Human mesenchymal stem cells target adhesion molecules and receptors involved in T cell extravasation

The Role of Mesenchymal Stromal Cells in the Treatment of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory joint disease characterised by the formation of a hyperplastic pannus, as well as cartilage and bone damage. The pathogenesis of RA is complex and involves broad interactions between various cells present in the inflamed synovium, including fibroblast-like synoviocytes (FLSs), macrophages, and T cells, among others. Under inflammatory conditions, these cells are activated, further enhancing inflammatory responses and angiogenesis and promoting bone and cartilage degradation. Novel treatment methods for RA are greatly needed, and mesenchymal stromal cells (MSCs) have been suggested as a promising new regenerative and immunomodulatory treatment. In this paper, we present the interactions between MSCs and RA-FLSs, and macrophages and T cells, and summarise studies examining the use of MSCs in preclinical and clinical RA studies.

Mesenchymal Stem Cells in the Pathogenesis and Therapy of Autoimmune and Autoinflammatory Diseases

Mesenchymal stem cells (MSCs) modulate immune responses and maintain self-tolerance. Their trophic activities and regenerative properties make them potential immunosuppressants for treating autoimmune and autoinflammatory diseases. MSCs are drawn to sites of injury and inflammation where they can both reduce inflammation and contribute to tissue regeneration. An increased understanding of the role of MSCs in the development and progression of autoimmune disorders has revealed that MSCs are passive targets in the inflammatory process, becoming impaired by it and exhibiting loss of immunomodulatory activity. MSCs have been considered as potential novel cell therapies for severe autoimmune and autoinflammatory diseases, which at present have only disease modifying rather than curative treatment options. MSCs are emerging as potential therapies for severe autoimmune and autoinflammatory diseases. Clinical application of MSCs in rare cases of severe disease in which other existing treatment modalities have failed, have demonstrated potential use in treating multiple diseases, including rheumatoid arthritis, systemic lupus erythematosus, myocardial infarction, liver cirrhosis, spinal cord injury, multiple sclerosis, and COVID-19 pneumonia. This review explores the biological mechanisms behind the role of MSCs in autoimmune and autoinflammatory diseases. It also covers their immunomodulatory capabilities, potential therapeutic applications, and the challenges and risks associated with MSC therapy.

Human Umbilical Cord-Based Therapeutics: Stem Cells and Blood Derivatives for Female Reproductive Medicine

There are several conditions that lead to female infertility, where traditional or conventional treatments have limited efficacy. In these challenging scenarios, stem cell (SC) therapies have been investigated as alternative treatment strategies. Human umbilical cord (hUC) mesenchymal stem cells (hUC-MSC), along with their secreted paracrine factors, extracts, and biomolecules, have emerged as promising therapeutic alternatives in regenerative medicine, due to their remarkable potential to promote anti-inflammatory and regenerative processes more efficiently than other autologous treatments. Similarly, hUC blood derivatives, such as platelet-rich plasma (PRP), or isolated plasma elements, such as growth factors, have also demonstrated potential. This literature review aims to summarize the recent therapeutic advances based on hUC-MSCs, hUC blood, and/or other plasma derivatives (e.g., extracellular vesicles, hUC-PRP, and growth factors) in the context of female reproductive medicine. We present an in-depth analysis of the principal molecules mediating tissue regeneration, compiling the application of these therapies in preclinical and clinical studies, within the context of the human reproductive tract. Despite the recent advances in bioengineering strategies that sustain delivery and amplify the scope of the therapeutic benefits, further clinical trials are required prior to the wide implementation of these alternative therapies in reproductive medicine.

Gross Total Resection Promotes Subsequent Recovery and Further Enhancement of Impaired Natural Killer Cell Activity in Glioblastoma Patients

Highlights

Natural killer cell activity is dramatically impaired in patients with glioblastoma.

Surgical resection of glioblastoma promotes redistribution of NK cell subsets and increases NK cell activity 30 days after surgery.

Gross total resection rather than subtotal resection significantly recovers and further increases the impaired NK cell activity in patients with glioblastoma.

Abstract

Glioblastoma is the most common primary malignant brain tumor, and median survival is relatively short despite aggressive standard treatment. Natural killer (NK) cell dysfunction is strongly associated with tumor recurrence and metastasis but is unclear in glioblastoma. NK activity (NKA) represents NK cell-secreted interferon-γ (IFN-γ), which modulates immunity and inhibits cancer progression. This study aimed to analyze NKA in glioblastoma patients to obtain a clearer overview of immunity surveillance. From 2020 to 2021, a total of 20 patients and six healthy controls were recruited. Peripheral blood samples were collected preoperatively and on postoperative days (POD) 3 and 30. Then, NKA was measured using the NK VUE kit. Although NKA decreased on POD3, it recovered and further significantly enhanced on POD30, with a nearly five-fold increase compared to baseline (p = 0.004). Furthermore, the percentage of CD56^brightCD16⁻ NK cells decreased significantly on POD3 (p = 0.022) and further recovered on PO30. Subgroup analysis of extent surgical resection further revealed that the recovery of impaired NKA was attributable to gross total resection (GTR) rather than subtotal resection (STR). In conclusion, NKA is significantly impaired in glioblastoma, and GTR has demonstrated superior benefit in improving the suppressed NKA and increased CD56^brightCD16⁻ NK subset in glioblastoma patients, which may be associated with subsequent patients’ prognosis. Therefore, the goal of performing GTR for glioblastoma should be achieved when possible since it appears to increase NKA cell immunity.

Osteogenic and Chondrogenic Potential of Periosteum-Derived Mesenchymal Stromal Cells: Do They Hold the Key to the Future?

The periosteum, with its outer fibrous and inner cambium layer, lies in a dynamic environment with a niche of pluripotent stem cells for their reparative needs. The inner cambium layer is rich in mesenchymal progenitors, osteogenic progenitors, osteoblasts, and fibroblasts in a scant collagen matrix environment. Their role in union and remodeling of fracture is well known. However, the periosteum as a source of mesenchymal stem cells has not been explored in detail. Moreover, with the continuous expansion of techniques, newer insights have been acquired into the roles and regulation of these periosteal cells. From a therapeutic standpoint, the periosteum as a source of tissue engineering has gained much attraction. Apart from its role in bone repair, analysis of the bone-forming potential of periosteum-derived stem cells is lacking. Hence, this article elucidates the role of the periosteum as a potential source of mesenchymal stem cells along with their capacity for osteogenic and chondrogenic differentiation for therapeutic application in the future.

Mesenchymal stem cells as a treatment for multiple sclerosis: a focus on experimental animal studies

Multiple sclerosis (MS) is a progressive and debilitating neurological condition in which the immune system abnormally attacks the myelin sheath insulating the nerves. Mesenchymal stem cells (MSCs) are found in most adult tissues and play a significant systemic role in self-repair. MSCs have promising therapeutic effects in many diseases, such as autoimmune diseases, including MS. MSCs have been tested in MS animal models, such as experimental autoimmune encephalomyelitis. Other studies have combined other agents with MSCs, genetically modified MSCs, or used culture medium from MSCs. In this review, we will summarize these studies and compare the main factors in each study, such as the source of MSCs, the type of animal model, the route of injection, the number of injected cells, and the mechanism of action.

Immunophenotypic characteristics of multipotent mesenchymal stromal cells that affect the efficacy of their use in the prevention of acute graft vs host disease

BACKGROUND

Multipotent mesenchymal stromal cells (MSCs) are widely used in the clinic due to their unique properties, namely, their ability to differentiate in all mesenchymal directions and their immunomodulatory activity. Healthy donor MSCs were used to prevent the development of acute graft vs host disease (GVHD) after allogeneic bone marrow transplantation (allo-BMT). The administration of MSCs to patients was not always effective. The MSCs obtained from different donors have individual characteristics. The differences between MSC samples may affect their clinical efficacy.

AIM

To study the differences between effective and ineffective MSCs.

METHODS

MSCs derived from the bone marrow of a hematopoietic stem cells donor were injected intravenously into allo-BMT recipients for GVHD prophylaxis at the moment of blood cell reconstitution. Aliquots of 52 MSC samples that were administered to patients were examined, and the same cells were cultured in the presence of peripheral blood mononuclear cells (PBMCs) from a third-party donor or treated with the pro-inflammatory cytokines IL-1β, IFN and TNF. Flow cytometry revealed the immunophenotype of the nontreated MSCs, the MSCs cocultured with PBMCs for 4 d and the MSCs exposed to cytokines. The proportions of CD25-, CD146-, CD69-, HLA-DR- and PD-1-positive CD4+ and CD8+ cells and the distribution of various effector and memory cell subpopulations in the PBMCs cocultured with the MSCs were also determined.

RESULTS

Differences in the immunophenotypes of effective and ineffective MSCs were observed. In the effective samples, the mean fluorescence intensity (MFI) of HLA-ABC, HLA-DR, CD105, and CD146 was significantly higher. After MSCs were treated with IFN or cocultured with PBMCs, the HLA-ABC, HLA-DR, CD90 and CD54 MFI showed a stronger increase in the effective MSCs, which indicated an increase in the immunomodulatory activity of these cells. When PBMCs were cocultured with effective MSCs, the proportions of CD4+ and CD8+central memory cells significantly decreased, and the proportion of CD8+CD146+ lymphocytes increased more than in the subpopulations of lymphocytes cocultured with MSC samples that were ineffective in the prevention of GVHD; in addition, the proportion of CD8+effector memory lymphocytes decreased in the PBMCs cocultured with the effective MSC samples but increased in the PBMCs cocultured with the ineffective MSC samples. The proportion of CD4+CD146+ lymphocytes increased only when cocultured with the inefficient samples.

CONCLUSION

For the first time, differences were observed between MSC samples that were effective for GVHD prophylaxis and those that were ineffective. Thus, it was shown that the immunomodulatory activity of MSCs depends on the individual characteristics of the MSC population.

Potential of Extracellular Vesicle-Associated TSG-6 from Adipose Mesenchymal Stromal Cells in Traumatic Brain Injury

Multipotent mesenchymal stromal cells (MSC) represent a promising strategy for a variety of medical applications. Although only a limited number of MSC engraft and survive after in vivo cellular infusion, MSC have shown beneficial effects on immunomodulation and tissue repair. This indicates that the contribution of MSC exists in paracrine signaling, rather than a cell-contact effect of MSC. In this review, we focus on current knowledge about tumor necrosis factor (TNF)-stimulated gene-6 (TSG-6) and mechanisms based on extracellular vesicles (EV) that govern long-lasting immunosuppressive and regenerative activity of MSC. In this context, in particular, we discuss the very robust set of findings by Jha and colleagues, and the opportunity to potentially extend their research focus on EV isolated in concentrated conditioned media (CCM) from adipose tissue derived MSC (ASC). Particularly, the authors showed that ASC-CCM mitigated visual deficits after mild traumatic brain injury in mice. TSG-6 knockdown ASC were, then, used to generate TSG-6-depleted CCM that were not able to replicate the alleviation of abnormalities in injured animals. In light of the presented results, we envision that the infusion of much distilled ASC-CCM could enhance the alleviation of visual abnormalities. In terms of EV research, the advantages of using size-exclusion chromatography are also highlighted because of the enrichment of purer and well-defined EV preparations. Taken together, this could further delineate and boost the benefit of using MSC-based regenerative therapies in the context of forthcoming clinical research testing in diseases that disrupt immune system homeostasis.

Immunosuppressive Property of MSCs Mediated by Cell Surface Receptors

In the past decade, mesenchymal stem cells (MSCs) tend to exhibit inherent tropism for refractory inflammatory diseases and engineered MSCs have appeared on the market as therapeutic agents. Recently, engineered MSCs target to cell surface molecules on immune cells has been a new strategy to improve MSC applications. In this review, we discuss the roles of multiple receptors (ICAM-1, Gal-9, PD-L1, TIGIT, CD200, and CXCR4) in the process of MSCs' immunosuppressive properties. Furthermore, we discuss the principles and strategies for developing receptor-regulated MSCs and their mechanisms of action and the challenges of using MSCs as immunosuppressive therapies.

Therapeutic effect of transplanted umbilical cord mesenchymal stem cells in a cynomolgus monkey model of multiple sclerosis

Multiple sclerosis (MS) is a demyelinating disease affecting 2.5 million young people worldwide because of its immune-mediated pathological mechanisms. Recent studies have shown that stem cell transplantation is a new potential therapy for MS. There has been renewed interest in cell therapy to improve quality of life for MS patients. In this study, the experimental autoimmune encephalomyelitis (EAE) model, which is the most commonly model to mimic MS, was successfully established in cynomolgus monkeys. To evaluate the therapeutic effect of human umbilical cord mesenchymal stem cells (UCMSCs) on MS, we intravenously transplanted UCMSCs into cynomolgus monkeys with EAE. Our results showed that UCMSC transplantation significantly ameliorated the clinical symptoms of MS. Magnetic resonance imaging and clinical signs indicated that demyelination was obviously decreased after UCMSCs therapy. Moreover, the present study showed that the mechanisms, involved in the effects of UCMSCs on MS, included their immunomodulatory functions to regulate cytokine secretion and affect functional differentiation of the T cell lineage.

Advanced Glycation End-Products-, C-Type Lectin- and Cysteinyl/ Leukotriene-Receptors in Distinct Mesenchymal Stromal Cell Populations: Differential Transcriptional Profiles in Response to Inflammation

OBJECTIVES

We aimed at characterizing the transcription profiles of immunological receptors associated with the biology of mesenchymal stromal cells (MSCs).

MATERIALS AND METHODS

In this experimental study, quantitative real time-polymerase chain reaction (qRTPCR) was performed to establish the transcription profiles of advanced glycation end-products (RAGE) receptor, C-type lectin receptors (CLRs, including DECTIN-1, DECTIN-2 and MINCLE), leukotriene B4 (LTB4) receptors (BLT1 and BLT2) and cysteinyl leukotrienes (CysLTs) receptors (CYSLTR1 and CYSLTR2) in distinct populations of MSCs grown under basic or inflammatory conditions.

RESULTS

MSCs derived from adipose tissue (AT), foreskin (FSK), Wharton's jelly (WJ) and bone marrow (BM) exhibited significantly different transcription levels for these genes. Interestingly, these transcription profiles substantially changed following exposure of MSCs to inflammatory signals.

CONCLUSIONS

Collectively, for the first time, our data highlights that MSCs depending on their tissue-source, present several relevant receptors potentially involved in the regulation of inflammatory and immunological responses. Understanding the roles of these receptors within MSCs immunobiology will incontestably improve the efficiency of utilization of MSCs during cell-based therapies.

Recent achievements in stem cell-mediated myelin repair

PURPOSE OF REVIEW

Following the establishment of a number of successful immunomodulatory treatments for multiple sclerosis, current research focuses on the repair of existing damage.

RECENT FINDINGS

Promotion of regeneration is particularly important for demyelinated areas with degenerated or functionally impaired axons of the central nervous system's white and gray matter. As the protection and generation of new oligodendrocytes is a key to the re-establishment of functional connections, adult oligodendrogenesis and myelin reconstitution processes are of primary interest. Moreover, understanding, supporting and promoting endogenous repair activities such as mediated by resident oligodendroglial precursor or adult neural stem cells are currently thought to be a promising approach toward the development of novel regenerative therapies.

SUMMARY

This review summarizes recent developments and findings related to pharmacological myelin repair as well as to the modulation/application of stem cells with the aim to restore defective myelin sheaths.

Lipopolysaccharide can modify differentiation and immunomodulatory potential of periodontal ligament stem cells via ERK1,2 signaling

Lipopolysaccharide (LPS) is a pertinent deleterious factor in oral microenvironment for cells which are carriers of regenerative processes. The aim of this study was to investigate the emerging in vitro effects of LPS (Escherichia coli) on human periodontal ligament stem cell (PDLSC) functions and associated signaling pathways. We demonstrated that LPS did not affect immunophenotype, proliferation, viability, and cell cycle of PDLSCs. However, LPS modified lineage commitment of PDLSCs inhibiting osteogenesis by downregulating Runx2, ALP, and Ocn mRNA expression, while stimulating chondrogenesis and adipogenesis by upregulating Sox9 and PPARγ mRNA expression. LPS promoted myofibroblast-like phenotype of PDLSCs, since it significantly enhanced PDLSC contractility, as well as protein and/or gene expression of TGF-β, fibronectin (FN), α-SMA, and NG2. LPS also increased protein and gene expression levels of anti-inflammatory COX-2 and pro-inflammatory IL-6 molecules in PDLSCs. Inhibition of peripheral blood mononuclear cells (MNCs) transendothelial migration in presence of LPS-treated PDLSCs was accompanied by the reduction of CD29 expression within MNCs. However, LPS treatment did not change the inhibitory effect of PDLSCs on mitogen-stimulated proliferation of CD4⁺ and the ratio of CD4⁺ CD25^high /CD4⁺ CD25^low lymphocytes. LPS-treated PDLSCs did not change the frequency of CD34⁺ and CD45⁺ cells, but decreased the frequency of CD33⁺ and CD14⁺ myeloid cells within MNCs. Moreover, LPS treatment attenuated the stimulatory effect of PDLSCs on CFC activity of MNCs, predominantly the CFU-GM number. The results indicated that LPS-activated ERK1,2 was at least partly involved in the observed effects on PDLSC differentiation capacity, acquisition of myofibroblastic attributes, and changes of their immunomodulatory features.

Regulatory perspective on in vitro potency assays for human mesenchymal stromal cells used in immunotherapy

Mesenchymal stromal cells (MSCs) are multipotent cells derived from various tissues that can differentiate into several cell types. MSCs are able to modulate the response of immune cells of the innate and adaptive immune system. Because of these multimodal properties, the potential use of MSCs for immunotherapies is currently explored in various clinical indications. Due to the diversity of potential MSC medicinal products at the level of cell source, manufacturing process and indication, distinct functionality tests may be needed to ensure the quality for each of the different products. In this review, we focus on in vitro potency assays proposed for characterization and release of different MSC medicinal products. We discuss the most used functional assays, as presented in scientific advices and literature, highlighting specific advantages and limitations of the various assays. Currently, the most proposed and accepted potency assay for release is based on in vitro inhibition of T cell proliferation or other functionalities. However, for some products, assays based on other MSC or responder cell properties may be more appropriate. In all cases, the biological relevance of the proposed assay for the intended clinical activity should be substantiated with appropriate product-specific (non-)clinical data. In case practical considerations prevent the use of the ideal potency assay at release, use of a surrogate marker or test could be considered if correlation with functionality has been demonstrated. Nevertheless, as the field of MSC immunology is evolving, improvements can be expected in relevant assays and consequently in guidance related to potency testing.

Mesenchymal Stromal Cells Modulate Monocytes Trafficking in Coxsackievirus B3-Induced Myocarditis

Mesenchymal stromal cell (MSC) application in Coxsackievirus B3 (CVB3)‐induced myocarditis reduces myocardial inflammation and fibrosis, exerts prominent extra‐cardiac immunomodulation, and improves heart function. Although the abovementioned findings demonstrate the benefit of MSC application, the mechanism of the MSC immunomodulatory effects leading to a final cardioprotective outcome in viral myocarditis remains poorly understood. Monocytes are known to be a trigger of myocardial tissue inflammation. The present study aims at investigating the direct effect of MSC on the mobilization and trafficking of monocytes to the heart in CVB3‐induced myocarditis. One day post CVB3 infection, C57BL/6 mice were intravenously injected with 1 x 10⁶ MSC and sacrificed 6 days later for molecular biology and flow cytometry analysis. MSC application reduced the severity of myocarditis, and heart and blood pro‐inflammatory Ly6C^high and Ly6C^middle monocytes, while those were retained in the spleen. Anti‐inflammatory Ly6C^low monocytes increased in the blood, heart, and spleen of MSC‐treated CVB3 mice. CVB3 infection induced splenic myelopoiesis, while MSC application slightly diminished the spleen myelopoietic activity in CVB3 mice. Left ventricular (LV) mRNA expression of the chemokines monocyte chemotactic protein‐1 (MCP)−1, MCP‐3, CCL5, the adhesion molecules intercellular adhesion molecule‐1, vascular cell adhesion molecule‐1, the pro‐inflammatory cytokines interleukin‐6, interleukin‐12, tumor necrosis factor‐α, the pro‐fibrotic transforming growth factorβ1, and circulating MCP‐1 and MCP‐3 levels decreased in CVB3 MSC mice, while LV stromal cell‐derived factor‐1α RNA expression and systemic levels of fractalkine were increased in CVB3 MSC mice. MSC application in CVB3‐induced myocarditis modulates monocytes trafficking to the heart and could be a promising strategy for the resolution of cardiac inflammation and prevention of the disease progression. Stem Cells Translational Medicine2017;6:1249–1261

Different Phenotyping Approaches Lead to Dissimilar Biologic Profiles in Men With Chronic Fatigue After Radiation Therapy

CONTEXT

Cancer-related fatigue (CRF) persists months after treatment completion. Although a CRF biomarker has not yet been identified, validated self-report questionnaires are used to define and phenotype CRF in the discovery of potential biomarkers.

OBJECTIVES

The purposes of this study are to identify CRF subjects using three well-known CRF phenotyping approaches using validated self-report questionnaires and to compare the biologic profiles that are associated with each CRF phenotype.

METHODS

Fatigue in men with nonmetastatic prostate cancer receiving external beam radiation therapy was measured at baseline (T1), midpoint (T2), end point (T3), and one-year post-external beam radiation therapy (T4) using the Functional Assessment of Cancer Therapy-Fatigue (FACT-F) and Patient Reported Outcomes Measurement Information System-Fatigue. Chronic fatigue (CF) and nonfatigue subjects were grouped based on three commonly used phenotyping approaches: 1) T4 FACT-F <43; 2) T1-T4 decline in FACT-F score ≥3 points; 3) T4 Patient Reported Outcomes Measurement Information System-Fatigue T-score >50. Differential gene expressions using whole-genome microarray analysis were compared in each of the phenotyping criterion.

RESULTS

The study enrolled 43 men, where 34%-38% had CF based on the three phenotyping approaches. Distinct gene expression patterns were observed between CF and nonfatigue subjects in each of the three CRF phenotyping approaches: 1) Approach 1 had the largest number of differentially expressed genes and 2) Approaches 2 and 3 had 40 and 21 differentially expressed genes between the fatigue groups, respectively.

CONCLUSION

The variation in genetic profiles for CRF suggests that phenotypic profiling for CRF should be carefully considered because it directly influences biomarker discovery investigations.

Immunomodulation by mesenchymal stem cells: Interplay between mesenchymal stem cells and regulatory lymphocytes

Mesenchymal stem cells (MSCs) possess immunomodulatory properties, which confer enormous potential for clinical application. Considerable evidence revealed their efficacy on various animal models of autoimmune diseases, such as multiple sclerosis, systemic lupus erythematosus and uveitis. MSCs elicit their immunomodulatory effects by inhibiting lymphocyte activation and proliferation, forbidding the secretion of proinflammatory cytokines, limiting the function of antigen presenting cells, and inducing regulatory T (Treg) and B (Breg) cells. The induction of Treg and Breg cells is of particular interest since Treg and Breg cells have significant roles in maintaining immune tolerance. Several mechanisms have been proposed regarding to the MSCs-mediated induction of Treg and Breg cells. Accordingly, MSCs induce regulatory lymphocytes through secretion of multiple pleiotropic cytokines, cell-to-cell contact with target cells and modulation of antigen-presenting cells. Here, we summarized how MSCs induce Treg and Breg cells to provoke immunosuppression.

Therapeutic effects of human gingiva-derived mesenchymal stromal cells on murine contact hypersensitivity via prostaglandin E2-EP3 signaling

BACKGROUND

The immunomodulatory and anti-inflammatory functions of human gingiva-derived mesenchymal stromal cells (GMSCs) have been demonstrated in contact hypersensitivity (CHS) models; however, their therapeutic effect during the late phase of CHS has been poor.

METHODS

The murine CHS model was induced by applying oxazolone to the ears of mice. Mesenchymal stromal cells were applied via two methods (intravenous or local injection) at three time points: 1 day before sensitization, 1 day before challenge, or 1 h after challenge. Prostaglandin E2 (PGE2) and sulprostone were administered subcutaneously 1 h after challenge.

RESULTS

The application of GMSCs, bone marrow mesenchymal stem cells, and adipose-derived stem cells all effectively suppressed CHS; however, GMSC treatment exhibited the greatest efficacy. Local injection of GMSCs led to a more marked attenuation of CHS compared with intravenous injection, especially during the late phase of CHS, and this manifested as decreased infiltration of inflammatory cells, suppression of the levels of various proinflammatory cytokines, reconstruction of the disrupted Th1/Th2 balance, and upregulation of regulatory T cells in the allergen contact areas. Pretreatment with indomethacin significantly abrogated the GMSC-mediated immunosuppressive effects, while PGE2 application reversed the effects of indomethacin pretreatment of GMSCs. Moreover, GMSC administration promoted the expression of EP3, a prostaglandin E receptor, and the application of sulprostone, an agonist of EP3, significantly attenuated CHS to a similar degree as that of GMSC administration.

CONCLUSIONS

GMSCs have reproducible and powerful immunomodulatory functions. Local injection of GMSCs is the superior mode for therapeutic application. PGE2-EP3 signaling plays an important role in the immunomodulatory functions of GMSCs in murine CHS.

The secretome of MUSE cells contains factors that may play a role in regulation of stemness, apoptosis and immunomodulation

Mesenchymal stromal cells (MSCs) are a heterogeneous population, which contain several cell phenotypes: mesenchymal stem cells, progenitor cells, fibroblasts and other type of cells. Previously, we identified unique stem cells that we named multilineage-differentiating stress enduring (Muse) cells as one to several percent of MSCs of the bone marrow, adipose tissue and dermis. Among different cell populations in MSCs, Muse cells, positive for pluripotent surface marker SSEA-3, may represent cells responsible for pluripotent-like property of MSCs, since they express pluripotency genes, able to differentiated into triploblastic cells from a single cells and are self-renewable. MSCs release biologically active factors that have profound effects on local cellular dynamics. A thorough examination of MSC secretome seems essential for understanding the physiological functions exerted by these cells in our organism and also for rational cellular therapy design. In this setting, studies on secretome of Muse cells may shed light on pathways that are associated with their specific features. Our findings evidenced that secretomes of MSCs and Muse cells contain factors that regulate extracellular matrix remodeling, ox-redox activities and immune system. Muse cells appear to secrete factors that may preserve their stem cell features, allow survival under stress conditions and may contribute to their immunomodulation capacity. In detail, the proteins belonging to protein kinase A signaling, FXR/RXR activation and LXR/RXR activation pathways may play a role in regulation of Muse stem cell features. These last 2 pathways together with proteins associated with antigen presentation pathway and coagulation system may play a role in immunomodulation.