Mesenchymal stromal cells augment CD4+ and CD8+ T-cell proliferation through a CCL2 pathway. Cytotherapy. 2013;15:1195-1207. [PMID: 23845188 DOI: 10.1016/j.jcyt.2013.05.009]

Bioinformatics investigation of adaptive immune-related genes in peri-implantitis and periodontitis: Characteristics and diagnostic values

BACKGROUND

Peri-implantitis and periodontitis have similar immunological bioprocesses and inflammatory phenotypes. In the inflammatory process, the adaptive immune cells can drive the development of disease. This research investigated the differences and diagnostic significance of peri-implantitis and periodontitis in adaptive immune responses.

METHODS

We acquired four GEO datasets of gene expressions in surrounding tissues in healthy person, healthy implant, periodontitis, and peri-implantitis patients. The structural characteristics and enrichment analyses of differential expression genes were examined. The adaptive immune landscapes in peri-implantitis and periodontitis were then evaluated using single sample gene set enrichment analysis. The STRING database and Cytoscape were used to identify adaptive hub genes, and the ROC curve was used to verify them. Finally, qRT-PCR method was used to verify the expression level of Hub gene in activated T cells on the titanium-containing or titanium-free culture plates.

RESULTS

At the transcriptome level, the data of healthy implant, peri-implantitis and periodontitis were highly dissimilar. The peri-implantitis and periodontitis both exhibited adaptive immune response. Except for the activated CD4+T cells, there was no significant difference in other adaptive immune cells between peri-implantitis and periodontitis. In addition, correlation analysis showed that CD53, CYBB, and PLEK were significantly positively linked with activated CD4+T cells in the immune microenvironment of peri-implantitis, making them effective biomarkers to differentiate it from periodontitis.

CONCLUSIONS

Peri-implantitis has a uniquely immunogenomic landscape that differs from periodontitis. This study provides new insights and ideas into the activated CD4+T cells and hub genes that underpin the immunological bioprocess of peri-implantitis.

Harnessing Normal and Engineered Mesenchymal Stem Cells Derived Exosomes for Cancer Therapy: Opportunity and Challenges

There remains a vital necessity for new therapeutic approaches to combat metastatic cancers, which cause globally over 8 million deaths per year. Mesenchymal stem cells (MSCs) display aptitude as new therapeutic choices for cancer treatment. Exosomes, the most important mediator of MSCs, regulate tumor progression. The potential of harnessing exosomes from MSCs (MSCs-Exo) in cancer therapy is now being documented. MSCs-Exo can promote tumor progression by affecting tumor growth, metastasis, immunity, angiogenesis, and drug resistance. However, contradictory evidence has suggested that MSCs-Exo suppress tumors through several mechanisms. Therefore, the exact association between MSCs-Exo and tumors remains controversial. Accordingly, the applications of MSCs-Exo as novel drug delivery systems and standalone therapeutics are being extensively explored. In addition, engineering MSCs-Exo for targeting tumor cells has opened a new avenue for improving the efficiency of antitumor therapy. However, effective implementation in the clinical trials will need the establishment of standards for MSCs-Exo isolation and characterization as well as loading and engineering methods. The studies outlined in this review highlight the pivotal roles of MSCs-Exo in tumor progression and the promising potential of MSCs-Exo as therapeutic drug delivery vehicles for cancer treatment.

Development of a decellularized hypopharynx with vascular pedicle scaffold for use in reconstructing hypopharynx

BACKGROUND

Hypopharynx reconstruction after hypopharyngectomy is still a great challenge. Perfusion decellularization is for extracellular matrix (ECM) scaffolding and had been used in organ reconstruction. Our study aimed to prepare an acellular, natural, three-dimensional biological hypopharynx with vascular pedicle scaffold as the substitute materials to reconstruct hypopharynx.

RESULT

Scanning electron microscope and histology staining showed that the decellularized hypopharynx with vascular pedicle scaffold retained intact native anatomical ECM structure. Myoblasts were observed on the recellularized scaffolds with bone marrow mesenchymal stem cells induced by 5-azacytidine implanted in the rabbit greater omentum by immunohistochemical analysis.

CONCLUSION

The decellularized hypopharynx with vascular pedicle scaffold prepared by detergent perfusion in our study has a potential to be an alternative material to pharynx reconstruction.

Immunomodulatory effects of mesenchymal stem cells in peripheral nerve injury

Various immune cells and cytokines are present in the aftermath of peripheral nerve injuries (PNI), and coordination of the local inflammatory response is of great significance for the recovery of PNI. Mesenchymal stem cells (MSCs) exhibit immunosuppressive and anti-inflammatory abilities which can accelerate tissue regeneration and attenuate inflammation, but the role of MSCs in the regulation of the local inflammatory microenvironment after PNI has not been widely studied. Here, we summarize the known interactions between MSCs, immune cells, and inflammatory cytokines following PNI with a focus on the immunosuppressive role of MSCs. We also discuss the immunomodulatory potential of MSC-derived extracellular vesicles as a new cell-free treatment for PNI.

Mesenchymal stem cell-derived exosome: A tumor regulator and carrier for targeted tumor therapy

Mesenchymal stem cells (MSCs) are multipotent stromal cells that have the ability to differentiate into multiple cell types. Several studies have shown that exosomes secreted by MSCs (MSCs-Exo) play an important role in tumor growth, angiogenesis, invasion, and drug resistance. However, contradictory results have suggested that MSCs-Exo can also suppress tumors through specific mechanisms, such as regulating immune responses and intercellular signaling. Consequently, the relationship between MSCs-Exo and tumors remains controversial. However, it is undeniable that exosomes, as natural vesicles, can be excellent drug carriers and show promise for application in targeted tumor therapy. Here, we review the current knowledge regarding the involvement of MSCs-Exo in tumor progression and their potential as drug delivery systems in targeted therapy. We argue that MSCs-Exo can be used as safe carriers of antitumor drugs.

Old Friends with Unexploited Perspectives: Current Advances in Mesenchymal Stem Cell-Based Therapies in Asthma

Mesenchymal stem cells (MSCs) have a great regenerative and immunomodulatory potential that was successfully tested in numerous pre-clinical and clinical studies of various degenerative, hematological and inflammatory disorders. Over the last few decades, substantial immunoregulatory effects of MSC treatment were widely observed in different experimental models of asthma. Therefore, it is tempting to speculate that stem cell-based treatment could become an attractive means to better suppress asthmatic airway inflammation, especially in subjects resistant to currently available anti-inflammatory therapies. In this review, we discuss mechanisms accounting for potent immunosuppressive properties of MSCs and the rationale for their use in asthma. We describe in detail an intriguing interplay between MSCs and other crucial players in the immune system as well as lung microenvironment. Finally, we reveal the potential of MSCs in maintaining airway epithelial integrity and alleviating lung remodeling.

Interactions of human mesenchymal stromal cells with peripheral blood mononuclear cells in a Mitogenic proliferation assay

BACKGROUND

Immunomodulation by mesenchymal stromal cells (MSCs) is a potentially important therapeutic modality. MSCs suppress peripheral blood mononuclear cell (PBMC) proliferation in vitro, suggesting a mechanism for suppressing inflammatory responses in vivo. This study details the interactions of PBMCs and MSCs.

METHODS

Pooled human PBMCs and MSCs were co-cultured at different MSC:PBMC ratios and harvested from 0 to 120 h, with and without phytohaemagglutin A (PHA) stimulation. Proliferation of adherent MSCs and non-adherent PBMCs was assessed by quantitation of ATP levels. PBMC surface marker expression was analyzed by flow cytometry. Indoleamine 2,3-dioxygenase (IDO) activity was determined by kynurenine assay and IDO mRNA by RT-PCR. Cytokine release was measured by ELISA. Immunofluorescent microscopy detected MSC, PBMC, monocyte (CD14+) and apoptotic events.

RESULTS

PBMC proliferation in response to PHA gave a robust ATP signal by 72 h, which was suppressed by co-culture with densely plated MSCs. Very low level MSC seeding densities relative to PBMC number reproducibly stimulated PBMC proliferation. The CD4+/CD3+ population significantly decreased over time while the CD8+/CD3+ population significantly increased. No change in CD4+/CD8+ ratio is seen with high density MSC co-culture; very low density MSCs augment the changes seen in PHA stimulated PBMCs alone. IDO activity in MSCs co-cultured with PBMCs correlated with PBMC suppression. MSCs increased the secretion of IL-10 and IL-6 from stimulated co-cultures and decreased TNF-α secretion. In stimulated co-culture, low density MSCs decreased in number; fluorescence immunomicroscopy detected association of PBMC with MSC and phosphatidyl serine externalization in both cell populations.

CONCLUSIONS

A bidirectional interaction between MSCs and PBMCs occurs during co-culture. High numbers of MSCs inhibit PHA-stimulated PBMC proliferation and the PBMC response to stimulation; low numbers of MSCs augment these responses. Low density MSCs are susceptible to attrition, apparently by PBMC-induced apoptosis. These results may have direct application when considering therapeutic dosing of patients; low MSC doses may have unintended detrimental consequences.

Mesenchymal stem cells and mesenchymal stem cell-derived extracellular vesicles: Potential roles in rheumatic diseases

BACKGROUND

Mesenchymal stem cells (MSCs) have been widely investigated in rheumatic disease due to their immunomodulatory and regenerative properties. Recently, mounting studies have implicated the therapeutic potency of MSCs mostly due to the bioactive factors they produce. Extracellular vesicles (EVs) derived from MSCs have been identified as a promising cell-free therapy due to low immunogenicity. Rheumatic disease, primarily including rheumatoid arthritis and osteoarthritis, is a group of diseases in which immune dysregulation and chronic progressive inflammation lead to irreversible joint damage. Targeting MSCs and MSC-derived EVs may be a more effective and promising therapeutic strategy for rheumatic diseases.

AIM

To evaluate the potential therapeutic effectiveness of MSCs and EVs generated from MSCs in rheumatic diseases.

METHODS

PubMed was searched for the relevant literature using corresponding search terms alone or in combination. Papers published in English language from January 1999 to February 2020 were considered. Preliminary screening of papers concerning analysis of "immunomodulatory function" or "regenerative function" by scrutinizing the titles and abstracts of the literature, excluded the papers not related to the subject of the article. Some other related studies were obtained by manually retrieving the reference lists of papers that comply with the selection criteria, and these studies were screened to meet the final selection and exclusion criteria.

RESULTS

Eighty-six papers were ultimately selected for analysis. After analysis of the literature, it was found that both MSCs and EVs generated from MSCs have great potential in multiple rheumatic diseases, such as rheumatoid arthritis and osteoarthritis, in repair and regeneration of tissues, inhibition of inflammatory response, and regulation of body immunity via promoting chondrogenesis, regulating innate and adaptive immune cells, and regulating the secretion of inflammatory factors. But EVs from MSCs exhibit much more advantages over MSCs, which may represent another promising cell-free restorative strategy. Targeting MSCs and MSC-derived EVs may be a more efficient treatment for patients with rheumatic diseases.

CONCLUSION

The enormous potential of MSCs and EVs from MSCs in immunomodulation and tissue regeneration offers a new idea for the treatment of rheumatism. However, more in-depth exploration is needed before their clinical application.

Signature quality attributes of CD146+ mesenchymal stem/stromal cells correlate with high therapeutic and secretory potency

CD146⁺ bone marrow-derived mesenchymal stem/stromal cells (BM-MSCs) play key roles in the perivascular niche, skeletogenesis, and hematopoietic support; however, comprehensive evaluation of therapeutic potency has yet to be determined. In this study, in vitro inflammatory priming to crude human BM-MSCs (n = 8) captured a baseline of signature responses, including enriched CD146⁺ with coexpression of CD107a^High , CXCR4^High , and LepR^High , transcriptional profile, enhanced secretory capacity, and robust immunomodulatory secretome and function, including immunopotency assays (IPAs) with stimulated immune cells. These signatures were significantly more pronounced in CD146⁺ (POS)-sorted subpopulation than in the CD146^- (NEG). Mechanistically, POS BM-MSCs showed a markedly higher secretory capacity with significantly greater immunomodulatory and anti-inflammatory protein production upon inflammatory priming compared with the NEG BM-MSCs. Moreover, IPAs with stimulated peripheral blood mononuclear cells and T lymphocytes demonstrated robust immunosuppression mediated by POS BM-MSC while inducing significant frequencies of regulatory T cells. in vivo evidence showed that POS BM-MSC treatment promoted pronounced M1-to-M2 macrophage polarization, ameliorating inflammation/fibrosis of knee synovium and fat pad, unlike treatment with NEG BM-MSCs. These data correlate the expression of CD146 with innately higher immunomodulatory and secretory capacity, and thus therapeutic potency. This high-content, reproducible evidence suggests that the CD146⁺ (POS) MSC subpopulation are the mediators of the beneficial effects achieved using crude BM-MSCs, leading to translational implications for improving cell therapy and manufacturing.

CAR-T Engineering: Optimizing Signal Transduction and Effector Mechanisms

The adoptive transfer of genetically engineered T cells expressing a chimeric antigen receptor (CAR) has shown remarkable results against B cell malignancies. This immunotherapeutic approach has advanced and expanded rapidly from preclinical models to the recent approval of CAR-T cells to treat lymphomas and leukemia by the Food and Drug Administration (FDA). Ongoing research efforts are focused on employing CAR-T cells as a therapy for other cancers, and enhancing their efficacy and safety by optimizing their design. Here we summarize modifications in the intracellular domain of the CAR that gave rise to first-, second-, third- and next-generation CAR-T cells, together with the impact that these different designs have on CAR-T cell biology and function. Further, we describe how the structure of the antigen-sensing ectodomain can be enhanced, leading to superior CAR-T cell signaling and/or function. Finally we discuss how tissue-specific factors may impact the clinical efficacy of CAR-T cells for bone and the central nervous system, as examples of specific indications that may require further CAR signaling optimization to perform in such inhospitable microenvironments.

Mesenchymal Stem Cells: Allogeneic MSC May Be Immunosuppressive but Autologous MSC Are Dysfunctional in Lupus Patients

Mesenchymal stem cells (MSCs) have a potently immunosuppressive capacity in both innate and adaptive immune responses. Consequently, MSCs transplantation has emerged as a potential beneficial therapy for autoimmune diseases even though the mechanisms underlying the immunomodulatory activity of MSCs is incompletely understood. Transplanted MSCs from healthy individuals with no known history of autoimmune disease are immunosuppressive in systemic lupus erythematosus (SLE) patients and can ameliorate SLE disease symptoms in those same patients. In contrast, autologous MSCs from SLE patients are not immunosuppressive and do not ameliorate disease symptoms. Recent studies have shown that MSCs from SLE patients are dysfunctional in both proliferation and immunoregulation and phenotypically senescent. The senescent phenotype has been attributed to multiple genes and signaling pathways. In this review, we focus on the possible mechanisms for the defective phenotype and function of MSCs from SLE patients and summarize recent research on MSCs in autoimmune diseases.

Extracellular vesicles from human umbilical cord mesenchymal stem cells improve nerve regeneration after sciatic nerve transection in rats

Peripheral nerve injury results in limited nerve regeneration and severe functional impairment. Mesenchymal stem cells (MSCs) are a remarkable tool for peripheral nerve regeneration. The involvement of human umbilical cord MSC-derived extracellular vesicles (hUCMSC-EVs) in peripheral nerve regeneration, however, remains unknown. In this study, we evaluated functional recovery and nerve regeneration in rats that received hUCMSC-EV treatment after nerve transection. We observed that hUCMSC-EV treatment promoted the recovery of motor function and the regeneration of axons; increased the sciatic functional index; resulted in the generation of numerous axons and of several Schwann cells that surrounded individual axons; and attenuated the atrophy of the gastrocnemius muscle. hUCMSC-EVs aggregated to rat nerve defects, down-regulated interleukin (IL)-6 and IL-1β, up-regulated IL-10 and modulated inflammation in the injured nerve. These effects likely contributed to the promotion of nerve regeneration. Our findings indicate that hUCMSC-EVs can improve functional recovery and nerve regeneration by providing a favourable microenvironment for nerve regeneration. Thus, hUCMSC-EVs have considerable potential for application in the treatment of peripheral nerve injury.

Effects of Gastric Cancer Cell-Derived Exosomes on the Immune Regulation of Mesenchymal Stem Cells by the NF-kB Signaling Pathway

Mesenchymal stem cells (MSCs) are important components of the tumor microenvironment, which play an important role in tumor development. Exosomes derived from tumor cells can affect the biological characteristics of MSCs. Our study examined the effects of exosomes derived from gastric cancer cells on MSC immunomodulatory functions. Exosomes were extracted from gastric cancer cell line AGS (AGS-Exos) and cultured with MSCs. MSCs were then cocultured with both human peripheral blood mononuclear cells and macrophages [phorbol-12-myristate-13-acetate (PMA)-stimulated THP1 cells]. The activation levels of T cells and macrophages were detected by flow cytometry and real-time quantitative polymerase chain reaction (RT-PCR). Changes in the MSC signaling pathway after AGS-Exos stimulation were studied using RNA Chip, and the molecular mechanisms of functional change in MSCs were studied by inhibiting the signaling pathway. MSCs treated with AGS-Exos could promote macrophage phagocytosis and upregulate the secretion of proinflammatory factor, and promote the activation of CD69 and CD25 on the surface of T cells. RNA Chip results indicated the abnormal activation of the NF-kB signaling pathway in MSCs after AGS-Exos stimulation, and this was verified by the identification of key proteins in the pathway using western blot analysis. After NF-kB signaling pathway inhibition, the effect of MSCs stimulated by AGS-Exos on T cells and macrophages was markedly weakened. Therefore, AGS-Exos affected the immunomodulation function of MSCs through the NF-kB signaling pathway, which enhanced the ability of MSCs to activate immune cells, maintain the inflammatory environment, and support tumor growth.

Immunomodulatory effect of mesenchymal stem cells: Cell origin and cell quality variations

The immunomodulatory property of mesenchymal stem cells (MSCs) has been previously reported. Still it is unclear if this property can be affected by the cell origin and cell quality. Using primary MSCs expanded from bone marrow (BM-MSCs) and adipose tissue (AD-MSCs) of mice, we investigated whether the immunomodulatory property of MSCs varied with cell origin and cell quality (early- vs. late-passaged BM-MSCs). BM-MSCs (p1) and AD-MSCs (p1) had a typical spindle shape, but morphological changes were observed in late-passaged BM-MSCs (p6). A pathway-focused array showed that the expression of chemokine/cytokine genes varied with different cell origins and qualities. By co-culturing with spleen mononuclear cells (MNC) for 3 days, the expression of CD4 was suppressed by all types of MSCs. By contrast, the expression of CD8 was suppressed by BM-MSCs and increased by AD-MSCs. The expression ratio of CD206 to CD86 was at a comparable level after co-culture with AD-MSCs and BM-MSCs, but was lower with late-passaged BM-MSCs. AD-MSCs highly induced the release of IL6, IL-10 and TGF-β in culture medium. Compared with early-passaged BM-MSCs (p1), late-passaged BM-MSCs (p6) released less TGF-β. Our data suggests that the immunomodulatory properties of MSCs vary with cell origin and cell quality and that BM-MSCs of good quality are likely the optimal source of immunomodulation.

Low-dose irradiated mesenchymal stromal cells break tumor defensive properties in vivo

Solid tumors, including gliomas, still represent a challenge to clinicians and first line treatments often fail, calling for new paradigms in cancer therapy. Novel strategies to overcome tumor resistance are mainly represented by multi-targeted approaches, and cell vector-based therapy is one of the most promising treatment modalities under development. Here, we show that mouse bone marrow-derived mesenchymal stromal cells (MSCs), when primed with low-dose irradiation (irMSCs), undergo changes in their immunogenic and angiogenic capacity and acquire anti-tumoral properties in a mouse model of glioblastoma (GBM). Following grafting in GL261 glioblastoma, irMSCs migrate extensively and selectively within the tumor and infiltrate predominantly the peri-vascular niche, leading to rejection of established tumors and cure in 29% of animals. The therapeutic radiation dose window is narrow, with effects seen between 2 and 15 Gy, peaking at 5 Gy. A single low-dose radiation decreases MSCs inherent immune suppressive properties in vitro as well as shapes their immune regulatory ability in vivo. Intra-tumorally grafted irMSCs stimulate the immune system and decrease immune suppression. Additionally, irMSCs enhance peri-tumoral reactive astrocytosis and display anti-angiogenic properties. Hence, the present study provides strong evidence for a therapeutic potential of low-dose irMSCs in cancer as well as giving new insight into MSC biology and applications.

Mesenchymal Stromal Cell Preconditioning: The Next Step Toward a Customized Treatment For Severe Burn

Over the last century, the clinical management of severe skin burns significantly progressed with the development of burn care units, topical antimicrobials, resuscitation methods, early eschar excision surgeries, and skin grafts. Despite these considerable advances, the present treatment of severe burns remains burdensome, and patients are highly susceptible to skin engraftment failure, infections, organ dysfunction, and hypertrophic scarring. Recent researches have focused on mesenchymal stromal cell (MSC) therapy and hold great promises for tissue repair, as reported in several animal studies and clinical cases. In the present review, we will provide an up-to-date outlook of the pathophysiology of severe skin burns, clinical treatment modalities and current limitations. We will then focus on MSCs and their potential in the burn wound healing both in in vitro and in vivo studies. A specific attention will be paid to the cell preconditioning approach, as a means of improving the MSC efficacy in the treatment of major skin burns. In particular, we will debate how several preconditioning cues would modulate the MSC properties to better match up with the burn pathophysiology in the course of the cell therapy. Finally, we will discuss the clinical interest and feasibility of a MSC-based therapy in comparison to their paracrine derivatives, including microvesicles and conditioned media for the treatment of major skin burn injuries.

The extracellular vesicles-derived from mesenchymal stromal cells: A new therapeutic option in regenerative medicine

Mesenchymal stem cells (MSCs) are adult multipotent cells that due to their ability to homing to damaged tissues and differentiate into specialized cells, are remarkable cells in the field of regenerative medicine. It's suggested that the predominant mechanism of MSCs in tissue repair might be related to their paracrine activity. The utilization of MSCs for tissue repair is initially based on the differentiation ability of these cells; however now it has been revealed that only a small fraction of the transplanted MSCs actually fuse and survive in host tissues. Indeed, MSCs supply the microenvironment with the secretion of soluble trophic factors, survival signals and the release of extracellular vesicles (EVs) such as exosome. Also, the paracrine activity of EVs could mediate the cellular communication to induce cell-differentiation/self-renewal. Recent findings suggest that EVs released by MSCs may also be critical in the physiological function of these cells. This review provides an overview of MSC-derived extracellular vesicles as a hopeful opportunity to advance novel cell-free therapy strategies that might prevail over the obstacles and risks associated with the use of native or engineered stem cells. EVs are very stable; they can pass the biological barriers without rejection and can shuttle bioactive molecules from one cell to another, causing the exchange of genetic information and reprogramming of the recipient cells. Moreover, extracellular vesicles may provide therapeutic cargo for a wide range of diseases and cancer therapy.

Mesenchymal stem cells and T cells in the formation of Tertiary Lymphoid Structures in Lupus Nephritis

Tertiary lymphoid structures (TLS) develop in the kidneys of lupus-prone mice and systemic lupus erythematosus (SLE) patients with lupus nephritis (LN). Here we investigated the presence of mesenchymal stem cells (MSCs) in the development of TLS in murine LN, as well as the role of human MSCs as lymphoid tissue organizer (LTo) cells on the activation of CD4+ T cells from three groups of donors including Healthy, SLE and LN patients. Mesenchymal stem like cells were detected within the pelvic wall and TLS in kidneys of lupus-prone mice. An increase in LTβ, CXCL13, CCL19, VCAM1 and ICAM1 gene expressions were detected during the development of murine LN. Human MSCs stimulated with the pro-inflammatory cytokines TNF-α and IL-1β significantly increased the expression of CCL19, VCAM1, ICAM1, TNF-α, and IL-1β. Stimulated MSCs induced proliferation of CD4⁺ T cells, but an inhibitory effect was observed when in co-culture with non-stimulated MSCs. A contact dependent increase in Th2 and Th17 subsets were observed for T cells from the Healthy group after co-culture with stimulated MSCs. Our data suggest that tissue-specific or/and migratory MSCs could have pivotal roles as LTo cells in accelerating early inflammatory processes and initiating the formation of kidney specific TLS in chronic inflammatory conditions.

Impaired lymph node stromal cell function during the earliest phases of rheumatoid arthritis

Background

Systemic autoimmunity can be present years before clinical onset of rheumatoid arthritis (RA). Adaptive immunity is initiated in lymphoid tissue where lymph node stromal cells (LNSCs) regulate immune responses through their intimate connection with leucocytes. We postulate that malfunctioning of LNSCs creates a microenvironment in which normal immune responses are not properly controlled, possibly leading to autoimmune disease. In this study we established an experimental model for studying the functional capacities of human LNSCs during RA development.

Methods

Twenty-four patients with RA, 23 individuals positive for autoantibodies but without clinical disease (RA risk group) and 14 seronegative healthy control subjects underwent ultrasound-guided inguinal lymph node (LN) biopsy. Human LNSCs were isolated and expanded in vitro for functional analyses. In analogous co-cultures consisting of LNSCs and peripheral blood mononuclear cells, αCD3/αCD28-induced T-cell proliferation was measured using carboxyfluorescein diacetate succinimidyl ester dilution.

Results

Fibroblast-like cells expanded from the LN biopsy comprised of fibroblastic reticular cells (gp38⁺CD31⁻) and double-negative (gp38⁻CD31⁻) cells. Cultured LNSCs stably expressed characteristic adhesion molecules and cytokines. Basal expression of C-X-C motif chemokine ligand 12 (CXCL12) was lower in LNSCs from RA risk individuals than in those from healthy control subjects. Key LN chemokines C-C motif chemokine ligand (CCL19), CCL21 and CXCL13 were induced in LNSCs upon stimulation with tumour necrosis factor-α and lymphotoxin α₁β₂, but to a lesser extent in LNSCs from patients with RA. The effect of human LNSCs on T-cell proliferation was ratio-dependent and altered in RA LNSCs.

Conclusions

Overall, we developed an experimental model to facilitate research on the role of LNSCs during the earliest phases of RA. Using this innovative model, we show, for the first time to our knowledge, that the LN stromal environment is changed during the earliest phases of RA, probably contributing to deregulated immune responses early in disease pathogenesis.

Electronic supplementary material

The online version of this article (10.1186/s13075-018-1529-8) contains supplementary material, which is available to authorized users.

Exosome and mesenchymal stem cell cross-talk in the tumor microenvironment

Mesenchymal stem cells (MSCs) are a major component of the tumor microenvironment (TME) and play a key role in promoting tumor progression. The tumor uses exosomes to co-opt MSCs and re-program their functional profile from normally trophic to pro-tumorigenic. These tumor-derived small vesicles called "TEX" carry and deliver a cargo rich in proteins and nucleic acids to MSCs. Upon interactions with surface receptors on MSCs and uptake of the exosome cargo by MSCs, molecular, transcriptional and translational changes occur that convert MSCs into producers of factors that are necessary for tumor growth and that also alter functions of non-tumor cells in the TME. The MSCs re-programmed by TEX become avid producers of their own exosomes that carry and deliver mRNA and miRNA species as well as molecular signals not only back to tumor cells, directly enhancing their growth, but also horizontally to fibroblasts, endothelial cells and immune cells in the TME, indirectly enhancing their pro-tumor functions. TEX-driven cross-talk of MSCs with immune cells blocks their anti-tumor activity and/or converts them into suppressor cells. MSCs re-programmed by TEX mediate pro-angiogenic activity and convert stromal cells into cancer-associated fibroblasts (CAFs). Although MSCs have a potential to exert anti-tumor activities, they largely provide service to the tumor using the multidirectional communication system established by exosomes in the TME. Future therapeutic options consider disruption of this complex vicious cycle by either molecular or gene-regulated silencing of pro-tumor effects mediated by MSCs in the TME.

Immunomodulatory effects of mesenchymal stromal cells-derived exosome

The mechanisms underlying immunomodulatory ability of mesenchymal stromal cells (MSCs) remain unknown. Recently, studies suggested that the immunomodulatory activity of MSCs is largely mediated by paracrine factors. Among which, exosome is considered to play a major role in the communication between MSCs and target tissue. The aim of our study is to investigate the effect of MSCs-derived exosome on peripheral blood mononuclear cells (PBMCs), especially T cells. We find that the MSCs-derived exosome extracted from healthy donors' bone marrow suppressed the secretion of pro-inflammatory factor TNF-α and IL-1β, but increased the concentration of anti-inflammatory factor TGF-β during in vitro culture. In addition, exosome may induce conversion of T helper type 1 (Th1) into T helper type 2 (Th2) cells and reduced potential of T cells to differentiate into interleukin 17-producing effector T cells (Th17). Moreover, the level of regulatory T cells (Treg) and cytotoxic T lymphocyte-associated protein 4 were also increased. These results suggested that MSC-derived exosome possesses the immunomodulatory properties. However, it showed no effects on the proliferation of PBMCs or CD3+ T cells, but increases the apoptosis of them. In addition, indoleamine 2, 3-dioxygenase (IDO) was previously shown to mediate the immunoregulation of MSCs, which was increased in PBMCs co-cultured with MSCs. In our study, IDO showed no significant changes in PBMCs exposed to MSCs-derived exosome. We conclude that exosome and MSCs might differ in their immune-modulating activities and mechanisms.

Immunomodulation in stem cell differentiation into neurons and brain repair

Immunomodulators regulate stem cell activity at all stages of development as well as during adulthood. Embryonic stem cell (ESC) proliferation as well as neurogenic processes during embryonic development are controlled by factors of the immune system. We review here immunophenotypic expression patterns of  different stem cell types, including ESC, neural (NSC) and tissue-specific mesenchymal stem cells (MSC), and focus on immunodulatory properties of these cells. Immune and inflammatory responses, involving actions of cytokines as well as toll-like receptor (TLR) signaling are known to affect the differentiation capacity of NSC and MSC. Secretion of pro- and anti-inflammatory messengers by MSC have been observed as the consequence of TLR and cytokine activation and promotion of differentiation into specified phenotypes. As result of augmented differentiation capacity, stem cells secrete angiogenic factors including vascular endothelial growth factor, resulting in multifactorial actions in tissue repair. Immunoregulatory properties of tissue specific adult stem cells are put into the context of possible clinical applications.

Secretome profiling of cytokines and growth factors reveals that neuro-glial differentiation is associated with the down-regulation of Chemokine Ligand 2 (MCP-1/CCL2) in amniotic fluid derived-mesenchymal progenitor cells

Secreted cytokines and growth factors play a key role in the modulation of stem cell proliferation, differentiation and survival. To investigate the interplay between the changes in their expression levels, we used the newly characterized human amniotic fluid derived-mesenchymal progenitor MePR-2B cell line differentiated to a neuro-glial phenotype and exploited the very high sensitivity and versatility of magnetic beads-based immunoassays. We found that a sub-set of proteins, including the cytokines IL-6, TNFα, IL-15, IFNγ, IL-8, IL-1ra, MCP-1/CCL2, RANTES and the growth factor PDGFbb, underwent a significant down-regulation following neuro-glial differentiation, whereas the expression levels of IL-12 p70, IL-5, IL-7, bFGF, VEGF and G-CSF were increased. The role of MCP-1/CCL2, previously identified as a regulator of neural progenitor stem cell differentiation, has been further investigated at transcriptional level, revealing that both the chemokine and its receptor are co-expressed in MePR-2B cells and that are regulated upon differentiation, suggesting the presence of an autocrine and paracrine loop in differentiating cells. Moreover, we demonstrated that exogenous CCL2 is capable to affect neuro-glial differentiation in MePR-2B cells, thus providing novel evidences for the potential involvement of chemokine-mediated signaling in progenitor/stem cells differentiation processes and fate specification.

Spheroid Culture of Mesenchymal Stem Cells

Compared with traditional 2D adherent cell culture, 3D spheroidal cell aggregates, or spheroids, are regarded as more physiological, and this technique has been exploited in the field of oncology, stem cell biology, and tissue engineering. Mesenchymal stem cells (MSCs) cultured in spheroids have enhanced anti-inflammatory, angiogenic, and tissue reparative/regenerative effects with improved cell survival after transplantation. Cytoskeletal reorganization and drastic changes in cell morphology in MSC spheroids indicate a major difference in mechanophysical properties compared with 2D culture. Enhanced multidifferentiation potential, upregulated expression of pluripotency marker genes, and delayed replicative senescence indicate enhanced stemness in MSC spheroids. Furthermore, spheroid formation causes drastic changes in the gene expression profile of MSC in microarray analyses. In spite of these significant changes, underlying molecular mechanisms and signaling pathways triggering and sustaining these changes are largely unknown.

Post-thaw non-cultured and post-thaw cultured equine cord blood mesenchymal stromal cells equally suppress lymphocyte proliferation in vitro

Multipotent mesenchymal stromal cells (MSC) are receiving increased attention for their non-progenitor immunomodulatory potential. Cryopreservation is commonly used for long-term storage of MSC. Post-thaw MSC proliferation is associated with a lag-phase in vitro. How this lag-phase affect MSC immunomodulatory properties is unknown. We hypothesized that in vitro there is no difference in lymphocyte suppression potential between quick-thawed cryopreserved equine cord blood (CB) MSC immediately included in mixed lymphocyte reaction (MLR) and same MSC allowed post-thaw culture time prior to inclusion in MLR. Cryopreserved CB-MSC from five unrelated foals were compared using two-way MLR. For each of the five unrelated MSC cultures, paired MLR assays of MSC allowed five days of post-thaw culture and MSC included in MLR assay immediately post-thawing were evaluated. We report no difference in the suppression of lymphocyte proliferation by CB-MSC that had undergone post-thaw culture and MSC not cultured post-thaw (p<0.0001). Also, there was no inter-donor variability between the lymphocyte suppressive properties of MSC harvested from the five different donors (p = 0.13). These findings suggest that cryopreserved CB-MSC may have clinical utility immediately upon thawing. One implication hereof is the possibility of using cryopreserved CB-MSC at third party locations without the need for cell culture equipment or competencies.

Regulation of mouse microglia activation and effector functions by bone marrow-derived mesenchymal stem cells

Mesenchymal stems or stromal cells (MSCs) are rare multipotent cells with potent regenerative and immunomodulatory properties. Microglial cells (MGs) are specialized tissue macrophages of the central nervous system (CNS) that continuously survey their environment with highly motile extensions. Recently, several studies have shown that MSCs are capable of reprogramming microglia into an "M2-like" phenotype characterized by increased phagocytic activity and upregulated expression of anti-inflammatory mediators in vitro. However, the precise polarization states of microglia in the presence of MSCs under physiological or under inflammatory conditions remain largely unknown. In this study, we found that MSCs induce a mixed microglia phenotype defined as Arg1-high, CD86-high, CD206-high, IL-10-high, PGE2-high, MCP-1/CCL2-high, IL-1β-moderate, NALP-3-low, and TNF-α-low cells. These MSC-elicited MGs have high phagocytic activity and antigen-presenting ability. Lipopolysaccharide is able to shape this microglia phenotype quantitatively, but not qualitatively in the presence of MSCs. This unique polarization state resembles a novel regulatory microglia phenotype, which might contribute to the resolution of inflammation and to tissue repair in the CNS.

Mesenchymal stem cells as cellular vectors for pediatric neurological disorders

Lysosomal storage diseases are a heterogeneous group of hereditary disorders characterized by a deficiency in lysosomal function. Although these disorders differ in their etiology and phenotype those that affect the nervous system generally manifest as a profound deterioration in neurologic function with age. Over the past several decades implementation of various treatment regimens including bone marrow and cord blood cell transplantation, enzyme replacement, and substrate reduction therapy have proved effective for managing some clinical manifestations of these diseases but their ability to ameliorate neurologic complications remains unclear. Consequently, there exists a need to develop alternative therapies that more effectively target the central nervous system. Recently, direct intracranial transplantation of tissue-specific stem and progenitor cells has been explored as a means to reconstitute metabolic deficiencies in the CNS. In this chapter we discuss the merits of bone marrow-derived mesenchymal stem cells (MSCs) for this purpose. Originally identified as progenitors of connective tissue cell lineages, recent findings have revealed several novel aspects of MSC biology that make them attractive as therapeutic agents in the CNS. We relate these advances in MSC biology to their utility as cellular vectors for treating neurologic sequelae associated with pediatric neurologic disorders.

Recent advances in mesenchymal stem cell immunomodulation: the role of microvesicles

Mesenchymal stem cells are the most widely used cell phenotype for therapeutic applications, the main reasons being their well-established abilities to promote regeneration of injured tissues and to modulate immune responses. Efficacy was reported in the treatment of several animal models of inflammatory and autoimmune diseases and, in clinical settings, for the management of disorders such as GVHD, systemic lupus erythematosus, multiple sclerosis, and inflammatory bowel disease. The effects of mesenchymal stem cells are believed to be largely mediated by paracrine signals, and several secreted molecules have been identified as contributors to the net biological effect. Recently, it has been recognized that bioactive molecules can be shuttled from cell to cell packed in microvesicles, tiny portions of cytoplasm surrounded by a membrane. Coding and noncoding RNAs are also carried in such microvesicles, transferring relevant biological activity to target cells. Several reports indicate that the regenerative effect of mesenchymal stem cells can be reproduced by microvesicles isolated from their culture medium. More recent evidence suggests that the immunomodulatory effects of mesenchymal stem cells are also at least partially mediated by secreted microvesicles. These findings allow better understanding of the mechanisms involved in cell-to-cell interaction and may have interesting implications for the development of novel therapeutic tools in place of the parent cells.