Mesenchymal stem cell transplantation reverses multiorgan dysfunction in systemic lupus erythematosus mice and humans

Mesenchymal Stem Cell-Based Therapy for Kidney Disease: A Review of Clinical Evidence

Mesenchymal stem cells form a population of self-renewing, multipotent cells that can be isolated from several tissues. Multiple preclinical studies have demonstrated that the administration of exogenous MSC could prevent renal injury and could promote renal recovery through a series of complex mechanisms, in particular via immunomodulation of the immune system and release of paracrine factors and microvesicles. Due to their therapeutic potentials, MSC are being evaluated as a possible player in treatment of human kidney disease, and an increasing number of clinical trials to assess the safety, feasibility, and efficacy of MSC-based therapy in various kidney diseases have been proposed. In the present review, we will summarize the current knowledge on MSC infusion to treat acute kidney injury, chronic kidney disease, diabetic nephropathy, focal segmental glomerulosclerosis, systemic lupus erythematosus, and kidney transplantation. The data obtained from these clinical trials will provide further insight into safety, feasibility, and efficacy of MSC-based therapy in renal pathologies and allow the design of consensus protocol for clinical purpose.

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.

Allogeneic Mesenchymal Stem Cell Treatment Induces Specific Alloantibodies in Horses

Background. It is unknown whether horses that receive allogeneic mesenchymal stem cells (MSCs) injections develop specific humoral immune response. Our goal was to develop and validate a flow cytometric MSC crossmatch procedure and to determine if horses that received allogeneic MSCs in a clinical setting developed measurable antibodies following MSC administration. Methods. Serum was collected from a total of 19 horses enrolled in 3 different research projects. Horses in the 3 studies all received unmatched allogeneic MSCs. Bone marrow (BM) or adipose tissue derived MSCs (ad-MSCs) were administered via intravenous, intra-arterial, intratendon, or intraocular routes. Anti-MSCs and anti-bovine serum albumin antibodies were detected via flow cytometry and ELISA, respectively. Results. Overall, anti-MSC antibodies were detected in 37% of the horses. The majority of horses (89%) were positive for anti-bovine serum albumin (BSA) antibodies prior to and after MSC injection. Finally, there was no correlation between the amount of anti-BSA antibody and the development of anti-MSC antibodies. Conclusion. Anti allo-MSC antibody development was common; however, the significance of these antibodies is unknown. There was no correlation between either the presence or absence of antibodies and the percent antibody binding to MSCs and any adverse reaction to a MSC injection.

Long noncoding RNA related to periodontitis interacts with miR-182 to upregulate osteogenic differentiation in periodontal mesenchymal stem cells of periodontitis patients

Periodontitis impairs the osteogenic differentiation of human periodontal mesenchymal stem cells (hPDLSCs), but the underlying molecular mechanisms are still poorly understood. Long noncoding RNAs (lncRNAs) have been demonstrated to have significant roles under both physiologic and pathological conditions. In this study, we performed comprehensive lncRNA profiling by lncRNA microarray analysis and identified a novel lncRNA, osteogenesis impairment-related lncRNA of PDLSCs from periodontitis patients (lncRNA-POIR), the expression of which was significantly decreased in PDLSCs from periodontitis patients (pPDLSCs) and was upregulated by osteogenic induction. To study the functions of lncRNA-POIR, we prepared cells with overexpression and knockdown of lncRNA-POIR and found that lncRNA-POIR positively regulated osteogenic differentiation of hPDLSCs and pPDLSCs both in vitro and in vivo. Using quantitative real-time PCRs (qPCRs) and luciferase reporter assays, we demonstrated that lncRNA-POIR may act as a competing endogenous RNA (ceRNA) for miR-182, leading to derepression of its target gene, FoxO1. In this process, lncRNA-POIR and miR-182 suppress each other and form a network to regulate FoxO1. FoxO1 increased bone formation of pPDLSCs by competing with TCF-4 for β-catenin and inhibiting the canonical Wnt pathway. Finally, inflammation increases miR-182 expression through the nuclear factor-κB pathway, and the miR-182 overexpression in the inflammatory microenvironment resulted in an imbalance in the lncRNA-POIR-miR-182 regulatory network. In conclusion, our results provide novel evidence that this lncRNA-miRNA (microRNA) regulatory network has a significant role in osteogenic differentiation of pPDLSCs and that it has potential as a therapeutic target in mesenchymal stem cells during inflammation.

Transplantation of Human Placenta-Derived Mesenchymal Stem Cells Alleviates Critical Limb Ischemia in Diabetic Nude Rats

Neovasculogenesis induced by stem cell therapy is an innovative approach to improve critical limb ischemia (CLI) in diabetes. Mesenchymal stem cells (MSCs) are ideal candidates due to their angiogenic and immunomodulatory features. The aim of this study is to determine the therapeutic effects of human placenta-derived MSCs (P-MSCs) on diabetic CLI, with or without exogenous insulin administration, and the underlying mechanism of any effect. A series of in vitro experiments were performed to assess the stemness and vasculogenic activity of P-MSCs. P-MSCs were intramuscularly injected at two different doses with and without the administration of insulin. The efficacy of P-MSC transplantation was evaluated by ischemia damage score, ambulatory score, laser Doppler perfusion image (LDPI), capillary, and vascular density. In vivo imaging was applied to track the implanted P-MSCs. In vivo differentiation and in situ secretion of angiogenic cytokines were determined. In vitro experimental outcomes showed the differentiation potential and potent paracrine effect of P-MSCs. P-MSCs survived in vivo for at least 3 weeks and led to the acceleration of ischemia recovery, due to newly formed capillaries, increased arterioles, and secretion of various proangiogenic factors. P-MSCs participate in angiogenesis and vascularization directly through differentiation and cytokine expression.

Pluripotent Nontumorigenic Adipose Tissue-Derived Muse Cells have Immunomodulatory Capacity Mediated by Transforming Growth Factor-β1

Adult mesenchymal stromal cell‐based interventions have shown promising results in a broad range of diseases. However, their use has faced limited effectiveness owing to the low survival rates and susceptibility to environmental stress on transplantation. We describe the cellular and molecular characteristics of multilineage‐differentiating stress‐enduring (Muse) cells derived from adipose tissue (AT), a subpopulation of pluripotent stem cells isolated from human lipoaspirates. Muse‐AT cells were efficiently obtained using a simple, fast, and affordable procedure, avoiding cell sorting and genetic manipulation methods. Muse‐AT cells isolated under severe cellular stress, expressed pluripotency stem cell markers and spontaneously differentiated into the three germ lineages. Muse‐AT cells grown as spheroids have a limited proliferation rate, a diameter of ∼15 µm, and ultrastructural organization similar to that of embryonic stem cells. Muse‐AT cells evidenced high stage‐specific embryonic antigen‐3 (SSEA‐3) expression (∼60% of cells) after 7–10 days growing in suspension and did not form teratomas when injected into immunodeficient mice. SSEA‐3⁺‐Muse‐AT cells expressed CD105, CD29, CD73, human leukocyte antigen (HLA) class I, CD44, and CD90 and low levels of HLA class II, CD45, and CD34. Using lipopolysaccharide‐stimulated macrophages and antigen‐challenged T‐cell assays, we have shown that Muse‐AT cells have anti‐inflammatory activities downregulating the secretion of proinflammatory cytokines, such as interferon‐γ and tumor necrosis factor‐α. Muse‐AT cells spontaneously gained transforming growth factor‐β1 expression that, in a phosphorylated SMAD2‐dependent manner, might prove pivotal in their observed immunoregulatory activity through decreased expression of T‐box transcription factor in T cells. Collectively, the present study has demonstrated the feasibility and efficiency of obtaining Muse‐AT cells that can potentially be harnessed as immunoregulators to treat immune‐related disorders. Stem Cells Translational Medicine2017;6:161–173

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.

Human embryonic mesenchymal stem cells alleviate pathologic changes of MRL/Lpr mice by regulating Th7 cell differentiation

Recent evidence indicates that mesenchymal stem cells (MSC) derived from early embryonic tissues have better therapeutic ability as compared with adult tissue-derived stem cells. In the present study, we transplanted human early embryonic MSC (hMSC) into MRL/Lpr mice via tail vein injection to observe the therapeutic efficacy of hMSC and their impact on T helper 17 (Th17) cell differentiation in MRL/Lpr mice. Animals in hMSC treatment group received hMSC (1 × 10⁶/200 μL) via the tail vein at the age of 16 and 19 weeks. We found that hMSC treatment prolonged the survival of MRL/Lpr mice without inducing tumorigenesis, reduced urine protein, and alleviated the renal pathologic changes. In addition, it reduced the proportion of Th17 cells in the spleen of MRL/Lpr mice and the serum interleukin 17 (IL-17) concentration. Our in vitro experiment also demonstrated that hMSC could secrete Th17 differentiation-related cytokines of PGE2, IL-10 and TGF-β, and IFN-γ stimulation up-regulated the secretion of these immune regulating factors. The results of the present study suggest that hMSC therapy could alleviate systemic and local renal lesions in MRL/Lpr mice, probably by secreting immune regulating factors and regulating Th17 cell differentiation in MRL/Lpr mice.

Long-term safety of umbilical cord mesenchymal stem cells transplantation for systemic lupus erythematosus: a 6-year follow-up study

The aim of this study is to assess the long-term safety of allogeneic umbilical cord mesenchymal stem cells (UC MSCs) transplantation for patients with refractory systemic lupus erythematosus (SLE). Nine SLE patients, who were refractory to steroid and immunosuppressive drugs treatment and underwent MSCs transplantation in 2009, were enrolled. One million allogeneic UC MSCs per kilogram of body weight were infused intravenously at days 0 and 7. The possible adverse events, including immediately after MSCs infusions, as well as the long-term safety profiles were observed. Blood and urine routine test, liver function, electrocardiogram, chest radiography and serum levels of tumor markers, including alpha fetal protein (AFP), cancer embryo antigen (CEA), carbohydrate antigen 155 (CA155) and CA199, were assayed before and 1, 2, 4 and 6 years after MSCs transplantation. All the patients completed two times of MSCs infusions. One patient had mild dizzy and warm sensation 5 min after MSCs infusion, and the symptoms disappeared quickly. No other adverse event, including fluster, headache, nausea or vomit, was observed. There was no change in peripheral white blood cell count, red blood cell count and platelet number in these patients after followed up for 6 years. Liver functional analysis showed that serum alanine aminotransferase, glutamic-oxalacetic transaminase, total bilirubin and direct bilirubin remained in normal range after MSCs infusions. No newly onset abnormality was detected on electrocardiogram and chest radiography. Moreover, we found no rise of serum tumor markers, including AFP, CEA, CA125 and CA199, before and 6 years after MSCs infusions. Our long-term observational study demonstrated a good safety profile of allogeneic UC MSCs in SLE patients.

Mesenchymal stem cells for treating autoimmune diseases: The Chinese experience from lab to clinics

Autoimmune diseases are a group of chronic inflammatory conditions diseases characterized by aberrant activation of the immune system involving either cells or antibodies directed against normal tissues. The current conventional strategies, notably corticosteroids and immunosuppressors, are responsible for high treatment-related morbidity and are still associated with significant disease and treatment-related mortality. Recently, experimental and clinical data has suggested that mesenchymal stem cell transplantation would be a promising therapy strategy for the treatment of autoimmune diseases. This article will review the rationale and Chinese experience of mesenchymal stem cell transplantation in treatment of autoimmune diseases.

Therapeutic effects and mechanism of conditioned media from human mesenchymal stem cells on anti-GBM glomerulonephritis in WKY rats

Recent studies have demonstrated that conditioned media derived from mesenchymal stem cells (MSC-CM) have therapeutic effects in various experimental diseases. However, the therapeutic mechanism is not fully understood. In the present study, we investigated the therapeutic effects and mechanism of MSC-CM in experimental antiglomerular basement membrane glomerulonephritis. We administered either MSC-CM or vehicle from day 0 to day 10 after the induction of nephrotoxic serum nephritis in Wistar-Kyoto rats. In vitro, we analyzed the effects of MSC-CM on TNF-α-mediated cytokine production in cultured normal human mesangial cells, proximal tubular (HK-2) cells, human umbilical vein endothelial cells, and monocytes (THP-1 and peripheral blood mononuclear cells). Compared with vehicle treatment, MSC-CM treatment improved proteinuria and renal dysfunction. Histologically, MSC-CM-treated rats had reduced crescent formation and glomerular ED1+ macrophage infiltration and increased glomerular ED2+ macrophage infiltration. Increased serum monocyte chemoattractant protein (MCP)-1 levels were observed in MSC-CM-treated rats. Renal cortical mRNA expression levels of proinflammatory cytokines, such as TNF-α and IL-6, and of the T helper cell 1 cytokine interferon-γ were greatly decreased by MSC-CM treatment. In vitro, pretreatment with MSC-CM blocked TNF-α-mediated IL-8 release in normal human mesangial cells and HK-2 cells. TNF-α-mediated MCP-1 release was enhanced by pretreatment with MSC-CM in human umbilical vein endothelial cells and HK-2 cells and was strikingly enhanced in THP-1 cells. Stimulation of peripheral blood mononuclear cells with a combination of MCP-1 and IL-4 enhanced the expression of M2-associated genes compared with IL-4 alone. We demonstrated that MSC-CM had therapeutic effects in experimental antiglomerular basement membrane glomerulonephritis that were mediated through anti-inflammatory effects that were partly due to acceleration of M2 macrophage polarization, which might be mediated by MCP-1 enhancement.

Chronic High Dose Alcohol Induces Osteopenia via Activation of mTOR Signaling in Bone Marrow Mesenchymal Stem Cells

Chronic consumption of excessive alcohol results in reduced bone mass, impaired bone structure, and increased risk of bone fracture. However, the mechanisms underlying alcohol-induced osteoporosis are not fully understood. Here, we show that high dose chronic alcohol consumption reduces osteogenic differentiation and enhances adipogenic differentiation of bone marrow mesenchymal stem cells (BMMSCs), leading to osteopenia in a mouse model. Mechanistically, impaired osteo/adipogenic lineage differentiation of BMMSCs is due to activation of a phosphatidylinositide 3-kinase/AKT/mammalian target of rapamycin (mTOR) signaling cascade, resulting in downregulation of runt-related transcription factor 2 and upregulation of peroxisome proliferator-activated receptor gamma via activation of p70 ribosomal protein S6 kinase. Blockage of the mTOR pathway by rapamycin treatment ameliorates alcohol-induced osteopenia by rescuing impaired osteo/adipogenic lineage differentiation of BMMSCs. In this study, we identify a previously unknown mechanism by which alcohol impairs BMMSC lineage differentiation and reveal a potential rapamycin-based drug therapy for alcohol-induced osteoporosis. Stem Cells 2016;34:2157-2168.

Interaction between Mesenchymal Stem Cells and B-Cells

Mesenchymal stem cells (MSCs) are multipotent; non-hematopoietic stem cells. Because of their immunoregulatory abilities; MSCs are widely used for different clinical applications. Compared with that of other immune cells; the investigation of how MSCs specifically regulate B-cells has been superficial and insufficient. In addition; the few experimental studies on this regulation are often contradictory. In this review; we summarize the various interactions between different types or states of MSCs and B-cells; address how different types of MSCs and B-cells affect this interaction and examine how other immune cells influence the regulation of B-cells by MSCs. Finally; we hypothesize why there are conflicting results on the interaction between MSCs and B-cells in the literature.

Autoantigen-specific immunosuppression with tolerogenic peripheral blood cells prevents relapses in a mouse model of relapsing-remitting multiple sclerosis

BACKGROUND

Dendritic cells (DCs) rendered suppressive by treatment with mitomycin C and loaded with the autoantigen myelin basic protein demonstrated earlier their ability to prevent experimental autoimmune encephalomyelitis (EAE), the animal model for multiple sclerosis (MS). This provides an approach for prophylactic vaccination against autoimmune diseases. For clinical application such DCs are difficult to generate and autoantigens hold the risk of exacerbating the disease.

METHODS

We replaced DCs by peripheral mononuclear cells and myelin autoantigens by glatiramer acetate (Copaxone(®)), a drug approved for the treatment of MS. Spleen cells were loaded with Copaxone(®), incubated with mitomycin C (MICCop) and injected into mice after the first bout of relapsing-remitting EAE. Immunosuppression mediated by MICCop was investigated in vivo by daily assessment of clinical signs of paralysis and in in vitro restimulation assays of peripheral immune cells. Cytokine profiling was performed by enzyme-linked immunosorbent assay (ELISA). Migration of MICCop cells after injection was examined by biodistribution analysis of (111)Indium-labelled MICCop. The number and inhibitory activity of CD4(+)CD25(+)FoxP3(+) regulatory T cells were analysed by histology, flow cytometry and in vitro mixed lymphocyte cultures. In order to assess the specificity of MICCop-induced suppression, treated EAE mice were challenged with the control protein ovalbumin. Humoral and cellular immune responses were then determined by ELISA and in vitro antigen restimulation assay.

RESULTS

MICCop cells were able to inhibit the harmful autoreactive T-cell response and prevented mice from further relapses without affecting general immune responses. Administered MICCop migrated to various organs leading to an increased infiltration of the spleen and the central nervous system with CD4(+)CD25(+)FoxP3(+) cells displaying a suppressive cytokine profile and inhibiting T-cell responses.

CONCLUSION

We describe a clinically applicable cell therapeutic approach for controlling relapses in autoimmune encephalomyelitis by specifically silencing the deleterious autoimmune response.

Attenuation of Postischemic Genomic Alteration by Mesenchymal Stem Cells: a Microarray Study

Intravenous administration of mesenchymal stem cells (IV-MSC) protects the ischemic rat brain in a stroke model, but the molecular mechanism underlying its therapeutic effect is unclear. We compared genomic profiles using the mRNA microarray technique in a rodent stroke model. Rats were treated with 1 × 10(6) IV-MSC or saline (sham group) 2 h after transient middle cerebral artery occlusion (MCAo). mRNA microarray was conducted 72 h after MCAo using brain tissue from normal rats (normal group) and the sham and MSC groups. Predicted pathway analysis was performed in differentially expressed genes (DEGs), and functional tests and immunohistochemistry for inflammation-related proteins were performed. We identified 857 DEGs between the sham and normal groups, with the majority of them (88.7%) upregulated in sham group. Predicted pathway analysis revealed that cerebral ischemia activated 10 signaling pathways mainly related to inflammation and cell cycle. IV-MSC attenuated the numbers of dysregulated genes in cerebral ischemia (118 DEGs between the MSC and normal groups). In addition, a total of 218 transcripts were differentially expressed between the MSC and sham groups, and most of them (175/218 DEGs, 80.2%) were downregulated in the MSC group. IV-MSC reduced the number of Iba-1(+) cells in the peri-infarct area, reduced the overall infarct size, and improved functional deficits in MCAo rats. In conclusion, transcriptome analysis revealed that IV-MSC attenuated postischemic genomic alterations in the ischemic brain. Amelioration of dysregulated inflammation- and cell cycle-related gene expression in the host brain is one of the molecular mechanisms of IV-MSC therapy for cerebral ischemia.

The Impact of Epigenetics on Mesenchymal Stem Cell Biology

Changes in epigenetic marks are known to be important regulatory factors in stem cell fate determination and differentiation. In the past years, the investigation of the epigenetic regulation of stem cell biology has largely focused on embryonic stem cells (ESCs). Contrarily, less is known about the epigenetic control of gene expression during differentiation of adult stem cells (AdSCs). Among AdSCs, mesenchymal stem cells (MSCs) are the most investigated stem cell population because of their enormous potential for therapeutic applications in regenerative medicine and tissue engineering. In this review, we analyze the main studies addressing the epigenetic changes in MSC landscape during in vitro cultivation and replicative senescence, as well as follow osteocyte, chondrocyte, and adipocyte differentiation. In these studies, histone acetylation, DNA methylation, and miRNA expression are among the most investigated phenomena. We describe also epigenetic changes that are associated with in vitro MSC trans-differentiation. Although at the at initial stage, the epigenetics of MSCs promise to have profound implications for stem cell basic and applied research. J. Cell. Physiol. 231: 2393-2401, 2016. © 2016 Wiley Periodicals, Inc.

Human embryonic stem cell-derived mesenchymal stromal cells ameliorate collagen-induced arthritis by inducing host-derived indoleamine 2,3 dioxygenase

Background

The immunosuppressive and anti-inflammatory properties of mesenchymal stromal cells (MSC) have prompted their therapeutic application in several autoimmune diseases, including rheumatoid arthritis. Adult MSC are finite and their clinical use is restricted by the need for long-term expansion protocols that can lead to genomic instability. Inhibition of Smad2/3 signaling in human pluripotent stem cells (hPSC) provides an infinite source of MSC that match the phenotype and functional properties of adult MSC. Here, we test the therapeutic potential of hPSC-MSC of embryonic origin (embryonic stem cell-derived mesenchymal stromal cells, hESC-MSC) in the experimental model of collagen-induced arthritis (CIA).

Methods

CIA was induced in DBA/1 mice by immunization with type II collagen (CII) in Complete Freund’s Adjuvant (CFA). Mice were treated with either a single dose (10⁶ cells/mouse) of hESC-MSC on the day of immunization (prophylaxis) or with three doses of hESC-MSC every other day starting on the day of arthritis onset (therapy). Arthritis severity was evaluated daily for six weeks and ten days, respectively. Frequency of Treg (FoxP3⁺), Th1 (IFNγ⁺) and Th17 (IL17⁺) CD4⁺ T cells in inguinal lymph nodes (ILN) was quantified by flow cytometry. Serum levels of anti-CII antibodies were determined by ELISA. Detection of hESC-MSC and quantification of murine and human indoleamine 2,3 dioxygenase (IDO1) expression was performed by quantitative real-time PCR. Statistical differences were analyzed by ANOVA and the Mann-Whitney U test.

Results

Administration of hESC-MSC to mice with established arthritis reduced disease severity compared to control-treated mice. Analysis of CD4 T cell populations in treated mice showed an increase in FoxP3⁺ Treg and IFNγ⁺ Th1 cells but not in Th17 cells in the ILN. Anti-CII antibody levels were not affected by treatment. Migration of hESC-MSC to the ILN in treated mice was associated with the induction of murine IDO1.

Conclusion

Treatment with hESC-MSC ameliorates CIA by inducing IFNγ⁺ Th1 cells and IDO1 in the host. Thus, hESC-MSC can provide an infinite cellular source for treatment of rheumatoid arthritis.

In Vivo Interleukin-13-Primed Macrophages Contribute to Reduced Alloantigen-Specific T Cell Activation and Prolong Immunological Survival of Allogeneic Mesenchymal Stem Cell Implants

Transplantation of mesenchymal stem cells (MSCs) into injured or diseased tissue-for the in situ delivery of a wide variety of MSC-secreted therapeutic proteins-is an emerging approach for the modulation of the clinical course of several diseases and traumata. From an emergency point-of-view, allogeneic MSCs have numerous advantages over patient-specific autologous MSCs since "off-the-shelf" cell preparations could be readily available for instant therapeutic intervention following acute injury. Although we confirmed the in vitro immunomodulatory capacity of allogeneic MSCs on antigen-presenting cells with standard coculture experiments, allogeneic MSC grafts were irrevocably rejected by the host's immune system upon either intramuscular or intracerebral transplantation. In an attempt to modulate MSC allograft rejection in vivo, we transduced MSCs with an interleukin-13 (IL13)-expressing lentiviral vector. Our data clearly indicate that prolonged survival of IL13-expressing allogeneic MSC grafts in muscle tissue coincided with the induction of an alternatively activated macrophage phenotype in vivo and a reduced number of alloantigen-reactive IFNγ- and/or IL2-producing CD8(+) T cells compared to nonmodified allografts. Similarly, intracerebral IL13-expressing MSC allografts also exhibited prolonged survival and induction of an alternatively activated macrophage phenotype, although a peripheral T cell component was absent. In summary, this study demonstrates that both innate and adaptive immune responses are effectively modulated in vivo by locally secreted IL13, ultimately resulting in prolonged MSC allograft survival in both muscle and brain tissue. Stem Cells 2016;34:1971-1984.

The murine Pbx1-d lupus susceptibility allele accelerates mesenchymal stem cell differentiation and impairs their immunosuppressive function

Pre–B cell leukemia homeobox 1 (Pbx1)-d is a dominant-negative splice isoform of the gene Pbx1 that corresponds to the NZM2410 lupus susceptibility locus Sle1a1. Pbx1 is required to maintain stem cell self-renewal, including that of mesenchymal stem cells (MSCs). MSCs have immunosuppressive functions that require stem cell maintenance. We tested the hypothesis that the expression of Pbx1-d favors MSC differentiation and impairs their immunosuppressive functions. We demonstrate that Sle1a1 MSCs express high levels of Pbx1-d as compared with congenic C57BL/6J (B6) MSCs. Sle1a1 MSCs grew faster and differentiated significantly more rapidly into osteoblasts than did B6 MSCs. This corresponded to a significant decrease in the expression of genes associated with stemness and an increase in the expression of genes associated with differentiation. Additionally, Sle1a1 MSCs express a gene expression profile associated with an enhanced innate immunity and inflammation. Suppression of Ig production from TLR-activated B6 B cells and IL-2 secretion from activated B6 CD4+ T cells was significantly impaired in Sle1a1 MSCs as compared with B6 MSCs. B6.Sle1a1 MSCs showed intermediate activity in suppressing lupus immunophenotypes in three different mouse models. Taken together, these data suggest that the expression of the lupus susceptibility allele Pbx1-d isoform impairs MSC functions, which may contribute to lupus pathogenesis both through a defective immunosuppression and the promotion of a proinflammatory environment.

Mesenchymal stem cells and immunomodulation: current status and future prospects

The unique immunomodulatory properties of mesenchymal stem cells (MSCs) make them an invaluable cell type for the repair of tissue/ organ damage caused by chronic inflammation or autoimmune disorders. Although they hold great promise in the treatment of immune disorders such as graft versus host disease (GvHD) and allergic disorders, there remain many challenges to overcome before their widespread clinical application. An understanding of the biological properties of MSCs will clarify the mechanisms of MSC-based transplantation for immunomodulation. In this review, we summarize the preclinical and clinical studies of MSCs from different adult tissues, discuss the current hurdles to their use and propose the future development of pluripotent stem cell-derived MSCs as an approach to immunomodulation therapy.

Human embryonic stem cell-derived mesenchymal cells preserve kidney function and extend lifespan in NZB/W F1 mouse model of lupus nephritis

Adult tissue-derived mesenchymal stromal cells (MSCs) are showing promise in clinical trials for systemic lupus erythematosus (SLE). However, the inability to manufacture large quantities of functional cells from a single donor as well as donor-dependent variability in quality limits their clinical utility. Human embryonic stem cell (hESC)-derived MSCs are an alternative to adult MSCs that can circumvent issues regarding scalability and consistent quality due to their derivation from a renewable starting material. Here, we show that hESC-MSCs prevent the progression of fatal lupus nephritis (LN) in NZB/W F1 (BWF1) mice. Treatment led to statistically significant reductions in proteinuria and serum creatinine and preserved renal architecture. Specifically, hESC-MSC treatment prevented disease-associated interstitial inflammation, protein cast deposition, and infiltration of CD3⁺ lymphocytes in the kidneys. This therapy also led to significant reductions in serum levels of tumor necrosis factor alpha (TNFα) and interleukin 6 (IL-6), two inflammatory cytokines associated with SLE. Mechanistically, in vitro data support these findings, as co-culture of hESC-MSCs with lipopolysaccharide (LPS)-stimulated BWF1 lymphocytes decreased lymphocyte secretion of TNFα and IL-6, and enhanced the percentage of putative regulatory T cells. This study represents an important step in the development of a commercially scalable and efficacious cell therapy for SLE/LN.

Comparing the Immunomodulatory Properties of Bone Marrow, Adipose Tissue, and Birth-Associated Tissue Mesenchymal Stromal Cells

Mesenchymal stromal cells (MSC) have gained immense attraction in regenerative medicine, tissue engineering, and immunotherapy. This is based on their differentiation potential and the supply of pro-regenerative and immunomodulatory signals. MSC can be isolated from a multitude of tissue sources, but mainly bone marrow, adipose tissue, and birth-associated tissues (e.g., umbilical cord, cord blood, placenta) appear to be relevant for clinical translation in immune-mediated disorders. However, only a few studies directly compared the immunomodulatory potency of MSC from different tissue sources. This review compiles the current literature regarding the similarities and differences between these three sources for MSCs with a special focus on their immunomodulatory effects on T-lymphocyte subsets and monocytes, macrophages, and dendritic cells.

Update on mesenchymal stem cell-based therapy in lupus and scleroderma

Current systemic therapies are rarely curative for patients with severe life-threatening forms of autoimmune diseases (ADs). During the past 15 years, autologous hematopoietic stem cell transplantation has been demonstrated to cure some patients with severe AD refractory to all other available therapies. As a consequence, ADs such as lupus and scleroderma have become an emerging indication for cell therapy. Multipotent mesenchymal stem cells (MSCs), isolated from bone marrow and other sites, display specific immunomodulation and anti-inflammatory properties and appear as ideal tools to treat such diseases. The present update aims at summarizing recent knowledge acquired in the field of MSC-based therapies for lupus and scleroderma.

Immunosuppression of breast cancer cells mediated by transforming growth factor-β in exosomes from cancer cells

Exosomes derived from tumor cells are essential for processes involved in tumor progression, including angiogenesis, tumor cell proliferation and immunoregulation. In addition, exosome secretion may contribute to the mechanisms of hypoxia-induced angiogenesis and metastasis of tumors. In the present study, as it is one of the most common cancers in females, breast cancer, cell lines were cultured under hypoxic (1% O₂) and normoxic conditions to evaluate the effects of hypoxia on exosome production. Under hypoxic conditions an increase in the number of exosomes in the medium, determined by CD63 immunoblotting, was observed. Application of these exosomes to T cells revealed that they were able to suppress T cell proliferation. As transforming growth factor-β (TGF-β), interleukin-10, and prostaglandin E2 are important factors in the mediation of T cell suppression, the exosomes were subsequently treated with antibodies against these three factors. The results revealed that anti-TGF-β was capable of ameliorating the immunosuppressive effects of exosomes. These data demonstrate that hypoxia enhances the secretion of exosomes by breast cancer cells, which acts to suppress T cell proliferation via TGF-β. The findings have significant implications for understanding the underlying mechanisms of immunosuppression in tumor microenvironments, and for the potential development of cancer therapies.

Effects of simvastatin on the osteogenic differentiation and immunomodulation of bone marrow mesenchymal stem cells

The present study aimed to investigate the effects of simvastatin on the bone differentiation capacity and immunological characteristics of bone marrow mesenchymal stem cells (BMSCs). BMSCs were isolated and cultured in medium containing 1.0 µmol/ml simvastatin. The alkaline phosphatase activity, mRNA expression levels of osteocalcin and bone sialoprotein, and calcium nodule formation were assessed to determine the osteogenic differentiation capability of BMSCs. To investigate alterations in the immunological properties of simvastation‑treated BMSCs, the immunogenicity of these cells and the effect of BMSCs on phytohemagglutinin‑stimulated lymphocyte proliferation were also assessed. Following treatment with simvastatin, the alkaline phosphatase activity, and mRNA expression levels of osteocalcin and bone sialoprotein were increased significantly in the BMSCs. In addition, von Kossa staining revealed a brown calcium‑positive reaction zone in simvastatin‑treated cells. Simvastatin‑induced BMSCs revealed no affect on the proliferation of allogeneic lymphocytes, however, inhibited phytohemagglutinin‑induced lymphocyte proliferation. Collectively, simvastatin promoted the osteogenic differentiation of BMSCs significantly without affecting their immunosuppressive properties.

MSC Transplantation Improves Osteopenia via Epigenetic Regulation of Notch Signaling in Lupus

Mesenchymal stem cell transplantation (MSCT) has been used to treat human diseases, but the detailed mechanisms underlying its success are not fully understood. Here we show that MSCT rescues bone marrow MSC (BMMSC) function and ameliorates osteopenia in Fas-deficient-MRL/lpr mice. Mechanistically, we show that Fas deficiency causes failure of miR-29b release, thereby elevating intracellular miR-29b levels, and downregulates DNA methyltransferase 1 (Dnmt1) expression in MRL/lpr BMMSCs. This results in hypomethylation of the Notch1 promoter and activation of Notch signaling, in turn leading to impaired osteogenic differentiation. Furthermore, we show that exosomes, secreted due to MSCT, transfer Fas to recipient MRL/lpr BMMSCs to reduce intracellular levels of miR-29b, which results in recovery of Dnmt1-mediated Notch1 promoter hypomethylation and thereby improves MRL/lpr BMMSC function. Collectively our findings unravel the means by which MSCT rescues MRL/lpr BMMSC function through reuse of donor exosome-provided Fas to regulate the miR-29b/Dnmt1/Notch epigenetic cascade.

Human umbilical cord mesenchymal stem cells improve the immune-associated inflammatory and prothrombotic state in collagen type-Ⅱ-induced arthritic rats

Human umbilical cord mesenchymal stem cells (hUC‑MSCs) hold great potential in the search for therapies to treat refractory diseases, including rheumatoid arthritis (RA), due to their potential regenerative ability and extensive source. However, the role of hUC‑MSCs in vivo and the repair mechanisms for RA remain to be fully elucidated. The present study aimed to determine whether hUC‑MSCs exert immunomodulatory effects and have anti‑inflammatory capabilities in the treatment of embolisms. Following the transplantation of hUC‑MSCs into collagen type Ⅱ‑induced arthritic (CIA) model rats, magnetic resonance imaging (MRI) in vivo was performed, and the levels of interleukin (IL)‑1, IL‑17, tumor necrosis factor (TNF)‑α, vascular endothelial growth factor (VEGF), tissue factor (TF), CD4+CD25+ T cells (Treg) and antithrombin (AT) were measured. Bromodeoxyuridine staining was performed for histopathological examinations. As revealed by immunofluorescence and MRI experiments, the injected hUC‑MSCs preferentially migrated to the inflammatory joint sites of the rats. The Treg cell percentage and AT levels in the hUC‑MSC‑treated group were markedly increased, whereas the levels of IL‑1, IL‑17, TNF‑α, VEGF and TF were decreased compared with those in the CIA model group. The values determined for these parameters in the hUC‑MSC‑treated group returned to approximately the identical values as those of the control group on day 35 post‑therapy. Superparamagnetic iron oxide nanoparticles (SPIONs) may serve as an effective, non‑invasive method for tracking transplanted cells in vivo. The present study provided direct evidence that hUC‑MSCs in the CIA rat model migrated to the inflammatory joint sites, effectively promoting recovery from collagen type II damage and thereby improving the immune‑associated prothrombotic state.

Clinical Trials With Mesenchymal Stem Cells: An Update

In the last year, the promising features of mesenchymal stem cells (MSCs), including their regenerative properties and ability to differentiate into diverse cell lineages, have generated great interest among researchers whose work has offered intriguing perspectives on cell-based therapies for various diseases. Currently the most commonly used adult stem cells in regenerative medicine, MSCs, can be isolated from several tissues, exhibit a strong capacity for replication in vitro, and can differentiate into osteoblasts, chondrocytes, and adipocytes. However, heterogeneous procedures for isolating and cultivating MSCs among laboratories have prompted the International Society for Cellular Therapy (ISCT) to issue criteria for identifying unique populations of these cells. Consequently, the isolation of MSCs according to ISCT criteria has produced heterogeneous, nonclonal cultures of stromal cells containing stem cells with different multipotent properties, committed progenitors, and differentiated cells. Though the nature and functions of MSCs remain unclear, nonclonal stromal cultures obtained from bone marrow and other tissues currently serve as sources of putative MSCs for therapeutic purposes, and several findings underscore their effectiveness in treating different diseases. To date, 493 MSC-based clinical trials, either complete or ongoing, appear in the database of the US National Institutes of Health. In the present article, we provide a comprehensive review of MSC-based clinical trials conducted worldwide that scrutinizes biological properties of MSCs, elucidates recent clinical findings and clinical trial phases of investigation, highlights therapeutic effects of MSCs, and identifies principal criticisms of the use of these cells. In particular, we analyze clinical trials using MSCs for representative diseases, including hematological disease, graft-versus-host disease, organ transplantation, diabetes, inflammatory diseases, and diseases in the liver, kidney, and lung, as well as cardiovascular, bone and cartilage, neurological, and autoimmune diseases.

Treatment of severe chronic graft-versus-host disease with decidual stromal cells and tracing with (111)indium radiolabeling

Decidual stromal cells (DSCs) isolated from fetal membranes of term placentas are easily expanded and are highly immunosuppressive in vitro. These cells express high levels of integrins that are of importance in homing to inflamed tissues. In this study, we investigated DSCs as a cellular therapy for chronic graft-versus-host disease (cGvHD), a severe complication after allogeneic hematopoietic stem cell transplantation. Subsequent to transplantation, three patients developed severe extensive cGvHD and were treated with DSCs (1-2.8 × 10(6) cells/kg). One-third of the DSCs administered to two patients were labeled with (111)Indium, and the in vivo distribution was tracked for 48 h. The (111)In-labeled DSCs were initially located in the lungs, followed by dissemination to the liver and spleen. The DSCs induced a partial response in two of the patients. Blood samples from the patients were extensively evaluated by flow cytometry, luminex, and enzyme-linked immunosorbent assay. The nonresponder had the highest proportion of T-cells with Th17 and Th2 phenotypes and the highest median plasma concentrations of IL-17 and IL-4. The same patient also had high frequencies of HLA-DR(+) T-cells and regulatory T-cells. To conclude, DSCs are safe to infuse with no adverse effects. We determined how stromal cells are distributed in vivo after infusion in a cGvHD setting. The methods established for analysis of blood samples will be useful in determining the effect of DSCs in a study comprising a larger patient material. This pilot study may provide a basis for further controlled investigations with DSCs in a clinical setting.

Immune regulatory properties of CD117(pos) amniotic fluid stem cells vary according to gestational age

Amniotic Fluid Stem (AFS) cells are broadly multipotent fetal stem cells derived from the positive selection and ex vivo expansion of amniotic fluid CD117/c-kit(pos) cells. Considering the differentiation potential in vitro toward cell lineages belonging to the three germ layers, AFS cells have raised great interest as a new therapeutic tool, but their immune properties still need to be assessed. We analyzed the in vitro immunological properties of AFS cells from different gestational age in coculture with T, B, and natural killer (NK) cells. Nonactivated (resting) first trimester-AFS cells showed lower expression of HLA class-I molecules and NK-activating ligands than second and third trimester-AFS cells, whose features were associated with lower sensitivity to NK cell-mediated lysis. Nevertheless, inflammatory priming with interferon gamma (IFN-γ) and tumor necrosis factor alpha (TNF-α) enhanced resistance of all AFS cell types to NK cytotoxicity. AFS cells modulated lymphocyte proliferation in a different manner according to gestational age: first trimester-AFS cells significantly inhibited T and NK cell proliferation, while second and third trimester-AFS cells were less efficient. In addition, only inflammatory-primed second trimester-AFS cells could suppress B cell proliferation, which was not affected by the first and third trimester-AFS cells. Indolamine 2,3 dioxygenase pathway was significantly involved only in T cell suppression mediated by second and third trimester-AFS cells. Overall, this study shows a number of significant quantitative differences among AFS cells of different gestational age that have to be considered in view of their clinical application.

Comparative Efficacies of Long-Term Serial Transplantation of Syngeneic, Allogeneic, Xenogeneic, or CTLA4Ig-Overproducing Xenogeneic Adipose Tissue-Derived Mesenchymal Stem Cells on Murine Systemic Lupus Erythematosus

Allogeneic and xenogeneic transplantation are suitable alternatives for treating patients with stem cell defects and autoimmune diseases. The purpose of this study was to compare the effects of long-term serial transplantation of adipose tissue-derived mesenchymal stem cells (ASCs) from (NZB × NZW) F1 mice (syngeneic), BALB/c mice (allogeneic), or humans (xenogeneic) on systemic lupus erythematosus (SLE). The effects of transplanting human ASCs overproducing CTLA4Ig (CTLA4Ig-hASC) were also compared. Animals were divided into five experimental groups, according to the transplanted cell type. Approximately 500,000 ASCs were administered intravenously every 2 weeks from 6 to 60 weeks of age to all mice except for the control mice, which received saline. The human ASC groups (hASC and CTLA4Ig-hASC) showed a 13-week increase in average life spans and increased survival rates and decreased blood urea nitrogen, proteinuria, and glomerular IgG deposition. The allogeneic group also showed higher survival rates compared to those of the control, up to 40, 41, 42, 43, 44, 45, 52, and 53 weeks of age. Syngeneic ASC transplantation did not accelerate the mortality of the mice. The mean life span of both the syngeneic and allogeneic groups was prolonged for 6-7 weeks. Both human ASC groups displayed increased serum interleukin-10 and interleukin-4 levels, whereas both mouse ASC groups displayed significantly increased GM-CSF and interferon-γ levels in the serum. The strongest humoral immune response was induced by xenogeneic transplantation, followed by allogeneic, CTLA4Ig-xenogeneic, and syngeneic transplantations. Long-term serial transplantation of the ASCs from various sources displayed different patterns of cytokine expression and humoral responses, but all of them increased life spans in an SLE mouse model.

Mesenchymal stem cells in autism spectrum and neurodevelopmental disorders: pitfalls and potential promises

OBJECTIVES

In this conceptual review, the authors discuss the promises and pitfalls in the use of mesenchymal stem cells as a potential experimental therapeutic for autism spectrum and other neurodevelopmental disorders.

METHODS

The relevant literature in autism spectrum disorders and other neurodevelopmental disorders regarding immune dysregulation and neuroinflammation and relevant therapeutics with mesenchymal stem cell infusion is reviewed. The relevant literature pertaining to mesenchymal stem cells and their clinical applications is also reviewed.

RESULTS

It is proposed that immune dysregulation and neuroinflammation play a role in the aetiology of autism spectrum disorders. Mesenchymal stem cells have been shown to have immune-modulating capabilities and are neuroprotective. There are three international studies that have utilized mesenchymal stem cell infusions as a treatment for children with autism spectrum disorders, all of which demonstrated improvement in autism rating scale scores, although each study has limitations which are described.

CONCLUSIONS

Mesenchymal stem cell transplantation for the treatment of autism spectrum disorders is a novel approach that deserves further investigation, however substantial methodological and theoretical challenges and pitfalls remain before this can be considered a viable therapeutic option.

Interleukin-25 Mediates Transcriptional Control of PD-L1 via STAT3 in Multipotent Human Mesenchymal Stromal Cells (hMSCs) to Suppress Th17 Responses

Multipotent human mesenchymal stromal cells (hMSCs) harbor immunomodulatory properties that are therapeutically relevant. One of the most clinically important populations of leukocytes is the interleukin-17A (IL-17A)-secreting T (Th17) lymphocytes. However, mechanisms of hMSC and Th17 cell interactions are incompletely resolved. We found that, along with Th1 responses, hMSCs strongly suppressed Th17 responses and this required both IL-25—also known as IL-17E—as well as programmed death ligand-1 (PD-L1), a potent cell surface ligand for tolerance induction. Knockdown of IL-25 expression in hMSCs abrogated Th17 suppression in vitro and in vivo. However, IL-25 alone was insufficient to significantly suppress Th17 responses, which also required surface PD-L1 expression. Critically, IL-25 upregulated PD-L1 surface expression through the signaling pathways of JNK and STAT3, with STAT3 found to constitutively occupy the proximal region of the PD-L1 promoter. Our findings demonstrate the complexities of hMSC-mediated Th17 suppression, and highlight the IL-25/STAT3/PD-L1 axis as a candidate therapeutic target.

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hMSC-secreted IL-25 suppress Th17 responses in vitro and in vivo

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IL-25 alone is insufficient to significantly suppress Th17 responses

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IL-25 upregulates PD-L1 expression in hMSCs to suppress Th17 cells

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IL-25-mediated PD-L1 expression can be driven by STAT3

Pulp-dentin Regeneration

The goal of regenerative endodontics is to reinstate normal pulp function in necrotic and infected teeth that would result in reestablishment of protective functions, including innate pulp immunity, pulp repair through mineralization, and pulp sensibility. In the unique microenvironment of the dental pulp, the triad of tissue engineering would require infection control, biomaterials, and stem cells. Although revascularization is successful in resolving apical periodontitis, multiple studies suggest that it alone does not support pulp-dentin regeneration. More recently, cell-based approaches in endodontic regeneration based on pulpal mesenchymal stem cells (MSCs) have demonstrated promising results in terms of pulp-dentin regeneration in vivo through autologous transplantation. Although pulpal regeneration requires the cell-based approach, several challenges in clinical translation must be overcome—including aging-associated phenotypic changes in pulpal MSCs, availability of tissue sources, and safety and regulation involved with expansion of MSCs in laboratories. Allotransplantation of MSCs may alleviate some of these obstacles, although the long-term stability of MSCs and efficacy in pulp-dentin regeneration demand further investigation. For an alternative source of MSCs, our laboratory developed induced MSCs (iMSCs) from primary human keratinocytes through epithelial-mesenchymal transition by modulating the epithelial plasticity genes. Initially, we showed that overexpression of ΔN p63α, a major isoform of the p63 gene, led to epithelial-mesenchymal transition and acquisition of stem characteristics. More recently, iMSCs were generated by transient knockdown of all p63 isoforms through siRNA, further simplifying the protocol and resolving the potential safety issues of viral vectors. These cells may be useful for patients who lack tissue sources for endogenous MSCs. Further research will elucidate the level of potency of these iMSCs and assess their transdifferentiation capacities into functional odontoblasts when transplanted into the root canal microenvironment.

Allogeneic mesenchymal stem cells inhibited T follicular helper cell generation in rheumatoid arthritis

T follicular helper (Tfh) cells provide help for antigen-specific B cells. We have previously shown that Tfh cell frequency was increased and associated with auto-antibodies in patients with rheumatoid arthritis (RA), suggesting a possible involvement of Tfh cells in its pathogenesis. Mesenchymal stem cells (MSCs) represent a promising alternative cell therapy for RA by modulating T and B cell activation and proliferation. However, it remains unknown whether MSCs have immunoregulation on Tfh cells. In this paper, we have demonstrated that allogeneic MSCs could suppress Tfh cell differentiation in RA patients partly via the production of indoleamine 2,3-dioxygenase (IDO). IFNγ generated from Tfh cell differentiation system induced IDO expression on MSCs. MSCs transplantation (MSCT) into collagen-induced arthritis (CIA) mice prevented arthritis progression by inhibiting both the number and function of Tfh cells in vivo. These findings reveal a novel suppressive function of MSCs in Tfh cells, which has implication in understanding the underlying mechanisms of the immunotherapeutic effects of MSCs on RA patients.

Insensitivity of Human iPS Cells-Derived Mesenchymal Stem Cells to Interferon-γ-induced HLA Expression Potentiates Repair Efficiency of Hind Limb Ischemia in Immune Humanized NOD Scid Gamma Mice

Adult mesenchymal stem cells (MSCs) are immunoprivileged cells due to the low expression of major histocompatibility complex (MHC) II molecules. However, the expression of MHC molecules in human-induced pluripotent stem cells (iPSCs)-derived MSCs has not been investigated. Here, we examined the expression of human leukocyte antigen (HLA) in human MSCs derived from iPSCs, fetuses, and adult bone marrow (BM) after stimulation with interferon-γ (IFN-γ), compared their repair efficacy, cell retention, inflammation, and HLA II expression in immune humanized NOD Scid gamma (NSG) mice of hind limb ischemia. In the absence of IFN-γ stimulation, HLA-II was expressed only in BM-MSCs after 7 days. Two and seven days after stimulation, high levels of HLA-II were observed in BM-MSCs, intermediate levels were found in fetal-MSCs, and very low levels in iPSC-MSCs. The levels of p-STAT1, interferon regulatory factor 1, and class II transactivator exhibited similar phenomena. Moreover, p-STAT1 antagonist significantly reversed the high expression of HLA-II in BM-MSCs. Compared to adult BM-MSCs, transplanting iPSC-MSCs into hu-PBMNC NSG mice revealed markedly more survival iPSC-MSCs, less inflammatory cell accumulations, and better recovery of hind limb ischemia. The expression of HLA-II in MSCs in the ischemia limbs was detected in BM-MSCs group but not in iPSC-MSCs group at 7 and 21 days after transplantation. Our results demonstrate that, compared to adult MSCs, human iPSC-MSCs are insensitive to proinflammatory IFN-γ-induced HLA-II expression and iPSC-MSCs have a stronger immune privilege after transplantation. It may attribute to a better therapeutic efficacy in allogeneic transplantation.

Mesenchymal stem cells and adaptive immune responses

Over the past decade, our understanding of the regulatory role of mesenchymal stem cells (MSCs) in adaptive immune responses through both preclinical and clinical studies has dramatically expanded, providing great promise for treating various inflammatory diseases. Most studies are focused on the modulatory effects of these cells on the properties of T cell-mediated immune responses, including activation, proliferation, survival, and subset differentiation. Interestingly, the immunosuppressive function of MSCs was found to be licensed by IFN-γ and TNF-α produced by T cells and that can be further amplified by cytokines such as IL-17. However, the immunosuppressive function of MSCs can be reversed in certain situation, such as suboptimal levels of inflammatory cytokines, or in the presence of immunosuppressive molecules. Here we review the influence of MSCs on adaptive immune system, especially their bidirectional interaction in tuning the immune microenvironment and subsequently repairing damaged tissue. Understanding MSC-mediated regulation of T cells is expected to provide fundamental information for guiding appropriate applications of MSCs in clinical settings.

New strategies for overcoming limitations of mesenchymal stem cell-based immune modulation

Mesenchymal stem cells (MSCs) have rapidly been applied in a broad field of immune-mediated disorders since the first successful clinical use of MSCs for treatment of graft-versus-host disease. Despite the lack of supporting data, expectations that MSCs could potentially treat most inflammatory conditions led to rushed application and development of commercialized products. Today, both pre-clinical and clinical studies present mixed results for MSC therapy and the discrepancy between expected and actual efficacy of MSCs in various diseases has evoked a sense of discouragement. Therefore, we believe that MSC therapy may now be at a critical milestone for re-evaluation and re-consideration. In this review, we summarize the current status of MSC-based clinical trials and focus on the discrepancy between expected and actual outcome of MSC therapy from bench to bedside. Importantly, we discuss the underlying limitations of MSCs and suggest a new guideline for MSC therapy in hopes of improving their therapeutic efficacy.

Transplantation of mesenchymal stem cells ameliorates secondary osteoporosis through interleukin-17-impaired functions of recipient bone marrow mesenchymal stem cells in MRL/lpr mice

Introduction

Secondary osteoporosis is common in systemic lupus erythematosus and leads to a reduction in quality of life due to fragility fractures, even in patients with improvement of the primary disorder. Systemic transplantation of mesenchymal stem cells could ameliorate bone loss and autoimmune disorders in a MRL/lpr mouse systemic lupus erythematosus model, but the detailed therapeutic mechanism of bone regeneration is not fully understood. In this study, we transplanted human bone marrow mesenchymal stem cells (BMMSCs) and stem cells from exfoliated deciduous teeth (SHED) into MRL/lpr mice and explored their therapeutic mechanisms in secondary osteoporotic disorders of the systemic lupus erythematosus model mice.

Methods

The effects of systemic human mesenchymal stem cell transplantation on bone loss of MRL/lpr mice were analyzed in vivo and ex vivo. After systemic human mesenchymal stem cell transplantation, recipient BMMSC functions of MRL/lpr mice were assessed for aspects of stemness, osteogenesis and osteoclastogenesis, and a series of co-culture experiments under osteogenic or osteoclastogenic inductions were performed to examine the efficacy of interleukin (IL)-17-impaired recipient BMMSCs in the bone marrow of MRL/lpr mice.

Results

Systemic transplantation of human BMMSCs and SHED recovered the reduction in bone density and structure in MRL/lpr mice. To explore the mechanism, we found that impaired recipient BMMSCs mediated the negative bone metabolic turnover by enhanced osteoclastogenesis and suppressed osteoblastogenesis in secondary osteoporosis of MRL/lpr mice. Moreover, IL-17-dependent hyperimmune conditions in the recipient bone marrow of MRL/lpr mice damaged recipient BMMSCs to suppress osteoblast capacity and accelerate osteoclast induction. To overcome the abnormal bone metabolism, systemic transplantation of human BMMSCs and SHED into MRL/lpr mice improved the functionally impaired recipient BMMSCs through IL-17 suppression in the recipient bone marrow and then maintained a regular positive bone metabolism via the balance of osteoblasts and osteoclasts.

Conclusions

These findings indicate that IL-17 and recipient BMMSCs might be a therapeutic target for secondary osteoporosis in systemic lupus erythematosus.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-015-0091-4) contains supplementary material, which is available to authorized users.

iPSC-MSCs Combined with Low-Dose Rapamycin Induced Islet Allograft Tolerance Through Suppressing Th1 and Enhancing Regulatory T-Cell Differentiation

Mesenchymal stem cell (MSC) differentiation is dramatically reduced after long-term in vitro culture, which limits their application. MSCs derived from induced pluripotent stem cells (iPSCs-MSCs) represent a novel source of MSCs. In this study, we investigated the therapeutic effect of iPSC-MSCs on diabetic mice. Streptozocin-induced diabetic mice transplanted with 400 islets alone or with 1×10(6) iPSC-MSCs were examined following rapamycin injection (0.1 mg/kg/day, i.p., from days 0 to 9) after transplantation. Our results showed that iPSC-MSCs combined with rapamycin significantly prolonged islet allograft survival in the diabetic mice; 50% of recipients exhibited long-term survival (>100 days). Histopathological analysis revealed that iPSC-MSCs combined with rapamycin preserved the graft effectively, inhibited inflammatory cell infiltration, and resulted in substantial release of insulin. Flow cytometry results showed that the proportion of CD4(+) and CD8(+) T cells was significantly reduced, and the number of T regulatory cells increased in the spleen and lymph nodes in the iPSC-MSCs combined with the rapamycin group compared with the rapamycin-alone group. Production of the Th1 proinflammatory cytokines interleukin-2 (IL-2) and interferon-γ was reduced, and secretion of the anti-inflammatory cytokines IL-10 and transforming growth factor-β was enhanced compared with the rapamycin group, as determined using enzyme-linked immunosorbent assays. Transwell separation significantly weakened the immunosuppressive effects of iPSC-MSCs on the proliferation of Con A-treated splenic T cells, which indicated that the combined treatment exerted immunosuppressive effects through cell-cell contact and regulation of cytokine production. Taken together, these findings highlight the potential application of iPSC-MSCs in islet transplantation.

Infusion of Human Bone Marrow-Derived Mesenchymal Stem Cells Alleviates Autoimmune Nephritis in a Lupus Model by Suppressing Follicular Helper T-Cell Development

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by the production of autoantibodies to components of the cell nucleus. These autoantibodies are predominantly produced with the help of follicular helper T (Tfh) cells and form immune complexes that trigger widespread inflammatory damage, including nephritis. In recent studies, mesenchymal stem cells (MSCs) elicited diverse, even opposing, effects in experimental and clinical SLE. Here we investigated the effect of human bone marrow-derived MSCs (hBM-MSCs) in a murine model of SLE, the F1 hybrid between New Zealand Black and New Zealand White strains (NZB/W). We found that infusion of female NZB/W mice with hBM-MSCs attenuated glomerulonephritis; it also decreased levels of autoantibodies and the incidence of proteinuria and improved survival. These effects coincided with a decrease in Tfh cells and downstream components. Infiltration of long-lived plasma cells into the inflamed kidney was also reduced in the hBM-MSC-treated mice. Importantly, hBM-MSCs directly suppressed the in vitro differentiation of naive CD4(+) T cells toward Tfh cells in a contact-dependent manner. These results suggest that MSCs attenuate lupus nephritis by suppressing the development of Tfh cells and the subsequent activation of humoral immune components. They thus reveal a novel mechanism by which MSCs regulate humoral autoimmune diseases such as SLE.