Cell therapy using allogeneic bone marrow mesenchymal stem cells prevents tissue damage in collagen-induced arthritis

The Fas/Fap-1/Cav-1 complex regulates IL-1RA secretion in mesenchymal stem cells to accelerate wound healing

Mesenchymal stem cells (MSCs) are capable of secreting exosomes, extracellular vesicles, and cytokines to regulate cell and tissue homeostasis. However, it is unknown whether MSCs use a specific exocytotic fusion mechanism to secrete exosomes and cytokines. We show that Fas binds with Fas-associated phosphatase-1 (Fap-1) and caveolin-1 (Cav-1) to activate a common soluble N-ethylmaleimide-sensitive factor (NSF) attachment protein receptor (SNARE)-mediated membrane fusion mechanism to release small extracellular vesicles (sEVs) in MSCs. Moreover, we reveal that MSCs produce and secrete interleukin-1 receptor antagonist (IL-1RA) associated with sEVs to maintain rapid wound healing in the gingiva via the Fas/Fap-1/Cav-1 cascade. Tumor necrosis factor-α (TNF-α) serves as an activator to up-regulate Fas and Fap-1 expression via the nuclear factor κB pathway to promote IL-1RA release. This study identifies a previously unknown Fas/Fap-1/Cav-1 axis that regulates SNARE-mediated sEV and IL-1RA secretion in stem cells, which contributes to accelerated wound healing.

Human adipose tissue-derived mesenchymal stem cells alleviate atopic dermatitis via regulation of B lymphocyte maturation

Mesenchymal stem cell (MSC) has been applied for the therapy of allergic disorders due to its beneficial immunomodulatory abilities. However, the underlying mechanisms for therapeutic efficacy are reported to be diverse according to the source of cell isolation or the route of administration. We sought to investigate the safety and the efficacy of human adipose tissue-derived MSCs (hAT-MSCs) in mouse atopic dermatitis (AD) model and to determine the distribution of cells after intravenous administration. Murine AD model was established by multiple treatment of Dermatophagoides farinae. AD mice were intravenously infused with hAT-MSCs and monitored for clinical symptoms. The administration of hAT-MSCs reduced the gross and histological signatures of AD, as well as serum IgE level. hAT-MSCs were mostly detected in lung and heart of mice within 3 days after administration and were hardly detectable at 2 weeks. All of mice administered with hAT-MSCs survived until sacrifice and did not demonstrate any adverse events. Co-culture experiments revealed that hAT-MSCs significantly inhibited the proliferation and the maturation of B lymphocytes via cyclooxygenase (COX)-2 signaling. Moreover, mast cell (MC) degranulation was suppressed by hAT-MSC. In conclusion, the intravenous infusion of hAT-MSCs can alleviate AD through the regulation of B cell function.

Immunomodulation By Therapeutic Mesenchymal Stromal Cells (MSC) Is Triggered Through Phagocytosis of MSC By Monocytic Cells

Mesenchymal stem or stromal cells (MSC) are under investigation as a potential immunotherapy. MSC are usually administered via intravenous infusion, after which they are trapped in the lungs and die and disappear within a day. The fate of MSC after their disappearance from the lungs is unknown and it is unclear how MSC realize their immunomodulatory effects in their short lifespan. We examined immunological mechanisms determining the fate of infused MSC and the immunomodulatory response associated with it. Tracking viable and dead human umbilical cord MSC (ucMSC) in mice using Qtracker beads (contained in viable cells) and Hoechst33342 (staining all cells) revealed that viable ucMSC were present in the lungs immediately after infusion. Twenty-four hours later, the majority of ucMSC were dead and found in the lungs and liver where they were contained in monocytic cells of predominantly non-classical Ly6C^low phenotype. Monocytes containing ucMSC were also detected systemically. In vitro experiments confirmed that human CD14⁺⁺ /CD16^- classical monocytes polarized toward a non-classical CD14⁺⁺ CD16⁺ CD206⁺ phenotype after phagocytosis of ucMSC and expressed programmed death ligand-1 and IL-10, while TNF-α was reduced. ucMSC-primed monocytes induced Foxp3⁺ regulatory T cell formation in mixed lymphocyte reactions. These results demonstrate that infused MSC are rapidly phagocytosed by monocytes, which subsequently migrate from the lungs to other body sites. Phagocytosis of ucMSC induces phenotypical and functional changes in monocytes, which subsequently modulate cells of the adaptive immune system. It can be concluded that monocytes play a crucial role in mediating, distributing, and transferring the immunomodulatory effect of MSC. Stem Cells 2018;36:602-615.

IL-17 down-regulates the immunosuppressive capacity of olfactory ecto-mesenchymal stem cells in murine collagen-induced arthritis

Olfactory ecto-mesenchymal stem cells (OE-MSCs) are a population of cells which has been recognized as a new resident stem cell type in the olfactory lamina propria. OE-MSCs have been shown to exert their immunosuppressive capacity by modulating T cell responses, including up-regulation of regulatory T cells (Tregs) and down-regulation of Th1/Th17 cells. As an inflammatory cytokine, IL-17 plays a critical role in orchestrating the inflammatory response during the development of collagen-induced arthritis (CIA). However, it is unclear whether the increased level of IL-17 may affect the immunosuppressive function of OE-MSCs under inflammatory condition. In this study, we found that IL-17 could significantly reduce the suppressive capacity of OE-MSCs on CD4+ T cells and down-regulate the suppressive factors produced by OE-MSCs. Notably, IL-17 treatment abolished the capacity of OE-MSCs in inducing Treg expansion. In addition, knockdown of IL-17R in OE-MSCs significantly enhanced their therapeutic effect in ameliorating CIA upon adoptive transfer. Moreover, IL-17R knockdown-OE-MSCs could efficiently induce Tregs expansion and reduce Th1 and Th17 responses. Taken together, all these data suggest that IL-17R knockdown in OE-MSCs may provide a novel strategy in maintaining their immunosuppressive properties for the treatment of autoimmune diseases.

Mesenchymal Stem Cell-Conditioned Medium Reduces Disease Severity and Immune Responses in Inflammatory Arthritis

We evaluated the therapeutic potential of mesenchymal stem cell-conditioned medium (CM-MSC) as an alternative to cell therapy in an antigen-induced model of arthritis (AIA). Disease severity and cartilage loss were evaluated by histopathological analysis of arthritic knee joints and immunostaining of aggrecan neoepitopes. Cell proliferation was assessed for activated and naïve CD4+ T cells from healthy mice following culture with CM-MSC or co-culture with MSCs. T cell polarization was analysed in CD4+ T cells isolated from spleens and lymph nodes of arthritic mice treated with CM-MSC or MSCs. CM-MSC treatment significantly reduced knee-joint swelling, histopathological signs of AIA, cartilage loss and suppressed TNFα induction. Proliferation of CD4+ cells from spleens of healthy mice was not affected by CM-MSC but reduced when cells were co-cultured with MSCs. In the presence of CM-MSC or MSCs, increases in IL-10 concentration were observed in culture medium. Finally, CD4+ T cells from arthritic mice treated with CM-MSC showed increases in FOXP3 and IL-4 expression and positively affected the Treg:Th17 balance in the tissue. CM-MSC treatment reduces cartilage damage and suppresses immune responses by reducing aggrecan cleavage, enhancing Treg function and adjusting the Treg:Th17 ratio. CM-MSC may provide an effective cell-free therapy for inflammatory arthritis.

Mesenchymal stem cells reverse high‑fat diet‑induced non‑alcoholic fatty liver disease through suppression of CD4+ T lymphocytes in mice

Although the multipotency of mesenchymal stem cells (MSCs) makes them an attractive choice for clinical applications, immune modulation is an important factor affecting MSC transplantation. At present, the effect of treatment with MSCs on non‑alcoholic fatty liver disease (NAFLD) has received little attention. In the present study, a compact bone‑derived method was used to isolate mouse MSCs (mMSCs) and a high‑fat diet was used to establish a mouse model of NAFLD. Immunophenotypic features of mMSCs were analyzed using flow cytometry. Paraffin sections were stained with hematoxylin and eosin to assess inflammation and steatosis, and with picrosirius red to assess fibrosis. Spleen leukocytes were analyzed by flow cytometry. The results demonstrated that compact bone‑derived MSC transplantation decreased high‑fat diet‑induced weight gain, expansion of subcutaneous adipose tissue, steatosis, lobular inflammation and liver fibrogenesis. Flow cytometry analysis of spleen leukocytes demonstrated that compact bone‑derived MSC transplantation suppressed the proliferation of cluster of differentiation (CD) 4+ T lymphocytes in the spleen, which had been induced by the high‑fat diet. In conclusion, compact bone‑derived MSCs may exhibit clinical value in the treatment of NAFLD through their capacity to suppress the activation of CD4+ T cells.

Mitochondrial Oxidative Stress Reduces the Immunopotency of Mesenchymal Stromal Cells in Adults With Coronary Artery Disease

RATIONALE

Mesenchymal stromal cells (MSCs) are promising therapeutic strategies for coronary artery disease; however, donor-related variability in cell quality is a main cause of discrepancies in preclinical studies. In vitro, MSCs from individuals with coronary artery disease have reduced ability to suppress activated T-cells. The mechanisms underlying the altered immunomodulatory capacity of MSCs in the context of atherosclerosis remain elusive.

OBJECTIVE

The aim of this study was to assess the role of mitochondrial dysfunction in the impaired immunomodulatory properties of MSCs from patients with atherosclerosis.

METHODS AND RESULTS

Adipose tissue-derived MSCs were isolated from atherosclerotic (n=38) and nonatherosclerotic (n=42) donors. MSCs:CD4⁺T-cell suppression was assessed in allogeneic coculture systems. Compared with nonatherosclerotic-MSCs, atherosclerotic-MSCs displayed higher levels of both intracellular (P=0.006) and mitochondrial (P=0.03) reactive oxygen species reflecting altered mitochondrial function. The increased mitochondrial reactive oxygen species levels of atherosclerotic-MSCs promoted a phenotypic switch characterized by enhanced glycolysis and an altered cytokine secretion (interleukin-6 P<0.0001, interleukin-8/C-X-C motif chemokine ligand 8 P=0.04, and monocyte chemoattractant protein-1/chemokine ligand 2 P=0.01). Furthermore, treatment of atherosclerotic-MSCs with the reactive oxygen species scavenger N-acetyl-l-cysteine reduced the levels of interleukin-6, interleukin-8/C-X-C motif chemokine ligand 8, and monocyte chemoattractant protein-1/chemokine ligand 2 in the MSC secretome and improved MSCs immunosuppressive capacity (P=0.03).

CONCLUSIONS

An impaired mitochondrial function of atherosclerotic-MSCs underlies their altered secretome and reduced immunopotency. Interventions aimed at restoring the mitochondrial function of atherosclerotic-MSCs improve their in vitro immunosuppressive ability and may translate into enhanced therapeutic efficiency.

In vivo immune interactions of multipotent stromal cells underlie their long-lasting pain-relieving effect

Systemic infusion of bone marrow stromal cells (BMSCs), a major type of multipotent stromal cells, produces pain relief (antihyperalgesia) that lasts for months. However, studies have shown that the majority of BMSCs are trapped in the lungs immediately after intravenous infusion and their survival time in the host is inconsistent with their lengthy antihyperalgesia. Here we show that long-lasting antihyperalgesia produced by BMSCs required their chemotactic factors such as CCL4 and CCR2, the integrations with the monocytes/macrophages population, and BMSC-induced monocyte CXCL1. The activation of central mu-opioid receptors related to CXCL1-CXCR2 signaling plays an important role in BMSC-produced antihyperalgesia. Our findings suggest that the maintenance of antihypergesia can be achieved by immune regulation without actual engraftment of BMSCs. In the capacity of therapeutic use of BMSCs other than structural repair and replacement, more attention should be directed to their role as immune modulators and subsequent alterations in the immune system.

Therapeutic potential of tonsil-derived mesenchymal stem cells in dextran sulfate sodium-induced experimental murine colitis

The therapeutic potential of tonsil-derived mesenchymal stem cells (TMSC) prepared from human tonsillar tissue has been studied in animal models for several diseases such as hepatic injury, hypoparathyroidism, diabetes and muscle dystrophy. In this study, we examined the therapeutic effects of TMSC in a dextran sulfate sodium (DSS)-induced colitis model. TMSC were injected in DSS-induced colitis mice via intraperitoneal injection twice (TMSC[x2]) or four times (TMSC[x4]). Control mice were injected with either phosphate-buffered saline or human embryonic kidney 293 cells. Body weight, stool condition and disease activity index (DAI) were examined daily. Colon length, histologic grading, and mRNA expression of pro-inflammatory cytokines, interleukin 1β (IL-1β), IL-6, IL-17 and tumor necrosis factor α, and anti-inflammatory cytokines, IL-10, IL-11 and IL-13, were also measured. Our results showed a significant improvement in survival rates and body weight gain in colitis mice injected with TMSC[x2] or TMSC[x4]. Injection with TMSC also significantly decreased DAI scores throughout the experimental period; at the end of experiment, almost complete reversal of DAI scores to normal was found in colitis mice treated with TMSC[x4]. Colon length was also significantly recovered in colitis mice treated with TMSC[x4]. However, histopathological alterations induced by DSS treatment were not apparently improved by injection with TMSC. Finally, treatment with TMSC[x4] significantly reversed the mRNA levels of IL-1β and IL-6, although expression of all pro-inflammatory cytokines tested was induced in colitis mice. Under our experimental conditions, however, no apparent alterations in the mRNA levels of all the anti-inflammatory cytokines tested were found. In conclusion, our findings demonstrate that multiple injections with TMSC produced a therapeutic effect in a mouse model of DSS-induced colitis.

Adipose-Derived Stem Cells Ameliorate Experimental Murine Colitis via TSP-1-Dependent Activation of Latent TGF-β

BACKGROUND

Adipose tissue-derived stem cells (ASCs) have been investigated as therapeutic tools for a variety of autoimmune diseases, including inflammatory diseases. However, the mechanisms underlying the immunomodulatory properties of ASCs are not well understood. Here, we investigated the mechanism of regulatory T cell (Treg) induction in ASC therapy in a murine model of inflammatory bowel disease.

METHODS

Acute colitis was induced in mice using dextran sulfate sodium and ASCs administered intraperitoneally. Tregs and CD103⁺ dendritic cells were analyzed in the mesenteric lymph nodes (MLNs), spleen, and colonic lamina propria (CLP). Activation of latent TGF-β by ASCs was analyzed in vitro using ELISA. siRNA technology was used to create ASCs in which TSP-1 or integrinαv was knocked down in order to investigate the involvement of these proteins in the activation of latent TGF-β. In addition, TSP-1-knockdown ASCs were administered to mice with colitis to assess their clinical efficacy in vivo.

RESULTS

Systemic administration of ASCs significantly lessened the clinical and histopathological severity of colitis. ASCs were distributed throughout the lymphatic system in the MLNs and spleen. Tregs were increased in the MLNs and CLP, but CD103⁺ dendritic cells were not significantly altered. The ASCs activated latent TGF-β. TSP-1 knockdown impaired TGF-β activation in vitro and abrogated the therapeutic effects of the ASCs in vivo. Furthermore, Tregs were not increased in the MLNs and CLP from mice treated with TSP-1-knockdown ASCs.

CONCLUSIONS

These results demonstrate that ASCs induce Tregs by activating latent TGF-β via TSP-1, independent of CD103⁺ dendritic cell induction.

Mesenchymal stem cells for the management of rheumatoid arthritis: immune modulation, repair or both?

PURPOSE OF REVIEW

Mesenchymal stromal/stem cells (MSCs) have potent anti-inflammatory and immunomodulatory properties, in addition to their ability to form cartilage and bone. The purpose of this review is to highlight recent developments and current knowledge gaps in our understanding of the protective effects of MSCs against inflammatory arthritis, and to discuss their clinical exploitation for the treatment of rheumatoid arthritis (RA).

RECENT FINDINGS

The weight of evidence for protective mechanisms of exogenously administered MSCs is on immunomodulatory effects, including inhibition of dendritic cell maturation, polarization of macrophages to an anti-inflammatory phenotype, and activation of regulatory T cells, thereby dampening inflammation and preventing joint damage. Evidence for direct effects on tissue repair is scant. Recent studies have identified MSC subsets in vivo and an important question is whether MSCs in their native tissues have similar immunoregulatory functions. Recent proof-of-concept clinical studies have shown a satisfactory safety profile of allogeneic MSC therapy in RA patients with promising trends for clinical efficacy.

SUMMARY

Allogeneic MSCs could be effective in RA. Larger, multicentre clinical studies are needed to provide robust evidence, and MSC treatment at early stages of RA should be explored to 'reset' the immune system.

Human limbal fibroblast-like stem cells induce immune-tolerance in autoreactive T lymphocytes from female patients with Hashimoto's thyroiditis

Background

Due to their “natural immune privilege” and immunoregulatory properties human fibroblast-like limbal stem cells (f-LSCs) have acquired great interest as a potential tool for achieving immunotolerance. Hashimoto’s thyroiditis (HT) is the most common thyroid autoimmune disease and cause of hypothyroidism. To date, conventional hormone replacement therapy and unspecific immunosuppressive regimens cannot provide a definitive cure for HT subjects. We explored the immunosuppressant potential of human f-LSCs on circulating lymphomonocytes (PBMCs) collected from healthy donors and female HT patients.

Methods

We assessed the immunophenotyping of f-LSCs, both untreated and after 48 h of proinflammatory cytokine exposure, by means of quantitative reverse-transcription polymerase chain reaction (qRT-PCR) and flow cytometry. The immunosuppressant effects of f-LSCs on healthy activated PBMCs were investigated in cell-cell contact and transwell settings through cell cycle assay, acridine orange staining, and caspase-3 detection. We also studied T-cell responses and possible Treg conversion by means of flow cytometry. Functional assays were conducted in activated HT lymphocytes cocultured with f-LSCs after carboxyfluorescein succinimidyl ester labeling and intracellular detection of pro- and anti-inflammatory cytokines.

Results

The hypo-immunogenicity of the f-LSC population depended on both cell contact and soluble factors produced, as well as the undetectable expression of all those molecules required to fully activate T lymphocytes. Following exposure to Th1 cytokines, f-LSCs augmented expression of programmed death-ligand 1 and 2 (PDL-1 and -2), indoleamine-pyrrole-2,3-dioxygenase (IDO), interleukin (IL)-6, and monocyte chemotactic protein 1 (MCP-1) while maintaining their negative phenotype for major histocompatibility (MHC) class II and costimulatory molecules. During coculture, f-LSCs suppressed up to 40% of proliferation in healthy activated PBMCs, arrested them in the G0/G1 cell cycle phase without inducing apoptosis cascade, inverted the CD4/CD8 ratio, and promoted sustained expression of the immunomodulator marker CD69. Under coculture conditions the Th imbalance of autoreactive T cells from female HT patients was fully restored.

Conclusions

Our study describes an in vitro coculture system able to prevent inappropriate activation of autoreactive T lymphocytes of female HT patients and to generate a tolerogenic environment even in an inflammatory background. Further investigations are necessary to establish whether this stem cell-based therapy approach in HT could avoid lifetime hormone replacement therapy by inducing T-cell education.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-017-0611-5) contains supplementary material, which is available to authorized users.

Data against a Common Assumption: Xenogeneic Mouse Models Can Be Used to Assay Suppression of Immunity by Human MSCs

Much of what we know about immunology suggests that little is to be gained from experiments in which human cells are administered to immunocompetent mice. Multiple reports have demonstrated that this common assumption does not hold for experiments with human mesenchymal stem/stromal cells (hMSCs). The data demonstrate that hMSCs can suppress immune responses to a variety of stimuli in immunocompetent mice by a range of different mechanisms that are similar to those employed by mouse MSCs. Therefore, further experiments with hMSCs in mice will make it possible to generate preclinical data that will improve both the efficacy and safety of the clinical trials with the cells that are now in progress.

Mesenchymal stromal cells and autoimmunity

Mesenchymal stromal cells (MSCs) are committed progenitors of mesodermal origin that are found virtually in every organ and exhibit multilineage differentiation into osteocytes, adipocytes and chondrocytes. MSCs also mediate a wide spectrum of immunoregulatory activities that usually dampen innate and adaptive immune responses. These features have attracted interest in the perspective of developing novel cell therapies for autoimmune disease. However, depending on the microenvironmental conditions, MSCs may show a plastic behavior and switch to an immunostimulatory phenotype. After thorough characterization of the effects of MSCs on the immune system, MSC cell therapy has been tested in animal models of autoimmunity using different cell sources, protocols of in vitro expansion and routes and schedules of administration. The pre-clinical results have been encouraging in some models [e.g. Crohn's disease (CD), multiple sclerosis] and heterogeneous in others (e.g. graft-versus-host disease, systemic lupus erythematosus, rheumatoid arthritis). Clinical trials have been carried out and many are ongoing. As discussed, the results obtained are too preliminary to draw any conclusion, with the only exception of topical administration of MSCs in CD that has proven efficacious. The mechanism of action of infused MSCs is still under investigation, but the apparent paradox of a therapeutic effect achieved in spite of the very low number of cells reaching the target organ has been solved by the finding that MSC-derived extracellular vesicles (EVs) closely mimic the therapeutic activity of MSCs in pre-clinical models. These issues are critically discussed in view of the potential clinical use of MSC-derived EVs.

Cotransfer of regulatory T cells improve the therapeutic effectiveness of mesenchymal stem cells in treating a colitis mouse model

Inflammatory bowel disease (IBD) is a severe inflammatory condition in the colon. To date, clinical solutions for this disease have been limited. Mesenchymal stem cells (MSCs), multipotential cells with immune regulation and anti-inflammatory functions, have been applied to treatment of IBD. However, the therapeutic effectiveness of MSCs still needs to be improved. Here, we were interested in whether regulatory T cells (Tregs) could enhance the immune regulation function of MSCs in treatment of mouse colitis. We generated a dextran sulfate sodium (DSS)-induced IBD mouse model. Combined cell therapy with both MSCs and Tregs was able to help increase body weight and preserve a better colon morphology compared with single cell therapy with MSCs or Tregs alone. Further studies demonstrated that combined cell therapy could reduce pro-inflammatory cytokines such as TNF-α,IL-10, IFN-γ, IL-17A, IL-1β and at the same time promote CD3+ T cells apoptosis. In conclusion, our study indicates that combined cell therapy could prevent the development of colitis in a mouse model, which may lead to a new effective therapeutic approach for treatment of human IBD.

Canine adipose tissue-derived mesenchymal stem cells ameliorate severe acute pancreatitis by regulating T cells in rats

Severe acute pancreatitis (SAP) is associated with systemic complications and high mortality rate in dogs. Mesenchymal stem cells (MSCs) have been investigated for their therapeutic potential in several inflammation models. In the present study, the effects of canine adipose tissue-derived (cAT)-MSCs in a rat model of SAP induced by retrograde injection of 3% sodium taurocholate solution into the pancreatic duct were investigated. cAT-MSCs labeled with dioctadecyl-3,3,3′-tetramethylindo-carbocyanine perchlorate (1 × 10⁷ cells/kg) were systemically administered to rats and pancreatic tissue was collected three days later for histopathological, quantitative real-time polymerase chain reaction, and immunocytochemical analyses. Greater numbers of infused cAT-MSCs were detected in the pancreas of SAP relative to sham-operated rats. cAT-MSC infusion reduced pancreatic edema, inflammatory cell infiltration, and acinar cell necrosis, and decreased pancreatic expression of the pro-inflammatory cytokines tumor necrosis factor-α, interleukin (IL)-1β, -6, -12, -17, and -23 and interferon-γ, while stimulating expression of the anti-inflammatory cytokines IL-4 and IL-10 in SAP rats. Moreover, cAT-MSCs decreased the number of clusters of differentiation 3-positive T cells and increased that of forkhead box P3-positive T cells in the injured pancreas. These results indicate that cAT-MSCs can be effective as a cell-based therapeutic strategy for treatment of SAP in dogs.

Pathogenic or Therapeutic Extracellular Vesicles in Rheumatic Diseases: Role of Mesenchymal Stem Cell-Derived Vesicles

Extracellular vesicles (EVs) are important mediators of cell-to-cell communication pathways via the transport of proteins, mRNA, miRNA and lipids. There are three main types of EVs, exosomes, microparticles and apoptotic bodies, which are classified according to their size and biogenesis. EVs are secreted by all cell types and their function reproduces that of the parental cell. They are involved in many biological processes that regulate tissue homeostasis and physiopathology of diseases. In rheumatic diseases, namely osteoarthritis (OA) and rheumatoid arthritis (RA), EVs have been isolated from synovial fluid and shown to play pathogenic roles contributing to progression of both diseases. By contrast, EVs may have therapeutic effect via the delivery of molecules that may stop disease evolution. In particular, EVs derived from mesenchymal stem cells (MSCs) reproduce the main functions of the parental cells and therefore represent the ideal type of EVs for modulating the course of either disease. The aim of this review is to discuss the role of EVs in OA and RA focusing on their potential pathogenic effect and possible therapeutic options. Special attention is given to MSCs and MSC-derived EVs for modulating OA and RA progression with the perspective of developing innovative therapeutic strategies.

Mesenchymal Stem Cells with eNOS Over-Expression Enhance Cardiac Repair in Rats with Myocardial Infarction

PURPOSE

Transplantation of mesenchymal stem cells (MSCs) is a promising therapeutic option for patients with acute myocardial infarction.

METHODS

We show here that the ectopic overexpression of endothelial nitric oxide synthases (eNOS), an endothelial form of NOS, could enhance the ability of MSCs in treating ischemic heart damage after the occlusion of the coronary artery.

RESULTS

Adenoviral delivery of human eNOS gene into mouse bone marrow-derived MSCs (BM-MSCs) conferred resistance to oxygen glucose deprivation (OGD)-induced cell death in vitro, and elevated the bioavailability of nitric oxide when injected into the myocardium in vivo. In a rat model of acute myocardial infarction, the transplantation of eNOS-overexpressing BM-MSCs significantly reduced myocardial infarct size, corrected hemodynamic parameters and increased capillary density. We also found that the synergistic effects were consistently better than either treatment alone.

CONCLUSIONS

These findings reveal a positive role of elevated eNOS expression in cardiac repair, and suggest the combination of eNOS and MSC transplant therapy as a potential approach for treating myocardial infarction.

A Proinflammatory Secretome Mediates the Impaired Immunopotency of Human Mesenchymal Stromal Cells in Elderly Patients with Atherosclerosis

Inflammation plays a pivotal role in the initiation and progression of atherosclerosis (ATH). Due to their potent immunomodulatory properties, mesenchymal stromal cells (MSCs) are evaluated as therapeutic tools in ATH and other chronic inflammatory disorders. Aging reduces MSCs immunopotency potentially limiting their therapeutic utility. The mechanisms that mediate the effect of age on MSCs immune-regulatory function remain elusive and are the focus of this study. Human adipose tissue-derived MSCs were isolated from patients undergoing coronary artery bypass graft surgery. MSCs:CD4⁺ T-cell suppression, a readout of MSCs' immunopotency, was assessed in allogeneic coculture systems. MSCs from elderly subjects were found to exhibit a diminished capacity to suppress the proliferation of activated T cells. Soluble factors and, to a lesser extent, direct cell-cell contact mechanisms mediated the MSCs:T-cell suppression. Elderly MSCs exhibited a pro-inflammatory secretome with increased levels of interleukin-6 (IL-6), IL-8/CXCL8, and monocyte chemoattractant protein-1 (MCP-1/CCL2). Neutralization of these factors enhanced the immunomodulatory function of elderly MSCs. In summary, our data reveal that in contrast to young MSCs, MSCs from elderly individuals with ATH secrete high levels of IL-6, IL-8/CXCL8 and MCP-1/CCL2 which mediate their reduced immunopotency. Consequently, strategies aimed at targeting pro-inflammatory cytokines/chemokines produced by MSCs could enhance the efficacy of autologous cell-based therapies in the elderly. Stem Cells Translational Medicine 2017;6:1132-1140.

Immunoselected STRO-3+ mesenchymal precursor cells reduce inflammation and improve clinical outcomes in a large animal model of monoarthritis

BACKGROUND

The purpose of this study was to investigate the therapeutic efficacy of intravenously administered immunoselected STRO-3 + mesenchymal precursor cells (MPCs) on clinical scores, joint pathology and cytokine production in an ovine model of monoarthritis.

METHODS

Monoarthritis was established in 16 adult merino sheep by administration of bovine type II collagen into the left hock joint following initial sensitization to this antigen. After 24 h, sheep were administered either 150 million allogeneic ovine MPCs (n = 8) or saline (n = 8) intravenously (IV). Lameness, joint swelling and pain were monitored and blood samples for leukocytes and cytokine levels were collected at intervals following arthritis induction. Animals were necropsied 14 days after arthritis induction and gross and histopathological evaluations were undertaken on tissues from the arthritic (left) and contralateral (right) joints.

RESULTS

MPC-treated sheep demonstrated significantly reduced clinical signs of lameness, joint pain and swelling compared with saline controls. They also showed decreased cartilage erosions, synovial stromal cell activation and angiogenesis. This was accompanied by decreased infiltration of the synovial tissues by CD4+ lymphocytes and CD14+ monocytes/macrophages. Over the 3 days following joint arthropathy induction, the numbers of neutrophils circulating in the blood and plasma concentrations of activin A were significantly reduced in animals administered MPCs.

CONCLUSIONS

The results of this study have demonstrated the capacity of IV-administered MPCs to mitigate the clinical signs and some of the inflammatory mediators responsible for joint tissue destruction in a large animal model of monoarthritis.

Mechanisms of Immune Suppression Utilized by Canine Adipose and Bone Marrow-Derived Mesenchymal Stem Cells

Mesenchymal stem cells (MSCs) from rodents and humans have been shown to suppress T cells by distinct primary pathways, with nitric oxide (NO)-dependent pathways dominating in rodents and indoleamine 2,3-deoxygenase (IDO)-dependent pathways dominating in humans. However, the immune suppressive pathways utilized by canine MSC have not been thoroughly studied, nor have bone marrow-derived MSC (BM-MSC) and adipose-derived MSC (Ad-MSC) been directly compared for their immune modulatory potency or pathway utilization. Therefore, canine BM-MSC and Ad-MSC were generated in vitro and their potency in suppressing T cell proliferation and cytokine production was compared, and differential gene expression. Mechanisms of T cells suppression were also investigated for both MSC types. We found that BM-MSC and Ad-MSC were roughly equivalent in terms of their ability to suppress T cell activation. However, the two MSC types used both shared and distinct biochemical pathways to suppress T cell activation. Ad-MSC utilized TGF-β signaling pathways and adenosine signaling to suppress T cell activation, whereas BM-MSC used cyclooxygenase, TGF-β and adenosine signaling pathways to suppress T cell activation. These results indicate that canine MSC are distinct from human and rodent MSC terms of their immune suppressive pathways, relying primarily on cyclooxygenase and TGF-β pathways for T cell suppression, rather than on NO or IDO-mediated pathways.

Effects of administration of adipose-derived stromal vascular fraction and platelet-rich plasma to dogs with osteoarthritis of the hip joints

OBJECTIVE To evaluate effects of simultaneous intra-articular and IV injection of autologous adipose-derived stromal vascular fraction (SVF) and platelet-rich plasma (PRP) to dogs with osteoarthritis of the hip joints. ANIMALS 22 client-owned dogs (12 placebo-treated [control] dogs and 10 treated dogs). PROCEDURES Dogs with osteoarthritis of the hip joints that caused signs of lameness or discomfort were characterized on the basis of results of orthopedic examination, goniometry, lameness score, the Canine Brief Pain Inventory (CBPI), a visual analogue scale, and results obtained by use of a pressure-sensing walkway at week 0 (baseline). Dogs received a simultaneous intraarticular and IV injection of SVF and PRP or a placebo. Dogs were examined again 4, 8, 12, and 24 weeks after injection. RESULTS CBPI scores were significantly lower for the treatment group at week 24, compared with scores for the control group. Mean visual analogue scale score for the treatment group was significantly higher at week 0 than at weeks 4, 8, or 24. Dogs with baseline peak vertical force (PVF) in the lowest 25th percentile were compared, and the treatment group had a significantly higher PVF than did the control group. After the SVF-PRP injection, fewer dogs in the treated group than in the control group had lameness confirmed during examination. CONCLUSIONS AND CLINICAL RELEVANCE For dogs with osteoarthritis of the hip joints treated with SVF and PRP, improvements in CBPI and PVF were evident at some time points, compared with results for the control group.

Etanercept-Synthesising Mesenchymal Stem Cells Efficiently Ameliorate Collagen-Induced Arthritis

Mesenchymal stem cells (MSCs) have multiple properties including anti-inflammatory and immunomodulatory effects in various disease models and clinical treatments. These beneficial effects, however, are sometimes inconsistent and unpredictable. For wider and proper application, scientists sought to improve MSC functions by engineering. We aimed to invent a novel method to produce synthetic biological drugs from engineered MSCs. We investigated the anti-arthritic effect of engineered MSCs in a collagen-induced arthritis (CIA) model. Biologics such as etanercept are the most successful drugs used in anti-cytokine therapy. Biologics are made of protein components, and thus can be theoretically produced from cells including MSCs. MSCs were transfected with recombinant minicircles encoding etanercept (trade name, Enbrel), which is a tumour necrosis factor α blocker currently used to treat rheumatoid arthritis. We confirmed minicircle expression in MSCs in vitro based on GFP. Etanercept production was verified from the conditioned media. We confirmed that self-reproduced etanercept was biologically active in vitro. Arthritis subsided more efficiently in CIA mice injected with mcTNFR2MSCs than in those injected with conventional MSCs or etanercept only. Although this novel strategy is in a very early conceptual stage, it seems to represent a potential alternative method for the delivery of biologics and engineering MSCs.

Compact Bone-Derived Multipotent Mesenchymal Stromal Cells (MSCs) for the Treatment of Sjogren's-like Disease in NOD Mice

Compact bone (cortical or dense bone) is among the organs that contain multipotent mesenchymal stromal cells (MSCs). Unlike bone marrow plugs where MSCs were initially isolated, compact bone has minimal (amount of) hematopoietic cells and thus facilitates the MSCs isolation process. In vitro, MSCs from compact bone show multipotency and differentiation into mesenchymal tissues such as bone, adipose, and cartilage, under certain conditions. MSCs therapy has been promising in preclinical and clinical studies against autoimmune diseases. Not only can MSCs replace the lost tissue through their regenerative properties, but they can also control the autoimmune attacks by immunoregulatory cytokines. This protocol describes the use of compact bone-derived MSCs to preserve salivary function (saliva flow/output) in the NOD (nonobese diabetic) mouse model affected with Sjogren's-like disease.

Biodistribution and Immunogenicity of Allogeneic Mesenchymal Stem Cells in a Rat Model of Intraarticular Chondrocyte Xenotransplantation

Xenogeneic chondrocytes and allogeneic mesenchymal stem cells (MSC) are considered a potential source of cells for articular cartilage repair. We here assessed the immune response triggered by xenogeneic chondrocytes when injected intraarticularly, as well as the immunoregulatory effect of allogeneic bone marrow-derived MSC after systemic administration. To this end, a discordant xenotransplantation model was established by injecting three million porcine articular chondrocytes (PAC) into the femorotibial joint of Lewis rats and monitoring the immune response. First, the fate of MSC injected using various routes was monitored in an in vivo imaging system. The biodistribution revealed a dependency on the injection route with MSC injected intravenously (i.v.) succumbing early after 24 h and MSC injected intraperitoneally (i.p.) lasting locally for at least 5 days. Importantly, no migration of MSC to the joint was detected in rats previously injected with PAC. MSC were then administered either i.v. 1 week before PAC injection or i.p. 3 weeks after to assess their immunomodulatory function on humoral and adaptive immune parameters. Anti-PAC IgM and IgG responses were detected in all PAC-injected rats with a peak at week 2 postinjection and reactivity remaining above baseline levels by week 18. IgG2a and IgG2b were the predominant and long-lasting IgG subtypes. By contrast, no anti-MSC antibody response was detected in the cohort injected with MSC only, but infusion of MSC before PAC injection temporarily augmented the anti-PAC antibody response. Consistent with a cellular immune response to PAC in PAC-injected rats, cytokine/chemokine profiling in serum by antibody array revealed a distinct pattern relative to controls characterized by elevation of multiple markers at week 2, as well as increases in proliferation in draining lymph nodes. Notably, systemic administration of allogeneic MSC under the described conditions did not diminish the immune response. IL-2 measurements in cocultures of rat peripheral blood lymphocytes with PAC indicated that PAC injection induced some T-cell hyporesponsiveness that was not enhanced in the cohorts additionally receiving MSC. Thus, PAC injected intraarticularly in Lewis rats induced a cellular and humoral immune response that was not counteracted by the systemic administration of allogeneic MSC under the described conditions.

IL-1β impedes the chondrogenic differentiation of synovial fluid mesenchymal stem cells in the human temporomandibular joint

Mesenchymal stem cell-based therapy has great therapeutic potential for temporomandibular joint (TMJ) cartilage repair. However, the behavior of mesenchymal stem cells in the inflammatory milieu following their delivery remains poorly understood. Synovial fluid-derived mesenchymal stem cells (SFMSCs) are a promising resource for TMJ cartilage repair, as they are easily obtained from patients with TMJ disorders (TMD). In this study, we obtained SFMSCs from patients with TMD and expanded them in vitro; we then stimulated the cells with interleukin (IL)‑8, IL-1β, IL-6, IL-10, tumor necrosis factor (TNF)-α and IL-12p. The cells expressed CD90, CD44, CD105 and CD73, and were negative for CD45, CD34, CD11b, CD19 and HLA-DR. They could be induced to differentiate into osteogenic, chondrogenic, adipogenic and neurogenic lineages in vitro. Only the levels of IL-6 and IL-8 were upregulated significantly following stimulation with IL-8, IL-1β, IL-6, IL-10, TNF-α and IL-12p. Furthermore, IL-6 and IL-8 expression was driven mainly by IL-1β-dependent nuclear factor-κB (NF-κB) pathway activation, and was independent of IL-8, IL-6, IL-10, TNF-α and IL-12p. IL-6 and IL-8 expression was inhibited completely by treatment with the NF-κB inhibitor, BAY11-7082. SRY-box 9 (SOX9) was downregulated and matrix metalloproteinase (MMP)13 was upregulated upon chondrogenic differentiation induced in the cells also exposed to IL-1β. Sulfated glycosaminoglycan production was also reduced upon chondrogenic differentiation in the presence of IL-6, but not IL-8. Thus, IL-1β in the inflammatory milieu is crucial in regulating SFMSCs. In doing so, IL-1β impedes the chondrogenic differentiation of SFMSCs. The upregulation of IL-6 and NF-κB pathway activation also contribute to this biological behavior. The findings of our study indicate the potential adverse effects of IL-1β on the chondrogenic differentiation of SFMSCs, and may thus provide new insight into the pathogenesis of TMD.

Toll-like receptor 3 pre-conditioning increases the therapeutic efficacy of umbilical cord mesenchymal stromal cells in a dextran sulfate sodium-induced colitis model

BACKGROUND AIMS

Immunomodulatory properties of human umbilical cord-derived mesenchymal stromal cells (UCMSCs) can be differentially modulated by toll-like receptors (TLR) agonists. Here, the therapeutic efficacy of short TLR3 and TLR4 pre-conditioning of UCMSCs was evaluated in a dextran sulfate sodium (DSS)-induced colitis in mice. The novelty of this study is that although modulation of human MSCs activity by TLRs is not a new concept, this is the first time that short TLR pre-conditioning has been carried out in a murine inflammatory model of acute colitis.

METHODS

C57BL/6 mice were exposed to 2.5% dextran sulfate sodium (DSS) in drinking water ad libitum for 7 days. At days 1 and 3, mice were injected intraperitoneally with 1 × 10(6) UCMSCs untreated or TLR3 and TLR4 pre-conditioned UCMSCs. UCMSCs were pre-conditioned with poly(I:C) for TLR3 and LPS for TLR4 for 1 h at 37°C and 5% CO2. We evaluated clinical signs of disease and body weights daily. At the end of the experiment, colon length and histological changes were assessed.

RESULTS

poly(I:C) pre-conditioned UCMSCs significantly ameliorated the clinical and histopathological severity of DSS-induced colitis compared with UCMSCs or LPS pre-conditioned UCMSCs. In contrast, infusion of LPS pre-conditioned UCMSCs significantly increased clinical signs of disease, colon shortening and histological disease index in DSS-induced colitis.

CONCLUSIONS

These results show that short in vitro TLR3 pre-conditioning with poly(I:C) enhances the therapeutic efficacy of UCMSCs, which is a major breakthrough for developing improved treatments to patients with inflammatory bowel disease.

Bone marrow mesenchymal stem cells and their conditioned media could potentially ameliorate ovalbumin-induced asthmatic changes

BACKGROUND

The major feature of asthma is governed by chronic airway inflammation. This investigation was proposed to achieve the suitable candidate for ameliorating long-term chronic asthmatic changes of respiratory tract.

METHODS

36 rats were classified into healthy (C) and ovalbumin (OVA)-sensitized animals (S). To sensitize, the rats were exposed to OVA over a course of 32±1days. One day after sensitization, equal six different groups were subjected to experimental procedure (n=6); Rats only received intratracheally 50ml PBS (CPT and SPT groups), 50μl conditioned medium (CM) (CST and SST groups) and 50μl PBS containing 2×10⁶ rat bone marrow-derived mesenchymal stem cells (rBMMSCs) (CCT and SCT groups). Two weeks after treatment, tracheal responsiveness, immunologic responses and recruitment of rBMMSCs into the lung as well as pathological changes were evaluated.

RESULTS

A high degree of tracheal responsiveness, total white blood cell and percentages of eosinophil and neutrophil was significantly recorded in all sensitized groups rather than of controls (p<0.001 to p<0.05). Of interest, all above-mentioned parameters decreased significantly in SST and notably SCT groups as compared to S group (p<0.001 to p<0.05). The results revealed decrease number of blood CD3⁺CD4⁺ and concurrent increase in CD3⁺CD8⁺ in all sensitized rats as compared to control (p<0.001 to p<0.05). Noticeably, no significant modulatory effects of either cell or CM administration were achieved on the CD3⁺CD4⁺ and CD3⁺CD8⁺ populations in non-asthmatic rats. Moreover, the number of CD3⁺CD4⁺ in SST and SCT groups tended to increase, which coincided with a decreased manner of CD3⁺CD8⁺ populations as compared with S group (p<0.001 to p<0.05). However, the CD3⁺CD4⁺ cells in SCT rats were significantly higher than the group SST (p<0.01) whereas CD3⁺CD8⁺ cells diminished simultaneously (p<0.001). Real-time PCR analysis further showed that both CM and particularly MSCs changed the expression of interleukin (IL)-4 and IL-10 in the asthmatic groups to the near level of control rats (p<0.001 to p<0.05). Histopathological analysis revealed a profound reduction of lungs injuries in asthmatic rats when received CM and peculiarly mesenchymal stem cells (p<0.01 to p<0.05).

CONCLUSION

Our study shed light on the superior effects of rBMMSCs, rather than CM, in attenuating of chronic asthmatic changes in the rat model.

Transplantation of gingiva-derived mesenchymal stem cells ameliorates collagen-induced arthritis

Background

Rheumatoid arthritis (RA) is a chronic, progressive, and inflammatory autoimmune disease which primarily affects the small arthrodial joints. The aim of this study was to test whether transplantation of mesenchymal stem cells derived from gingival tissue (GMSCs) could ameliorate collagen-induced arthritis (CIA), and to explore the role of the FasL/Fas pathway in the underlying mechanism.

Methods

DBA/1 mice with collagen II-induced arthritis were treated with GMSCs from the C57BL/6 J mouse, the B6Smn.C3-FasL^gld/J mouse (FasL^–/– GMSCs), and FasL overexpressed FasL^–/– GMSCs (FasL TF GMSCs). Inflammation was evaluated by measuring clinical score, tumor necrosis factor (TNF)-α and anti-collagen II antibody levels, and histological analyses. The levels of CD4⁺ Th cell subsets in spleens and draining lymph nodes were assessed by flow cytometric analysis.

Results

Systemic infusion of GMSCs can significantly reduce the severity of experimental arthritis, and resume the balance of Th cell subsets. FasL^–/– GMSCs failed to induce apoptosis of activated T cells in vitro and in vivo, and therefore show no therapeutic effects, whereas FasL TF GMSCs can rescue the immunosuppressant effects in the treatment of CIA.

Conclusions

GMSC-based therapy induces T-cell apoptosis via the FasL/Fas pathway and results in immune tolerance and amelioration of the CIA inflammation.

Curcumin protects human adipose-derived mesenchymal stem cells against oxidative stress-induced inhibition of osteogenesis

The detrimental effects of oxidative stress on the skeletal system have been documented, and understanding the mechanisms is important to design a therapeutic strategy. As an antioxidant and anti-inflammatory agent, the active ingredient of turmeric curcumin has been used as medication for numerous complications including bone loss. However, it is unclear if curcumin could influence the osteogenic potential of mesenchymal stem cells (MSCs), particularly in oxidative injuries. Here we demonstrate that curcumin treatment protects cell death caused by hydrogen peroxide (H₂O₂) exposure in human adipose-derived MSCs in vitro. Importantly, curcumin is able to enhance the osteoblast differentiation of human adipose-derived MSCs that is inhibited by H₂O₂. Notably, both oxidative stress and the inhibition of Wnt/β-catenin signaling are attenuated by curcumin treatment. These results suggest that curcumin can promote osteoblast differentiation of MSCs and protect the inhibitory effect elicited by oxidative injury. The findings support potential use of curcumin or related antioxidants in MSC-based bone regeneration for disease related with oxidative stress-induced bone loss.

Differential TLR activation of murine mesenchymal stem cells generates distinct immunomodulatory effects in EAE

Background

Recently, it has been observed that mesenchymal stem cells (MSCs) can modulate their immunoregulatory properties depending on the specific in-vitro activation of different Toll-like receptors (TLR), such as TLR3 and TLR4. In the present study, we evaluated the effect of polyinosinic:polycytidylic acid (poly(I:C)) and lipopolysaccharide (LPS) pretreatment on the immunological capacity of MSCs in vitro and in vivo.

Methods

C57BL/6 bone marrow-derived MSCs were pretreated with poly(I:C) and LPS for 1 hour and their immunomodulatory capacity was evaluated. T-cell proliferation and their effect on Th1, Th17, and Treg differentiation/activation were measured. Next, we evaluated the therapeutic effect of MSCs in an experimental autoimmune encephalomyelitis (EAE) model, which was induced for 27 days with MOG_35–55 peptide following the standard protocol. Mice were subjected to a single intraperitoneal injection (2 × 10⁶ MSCs/100 μl) on day 4. Clinical score and body weight were monitored daily by blinded analysis. At day 27, mice were euthanized and draining lymph nodes were extracted for Th1, Th17, and Treg detection by flow cytometry.

Results

Pretreatment of MSCs with poly(I:C) significantly reduced the proliferation of CD3⁺ T cells as well as nitric oxide secretion, an important immunosuppressive factor. Furthermore, MSCs treated with poly(I:C) reduced the differentiation/activation of proinflammatory lymphocytes, Th1 and Th17. In contrast, MSCs pretreated with LPS increased CD3⁺ T-cell proliferation, and induced Th1 and Th17 cells, as well as the levels of proinflammatory cytokine IL-6. Finally, we observed that intraperitoneal administration of MSCs pretreated with poly(I:C) significantly reduced the severity of EAE as well as the percentages of Th1 and Th17 proinflammatory subsets, while the pretreatment of MSCs with LPS completely reversed the therapeutic immunosuppressive effect of MSCs.

Conclusions

Taken together, these data show that pretreatment of MSCs with poly(I:C) improved their immunosuppressive abilities. This may provide an opportunity to better define strategies for cell-based therapies to autoimmune diseases.

Human umbilical cord blood-derived mesenchymal stem cells ameliorate psoriasis-like skin inflammation in mice

Mesenchymal stem cells (MSCs) inhibit the proliferation or activation of lymphocytes, and their inhibitory effects do not require human leukocyte antigen (HLA)-matching because MSCs express low levels of HLA molecules. Therefore, MSCs may be able to regulate immune responses. In this study, we determined whether MSCs could inhibit psoriasis-like skin inflammation in mice. After induction of psoriasis-like skin inflammation using intradermal injection of IL-23 or topical application of imiquimod with or without treatment with MSC, mouse skins were collected, and H&E staining and real-time PCR were performed. IL-23-induced skin inflammation was inhibited when MSCs were injected on day −1 and day 7. The expression of proinflammatory cytokines such as IL-6, IL-17, and TNF-α was inhibited by MSC injection, and the expression of chemokines such as CCL17, CCL20, and CCL27 was also decreased in mouse skin. We also determined whether MSCs could not only prevent but also treat psoriasis-like skin inflammation in mice. Furthermore, in vitro experiments also showed anti-inflammatory effects of MSCs. Dendritic cells which are co-cultured with MSCs suppressed CD4+ T cell activation and differentiation, which are important for the pathogenesis of psoriasis. These results suggest that MSCs could be useful for treating psoriasis.

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Mesenchymal stem cells inhibit psoriasis-like skin inflammation in mice.

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Mesenchymal stem cells modulate dendritic cell function.

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Dendritic cells that co-cultured with mesenchymal stem cells regulate CD4+ T cell differentiation.

Utility of a Mouse Model of Osteoarthritis to Demonstrate Cartilage Protection by IFNγ-Primed Equine Mesenchymal Stem Cells

Objective

Mesenchymal stem cells isolated from adipose tissue (ASC) have been shown to influence the course of osteoarthritis (OA) in different animal models and are promising in veterinary medicine for horses involved in competitive sport. The aim of this study was to characterize equine ASCs (eASCs) and investigate the role of interferon-gamma (IFNγ)-priming on their therapeutic effect in a murine model of OA, which could be relevant to equine OA.

Methods

ASC were isolated from subcutaneous fat. Expression of specific markers was tested by cytometry and RT-qPCR. Differentiation potential was evaluated by histology and RT-qPCR. For functional assays, naïve or IFNγ-primed eASCs were cocultured with peripheral blood mononuclear cells or articular cartilage explants. Finally, the therapeutic effect of eASCs was tested in the model of collagenase-induced OA (CIOA) in mice.

Results

The immunosuppressive function of eASCs on equine T cell proliferation and their chondroprotective effect on equine cartilage explants were demonstrated in vitro. Both cartilage degradation and T cell activation were reduced by naïve and IFNγ-primed eASCs, but IFNγ-priming enhanced these functions. In CIOA, intra-articular injection of eASCs prevented articular cartilage from degradation and IFNγ-primed eASCs were more potent than naïve cells. This effect was related to the modulation of eASC secretome by IFNγ-priming.

Conclusion

IFNγ-priming of eASCs potentiated their antiproliferative and chondroprotective functions. We demonstrated that the immunocompetent mouse model of CIOA was relevant to test the therapeutic efficacy of xenogeneic eASCs for OA and confirmed that IFNγ-primed eASCs may have a therapeutic value for musculoskeletal diseases in veterinary medicine.

Co‑culture of fibroblast‑like synoviocytes with umbilical cord‑mesenchymal stem cells inhibits expression of pro‑inflammatory proteins, induces apoptosis and promotes chondrogenesis

The present study aimed to investigate the effect of co‑culture of fibroblast‑like synoviocytes (FLS) with human umbilical cord‑mesenchymal stem cells (UC‑MSCs) on rheumatoid arthritis (RA) and to understand the mechanisms that mediate the induced changes. FLS and UC‑MSCs were isolated and cultured individually, FLS were then cultured with or without UC‑MSCs. The phenotype of UC‑MSCs was analyzed prior to co‑culture. The UC‑MSCs were successfully isolated and expanded, and exhibited a fibroblast‑like morphology. Enzyme‑linked immunosorbent assay (ELISA) and reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) were performed to determine the expression levels of interleukin (IL)‑1β, IL‑6, and chemokine (C‑C motif) ligand (CCL)‑2. The cell apoptosis rate was determined by flow cytometry. Furthermore, the RNAs of aggrecan and collagen type II were isolated and assessed in a chondrogenesis assay following co‑culture for 7, 14, 21 and 28 days. Protein expression levels of apoptosis‑related proteins, including B‑cell lymphoma (Bcl‑2), Bcl‑2‑associated X protein, p53 and phospho (p)‑AKT, and growth differentiation factor‑5 were analyzed by western blotting. ELISA and qRT‑PCR demonstrated that compared with FLS cultured alone, co‑culture with UC‑MSCs significantly downregulates the expression levels of IL‑1β, IL‑6 and CCL‑2. Additionally, the percentage of apoptotic cells was significantly increased in the co‑cultured cells (P<0.05), and the relative RNAs levels of aggrecan and collagen type II were increased compared with FLS alone. Furthermore, the expression levels of Bcl‑2 (P<0.05) and p‑AKT (P<0.05) were significantly decreased, whereas, p53 (P=0.001), Bax (P<0.01) and GDF‑5 (P<0.01) were increased by co‑culture of FLS with UC‑MSCs compared with FLS alone. In conclusion, co‑culture of FLS with UC‑MSCs may be important and clinically useful for the treatment of RA by inhibiting the expression of pro‑inflammatory mediators, inducing apoptosis and promoting chondrogenesis.

Modulation of Immune Responses by Mesenchymal Stromal Cells

This concise review provides an assessment of one of the most conceptually and practically important properties of mesenchymal stromal cells, their ability to modulate immune responses, including underlying cellular and molecular mechanisms and prospects of clinical application in the treatment of autoimmune and other immunological disorders.

Human mesenchymal stromal cells modulate T-cell immune response via transcriptomic regulation

BACKGROUND AIMS

Mesenchymal stromal cells (MSCs) have been identified as pan-immunosuppressant in various in vitro and in vivo inflammatory models. Although the immunosuppressive activity of MSCs has been explored in various contexts, the precise molecular signaling pathways that govern inhibitory functions remain poorly elucidated.

METHODS

By using a microarray-based global gene expression profiling system, this study aimed to decipher the underlying molecular pathways that may mediate the immunosuppressive activity of umbilical cord-derived MSCs (UC-MSCs) on activated T cells.

RESULTS

In the presence of UC-MSCs, the proliferation of activated T cells was suppressed in a dose-depended manner by cell-to-cell contact mode via an active cell-cycle arrest at the G0/G1 phase of the cell cycle. The microarray analysis revealed that particularly, IFNG, CXCL9, IL2, IL2RA and CCND3 genes were down-regulated, whereas IL11, VSIG4, GFA1, TIMP3 and BBC3 genes were up-regulated by UC-MSCs. The dysregulated gene clusters associated with immune-response-related ontologies, namely, lymphocyte proliferation or activation, apoptosis and cell cycle, were further analyzed.

CONCLUSIONS

Among the nine canonical pathways identified, three pathways (namely T-helper cell differentiation, cyclins and cell cycle regulation, and gap/tight junction signalling pathways) were highly enriched with these dysregulated genes. The pathways represent putative molecular pathways through which UC-MSCs elicit immunosuppressive activity toward activated T cells. This study provides a global snapshot of gene networks and pathways that contribute to the ability of UC-MSCs to suppress activated T cells.

Inactivated Mesenchymal Stem Cells Maintain Immunomodulatory Capacity

Mesenchymal stem cells (MSC) are studied as a cell therapeutic agent for treatment of various immune diseases. However, therapy with living culture-expanded cells comes with safety concerns. Furthermore, development of effective MSC immunotherapy is hampered by lack of knowledge of the mechanisms of action and the therapeutic components of MSC. Such knowledge allows better identification of diseases that are responsive to MSC treatment, optimization of the MSC product, and development of therapy based on functional components of MSC. To close in on the components that carry the therapeutic immunomodulatory activity of MSC, we generated MSC that were unable to respond to inflammatory signals or secrete immunomodulatory factors, but preserved their cellular integrity [heat-inactivated MSC (HI-MSC)]. Secretome-deficient HI-MSC and control MSC showed the same biodistribution and persistence after infusion in mice with ischemic kidney injury. Both control and HI-MSC induced mild inflammatory responses in healthy mice and dramatic increases in interleukin-10, and reductions in interferon gamma levels in sepsis mice. In vitro experiments showed that opposite to control MSC, HI-MSC lacked the capability to suppress T-cell proliferation or induce regulatory B-cell formation. However, both HI-MSC and control MSC modulated monocyte function in response to lipopolysaccharides. The results of this study demonstrate that, in particular disease models, the immunomodulatory effect of MSC does not depend on their secretome or active cross-talk with immune cells, but on recognition of MSC by monocytic cells. These findings provide a new view on MSC-induced immunomodulation and help identify key components of the therapeutic effects of MSC.

Intraperitoneal injection (IP), Intravenous injection (IV) or anal injection (AI)? Best way for mesenchymal stem cells transplantation for colitis

Stem cell transplantation showed promising results in IBD management. However, the therapeutic impacts of cell delivery route that is critical for clinical translation are currently poorly understood. Here, three different MSCs delivery routes: intraperitoneal (IP), intravenous (IV), and anal injection (AI) were compared on DSS-induced colitic mice model. The overall therapeutic factors, MSCs migration and targeting as well as local immunomodulatory cytokines and FoxP3⁺ cells infiltration were analyzed. Colitis showed varying degrees of alleviation after three ways of MSCs transplantation, and the IP injection showed the highest survival rate of 87.5% and displayed the less weight loss and quick weight gain. The fecal occult blood test on the day 3 also showed nearly complete absence of occult blood in IP group. The fluorescence imaging disclosed higher intensity of engrafted cells in inflamed colon and the corresponding mesentery lymph nodes (MLNs) in IP and AI groups than the IV group. Real time-PCR and ELISA also demonstrate lower TNF-α and higher IL-10, TSG-6 levels in IP group. The immunohistochemistry indicated higher repair proliferation (Ki-67) and more FoxP3⁺ cells accumulation of IP group. IP showed better colitis recovery and might be the optimum MSCs delivery route for the treatment of DSS-induced colitis.

Mesenchymal Stem Cell Therapy for rheumatic diseases

Mesenchymal stem cell therapy (MSCT) is an innovative treatment for rheumatic diseases. Underlying mechanism of how MSCT works in rheumatic diseases are still uncertain and with various hypotheses. Animal studies in MSCT show conflicting results mainly attributed by the differences in administration methods of MSCT, types of MSC use and randomization procedures. Human studies of MSCT are so far small scale but with satisfactory results in patients with systemic lupus erythematosus (SLE). Human studies of MSCT, however, showed less rewarding results in patients with rheumatoid arthritis (RA) and systemic sclerosis (SSc). Larger scale studies are needed to confirm the efficiency of MSCT as well as the safety profile in human use.

Mesenchymal Stromal Cells from Osteoarthritic Synovium Are a Distinct Population Compared to Their Bone-Marrow Counterparts regarding Surface Marker Distribution and Immunomodulation of Allogeneic CD4+ T-Cell Cultures

Introduction. The participation of an inflammatory joint milieu has been described in osteoarthritis (OA) pathogenesis. Mesenchymal stromal cells (MSCs) play an important role in modulating inflammatory processes. Based on previous studies in an allogeneic T-cell coculture model, we aimed at further determining the role of synovial MSCs in OA pathogenesis. Methods. Bone-marrow (BM) and synovial membrane (SM) MSCs from hip joints of late stage OA patients and CD4+ T-cells from healthy donors were analysed regarding surface marker expression before and after coculture. Proliferation upon CD3/CD28 stimulation and cytokine analyses were compared between MSCs. Results. SM-MSCs differed from BM-MSCs in several surface markers and their osteogenic differentiation potential. Cocultures of both MSCs with CD4+ T-cells resulted in recruitment of CD45RA+ FoxP3+ regulatory T-cells. Upon stimulation, only SM-MSCs suppressed CD4+ T-cell proliferation, while both SM-MSCs and BM-MSCs modified cytokine profiles through suppressing IL-2 and TNF-α as well as increasing IL-6 secretion. Conclusions. Synovial MSCs from OA joints are a unique fraction that can be distinguished from their bone-marrow derived counterparts. Their unique ability to suppress CD3/CD28 induced CD4+ T-cell proliferation makes them a potential target for future therapeutic approaches.

Local Inhibition of Complement Improves Mesenchymal Stem Cell Viability and Function After Administration

The results of recent clinical trials using mesenchymal stem cells (MSCs) have been unsatisfactory, indicating that current MSC-based therapies need to be improved. We and others have previously demonstrated that MSCs activate complement by unknown mechanisms after infusion, leading to damaged MSCs. In the study reported here, we found that incorporation of N-glycolylneuraminic acid onto MSCs during in vitro culture was a factor in the activation of complement by MSCs. In addition, we developed a way to "paint" heparin onto MSCs. This novel method improved the viability of MSCs and enhanced their function after infusion by directly inhibiting complement and by recruiting factor H, another potent complement inhibitor in serum, onto the surface of the MSCs. These data suggest that cell-surface engineering of MSCs with heparin to locally inhibit complement activation on MSCs might be a straightforward and effective method for improving the outcome of current MSC-based therapies.

Mesenchymal stem cells alleviate experimental rheumatoid arthritis through microRNA-regulated IκB expression

Previous studies have demonstrated that mesenchymal stem cell (MSC) transplantation reduces the severity of collagen-induced arthritis (CIA) in mice, which is a model for rheumatoid arthritis (RA) in humans. However, the underlying molecular mechanisms remain ill-defined. Here, we showed that MSC transplantation reduced the activities of NF-κB signaling and decreased microRNA-548e (miR-548e) levels in the joint tissue in CIA-mice, seemingly through activation of transforming growth factor β receptor signaling. Bioinformatics analyses revealed that miR-548e inhibited protein translation of the NF-κB inhibitor, IκB, through binding to the 3′-UTR of the IκB mRNA. MSCs co-transplanted with adeno-associated virus (AAV) carrying miR-548e abolished the therapeutic effects of MSCs on CIA. On the other hand, transplantation of AAV carrying antisense of miR-548e (as-miR-548e) partially mimicked the effects of MSC transplantation on CIA. Together, these data suggest that MSC transplantation may alleviate experimental RA partially through suppressing miR-548e-mediated IκB inhibition.

MicroRNA-21 Promotes Proliferation of Fibroblast-Like Synoviocytes through Mediation of NF-κB Nuclear Translocation in a Rat Model of Collagen-Induced Rheumatoid Arthritis

MicroRNA-21 (miR-21) is overexpressed in patients with rheumatoid arthritis (RA). This study was designed to investigate the effect and mechanism of miR-21 on cell proliferation in fibroblast-like synoviocytes (FLS) of RA. FLS were primary-cultured from a rat RA model. RA-FLS and normal FLS were infected with lentivirus (anti-miR-21 or pro-miR-21) for overexpression or downregulation of miR-21, respectively. The effects of miR-21 overexpression or inhibition on nucleoprotein NF-κB levels and FLS cell proliferation were evaluated by western blotting and MTT assays. The effects of an inhibitor of NF-κB nuclear translocation (BAY 11-7082) were also evaluated. The results showed that the levels of miR-21 and nucleoprotein NF-κB were increased in FLS of RA model rats compared to the control group. Downregulation of miR-21 in RA FLS led to a significant decrease in nucleoprotein NF-κB levels and cell proliferation rates compared to the antinegative control (NC) group. However, miR-21 overexpression in normal FLS resulted in a significant increase of nucleoprotein NF-κB levels and cell proliferation rates compared to the pro-NC group. The effects of miR-21 overexpression were reversed by BAY 11-7082. We concluded that upregulated miR-21 in FLS in RA model rats may promote cell proliferation by facilitating NF-κB nuclear translocation, thus affecting the NF-κB pathway.

Treatment of Collagen-Induced Arthritis Using Immune Modulatory Properties of Human Mesenchymal Stem Cells

Mesenchymal stem cells (MSCs) have immune modulatory properties. We investigated the potential therapeutic effects of human bone marrow (BM)-, adipose tissue (AD)-, and cord blood (CB)-derived MSCs in an experimental animal model of rheumatoid arthritis (RA) and explored the mechanism underlying immune modulation by MSCs. We evaluated the therapeutic effect of clinically available human BM-, AD-, and CB-derived MSCs in DBA/1 mice with collagen-induced arthritis (CIA). CIA mice were injected intraperitoneally with three types of MSCs. Treatment control animals were injected with 35 mg/kg methotrexate (MTX) twice weekly. Clinical activity in CIA mice, degree of inflammation, cytokine expression in the joint, serum cytokine levels, and regulatory T cells (Tregs) were evaluated. Mice treated with human BM-, AD-, and CB-MSCs showed significant improvement in clinical joint score, comparable to MTX-treated mice. Histologic examination showed greatly reduced joint inflammation and damage in MSC-treated mice compared with untreated mice. Microcomputed tomography also showed little joint damage in the MSC-treated group. MSCs significantly decreased serum interleukin (IL)-1β, tumor necrosis factor (TNF)-α, IL-6, and interferon-γ and increased IL-10 and transforming growth factor-β levels. Tregs were increased in mice treated with MSCs compared to untreated or MTX-treated mice. Human BM-, AD-, and CB-MSCs significantly suppressed joint inflammation in CIA mice. The cells decreased proinflammatory cytokines and upregulated anti-inflammatory cytokines and induced Tregs. Therefore, our study suggests that the use of human BM-, AD-, and CB-MSCs could be an effective therapeutic approach for RA.

Hydrogel is Superior to Fibrin Gel as Matrix of Stem Cells in Alleviating Antigen-Induced Arthritis

Recently, therapy with bone marrow mesenchymal stem cells (BMMSCs) has been attempted to relieve rheumatoid arthritis (RA) and reconstruct cartilage injury. However, treatment has been unsuccessful in complete prevention of persistent cartilage destruction and resulted in inferior outcomes of cartilage regeneration. Scaffolds are an important construct in the field of cartilage tissue engineering, but their role in arthritis treatment has not yet been fully examined. Here, we transplanted two types of scaffold-assisted BMMSCs: fibrin gel- and poly(l-lactide-co-glycolide)-poly(ethylene glycol)-poly(l-lactide-co-glycolide) (PLGA-PEG-PLGA) hydrogel-assisted BMMSCs referred as FGB and HGB groups, respectively, into subchondral defects for the treatment of antigen-induced arthritis. The administration of exogenous BMMSCs ameliorated joint swelling and decreased both joint surface temperature and inflammatory cytokine levels in both groups. Immune cell composition of the inflammation of surrounding synovium, protection of adjacent cartilage, and improved cartilage repair were also observed. Overall, the HGB group had a better therapeutic efficacy than the FGB group. In conclusion, local transplantation of BMMSCs in subchondral defects presents a novel approach in inducing RA remission and recovery of RA-induced cartilage injury. To induce these changes, the selection of scaffold for cell support is exceedingly important. Further studies are needed regarding the treatment options of subchondral defects in arthritis based on modified scaffold development, application of defined MSCs sources, combination of pharmacotherapeutics, and the addition of factors that inhibit the processes of RA remission, promote the recovery of RA-induced cartilage injury and the relationship between these factors.