Search

Mesenchymal stromal cells (MSCs) are attractive candidates for immunomodulatory cell therapy. However, it remains unknown how far therapeutic efficacy and potency are dependent on the dosage and activity of the MSCs. We previously observed that infusion of MSCs leads to rapid and transient changes in cytokine expression in blood, lung, and liver. In the present study, increasing doses of syngeneic adipose tissue-derived MSCs were infused in healthy mice and systemic changes in G-CSF, IL6, IL-10, and CXCL5 were detected 2 h after administration of 3 × 10 5 MSCs per animal, but not at lower doses. In lung and liver tissue, dose-dependent effects of MSCs on cytokine mRNA expression levels were detected from doses as low as 3 × 10 3 MSCs. Infusion of secretome-deficient or IFNγ-activated MSCs in healthy mice had similar effects on systemic cytokine levels as control MSCs, suggesting that in vivo at least the initial systemic effect of MSC administration is independent of the level of activity of MSCs, but depends on the response of host cells to MSCs. The results of this study reveal a rapid dose-dependent effect of MSCs and stress the important role of host cells in MSC treatment. This knowledge contributes to the design of rational MSC trials and to the quest for clinical efficacy of MSC therapy.

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., (© AlphaMed Press 2018.)

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.

Mesenchymal stromal cells (MSCs) are considered to be promising agents for the treatment of immunological disease. Although originally identified as precursor cells for mesenchymal lineages, in vitro studies have demonstrated that MSCs possess diverse immune regulatory capacities. Pre-clinical models have shown beneficial effects of MSCs in multiple immunological diseases and a number of phase 1/2 clinical trials carried out so far have reported signs of immune modulation after MSC infusion. These data indicate that MSCs play a central role in the immune response. This raises the academic question whether MSCs are immune cells or whether they are tissue precursor cells with immunoregulatory capacity. Correct understanding of the immunological properties and origin of MSCs will aid in the appropriate and safe use of the cells for clinical therapy. In this review the whole spectrum of immunological properties of MSCs is discussed with the aim of determining the position of MSCs in the immune system.

Background: Liver transplantation is the definitive treatment for many end-stage liver diseases. However, the life-long immunosuppression needed to prevent graft rejection causes clinically significant side effects. Cellular immunomodulatory therapies may allow the dose of immunosuppressive drugs to be reduced. In the current protocol, we propose to complement immunosuppressive pharmacotherapy with third-party multipotent adult progenitor cells (MAPCs), a culture-selected population of adult adherent stem cells derived from bone marrow that has been shown to display potent immunomodulatory and regenerative properties. In animal models, MAPCs reduce the need for pharmacological immunosuppression after experimental solid organ transplantation and regenerate damaged organs., Methods: Patients enrolled in this phase I, single-arm, single-center safety and feasibility study (n = 3-24) will receive 2 doses of third-party MAPCs after liver transplantation, on days 1 and 3, in addition to a calcineurin-inhibitor-free "bottom-up" immunosuppressive regimen with basiliximab, mycophenolic acid, and steroids. The study objective is to evaluate the safety and clinical feasibility of MAPC administration in this patient cohort. The primary endpoint of the study is safety, assessed by standardized dose-limiting toxicity events. One secondary endpoint is the time until first biopsy-proven acute rejection, in order to collect first evidence of efficacy. Dose escalation (150, 300, 450, and 600 million MAPCs) will be done according to a 3 + 3 classical escalation design (4 groups of 3-6 patients each)., Discussion: If MAPCs are safe for patients undergoing liver transplantation in this study, a phase II/III trial will be conducted to assess their clinical efficacy.

Mesenchymal stromal cells (MSC) are a promising therapy for inflammatory diseases. However, MSC are large and become trapped in the lungs after intravenous infusion, where they have a short survival time. To steer MSC immunoregulatory therapy beyond the lungs, we generated nm-sized particles from MSC membranes (membrane particles, MP), which have immunomodulatory properties, and investigated their internalization and mode of interaction in macrophages subtypes and human umbilical vein endothelial cells (HUVEC) under control and inflammatory conditions. We found that macrophages and HUVEC take up MP in a dose, time, and temperature-dependent manner. Specific inhibitors for endocytotic pathways revealed that MP internalization depends on heparan sulfate proteoglycan-, dynamin-, and clathrin-mediated endocytosis but does not involve caveolin-mediated endocytosis. MP uptake also involved the actin cytoskeleton and phosphoinositide 3-kinase, which are implicated in macropinocytosis and phagocytosis. Anti-inflammatory M2 macrophages take up more MP than pro-inflammatory M1 macrophages. In contrast, inflammatory conditions did not affect the MP uptake by HUVEC. Moreover, MP induced both anti- and pro-inflammatory responses in macrophages and HUVEC by affecting gene expression and cell surface proteins. Our findings on the mechanisms of uptake of MP under different conditions help the development of target-cell specific MP therapy to modulate immune responses. [ABSTRACT FROM AUTHOR]

Summary: Cellular therapy is a promising tool for improving the outcome of organ transplantation. Various cell types with different immunoregulatory and regenerative properties may find application for specific transplant rejection or injury‐related indications. The current era is crucial for the development of cellular therapies. Preclinical models have demonstrated the feasibility of efficacious cell therapy in transplantation, early clinical trials have shown safety of several of these therapies, and the first steps towards efficacy studies in humans have been made. In this review, we address the current state of the art of cellular therapies in clinical transplantation and discuss monitoring tools and endpoints for these studies. [ABSTRACT FROM AUTHOR]

Mesenchymal stem cells (MSCs) are used in various clinical and preclinical models for immunomodulation. However, it remains unclear how the immunomodulatory effect of MSC is communicated. MSC-induced immunomodulation is known to be mediated through both MSC-secreted cytokines and direct cell-cell interactions. Recently, it has been demonstrated that metabolically inactive, heat-inactivated MSCs (HI-MSCs) have similar anti-inflammatory capacities in LPS-induced sepsis compared with viable MSC. To further investigate the immunomodulatory effects of MSC, we introduced MSC and HI-MSC in two animal models with different immunological causes. In the first model, allogeneic hearts were transplanted from C57BL/6 mice to BALB/c recipients. MSC in combination with mycophenolate mofetil (MMF) significantly improved graft survival compared with MMF alone, whereas the application of HI-MSC had no effect on graft survival. We revealed that control MSC dose-dependently inhibited CD3+ and CD8+ T-cell proliferation in vitro, whereas HI-MSC had no effect. In the second model, sepsis was induced in mice via cecal ligation and puncture. HI-MSC treatment significantly improved the overall survival, whereas controlMSCs had no effect. in vitro studies demonstrated that HI-MSCs are more effectively phagocytosed by monocytes than control MSCs and induced cell death in particular of activated CD16+ monocytes, which may explain the immune protective effect of HI-MSC in the sepsis model. The results of our study demonstrate that MSC-mediated immunomodulation in sepsis is dependent on a passive recognition of MSC by monocytes, whereas fully functional MSCs are required for inhibition of T-cell-mediated allograft rejection. [ABSTRACT FROM AUTHOR]

Caplan et al. summarized how delivery methods shape the outcome of MSC therapy, differentiating between specific types of local and systemic delivery, and they further elaborate on the role of innate and adaptive immune responses, in particular cell product hemocompatibility aspects, on steering the clinical outcome. In line with this, Diedrichs et al. present their results on the clinical development of cardiac-derived MSC products and in particular the impact of interferon-gamma (IFN-g) inflammatory licensing on cell product properties in the context of allogeneic cell therapy. Clinical effects may result from a bi-directional crosstalk between MSCs and host cells (as long as MSCs are present), and from the initiation of secondary responses of varying duration, which complicates attempts to model kinetics and dosing in "cell pharmacology" ([11]). Oja et al. shared their hands-on experience on how freezing steps in MSC manufacturing impact quality and cell functionality attributes, and how a short-term 24-h culture recovery post thawing can restore the full functionality of the cells. [Extracted from the article]

The immunomodulatory capacity of mesenchymal stem or stromal cells (MSC) makes them a promising tool for treatment of immune disease and organ transplantation. The effects of MSC on B cells are characterized by an abrogation of plasmablast formation and induction of regulatory B cells (Bregs). It is, however, unknown how MSC interact with B cells under inflammatory conditions. In this study, adipose tissue-derived MSC were pretreated with 50 ng/ml IFN-γ for 96 h (MSC-IFN-γ) to simulate inflammatory conditions. Mature B cells were obtained from spleens by CD43- selection. B cells were co-cultured with MSC and stimulated with anti-IgM, anti-CD40, and IL-2; and after 7 days, B cell proliferation, phenotype, Immunoglobulin-G (IgG), and IL-10 production were analyzed. MSC did not inhibit B cell proliferation but increased the percentage of CD38high CD24high B cells (Bregs) and IL-10 production, while MSC-IFN-γ significantly reduced B cell proliferation and inhibited IgG production by B cells in a more potent fashion but did not induce Bregs or IL-10 production. Both MSC and MSC-IFN-γ required proximity to target cells and being metabolically active to exert their effects. Indoleamine 2,3 dioxygenase expression was highly induced in MSC-IFN-γ and was responsible of the anti-proliferative and Breg reduction since addition of tryptophan (TRP) restored MSC properties. Immunological conditions dictate the effect of MSC on B cell function. Under immunological quiescent conditions, MSC stimulate Breg induction; whereas, under inflammatory conditions, MSC inhibit B cell proliferation and maturation through depletion of TRP. This knowledge is useful for customizing MSC therapy for specific purposes by appropriate pretreatment of MSC. [ABSTRACT FROM AUTHOR]

Background aims. In regenerative medicine, the use of allogeneic cells could enable the development of "off the shelf" therapies for patients with critical size bone defects, reducing limitations observed with the use of autologous cells, such as cost and time to treat the patient. The idea of the use of allogeneic bone marrow mesenchymal stromal cells (BMSCs) has been of interest in tissue engineering studies. However, little is known about the properties of these cells upon differentiation. Chondrogenically differentiated BMSCs have already been shown to form endochondral bone in immunodeficient and immunocompetent animals. The success of this bone formation is dependent on the host's endogenous cells. This study investigates the interactions between allogeneic chondrogenically differentiated human bone marrow mesenchymal stromal cell (hBMSC) pellets and T lymphocytes in vitro. Methods. Non-chondrogenic (-transforming growth factor (TGF)β3) and chondrogenic hBMSC (+TGFβ3) pellets were directly co-cultured with unstimulated and CD3/CD28-stimulated peripheral blood mononuclear cells (PBMCs) for 7 days. hBMSC pellets from the co-culture were either fixed for histological analysis or quantitative real time polymerase chain reaction (qRT-PCR). PBMCs were harvested for flow cytometry. Results. Flow cytometic analysis revealed that chondrogenically differentiated hBMSC pellets did not alter the number or proliferation of CD4+, CD8+T cells or FoxP3+T regulatory cells (CD4+CD25+CD127-). Chondrogenic hBMSC pellets did not induce immunogenic responses in unstimulated PBMCs. Infiltrating CD3 T cells were found in the matrix of hBMSC pellets. Furthermore, qRT-PCR demonstrated low levels ofT-cell activation genes (CD25, CD69, PRF1 and GZMB) in addition to low gene expression levels of the pro-inflammatory gene tumor necrosis factor alpha (TNFα) in chondrogenically differentiated hBMSC pellets cultured with unstimulated PBMCs in comparison with non-chondrogenic hBMSC pellets. Conclusions. Collectively the results of this study demonstrate that allogeneic chondrogenically differentiated hBMSC pellets are nonimmunogenic and do not induce the activation of destructive T-cell responses in vitro. [ABSTRACT FROM AUTHOR]

Mesenchymal stem cells (MSC) are under development as an immunomodulatory therapy. The anticipated immunomodulatory effects of MSC are broad, from direct inhibition of lymphocyte proliferation, induction of regulatory T and B cells, to resetting the immune system via a hit-and-run principle. There are endless flavors of MSC. Differences between MSC are originating from donors variation, differences in tissue of origin, the effects of culture conditions, and expansion time. Even standard culture conditions change the properties of MSC dramatically and generate MSC that only remotely resemble their in vivo counterparts. Adjustments in culture protocols can further emphasize properties of interest in MSC, thereby generating cells fitted for specific purposes. Culture improved immunomodulatory MSC can be designed to target particular immune disorders. In this review, we describe the observed and the desired immunomodulatory effects of MSC and propose approaches how MSC with optimal immunomodulatory properties can be developed. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Mesenchymal stem cells (MSC) are widely studied for their immunomodulatory properties. Data from in vitro and pre-clinical models demonstrate that MSC suppress activated immune cells and ameliorate the severity of experimental immune disease. In complex human studies, the immunomodulatory efficacy of MSC therapy is not well established. We conducted a systematic review of clinical studies which used MSC with the purpose of immunomodulation and included at least 10 patients to investigate the efficacy of MSC therapy. Sixty-two studies comprising 10 different immune disorders were included in the analysis, of which 18 studies represented controlled trials. Although several of the studies reported an amelioration of disease severity, other studies failed to observe a beneficial effect of MSC. The low number of randomized controlled trials, small number of studies per disease category and limited immunological readout parameters made it difficult to draw a definitive conclusion on the efficacy of MSC immune therapy. [ABSTRACT FROM AUTHOR]

Mesenchymal stem cells ( MSCs) possess immunomodulatory properties which are of key interest for their application in autoimmunity and transplantation. In transplantation, administration of MSCs has shown promising results in preclinical models and has recently moved to clinical trials. Therefore, it is important to study the interactions between MSCs and immunosuppressive drugs currently used in transplantation. We aimed to analyze the effect of rabbit antithymocyte globulin ( rATG) MSCs. MSCs were obtained from perirenal fat of kidney donors and exposed to ranging doses of rATG (Thymoglobulin®, Genzyme; 0.5-100 μg/ml). Binding of rATG, effects on viability and susceptibility to be killed by cytotoxic lymphocytes as well as effects on their immunosuppressive potential of MSCs were tested. rATG binds dose-dependently to MSCs. This binding was associated with slightly impaired viability after 48 and 72 h when compared with nonexposed MSCs. In contrast to nontreated MSCs, rATG preexposed MSCs were susceptible to be lysed by cytokine-activated CD8+ cytotoxic cells and NKT cells. The capacity of MSCs to suppress the proliferation of anti-CD3/CD28 activated CD4 and CD8 T cells were reduced by the presence of rATG in the culture. rATG reduces the viability and antiproliferative capacity of MSCs in a dose-dependent manner and converts them into targets for CD8 T cells and NKT cell lysis. [ABSTRACT FROM AUTHOR]

Background: In diseased joints, the catabolic environment results in progressive joint dam-age. Mesenchymal stem cells (MSCs) can have immunomodulatory effects by secreting anti-inflammatory factors. To exert these effects, MSCs need to be triggered by pro-inflammatory cytokines. To explore the potential of MSCs as a treatment for diseased joints, we studied the effect of synovial fluid (SF) from donors with different joint diseases and donors without joint pathology on the immunomodulatory capacities of human MSCs in vitro. We hypothesized that SF of diseased joints influences the immunomodulatory effects of MSCs. Materials and Methods: MSCs were cultured in medium with SF of six osteoarthritis (OA) or six rheumatoid arthritis (RA) donors and three donors without joint pathology were used as control. Gene expressions of IL-6, HGF, TNFa, TGFb1, and indoleamine 2,3-dioxygenase (IDO) were analyzed. L-kynurenine concentration in condi-tioned medium (CM) by MSCs with SF was determined as a measure of IDO activity by MSCs. Furthermore, the effect of CM with SF on proliferation of activated lymphocytes was analyzed. Results: Addition of SF significantly up-regulated the mRNA expression of IL-6 and IDO in MSCs. SF(OA) induced significantly higher expression of IDO than SF(control), although no difference in IDO activity of the MSCs could be shown with a L-kynurenine assay. Medium conditioned by MSCs with SF(OA or RA) suppressed acti-vated lymphocyte proliferation in vitro more than medium conditioned by MSCs without SF or with SF(control). Discussion: SF can influence the expression of genes involved in immunomodulation by MSCs and the effect on lymphocyte proliferation.We found indica-tions for disease-specific differences between SFs but the variation between donors, even within one disease group was high. These data warrant further research to examine the potential application of MSC therapy in arthritic joints. [ABSTRACT FROM AUTHOR]

Abstract: There is growing interest in the use of mesenchymal stem cells (MSC) for immune therapy. Clinical trials that use MSC for treatment of therapy resistant graft versus host disease, Crohn''s disease and organ transplantation have initiated. Nevertheless, the immunomodulatory effects of MSC are only partly understood. Clinical trials that are supported by basic research will lead to better understanding of the potential of MSC for immunomodulatory applications and to optimization of such therapies. In this manuscript we review some recent literature on the mechanisms of immunomodulation by MSC in vitro and animal models, present new data on the secretion of pro-inflammatory and anti-inflammatory cytokines, chemokines and prostaglandins by MSC under resting and inflammatory conditions and discuss the hopes and expectations of MSC-based immune therapy. [Copyright &y& Elsevier]

[Display omitted] • MSC membrane particles (MP) reduce disease activity in the colitis model. • MP balances Th1 and Th2 activity, modulating cytokine production. • MP prevents globet cell loss and maintain the colonic epithelial barrier function. • MP is a promising, safe and low-cost cell-free therapy for inflammatory diseases. Inflammatory bowel diseases (IBD), including ulcerative colitis, are chronic and idiopathic inflammations of the gastrointestinal tract. A disruption of the epithelial barrier and an imbalance between Th1 and Th2 subsets are associated with the onset and progression of these diseases. Mesenchymal stromal cells (MSC) are a promising therapy for IBD. However, cell-tracking studies have shown that intravenously infused MSC localize to the lungs and present short-term survival. To reduce practical complexities arising from living cells, we generated membrane particles (MP) from MSC membranes, which possess some of the immunomodulatory properties of MSC. This study investigated the effect of MSC-derived MP and conditioned media (CM) as cell-free therapies in the dextran sulfate sodium (DSS)-induced colitis model. Acute colitis was induced in C57BL/6 mice by oral administration of 2% DSS in drinking water ad libitum from days 0 to 7. Mice were treated with MP, CM, or living MSC on days 2 and 5. Our findings revealed that MP, CM, and living MSC ameliorated DSS-induced colitis by reducing colonic inflammation, the loss of colonic goblet cells, and intestinal mucosa permeability, preventing apoptosis of damaged colonic cells and balancing Th1 and Th2 activity. Therefore, MSC-derived MP have high therapeutic potential for treating IBD, overcoming the deficiencies of living MSC therapy, and opening novel frontiers in inflammatory diseases medicine. [ABSTRACT FROM AUTHOR]

Background aims. Mesenchymal stromal cells (MSCs) are used as experimental immunotherapy. Extensive culture expansion is necessary to obtain clinically relevant cell numbers, although the impact on MSCs stability and function is unclear. This study investigated the effects of long-term in vitro expansion on the stability and function of MSCs. Methods. Human bone marrow-derived (bmMSCs) and umbilical cord-derived (ucMSCs) MSCs were in vitro expanded. During expansion, their proliferative capacity was examined. At passages 4, 8 and 12, analyses were performed to investigate the ploidy, metabolic stability, telomere length and immunophenotype. In addition, their potential to suppress lymphocyte proliferation and susceptibility to natural killer cell lysis was examined. Results. BmMSCs and ucMSCs showed decreasing proliferative capacity over time, while their telomere lengths and mitochondrial activity remained stable. Percentage of aneuploidy in cultures was unchanged after expansion. Furthermore, expression of MSC markers and markers associated with stress or aging remained unchanged. Reduced capacity to suppress CD4 and CD8 T-cell proliferation was observed for passage 8 and 12 bmMSCs and ucMSCs. Finally, susceptibility of bmMSCs and ucMSCs to NK-cell lysis remained stable. Conclusions. We showed that after long-term expansion, phenotype of bmMSCs and ucMSCs remains stable and cells exhibit similar immunogenic properties compared with lower passage cells. However, immunosuppressive properties of MSCs are reduced. These findings reveal the consequences of application of higher passage MSCs in the clinic, which will help increase the yield of therapeutic MSCs but may interfere with their efficacy. [ABSTRACT FROM AUTHOR]