with other age related disorders a common inflammatory background. Here, we highlight these recent discoveries and the new landscape that is emerging.

Method

Extensive literature search in PubMed central.

Results

While the inflammatory nature of osteoporosis has been clearly recognized, other interesting aspects of osteoimmunology are currently emerging. In addition, mounting evidence indicates that the immunoskeletal interface is involved in the regulation of important body functions beyond bone remodeling. Bone cells take part with cells of the immune system in various immunological functions, configuring a real expanded immune system, and are therefore variously involved not only as target but also as main actors in various pathological conditions affecting primarily the immune system, such as autoimmunity and immune deficiencies, as well as in aging, menopause and other diseases sharing an inflammatory background.

Conclusion

The review highlights the complexity of interwoven pathways and shared mechanisms of the crosstalk between the immune and bone systems. More interestingly, the interdisciplinary field of osteoimmunology is now expanding beyond bone and immune cells, defining new homeostatic networks in which other organs and systems are functionally interconnected. Therefore, the correct skeletal integrity maintenance may be also relevant to other functions outside its involvement in bone mineral homeostasis, hemopoiesis and immunity.