No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Mesenchymal Stem Cells Inhibit Dendritic Cell Differentiation and Function by Preventing Entry Into the Cell Cycle
Abstract
Mesenchymal stem cells (MSCs) play a crucial role in hematopoietic development and have been shown to exert a powerful immunosuppressive effect. In this study, we investigated the effect of bone marrow MSC on the differentiation and function of peripheral blood monocytes into dendritic cells (DCs).
Human MSCs, generated from normal bone marrow, were added to peripheral blood monocytes stimulated in vitro with granulocyte-macrophage colony stimulating factor and interleukin-4 to become DCs. Monocytes were then examined for the expression of markers characteristic of DCs and their ability to stimulate allogeneic T cells. In addition, the effect of MSCs on the cell cycle of monocyte-derived DCs and the expression of various cell cycle proteins were analyzed by cytometric analysis and Western blotting with specific antibodies.
MSCs blocked the differentiation of monocytes into DCs and impaired their antigen-presenting ability. This resulted from a block of monocytes from entering the G1 phase of the cell cycle with a progressive number of cells accumulating in the G0 phase. Cyclin D2 was downregulated. However, differently from what was observed in T-cells stimulated in the presence of MSCs, the expression of p27 was found decreased, suggesting the involvement of similar but not identical pathways.
We conclude that MSCs impair monocyte differentiation and function by interfering with the cell cycle. These findings imply that MSC-induced immunosuppression might be a side product of a more general antiproliferative effect.
... However, MSCs are now being actively investigated for applications in therapies against immune-mediated diseases, such as acute graft-versus-host disease (GVHD), because of their anti-inflammatory effects mediated by suppressing excessive immune responses and low risk of causing further immune responses upon administration owing to their low immunogenicity [3,18,19]. MSCs modulate both innate and adaptive immune responses by interacting with various immune cell types, including T cells [20,21], B cells [22], natural killer cells [23], dendritic cells [24], macrophages/monocytes [25,26], and neutrophils [27]. Among them, the interactions with T cells and macrophages play a particularly important role in the immunomodulatory actions of MSCs, and numerous studies have reported that MSCs exert their therapeutic effects by altering the phenotype and function of these cells [18,28]. ...
... Sci. 2023, 24, 17484 ...
Mesenchymal stem cells (MSCs) are a promising cell source for stem cell therapy of intractable diseases in veterinary medicine, but donor-dependent cellular heterogeneity is an issue that influences therapeutic efficacy. Thus, we previously established immortalized cells that maintain the fundamental properties of primary cells, but functional evaluation had not been performed. Therefore, we evaluated the immunomodulatory capacity of the immortalized canine adipose-derived MSCs (cADSCs) in vitro and in vivo to investigate whether they maintain primary cell functions. C57BL/6J mice were treated with dextran sulfate sodium (DSS) to induce colitis, injected intraperitoneally with immortalized or primary cADSCs on day 2 of DSS treatment, and observed for 10 days. Administration of immortalized cADSCs improved body weight loss and the disease activity index (DAI) in DSS-induced colitic mice by shifting peritoneal macrophage polarity from the M1 to M2 phenotype, suppressing T helper (Th) 1/Th17 cell responses and inducing regulatory T (Treg) cells. They also inhibited the proliferation of mouse and canine T cells in vitro. These immunomodulatory effects were comparable with primary cells. These results highlight the feasibility of our immortalized cADSCs as a cell source for stem cell therapy with stable therapeutic efficacy because they maintain the immunomodulatory capacity of primary cells.
... According to published research, N-MSCs co-cultured with in vitro tumor cells might inhibit tumor cell proliferation. Ramasamy et al. [9] demonstrated that N-MSCs could prevent in vitro proliferation of leukemia cell lines and solid tumor cell lines. However, the inhibitory action of N-MSCs was dose-dependent, the inhibition rate was reduced at higher N-MSC proportions [9]. ...
... Ramasamy et al. [9] demonstrated that N-MSCs could prevent in vitro proliferation of leukemia cell lines and solid tumor cell lines. However, the inhibitory action of N-MSCs was dose-dependent, the inhibition rate was reduced at higher N-MSC proportions [9]. The inhibitory effect of N-MSC could include the N-MSC-mediated secretion of soluble factors such as Dickkopf-related protein 1 (Dkk1), which prevents Wnt signaling pathways in tumor cells. ...
Mesenchymal stem cells (MSCs), as self-renewing multipotent stromal cells, have been considered promising agents for cancer treatment. A large number of studies have demonstrated the valuable properties of MSC-based treatment, such as low immunogenicity and intrinsic tumor-trophic migratory properties. To enhance the potency of MSCs for therapeutic purposes, equipping MSCs with targeted delivery functions using genetic engineering is highly beneficial. Genetically engineered MSCs can express tumor suppressor agents such as proapoptotic, anti-proliferative, anti-angiogenic factors and act as ideal delivery vehicles. MSCs can also be loaded with nanoparticle drugs for increased efficacy and externally moderated targeting. Moreover, exosomes secreted by MSCs have important physiological properties, so they can contribute to intercellular communication and transfer cargo into targeted tumor cells. The precise role of genetically modified MSCs in tumor environments is still up for debate, but the beginning of clinical trials has been confirmed by promising results from preclinical investigations of MSC-based gene therapy for a wide range of malignancies. This review highlights the advanced techniques of engineering/nano-engineering and MSC-derived exosomes in tumor-targeted therapy.
... According to published research, N-MSCs co-cultured with in vitro tumor cells might inhibit tumor cell proliferation. Ramasamy et al. [9] demonstrated that N-MSCs could prevent in vitro proliferation of leukemia cell lines and solid tumor cell lines. However, the inhibitory action of N-MSCs was dose-dependent, the inhibition rate was reduced at higher N-MSC proportions [9]. ...
... Ramasamy et al. [9] demonstrated that N-MSCs could prevent in vitro proliferation of leukemia cell lines and solid tumor cell lines. However, the inhibitory action of N-MSCs was dose-dependent, the inhibition rate was reduced at higher N-MSC proportions [9]. The inhibitory effect of N-MSC could include the N-MSC-mediated secretion of soluble factors such as Dickkopf-related protein 1 (Dkk1), which prevents Wnt signaling pathways in tumor cells. ...
Mesenchymal stem cells (MSCs), as self-renewing multipotent stromal cells, have been considered promising agents for cancer treatment. A large number of studies have demonstrated the valuable properties of MSC-based treatment, such as low immunogenicity and intrinsic tumor-trophic migratory properties. To enhance the potency of MSCs for therapeutic purposes, equipping MSCs with targeted delivery functions using genetic engineering is highly beneficial. Genetically engineered MSCs can express tumor suppressor agents such as pro-apoptotic, anti-proliferative, anti-angiogenic factors and act as ideal delivery vehicles. MSCs can also be loaded with nanoparticle drugs for increased efficacy and externally moderated targeting. Moreover, exosomes secreted by MSCs have important physiological properties, so they can contribute to intercellular communication and transfer cargo into targeted tumor cells. The precise role of genetically modified MSCs in tumor environments is still up for debate, but the beginning of clinical trials has been confirmed by promising results from preclinical investigations of MSC-based gene therapy for a wide range of malignancies. This review highlights the advanced techniques of engineering/nano-engineering and MSC-derived exosomes in tumor-targeted therapy.
... The ability to modulate the immune system is exerted by MSCs on both the adaptive and innate immune systems by soluble factors and direct cell-cell interactions in response to immune cells. They realize these effects by multiple mechanisms: (1) interfering with human B-cells at multiple levels such as proliferation, differentiation to antibody-producing cells, and chemotaxis [49]; (2) suppressing the T cells proliferation and inhibiting their production of inflammatory cytokines [50]; (3) blocking the differentiation of monocytes into dendritic cells (DCs) and impairing their antigen-presenting capacity [51]; (4) reducing the proliferation and cytotoxicity of natural killer cells [52]; (5) facilitating the generation of regulatory T cells. By releasing pro-angiogenic factors and trophic immunomodulators, they attenuate the immune response and inflammation, reduce ischemic injury, and promote tissue repair and regeneration [53,54]. ...
Patients affected by inflammatory bowel diseases (IBD) can nowadays benefit from a growing number of pharmacological options. However, in moderate-to-severe cases, the therapeutic response is still far from optimal, and treatment changes and optimizations are often required. Thus, researchers in this field are strongly engaged in studies aiming to identify new potential therapeutic targets. Extracellular vesicles (EVs) are tiny subcellular bodies with a phospholipid bilayer envelope containing bioactive molecules, which are released from different cells and are involved in intercellular communication. Recent pre-clinical data show their emerging role in the pathogenesis and treatment of IBD. In our review, we summarize current evidence about the function of EVs as active therapeutic agents in ulcerative colitis and Crohn’s disease, analyzing the properties of EVs derived from different cellular sources and the mechanisms through which they may improve intestinal inflammation.
... The immune-modulatory properties of mesenchymal/ stromal stem cells (MSCs) have been widely assessed in various in vitro and in vivo settings. [14][15][16][17][18][19][20][21][22] In RA in vivo models, administration of MSCs significantly improved the severity of symptoms by modulating the inflammatory response and by reducing the damage to bone and cartilage. 23,24 Despite MSCs great potential, their application in clinics is lagging behind due to concerns relating to heterogeneity of MSCs resulted to donor variations, stemness stability, inadvertent differentiation, and limited expansion during the preparation of MSCs, homing capacity of MSCs, risk of rejection and transformation of MSCs into malignant sarcoma cells at the state of application. ...
Currently available therapies for rheumatoid arthritis (RA) are inadequate to alleviate the inflammation and reduce joint damage. While the immune-regulatory effect of human mesenchymal/stromal stem cells (MSCs) extracellular vesicles (EVs) has been tested in many inflammation-related diseases, little is known regarding their effect on patients with RA. Thus, we assessed the effect of human MSCs and MSC-EVs (from naïve or IFN-β-primed MSCs) on CD4+ T cells from patients with RA. Moreover, we investigated the effect of MSC-EVs on RA patients-derived synovial fibroblasts (FLS). MSC-EVs were prepared using a PEG precipitation followed by ultracentrifugation-based protocol. Applied to RA CD4+ T cells, EVs from IFN-β-primed MSCs, suppressed the expression of more key RA-associated cytokines (IL-4, GM-CSF IFN-γ, IL-2, TNF-α), and decreased CD4+ T-cell polyfunctionality than MSCs or EVs from naïve MSCs. MSCs mediated a slight decrease in the frequency of T-regulatory cells, while MSC-EVs rescued the frequency of T-regulatory cells. MSCs significantly inhibited CD4+ T-cell proliferation (P < .05), while no inhibition was observed in response to EV preparations. EVs from IFN-β-primed MSCs inhibited (P < .01) RA FLS migration and downregulated (P < .05) RA FLS surface markers CD34 and HLA-DR. Collectively, we demonstrated the immune-modulatory function of MSCs and their derived EVs in RA CD4+ T cells, which could be further enhanced by priming MSCs with IFN-β. Moreover, EVs from IFN-β-primed MSCs more efficiently inhibit RA FLS migration, and expression of RA FLS-related surface markers, suggesting these EVs as a potent therapy for RA.
... MSCs engage in immune modulation through a range of mechanisms. They suppress natural killer (NK) cell activation, lessening the activation and fundamental activities of dendritic cells (DC); affect B cell proliferation and functions; and promote regulatory T cell expansion [48][49][50][51]. Another mechanism used by MSCs to immunomodulate the microenvironment around them is by direct cell-to-cell contact or the release of soluble factors. ...
The ability of cancer cells to detach from the primary site and metastasize is the main cause of cancer- related death among all cancer types. Epithelial-to-mesenchymal transition (EMT) is the first event of the metastatic cascade, resulting in the loss of cell–cell adhesion and the acquisition of motile and stem-like phenotypes. A critical modulator of EMT in cancer cells is the stromal tumor microenvironment (TME), which can promote the acquisition of a mesenchymal phenotype through direct interaction with cancer cells or changes to the broader microenvironment. In this review, we will explore the role of stromal cells in modulating cancer cell EMT, with particular emphasis on the function of mesenchymal stromal/stem cells (MSCs) through the activation of EMT-inducing pathways, extra cellular matrix (ECM) remodeling, immune cell alteration, and metabolic rewiring.
... MSCs can inhibit monocyte differentiation from CD34+ HSCs and promote macrophage polarization into an anti-inflammatory M2 phenotype [62,63]. MSCs can affect the differentiation of dendritic cells (DCs) from monocyte precursors [64][65][66]. They could inhibit DC maturation and activation by downregulating the expression of presentation molecules (HLA-DR and CD1a) and costimulatory molecules (CD80 and CD86) in DCs [67,68]. ...
Aplastic anemia (AA), a rare but potentially life-threatening disease, is a paradigm of bone marrow failure syndromes characterized by pancytopenia in the peripheral blood and hypocellularity in the bone marrow. The pathophysiology of acquired idiopathic AA is quite complex. Mesenchymal stem cells (MSCs), an important component of the bone marrow, are crucial in providing the specialized microenvironment for hematopoiesis. MSC dysfunction may result in an insufficient bone marrow and may be associated with the development of AA. In this comprehensive review, we summarized the current understanding about the involvement of MSCs in the pathogenesis of acquired idiopathic AA, along with the clinical application of MSCs for patients with the disease. The pathophysiology of AA, the major properties of MSCs, and results of MSC therapy in preclinical animal models of AA are also described. Several important issues regarding the clinical use of MSCs are discussed finally. With evolving knowledge from basic studies and clinical applications, we anticipate that more patients with the disease can benefit from the therapeutic effects of MSCs in the near future.
... MSCs inhibited myeloid DCs maturation, thereby preventing antigen presentation from DCs to T cells, and also inhibited tumor necrosis factor (TNF) to reduce the proinflammatory potential of DCs [205][206][207][208]. It also induced IL-10 production by pDCs to promote Treg production and inhibit immune system activation, thus contributing to the maintenance of homeostasis and tolerance to autoantigens in vivo [201,209].MSCs suppressed CD8+ cytotoxicity by inhibiting IFN-γ production and proliferation of CD4+ and CD8+ T lymphocytes, keeping T cells in the G0/G1 phase and supporting their survival in that state, and promoted CD4 + CD25+ Treg production by regulating immunosuppressive factors such as PGE2, IL-10, and diamino-2,3-dioxygenase (IDO) [189,[210][211][212]. ...
Mesenchymal stem cells (MSCs), as a kind of pluripotent stem cells, have attracted much attention in orthopedic diseases, geriatric diseases, metabolic diseases, and sports functions due to their osteogenic potential, chondrogenic differentiation ability, and adipocyte differentiation. Anti-inflammation, anti-fibrosis, angiogenesis promotion, neurogenesis, immune regulation, and secreted growth factors, proteases, hormones, cytokines, and chemokines of MSCs have been widely studied in liver and kidney diseases, cardiovascular and cerebrovascular diseases. In recent years, many studies have shown that the extracellular vesicles of MSCs have similar functions to MSCs transplantation in all the above aspects. Here we review the research progress of MSCs and their exocrine vesicles in recent years.
... Moreover, antiinflammatory, antiapoptotic, and immunomodulatory properties were attributed to MSCs [17][18][19]. Mesenchymal stromal cells affect the functions of many types of immune cells, i.e., they inhibit T lymphocyte proliferation, cytotoxicity and cytokine secretion [20,21], proliferation of B lymphocytes, and antibody production [22], and they also suppress IL-2-induced proliferation of resting natural killer cells [23], inhibit maturation and activation of dendritic cells [24,25], and induce the switch in macrophages from proinflammatory M1 to anti-inflammatory M2 phenotype [26]. ...
Facial nerve palsy is a serious neurological condition that strongly affects patient everyday life. Standard treatments provide insufficient improvement and are burdened with the risk of severe complications, e.g., facial synkinesis. Mesenchymal stromal cell-based therapies are a novel and extensively developed field which offers new treatment approaches with promising results in regards to the nervous tissue regeneration. The potential of mesenchymal stromal cells (MSCs) to aid the regeneration of damaged nerves has been demonstrated in several preclinical models, as well as in several clinical trials. However, therapies based on cell transplantation are difficult to standardize in the manner similar to that of routine clinical practices. On the other hand, treatments based on mesenchymal stromal cell secretome harness the proregenerative features of mesenchymal stromal cells but relay on a product with measurable parameters that can be put through standardization procedures and deliver a fully controllable end-product. Utilization of mesenchymal stromal cell secretome allows the controlled dosage and standardization of the components to maximize the therapeutic potential and ensure safety of the end-product.
... The anti-inflammatory effect of MSCs is mostly executed via secretion of various enzymes and soluble factors and their paracrine actions on T lymphocytes, including naïve CD4 + T-cells, Th1 cells, Th2 Cells, Th17 Cells, CD4 + FoxP3 + Regulatory T-Cells (Tregs), and CD8 + T-cells (Mattar and Bieback, 2015). They also have multiple anti-inflammatory effects that include affecting the chemotactic properties of B cells (Corcione et al., 2006), suppressing interleukin-2 (IL-2) induced natural killer (NK) cell activation (Spaggiari et al., 2006), downregulating NK-activating receptors (Yen et al., 2009), and affect functions of myeloid cells such as monocytes (Jiang et al., 2005), dendritic cells (Ramasamy et al., 2007), and macrophages (Ylöstalo et al., 2012; Figure 1). MSCs modulate immune cells by disrupting their activation, proliferation, maturation, cytolytic activity, cytokine production, or antibody production (Gao et al., 2016). ...
Mesenchymal stem cells (MSCs) are multipotent stem cells, whose paracrine and immunomodulatory potential has made them a promising candidate for central nervous system (CNS) regeneration. Numerous studies have demonstrated that MSCs can promote immunomodulation, anti-apoptosis, and axon re-extension, which restore functional neural circuits. The therapeutic effects of MSCs have consequently been evaluated for application in various CNS diseases including spinal cord injury, cerebral ischemia, and neurodegenerative disease. In this review, we will focus on the research works published in the field of mechanisms and therapeutic effects of MSCs in CNS regeneration.
... Les MSC inhibent de façon partiellement réversible la différenciation des monocytes en DC, via la sécrétion de facteurs solubles tels que l'IL6[491] [492][493], le macrophage stimulating factor (M-CSF)[491] [492], la PGE2[494] et le blocage des monocytes dans la phase G1 du cycle cellulaire associé à une diminution de la cycline D2[495].De plus, les MSC modifient le phénotype des DC matures en induisant une diminution de l'expression du marqueur de maturation CD83, de HLA DR, CD1a, des molécules de costimulation CD80 et CD86 et de la sécrétion d'IL12, associée à une perte de leurs fonctions d'allostimulation des lymphocytes T [491] [492]. En effet, les MSC peuvent également altérer la réorganisation du cytosquelette des DC matures les rendant incapables de former une synapse avec les lymphocytes T [496]. ...
Depuis leur première utilisation clinique en 2001 dans l’ostéogénèse imparfaite, l’engouement pour le recours aux cellules stromales mésenchymateuses (MSC) comme approche thérapeutique dans le traitement des désordres dysimmunitaires, en médecine régénératrice et plus récemment dans la prise en charge de patients atteints d’une infection à coronavirus (COVID19) ne cesse d’augmenter. Cependant, des résultats contradictoires dus à la variabilité des procédés de production, à la diversité des patients inclus et des pathologies ciblées perturbent le développement de cette approche thérapeutique. De plus, l’hétérogénéité des MSC elles-mêmes rend difficile leur caractérisation fonctionnelle. Par ailleurs, la phase d’amplification en culture n’est pas associée à un risque de transformation mais peut entraîner une entrée en sénescence qui peut impacter leurs propriétés. Initialement, leur efficacité a été attribuée à leur capacité de différenciation, il est maintenant avéré que c’est leur pouvoir immunorégulateur qui. Dans ce travail, nous avons étudié plusieurs facteurs de variabilité qui jouent un rôle dans l’efficacité thérapeutique des MSC. Tout d’abord, nous avons validé que l’origine tissulaire des MSC impacte fortement leurs propriétés : les MSC dérivées du tissu adipeux ont des fonctions immunorégulatrices plus intéressantes que les MSC dérivées de la moelle osseuse pour leur utilisation thérapeutique. Par ailleurs, nous avons démontré que la capacité à inhiber les lymphocytes T diminue lorsque les MSC entrent en sénescence réplicative en raison d’une augmentation de la dégradation de l’enzyme indoléamine 2,3-dioxygénase par le protéasome. Enfin, nous avons montré que dans un contexte inflammatoire, l’interaction des MSC avec les lymphocytes T CD4 via CD40/CD40L entraîne le recrutement des polynucléaires neutrophiles de façon IL8 dépendante. Ainsi, la source tissulaire, l’amplification en culture et la capacité des MSC à interagir avec les cellules immunitaires sont des paramètres qu’il est important d’évaluer grâce à la mise en place de tests de validation afin d’améliorer l’efficacité des études cliniques.
... MSCs remain at the site of the skin wound, even after the wound has been closed. These cells play a pivotal role in almost all of the processes of inflammation, fibrosis, tissue repair, angiogenesis, wound contraction, scar development, and granulation tissue formation [117][118][119][120]. The studies have shown that mesenchymal stem cells have immunomodulatory effects such as inhibition of proliferation and reduced function in various immune cells, including natural killer (NK) cells, dendritic cells (DC), and lymphocytes [121][122][123]. Mesenchymal stem cells reduce the secretion of inflammatory cytokines [124] and secrete various anti-inflammatory cytokines such as TGFβ, IDO, PGE2, nitric oxide, IL-6, semaphorin-3A, and the Gal-1 and Gal-9 of galactins [125][126][127][128][129][130][131]. ...
Management and treatment of chronic wounds remain a significant problem in clinical practice. Stem cell therapies are an important and promising approach for regenerative medicine because of their self-renewal and differentiation potential. Mesenchymal stem cells (MSCs), a major cellular source for regeneration, are present in almost all tissues. The use of embryonic stem cells is morally controversial because of the need to nurture and destroy embryonic cells. Therefore, adult umbilical cord tissues are of particular importance as an alternative source of perinatal tissues. Wharton Jelly is a gelatinous connective tissue in the umbilical cord containing MSCs that can differentiate into osteogenic, adipose, chondrogenic, and other lineages. These cells do not express the MHC-II molecule and show immunomodulatory properties that make them viable for allogeneic and xenogenic transplants in cell therapy. Therefore, the umbilical cord, especially the part named Wharton's jelly, is an important and promising source of mesenchymal stem cells.
... Immunomodulatory, anti-inflammatory, anti-fibrotic, and anti-microbial effects have been linked to MSCs in many published pre-clinical studies. MSCs are fairly unique cells from an immunological standpoint and their properties enable the MSCs to escape recognition by the immune system, thereby modulating/mediating the T-cell, B-cell, NK, dendritic cell (DC), and macrophage functions [8][9][10][11]. ...
Mesenchymal stem/stromal cells (MSCs) are widely used in disease models in order to control several phases in the response to injuries, immune reaction, wound healing, and regeneration. MSCs can act upon both the innate and adaptive immune systems and target a broad number of functions, such as the secretion of cytokines, proteolytic enzymes, angiogenic factors, and the regulating of cell proliferation and survival. The role of MSCs in coagulation has been less studied. This review evaluates the properties and main functions of MSCs in coagulation. MSCs can regulate coagulation in a wide range of pathways. MSCs express and release tissue factors (TF), one of the key regulators of the extrinsic coagulation pathways; MSCs can trigger platelet production and contribute to platelet activation. Altogether, MSCs seem to have a pro-thrombotic role and their superior characterization prior to their administration is necessary in order to prevent adverse coagulation events.
... Ramasamy et al. found that monocytes were blocked in the G0 phase after co-culturing with MSCs. Additionally, co-culture of mature DCs with MSCs reduced the secretion of IL-12 and downregulated the expression of MHC I and MHC II molecules, cell surface molecule CD83, as well as the costimulatory molecules, thereby interfering with the antigen-presenting ability of DCs [22]. ...
Mesenchymal stem cells (MSCs) are multipotent stem cells with the capacity of self-renewal, homing, and low immunogenicity. These distinct biological characteristics have already shown immense potential in regenerative medicine. MSCs also possess immunomodulatory properties that can maintain immune homeostasis when the immune response is over-activated or under-activated. The secretome of MSCs consists of cytokines, chemokines, signaling molecules, and growth factors, which effectively contribute to the regulation of immune and inflammatory responses. The immunomodulatory effects of MSCs can also be achieved through direct cell contact with microenvironmental factors and immune cells. Furthermore, preconditioned and engineered MSCs can specifically improve the immunomodulation effects in diverse clinical applications. These multifunctional properties of MSCs enable them to be used as a prospective therapeutic strategy to treat immune disorders, including autoimmune diseases and incurable inflammatory diseases. Here we review the recent exploration of immunomodulatory mechanisms of MSCs and briefly discuss the promotion of the genetically engineered MSCs. Additionally, we review the potential clinical applications of MSC-mediated immunomodulation in four types of immune diseases, including systemic lupus erythematosus, Crohn’s disease, graft-versus-host disease, and COVID-19.
... Current evidence from preclinical models and human studies suggest that MSCs influence the immune response in several ways, including inhibition of T-cell proliferation, cytokine production, and cytotoxicity [60,61]; induction and regulation of regulatory T cell (T reg ) [62] and regulatory B cells (B reg ) [63]; induction of IL-10 production [64][65][66][67]; inhibition of B cell proliferation and antibody production [68]; inhibition of antigenpresenting cells [69]; and inhibition of IL-2 mediated natural killer cell activation [70]. ...
Background:
Despite the advances in burn care, severe burns still impose significant morbidity and mortality. Severe burns are associated with an inflammatory response that ranges from alterations in vital signs to shock, multiorgan failure, and death. Mesenchymal stem cells (MSCs) are known for their anti-inflammatory and immunomodulatory effects. Therefore, MSCs were investigated for their potential benefits in modulating burn-induced inflammation and organ damage in several studies.
Aim:
We have conducted a systematic review of the literature to evaluate the efficacy of MSCs in modulating burn-induced systemic inflammation and organ damage in animal models.
Methods:
Four databases were searched: PubMed, Cumulative Index of Nursing and Allied Health Literature, Scopus, and Web of Science. We used the Preferred Reporting Items for Systematic Reviews and Meta-Analysis as our basis of organization.
Results:
Eight studies were included in the study. Bone marrow derived MSCs, umbilical cord derived MSCs (UC-MSCs), and UC-MSCs exosomes were used to modulate the burn-induced inflammation. MSCs therapy reduced serum levels of pro-inflammatory cytokines, improved renal function, inhibited tissue damage, and improved survival after burn. Furthermore, MSCs reversed all the burn-induced pathological changes in blood brain barrier (BBB).
Conclusion:
MSCs may attenuate the burn-induced inflammation by decreasing serum levels of inflammatory cytokines. However, the effect on anti-inflammatory cytokines is conflicting and mandates more substantial evidence. Furthermore, MSCs reduce tissue inflammation, tissue damage, and apoptosis in the lungs and kidneys. In addition, MSCs reversed the burn-induced pathophysiologic changes in the BBB. The underlying mechanisms of these effects are poorly understood and should be the focus of future stem cell research.
Relevance to patients:
Severe burn patients are liable to systemic inflammation due to the release of inflammatory cytokines into the circulation. This inflammatory response has a broad spectrum of severity that ranges from alterations in vital signs to multiorgan failure and death. Despite the advances in burn care, burn-induced inflammation still imposes significant morbidity and mortality. This systematic review evaluates the potential benefits of stem cells in modulating burn-induced systemic inflammation in animal burn models.
... Indeed, MSCs interact with each cellular component of the immune system. MSCs (1) inhibit the antigen-presenting and phagocytic capacity of monocytes/macrophages while inducing their expression of interleukin (IL)-10 and programmed cell death ligand 1 [14]; (2) affect the maturation of dendritic cells and their secretion of pro-inflammatory cytokines [15]; (3) inhibit the proliferation [16] and pro-inflammatory properties of CD4 + T helper (Th)1 and Th17 cells [17], while stimulating the proliferation of regulatory T cells [18]; (4) impair the expansion, cytokine secretion, and cytotoxic activity of CD8 + T cells [16]; (5) inhibit B-cell differentiation, proliferation, and antibody secretion and enhance the generation of IL-10-producing cell subsets [19]. MSC therapy has a proven therapeutic efficacy in the setting of graft versus host disease (GvHD) [20,21]. ...
Background and objectives:
Children with multi-drug resistant idiopathic nephrotic syndrome (MDR-INS) usually progress to end-stage kidney disease with a consistent risk of disease recurrence after transplantation. New therapeutic options are needed for these patients. Mesenchymal stromal cells (MSCs) are multipotential non-hematopoietic cells with several immunomodulatory properties and growing clinical applications. Cord blood-derived MSC have peculiar anti-inflammatory and immunosuppressive properties. We aimed at assessing safety and efficacy of cord-blood-derived MSCs (CB-MSCs) in children with MDR-INS.
Design, setting, participants:
Prospective, open-label, single arm phase I-II pilot study. Pediatric patients with MDR-INS, resistant to at least two lines of therapy, were enrolled. Allogenic CB-MSCs were administered intravenously on days 0, 14, and 21 at a dose of 1.5 × 106 cells/kg. Patients were followed for at least 12 months. The primary outcomes were safety and toxicity. The secondary outcome was remission at 12 months evaluated by urinary protein/urinary creatinine ratio (uPr/uCr). Circulating regulatory T cells (Tregs) were monitored.
Results:
Eleven pediatric patients with MDR-INS (10 females, median age 13 years) resistant to a median of 3 previous lines of therapy were enrolled. All patients completed the CB-MSC infusion schedule. No patient experienced any infusion-related adverse event or toxicity. Nine patients were assessable for efficacy. At the 12 months follow-up after the treatment, the median uPr/uCr did not change significantly from baseline (8.13 vs. 9.07; p = 0.98), while 3 patients were in partial or complete remission. A lower baseline uPr/uCr was a predictor of remission (2.55 vs. 8.74; p = 0.0238). Tregs count was not associated with CB-MSCs therapy.
Conclusions:
CB-MSCs are safe and may have a role in the immunosuppressive therapy of pediatric patients with MDR-INS. This preliminary experience paves the way toward further phase II studies addressing MSC efficacy in immune-mediated kidney diseases.
... With the expression of immunosuppressive ligands such as programmed cell death protein 1 (PD-1) and Fas-ligand on their surface, MSCs can bind receptors on the surface of immune cells and result in loss of function in immune cells [8,9]. MSCs can block the differentiation of monocytes into dendritic cells and impair their antigen-presenting ability [10]. The MSC-mediated inhibitory effects may be dependent on IL-6 and hepatocyte growth factor (HGF) secreted by MSCs, and this effect can induce monocyte-derived cells to produce IL-10, which might indirectly strengthen the suppressive effects of MSCs [11]. ...
The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has been a major public health challenge worldwide. Owing to the emergence of novel viral variants, the risks of reinfections and vaccine breakthrough infections has increased considerably despite a mass of vaccination. The formation of cytokine storm, which subsequently leads to acute respiratory distress syndrome, is the major cause of mortality in patients with COVID-19. Based on results of preclinical animal models and clinical trials of acute lung injury and acute respiratory distress syndrome, the immunomodulatory, tissue repair, and antiviral properties of MSCs highlight their potential to treat COVID-19. This review article summarizes the potential mechanisms and outcomes of MSC therapy in COVID-19, along with the pathogenesis of the SARS-CoV-2 infection. The properties of MSCs and lessons from preclinical animal models of acute lung injury are mentioned ahead. Important issues related to the use of MSCs in COVID-19 are discussed finally.
... MSCs immunomodulatory effect can also be explained by their ability to interfere with the differentiation, the maturation and the function of dendritic cells (DC) (Jiang et al., 2005;Ramasamy et al., 2007). Indeed, MSCs can inhibit antigen presentation by DC via negative regulation of the CD11c, CD83 and MHC Class II DC-cell surface molecules expression (Beyth et al., 2005). ...
Autism spectrum disorder (ASD) represents a set of heterogeneous neurodevelopmental conditions defined by impaired social interactions and repetitive behaviors. The number of reported cases has increased over the past decades, and ASD is now a major public health burden. So far, only treatments to alleviate symptoms are available, with still unmet need for an effective disease treatment to reduce ASD core symptoms. Genetic predisposition alone can only explain a small fraction of the ASD cases. It has been reported that environmental factors interacting with specific inter-individual genetic background may induce immune dysfunctions and contribute to the incidence of ASD. Such dysfunctions can be observed at the central level, with increased microglial cells and activation in ASD brains or in the peripheral blood, as reflected by high circulating levels of pro-inflammatory cytokines, abnormal activation of T-cell subsets, presence of auto-antibodies and of dysregulated microbiota profiles. Altogether, the dysfunction of immune processes may result from immunogenetically-determined inefficient immune responses against a given challenge followed by chronic inflammation and autoimmunity. In this context, immunomodulatory therapies might offer a valid therapeutic option. Mesenchymal stromal cells (MSC) immunoregulatory and immunosuppressive properties constitute a strong rationale for their use to improve ASD clinical symptoms. In vitro studies and pre-clinical models have shown that MSC can induce synapse formation and enhance synaptic function with consequent improvement of ASD-like symptoms in mice. In addition, two preliminary human trials based on the infusion of cord blood-derived MSC showed the safety and tolerability of the procedure in children with ASD and reported promising clinical improvement of core symptoms. We review herein the immune dysfunctions associated with ASD provided, the rationale for using MSC to treat patients with ASD and summarize the current available studies addressing this subject.
... MPCs are also believed to play a regulatory role during an immune response (Uccelli et al. 2008). Evidence suggests that MPCs inhibit the pro-inflammatory activity of various innate immune cells, such as natural killer cells, dendritic cells, and neutrophils, modulating their ability to generate and perpetuate a chronic inflammatory response (Jiang et al. 2005;Nauta et al. 2006;Ramasamy et al. 2007;Almeida-Porada et al. 2020). MPCs also suppress the activity of adaptive immune cells (Bartholomew et al. 2002;Di Nicola et al. 2002;Aggarwal and Pittenger 2005), yet can upregulate major histocompatibility complex II expression to promote the production of alloantibodies (Almeida-Porada et al. 2020). ...
Mesenchymal progenitor cells (MPCs) have been recently identified in human and murine epidural fat and have been hypothesized to contribute to the maintenance/repair/regeneration of the dura mater. MPCs can secrete proteoglycan 4 (PRG4/lubricin), and this protein can regulate tissue homeostasis through bio-lubrication and immunomodulatory functions. MPC lineage tracing reporter mice (Hic1) and human epidural fat MPCs were used to determine if PRG4 is expressed by these cells in vivo. PRG4 expression co-localized with Hic1⁺ MPCs in the dura throughout skeletal maturity and was localized adjacent to sites of dural injury. When Hic1⁺ MPCs were ablated, PRG4 expression was retained in the dura, yet when Prx1⁺ MPCs were ablated, PRG4 expression was completely lost. A number of cellular processes were impacted in human epidural fat MPCs treated with rhPRG4, and human MPCs contributed to the formation of epidural fat, and dura tissues were xenotransplanted into mouse dural injuries. We have shown that human and mouse MPCs in the epidural/dura microenvironment produce PRG4 and can contribute to dura homeostasis/repair/regeneration. Overall, these results suggest that these MPCs have biological significance within the dural microenvironment and that the role of PRG4 needs to be further elucidated.
... Immunomodulatory functions of MSCs could be due to both cellÀcell interactions and secretion of soluble factors such as cytokines and chemokines [7]. MSCs are known to directly interact with immune cells such as T and B cells, dendritic cells (DCs) and natural killer (NK) cells and alter their function by inhibiting the proliferation of T and B lymphocytes, inhibiting maturation of dendritic cells and polarizing the macrophages from proinflammatory (M1 phenotype) to anti-inflammatory (M2) or tolerogenic phenotype [8,9]. It has been shown that they exert immunomodulatory functions under stimulated conditions in which their microenvironment, including inflammatory conditions, plays a crucial role in effecting their immunomodulatory functions [10À14]. ...
Mesenchymal stromal cells (MSCs) are very advantageous in the field of regenerative medicine because of
their immunomodulatory properties. However, reports show that these properties vary from source to
source. Hence, understanding the source-dependent specificity of MSCs and their immunomodulatory abili�ties will enable optimal use of MSCs in cell-based therapies. Here, we studied human MSCs from three differ�ent sources, adipose tissue (AT), bone marrow (BM) and Wharton’s jelly (WJ), with respect to phenotypic
responses of human peripheral blood mononuclear immune cells (hPBMCs/MNCs) and the concurrent
changes in cytokine expression in MSCs, under mitogen-stimulated co-culture conditions. We used cytomet�ric analysis to study the immunoregulatory properties of MSCs on MNCs and cytokine profiling of MSCs using
a customized PCR array and solid-phase sandwich enzyme-linked immunosorbent assay. Our results reveal
differential modulation of immune cells as well as MSCs upon activation by the mitogen phytohemaggluti�nin, independently and in co-culture. Notably, we observed source-specific MSC-cytokine signatures under
stimulated conditions. Our results show that AT-MSCs up-regulate VEGF, BM-MSCs up-regulate PTGS-2 and
WJ-MSCs increase expression of IDO considerably compared with controls. This remarkable modulation in
source-specific cytokine expression was also validated at a functional level by quantitative protein expres�sion studies. In our hands, even though MSCs from AT, BM and WJ sources exhibit characteristic immuno�modulatory properties, our results highlight that MSCs sourced from different tissues may exhibit unique
cytokine signatures and thus may be suitable for specific regenerative applications.
... Immunomodulatory functions of MSCs could be due to both cellÀcell interactions and secretion of soluble factors such as cytokines and chemokines [7]. MSCs are known to directly interact with immune cells such as T and B cells, dendritic cells (DCs) and natural killer (NK) cells and alter their function by inhibiting the proliferation of T and B lymphocytes, inhibiting maturation of dendritic cells and polarizing the macrophages from proinflammatory (M1 phenotype) to anti-inflammatory (M2) or tolerogenic phenotype [8,9]. It has been shown that they exert immunomodulatory functions under stimulated conditions in which their microenvironment, including inflammatory conditions, plays a crucial role in effecting their immunomodulatory functions [10À14]. ...
Mesenchymal stromal cells (MSCs) are very advantageous in the field of regenerative medicine because of their immunomodulatory properties. However, reports show that these properties vary from source to source. Hence, understanding the source-dependent specificity of MSCs and their immunomodulatory abilities will enable optimal use of MSCs in cell-based therapies. Here, we studied human MSCs from three different sources, adipose tissue (AT), bone marrow (BM) and Wharton's jelly (WJ), with respect to phenotypic responses of human peripheral blood mononuclear immune cells (hPBMCs/MNCs) and the concurrent changes in cytokine expression in MSCs, under mitogen-stimulated co-culture conditions. We used cytomet-ric analysis to study the immunoregulatory properties of MSCs on MNCs and cytokine profiling of MSCs using a customized PCR array and solid-phase sandwich enzyme-linked immunosorbent assay. Our results reveal differential modulation of immune cells as well as MSCs upon activation by the mitogen phytohemaggluti-nin, independently and in co-culture. Notably, we observed source-specific MSC-cytokine signatures under stimulated conditions. Our results show that AT-MSCs up-regulate VEGF, BM-MSCs up-regulate PTGS-2 and WJ-MSCs increase expression of IDO considerably compared with controls. This remarkable modulation in source-specific cytokine expression was also validated at a functional level by quantitative protein expression studies. In our hands, even though MSCs from AT, BM and WJ sources exhibit characteristic immuno-modulatory properties, our results highlight that MSCs sourced from different tissues may exhibit unique cytokine signatures and thus may be suitable for specific regenerative applications.
... Indeed, MSCs interact with each cellular component of the immune system. MSCs 1) inhibit the antigen-presenting and phagocytic capacity of monocytes/macrophages while inducing their expression of interleukin (IL)-10 and programmed cell death ligand 1 14 ; 2) affect the maturation of dendritic cells and their secretion of proin ammatory cytokines 15 ; 3) inhibit the proliferation 16 and pro-in ammatory properties of CD4 + T helper (Th)1 and Th17 cells 17 , while stimulating the proliferation of regulatory T cells 18 ; 4) impair the expansion, cytokine secretion, and cytotoxic activity of CD8 + T cells 16 ; 5) inhibit B-cell differentiation, proliferation, and antibody secretion and enhance the generation of IL-10-producing cell subsets 19 . MSC therapy has a proven therapeutic e cacy in the setting of graft versus host disease (GvHD) 20,21 . ...
Background and objectives. Children with multi-drug resistant idiopathic nephrotic syndrome (MDR-INS) usually progress to end-stage kidney disease with a consistent risk of disease recurrence after transplantation. New therapeutic options are needed for these patients. Mesenchymal stromal cells (MSCs) are multipotential non-hematopoietic cells with several immunomodulatory properties and growing clinical applications. Cord blood-derived MSC have peculiar anti-inflammatory and immunosuppressive properties.
We aimed at assessing safety and efficacy of cord-blood derived MSCs (CB-MSCs) in children with MDR-INS.
Design, setting, participants. Prospective, open-label, single arm phase I-II pilot study. Pediatric patients with MDR-INS, resistant to at least two lines of therapy, were enrolled. Allogenic CB-MSCs were administered intravenously on days 0, 14, and 21 at a dose of 1.5 x 10⁶ cells/kg. Patients were followed for at least 12 months. The primary outcomes were safety and toxicity. The secondary outcome was remission at 12 months evaluated by urinary protein/urinary creatinine ratio (uPr/uCr). Circulating regulatory T cells (Tregs) were monitored.
Results. Eleven pediatric patients with MDR-INS (10 females, median age 13 years) resistant to a median of 3 previous lines of therapy were enrolled. All patients completed the CB-MSC infusion schedule. No patient experienced any infusion-related adverse event or toxicity.
Nine patients were assessable for efficacy. At the 12 months follow-up after the treatment, the median uPr/uCr did not change significantly from baseline (8.13 vs 9.07; p = 0.98), while 3 patients were in partial or complete remission. A lower baseline uPr/uCr was a predictor of remission (2.55 vs 8.74; p = 0.0238). Tregs count was not associated with CB-MSCs therapy.
Conclusions CB-MSCs are safe and may have a role in the immunosuppressive therapy of pediatric patients with MDR-INS. This preliminary experience paves the way towards further phase II studies addressing MSC efficacy in immune mediated kidney diseases.
... There are many reports that MSCs can affect the immune system by interacting with myeloid and lymphoid cells [6]. It has recently been shown that they can inhibit activity B cells [7][8][9], T cells [8][9][10][11], NK cells [12], dendritic cells [13,14], and macrophages [9] through direct cell-to-cell interaction and secretion of soluble factors including prostaglandin E2 (PGE2), indoleamine-2,3-dioxygenase (IDO), and transforming growth factor-beta (TGF-β) [15][16][17][18]. MSCs due to regulate the immune system can reduce GVHD in allogeneic HSCT [19,20]. ...
Natural killer cells (NK cells) are innate immune cells that are activated to fight tumor cells and virus-infected cells. NK cells also play an important role in the graft versus leukemia response. However, they can over-develop inflammatory reactions by secreting inflammatory cytokines and increasing Th1 differentiation, eventually leading to tissue damage. Today, researchers have attributed some autoimmune diseases and GVHD to NK cells. On the other hand, it has been shown that mesenchymal stem cells (MSCs) can modulate the activity of NK cells, while some researchers have shown that NK cells can cause MSCs to lysis. Therefore, we considered it is necessary to investigate the effect of these two cells and their signaling pathway in contact with each other, also their clinical applications.
... Particularly, BM-MSCs can suppress the expression of CD4 and CD8 by mononuclear cells and induce IL-6, IL-10, and TGF-b1 secretion [23], inhibit proliferation of B-lymphocytes and impair the secretion of immunoglobulins (IgM, IgG, IgA) [24]. Moreover, BM-MSCs have been reported to prevent the differentiation of monocytes into dendritic cells and to affect their antigen-presenting capacity [25]. ...
An in-vitro model of human bone marrow mesenchymal stem cells (hBM-MSCs) myogenic commitment by synergic effect of a differentiation media coupled with human primary skeletal myoblasts (hSkMs) co-culture was developed adopting both conventional static co-seeding and perfused culture systems. Static co-seeding provided a notable outcome in terms of gene expression with a significant increase of Desmin (141-fold) and Myosin heavy chain II (MYH2, 32-fold) at day 21, clearly detected also by semi-quantitative immunofluorescence. Under perfusion conditions, myogenic induction ability of hSkMs on hBM-MSCs was exerted by paracrine effect with an excellent gene overexpression and immunofluorescence detection of MYH2 protein; furthermore, due to the dynamic cell culture in separate wells, western blot data were acquired confirming a successful cell commitment at day 14. A significant increase of anti-inflammatory cytokine gene expression, including IL-10 and IL-4 (15-fold and 11-fold, respectively) at day 14, with respect to the pro-inflammatory cytokines IL-12A (7-fold at day 21) and IL-1β (1.4-fold at day 7) was also detected during dynamic culture, confirming the immunomodulatory activity of hBM-MSCs along with commitment events. The present study opens interesting perspectives on the use of dynamic culture based on perfusion as a versatile tool to study myogenic events and paracrine cross-talk compared to the simple co-seeding static culture.
... Inspired by this work, the immunomodulation effects of MSC have been extensively explored [17]. So far, apart from affecting lymphocytes proliferation, it has been shown that MSCs mediate immune response through a variety of ways, including inhibiting the activation of nature killer (NK) cells [18], repressing the activation as well as [19], modulating proliferation and functions of B cells [20], and inducing the expansion of regulatory T cells [21]. Furthermore, the immunomodulatory potentials of MSCs are exerted by direct cell-to-cell contact or paracrine secretion of soluble factors [22]. ...
The multipotent mesenchymal stem/stromal cells (MSCs), initially discovered from bone marrow in 1976, have been identified in nearly all tissues of human body now. The multipotency of MSCs allows them to give rise to osteocytes, chondrocytes, adipocytes, and other lineages. Moreover, armed with the immunomodulation capacity and tumor-homing property, MSCs are of special relevance for cell-based therapies in the treatment of cancer. However, hampered by lack of knowledge about the controversial roles that MSC plays in the crosstalk with tumors, limited progress has been made with regard to translational medicine. Therefore, in this review, we discuss the prospects of MSC-associated anticancer strategies in light of therapeutic mechanisms and signal transduction pathways. In addition, the clinical trials designed to appraise the efficacy and safety of MSC-based anticancer therapies will be assessed according to published data.
... Immunomodulatory functions of MSCs could be due to both cellÀcell interactions and secretion of soluble factors such as cytokines and chemokines [7]. MSCs are known to directly interact with immune cells such as T and B cells, dendritic cells (DCs) and natural killer (NK) cells and alter their function by inhibiting the proliferation of T and B lymphocytes, inhibiting maturation of dendritic cells and polarizing the macrophages from proinflammatory (M1 phenotype) to anti-inflammatory (M2) or tolerogenic phenotype [8,9]. It has been shown that they exert immunomodulatory functions under stimulated conditions in which their microenvironment, including inflammatory conditions, plays a crucial role in effecting their immunomodulatory functions [10À14]. ...
Mesenchymal stromal cells (MSCs) are very advantageous in the field of regenerative medicine because of their immunomodulatory properties. However, reports show that these properties vary from source to source. Hence, understanding the source-dependent specificity of MSCs and their immunomodulatory abilities will enable optimal use of MSCs in cell-based therapies. Here, we studied human MSCs from three different sources, adipose tissue (AT), bone marrow (BM) and Wharton's jelly (WJ), with respect to phenotypic responses of human peripheral blood mononuclear immune cells (hPBMCs/MNCs) and the concurrent changes in cytokine expression in MSCs, under mitogen-stimulated co-culture conditions. We used cytometric analysis to study the immunoregulatory properties of MSCs on MNCs and cytokine profiling of MSCs using a customized PCR array and solid-phase sandwich enzyme-linked immunosorbent assay. Our results reveal differential modulation of immune cells as well as MSCs upon activation by the mitogen phytohemagglutinin, independently and in co-culture. Notably, we observed source-specific MSC-cytokine signatures under stimulated conditions. Our results show that AT-MSCs up-regulate VEGF, BM-MSCs up-regulate PTGS-2 and WJ-MSCs increase expression of IDO considerably compared with controls. This remarkable modulation in source-specific cytokine expression was also validated at a functional level by quantitative protein expression studies. In our hands, even though MSCs from AT, BM and WJ sources exhibit characteristic immunomodulatory properties, our results highlight that MSCs sourced from different tissues may exhibit unique cytokine signatures and thus may be suitable for specific regenerative applications.
... In other studies, investigators have demonstrated that MSC transplantation can reduce fibrosis in the heart, lung, liver, and kidney in experimental animal models [38][39][40][41][42][43] . Along with having anti-inflammatory properties, MSCs can inhibit the proliferative effects of monocytes, tumor cells, and cardiac fibroblasts [44][45][46][47] . ...
Background:
Hemodialysis arteriovenous fistulas (AVFs) are the preferred vascular access for patients on hemodialysis. In the Hemodialysis Fistula Maturation Study, 44% of the patients achieved unassisted maturation of their fistula without needing an intervention. Venous neointimal hyperplasia (VNH) and subsequent venous stenosis are responsible for lack of maturation. There are no therapies that can prevent VNH/VS formation. The goal of this paper is to present the background, rationale, and trial design of an innovative phase 1/2 clinical study that is investigating the safety of autologous adipose-derived mesenchymal stem cells delivered locally to the adventitia of newly created upper extremity radiocephalic (RCF) or brachiocephalic fistula (BCF).
Methods:
The rationale and preclinical studies used to obtain a physician-sponsored investigational new drug trial are discussed. The trial design and end points are discussed.
Results:
This is an ongoing trial that will complete this year.
Conclusion:
This is a phase 1/2 single-center, randomized trial that will investigate the safety and efficacy of autologous AMSCs in promoting maturation in new upper-extremity AVFs.Clinical Trial registration number: NCT02808208.
... In both the DCs differentiation [50] and lymphocyte proliferation [51] experiments, MSC can directly cause irreversible cell cycle arrest at the G0/G1 phase. Another mechanism is related to the secretion of IL6 [38]. ...
A comparative analysis of the cell surface markers and immunological properties of cell cultures originating from normal endometrium and endometrioid heterotopias of women with extragenital endometriosis was carried out. Both types of cell cultures expressed surface molecules typical of mesenchymal stromal cells and did not express hematopoietic and epithelial markers. Despite similar phenotype, the mesenchymal stromal cells derived from the two sources had different immunomodulation capacities: the cells of endometrioid heterotopias but not eutopic endometrium could suppress dendritic cell differentiation from monocytes as well as lymphocyte proliferation in allogeneic co-cultures. A comparative multiplex analysis of the secretomes revealed a significant increase in the secretion of pro-inflammatory mediators, including IL6, IFN-γ, and several chemokines associated with inflammation by the stromal cells of ectopic lesions. The results demonstrate that the stromal cells of endometrioid heterotopias display enhanced pro-inflammatory and immunosuppressive activities, which most likely impact the pathogenesis and progression of the disease.
... Early experiments showed that MSCs decreased ability of co-cultured dendritic cells (DCs) to stimulate T cells, including in an allostimulatory context (72). Further experimentation showed that this effect was in part due to the inhibition of DCs from entering the cell cycle (73) and potentially mediated by the soluble factors IL-6, IL-10, and hepatocyte growth factor (74). Additionally, MSC conditioned DCs have been shown to preference the generation of Treg via a CCL18 dependent mechanism (75). ...
Donor specific transfusions have been the basis of tolerance inducing protocols since Peter Medawar showed that it was experimentally feasible in the 1950s. Though trials of cellular therapies have become increasingly common in solid organ transplantation, they have not become standard practice. Additionally, whereas some protocols have focused on cellular therapies as a method for donor antigen delivery—thought to promote tolerance in and of itself in the correct immunologic context—other approaches have alternatively focused on the intrinsic immunosuppressive properties of the certain cell types with less emphasis on their origin, including mesenchymal stem cells, regulatory T cells, and regulatory dendritic cells. Regardless of intent, all cellular therapies must contend with the potential that introducing donor antigen in a new context will lead to sensitization. In this review, we focus on the variety of cellular therapies that have been applied in human trials and non-human primate models, describe their efficacy, highlight data regarding their potential for sensitization, and discuss opportunities for cellular therapies within our current understanding of the immune landscape.
... MSCs have been widely used to treat animal model of DN in the last decade because multiple studies showed that MSCs reduce the expression of MHC class II, CD40, and CD86 costimulatory molecules on mature DCs, which is responsible for a decrease in T cell proliferation [71][72][73][74][75] and inhibit kidney damage through decreasing inflammatory conditions induced by high glucose [76,77]. However, the potential protective mechanisms for MSC-based therapy associated with DCs in DN remain obscure. ...
Diabetic nephropathy (DN) is one of the most significant microvascular complications in diabetic patients. DN is the leading cause of end-stage renal disease, accounting for approximately 50% of incident cases. The current treatment options, such as optimal control of hyperglycemia and elevated blood pressure, are insufficient to prevent its progression. DN has been considered as a nonimmune, metabolic, or hemodynamic glomerular disease initiated by hyperglycemia. However, recent studies suggest that DN is an inflammatory disease, and immune cells related with innate and adaptive immunity, such as macrophage and T cells, might be involved in its development and progression. Although it has been revealed that kidney dendritic cells (DCs) accumulation in the renal tissue of human and animal models of DN require activated T cells in the kidney disease, little is known about the function of DCs in DN. In this review, we describe kidney DCs and their subsets, and the role in the pathogenesis of DN. We also suggest how to improve the kidney outcomes by modulating kidney DCs optimally in the patients with DN.
... MSCs can also arrest B cell cycling and inhibit their division and antibody production (Corcione et al., 2006). Moreover, MSCs affect natural killer cells and dendritic cells by inhibiting their activation and maturation (Ramasamy et al., 2007;Burchell et al., 2010), and exert immunosuppressive activity by modulation of regulatory T cell function (Selmani et al., 2008). Several MSCs-derived soluble factors including transforming growth factor (TGF)-β1, prostaglandin E2 (PGE2), hepatocyte growth factor (HGF), indoleamine-pyrrole 2,3dioxygenase, NO, and IL-10 have been proposed to mediate the immunosuppressive effects of MSCs (Gao et al., 2016). ...
Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system characterized by demyelination and axonal degeneration. MS patients typically present with a relapsing-remitting (RR) disease course, manifesting as sporadic attacks of neurological symptoms including ataxia, fatigue, and sensory impairment. While there are several effective disease-modifying therapies able to address the inflammatory relapses associated with RRMS, most patients will inevitably advance to a progressive disease course marked by a gradual and irreversible accrual of disabilities. Therapeutic intervention in progressive MS (PMS) suffers from a lack of well-characterized biological targets and, hence, a dearth of successful drugs. The few medications approved for the treatment of PMS are typically limited in their efficacy to active forms of the disease, have little impact on slowing degeneration, and fail to promote repair. In looking to address these unmet needs, the multifactorial therapeutic benefits of stem cell therapies are particularly compelling. Ostensibly providing neurotrophic support, immunomodulation and cell replacement, stem cell transplantation holds substantial promise in combatting the complex pathology of chronic neuroinflammation. Herein, we explore the current state of preclinical and clinical evidence supporting the use of stem cells in treating PMS and we discuss prospective hurdles impeding their translation into revolutionary regenerative medicines.
Ongoing research on cellular heterogeneity of Cancer stem cells (CSCs) and its synergistic involvement with tumor milieu reveals enormous complexity, resulting in diverse hindrance in immune therapy. CSCs has captured attention for their contribution in shaping of tumor microenvironment and as target for therapeutic intervention. Recent studies have highlighted cell-extrinsic and intrinsic mechanisms of reciprocal interaction between tumor stroma constituents and CSCs. Therapeutic targeting requires an in-depth understanding of the underlying mechanisms involved with the rate limiting factors in tumor aggressiveness and pinpoint role of CSCs. Some of the major constituents of tumor microenvironment includes resident and infiltrating immune cell, both innate and adaptive. Some of these immune cells play crucial role as adjustors of tumor immune response. Tumor-adjustor immune cell interaction confer plasticity and features enabling tumor growth and metastasis in one hand and on the other hand blunts anti-tumor immunity. Detail understanding of CSC and TME resident immune cells interaction can shape new avenues for cancer immune therapy. In this review, we have tried to summarize the development of knowledge on cellular, molecular and functional interaction between CSCs and tumor microenvironment immune cells, highlighting immune-mediated therapeutic strategies aimed at CSCs. We also discussed developing a potential CSC and TME targeted therapeutic avenue.
Over 20 years of intensified research in the field of stem cells brought about unprecedented possibilities in treating heart diseases. The investigators were initially fascinated by the idea of regenerating the lost myocardium and replacing it with new functional cardiomyocytes, but this was extremely challenging. However, the multifactorial effects of stem cell-based therapies beyond mere cardiomyocyte generation, caused by paracrine signaling, would open up new possibilities in treating cardiovascular diseases. To date, there is a strong body of evidence that the anti-inflammatory, anti-apoptotic, and immunomodulatory effects of stem cell therapy may alleviate atherosclerosis progression. In the present review, our objective is to provide a brief overview of the stem cell-based therapeutic options. We aim to delineate the pathophysiological mechanisms of their beneficial effects in cardiovascular diseases especially in coronary artery disease and to highlight some conclusions from important clinical studies in the field of regenerative medicine in cardiovascular diseases and how we could further move onwards.
The jaw periosteal tissue is generally recognized as a suitable source for the isolation of mesenchymal stem cells (MSCs). In previous studies we showed evidence that two- and three-dimensionally cultured jaw periosteum-derived MSCs (JPCs) are able to induce a more immature phenotype of dendritic cells (DCs). To further expand our knowledge of JPCs’ immunoregulative function, we investigated the effects of JPC secretomes derived from undifferentiated (CO) or osteogenically differentiated cells (treated with or without dexamethasone: OB+/-D) on CD14⁺ monocyte-derived DCs (MoDCs). We detected a remarkably reduced formation of MoDC homotypic clusters under the influence of secretomes from osteogenically induced JPCs. Further, significantly decreased numbers of CD83⁺ cells, up-regulated CD209 and down-regulated CD80, CD86 and CD197 expression levels were detected on the surface of MoDCs. Whereas secretomes from JPCs osteogenically stimulated with dexamethasone significantly enhanced FITC-dextran uptake capacity of MoDCs, the increase by secretomes of JPCs treated without dexamethasone did not reach significance. The analysis of mixed lymphocyte reactions revealed that OB+/-D secretomes were able to significantly reduce the numbers of proliferating CD14⁻ peripheral blood mononuclear cells (PBMCs) and of proliferating CD4⁺ T cells. The OB-D secretome significantly promoted the expansion of regulatory CD25⁺ T cells. Regarding gene expression of MoDCs, remarkably up-regulated mRNA expression of CD209, HLA-DRA, CSF3, IL10 and IL8 was detected when DCs were cultured in the presence of OB+/-D secretomes. At the same time, secretomes seemed to have an impact in the down-regulation of IFNγ and IL12B gene expression. At protein level, OB+/-D secretomes significantly up-regulated IL-10 and IDO (indoleamine-pyrrole 2,3-dioxygenase) levels whereas IL-12/IL-23p40 levels were down-regulated in supernatants of MoDCs when cultured under the presence of OB+/-D secretomes. Taken together, while secretomes from untreated JPCs had only little effects on the process of maturation of MoDCs, secretomes derived from osteogenically induced JPCs were able to inhibit the phenotypic and functional maturation of MoDCs.
Mesenchymal stromal cells (MSCs) are multipotent cells showing promise in pre-clinical studies and currently used in many clinical trials. The regenerative potential of MSCs is mediated, at least in part, by direct and indirect immunomodulatory processes. However, the mechanism of action is not fully understood yet, and there are still concerns about possible undesired negative effects associated with the administration of living cells. In this study, we (i) compare the long-term fate and safety of umbilical cord (UC-)MSCs administered to immunocompetent and immunocompromised (severe combined immunodeficient (SCID) and non-obese diabetic (NOD)/SCID) animals, and (ii) investigate the immunological response of the host to the administered cells. Intravenous administration of firefly luciferase expressing UC-MSCs revealed that the cells get trapped in the lungs of both immunocompetent and immunocompromised animals, with > 95% of the cells disappearing within 72 h after administration. In 27% of the SCID and 45% of the NOD/SCID, a small fraction of the cells lived up to day 14 but in most cases they all disappeared earlier. One NOD/SCID mouse showed a weak signal up to day 31. Immunocompetent mice displayed elevated percentages of neutrophils in the lungs, the blood, and the spleen 2 h after the administration of the cells. The concentration of neutrophil chemoattractants (MCP1, CCL7, Gro-α and IP-10) were also increased in the plasma of the animals 2 h after the administration of the MSCs. Our results suggest that although the UC-MSCs are short-lived in mice, they still result in an immunological response that might contribute to a therapeutic effect.
Co-culture of primary or mesenchymal stem cells (MSC) with M2 macrophages produces a very special conditioned medium with a recognizable and stable cytokine pattern (PRS CK STORM), independent of the donor, with unique anti-inflammatory properties. This product can regulate certain pathways of inflammation in an anti-inflammatory manner, including TLR3, TLR4, the inflammasome, and the purinergic system. The anti-inflammatory action of PRS CK STORM is demonstrated both by its composition and by its action in in vitro and in vivo inflammatory models. The study of the mechanism of action showed changes in the pattern of toll-like receptors (TLR) and purinergic receptors, with an increase in the relative expression of mRNA encoding A2a and A3 receptors, together with a decrease in the relative expression of mRNA encoding P2X7 receptors. Second, it mitigated the adverse effects of a systemic inflammatory process in mice, especially in comparison with a known anti-inflammatory drug (Anakinra). Thus, due to its profile in terms of biosafety and efficacy, PRS CK STORM may be a strong candidate to treat inflammatory processes, such as cytokine storm associated with severe infectious processes, including COVID-19.
Heterogeneity of bone marrow mesenchymal stromal cells (MSCs, frequently referred to as “mesenchymal stem cells”) clouds biological understanding and hampers their clinical development. In MSC cultures most commonly used in research and therapy, we have identified an MSC subtype characterized by CD317 expression (CD317pos (29.77 ± 3.00% of the total MSC population), comprising CD317dim (28.10 ± 4.60%) and CD317bright (1.67 ± 0.58%) MSCs) and a constitutive interferon signature linked to human disease. We demonstrate that CD317pos MSCs induced cutaneous tissue damage when applied a skin explant model of inflammation, whereas CD317neg MSCs had no effect. Only CD317neg MSCs were able to suppress proliferative cycles of activated human T cells in vitro, whilst CD317pos MSCs increased polarization towards pro-inflammatory Th1 cells and CD317neg cell lines did not. Using an in vivo peritonitis model, we found that CD317neg and CD317pos MSCs suppressed leukocyte recruitment but only CD317neg MSCs suppressed macrophage numbers. Using MSC-loaded scaffolds implanted subcutaneously in immunocompromised mice we were able to observe tissue generation and blood vessel formation with CD317neg MSC lines, but not CD317pos MSC lines. Our evidence is consistent with the identification of an immune stromal cell, which is likely to contribute to specific physiological and pathological functions and influence clinical outcome of therapeutic MSCs.
Intercellular communication between monocytes/macrophages and cells involved in tissue regeneration, such as mesenchymal stromal cells (MSCs) and primary tissue cells, is essential for tissue regeneration and recovery of homeostasis. Typically, in the final phase of the inflammationresolving process, this intercellular communication drives an anti-inflammatory immunomodulatory response. To obtain a safe and effective treatment to counteract the cytokine storm associated with a disproportionate immune response to severe infections, including that associated with COVID-19, by means of naturally balanced immunomodulation, our group has standardized the production under GMP-like conditions of a secretome by coculture of macrophages and MSCs. To characterize this proteome, we determined the expression of molecules related to cellular immune response and tissue regeneration, as well as its possible toxicity and anti-inflammatory potency. The results show a specific molecular pattern of interaction between the two cell types studied, with an anti-inflammatory and regenerative profile. In addition, the secretome is not toxic by itself on human PBMC or on THP-1 monocytes and prevents lipopolysaccharide (LPS)-induced growth effects on those cell types. Finally, PRS CK STORM prevents LPS-induced TNF-A and IL-1B secretion from PBMC and from THP-1 cells at the same level as hydrocortisone, demonstrating its anti-inflammatory potency.
Autoimmune diseases (ADs) are characterized by the activation of the immune system against self-antigens. More common in women than in men and with an early onset, their incidence is increasing worldwide, and this, combined with their chronic nature, is contributing to an enlarged medical and economic burden. Conventional immunosuppressive agents are designed to alleviate symptoms but do not constitute an effective therapy, highlighting a need to develop new alternatives. In this regard, mesenchymal stem cells (MSCs) have demonstrated powerful immunosuppressive and regenerative effects. MSC-derived extracellular vesicles (MSC-EVs) have shown some advantages, such as less immunogenicity, and are proposed as novel therapies for ADs. In this review, we summarize current perspectives on therapeutic options for ADs based on MSCs and MSC-EVs, focusing particularly on their mechanism of action exerted through their non-coding RNA (ncRNA) cargo. A complete state-of-the-art review was performed, centralized on some of the most severe ADs (rheumatoid arthritis, autoimmune type 1 diabetes mellitus, and systemic lupus erythematosus), giving evidence that a promising field is evolving to overcome the current knowledge and provide new therapeutic possibilities centered on MSC-EVs and their role as ncRNA delivery vehicles for AD gene therapy.
Mesenchymal stromal cell (MSC) heterogeneity clouds biological understanding and hampers their clinical development. In MSC cultures most commonly used in research and therapy, we have identified an MSC subtype characterised by CD317 expression (CD317 pos ) (29.77±3.00% of the total MSC population), comprising CD317 dim (28.10±4.60%) and CD317 bright (1.67±0.58%) MSCs) and a constitutive interferon signature linked to human disease. We demonstrate that CD317 pos MSCs induced cutaneous tissue damage when applied a skin explant model of inflammation, whereas CD317 neg MSCs had no effect. Only CD317 neg MSCs were able to suppress proliferative cycles of activated human T cells in vitro , whilst CD317 pos MSCs increased polarisation towards pro-inflammatory Th1 cells and CD317 neg cell lines did not. Using an in vivo peritonitis model, we found that CD317 neg and CD317 pos MSCs suppressed leukocyte recruitment but only CD317 neg MSCs suppressed macrophage numbers. Using MSC-loaded scaffolds implanted subcutaneously in immunocompromised mice we were able to observe tissue generation and blood vessel formation with CD317 neg MSC lines, but not CD317 pos MSC lines. Our evidence is consistent with the identification of an immune stromal cell, which is likely to contribute to specific physiological and pathological functions and influence clinical outcome of therapeutic MSCs.
Critical bone defects and related delayed union and nonunion are still worldwide problems to be solved. Bone tissue engineering is mainly aimed at achieving satisfactory bone reconstruction. Mesenchymal stem cells (MSCs) are a kind of pluripotent stem cells that can differentiate into bone cells and can be used as one of the key pillars of bone tissue engineering. In recent decades, immune responses play an important role in bone regeneration. Innate immune responses provide a suitable inflammatory microenvironment for bone regeneration and initiate bone regeneration in the early stage of fracture repair. Adaptive immune responses maintain bone regeneration and bone remodeling. MSCs and immune cells regulate each other. All kinds of immune cells and secreted cytokines can regulate the migration, proliferation, and osteogenic differentiation of MSCs, which have a strong immunomodulatory ability to these immune cells. This review mainly introduces the interaction between MSCs and immune cells on bone regeneration and its potential mechanism, and discusses the practical application in bone tissue engineering by modulating this kind of cell-to-cell crosstalk. Thus, an in-depth understanding of these principles of bone immunology can provide a new way for bone tissue engineering.
Background
Allogeneic hematopoietic stem cell transplantation (Allo-HSCT) has been increasingly used as a therapeutic approach for hematological malignancies. Several potential strategies have been developed for treating or preventing allo-HSCT complications, specifically graft-versus-host disease (GVHD). GVHD could significantly affect the morbidity and mortality of patients after allo-HSCT. Curative treatment and prophylaxis regimens for GVHD could reduce GVHD incidence and improve survival rate. Among these therapeutic strategies, mesenchymal stem cell (MSCs) mediated immunomodulation has been explored widely in clinical trials. MSCs immunomodulation ability in GVHD correlates with the interactions of MSCs with innate and adaptive immune cells. However, signaling pathways responsible for MSCs' impact on GVHD regulation, like JAK/STAT, NOTCH, MAPK/ERK, and NFκβ signaling pathways, have not been clearly described yet. This review aims to illuminate the effect of MSCs-mediated immunomodulation in GVHD management after allo-HSCT representing the role of MSCs therapy on signaling pathways in GVHD.
Conclusion
MSCs could potentially modulate immune responses, prevent GVHD, and improve survival after allo-HSCT. Previous studies have investigated different signaling pathways' contributions to MSCs immunoregulatory ability. Accordingly, targeting signaling pathways components involved in MSCs related GVHD regulation is proven to be beneficial.
Introduction: Acute Graft-versus-Host Disease (GVHD) is the major toxicity of allogeneic hematopoietic cell transplantation (HCT). Systemic steroids are the standard primary treatment but only half of patients will respond completely and the survival of steroid-refractory patients is poor. The gastrointestinal (GI) tract is a key target organ that usually determines a patient’s response to therapy. Serum biomarkers (ST2 and REG3a) predict response to therapy better than the standard Grade I-IV clinical severity scale and identify one third of patients who have significant GI crypt damage. These biomarkers also identify low risk patients who may be treated with new strategies that avoid broad immunosuppression.
Areas Covered: This review summarizes the use of clinical grading systems and biomarkers in GVHD treatment and highlights pathophysiologic phases of acute GVHD as context for the mechanisms of action and therapeutic targets of various approaches such as JAK inhibitors. We then summarize the most important current clinical trials according to their targeting strategies. We reviewed >100 publications and performed a search of ongoing, current clinical trials on the emerging therapeutic targets for prophylaxis and treatment of acute GVHD. Search databases included clinicaltrials.gov and PUBMED. Search terms and keywords included “acute graft-versus-host disease,” “GVHD,” “graft versus host,” “treatment.”
Expert Opinion: Future strategies will employ a risk-adapted therapy using biomarkers, which more accurately predict 6-month NRM (see figure 1). Strategies for high risk patients will inhibit GI tract damage either by selective targeting of effectors (e.g. inhibition of JAK signaling in T cells, blockade of trafficking through mAbs against integrin receptors, or enhancement of target cell survival through addition of growth factors such as IL-22); future strategies for low risk patients will reduce immunosuppression to avoid risks of infections and relapse.
Multipotent stromal cells (MSCs) are widely utilized in therapy for their immunomodulatory properties, but their usage in infectious viral diseases is less explored. This review aimed to collate the current novel use of MSCs in virus-associated conditions, including MSC’s susceptibility to virus infection, antiviral properties of MSCs and their effects on cell-based immune response and implementation of MSC therapy in animal models and human clinical trials of viral diseases. Recent discoveries shed lights on MSC’s capability in suppressing viral replication and augmenting clearance through enhancement of antiviral immunity. MSC therapy may maintain a crucial balance between aiding pathogen clearance and suppressing hyperactive immune response.
Graphical Abstract
Stimulation of quiescent Balb/c 3T3 fibroblasts into S phase requires the synergistic action of platelet-derived growth factor (PDGF) and progression factors found in platelet-poor plasma (PPP). Traverse of the G/S phase boundary and the initiation of DNA replication require functional cyclin E-cyclin-dependent kinase (Cdk) 2 and cyclin A-Cdk2 complexes; however, the mechanisms by which PDGF and PPP regulate Cdk2 activation are not known. Density-arrested fibroblasts contain low levels of cyclins E and A, and high levels of the Cdk inhibitor p27. Exposure to PDGF, which stimulates cell cycle entry but not progression through G, induces the formation of cyclin D-Cdk4 complexes that bind p27 and titrate the pool of Kip1 available to inhibit Cdk2. In addition, PDGF stimulates a moderate transient reduction in the abundance of p27 protein. However, limited expression of cyclin E and cyclin A is observed after PDGF treatment, and in the absence of PPP, p27 levels are sufficient to bind and inactivate existing cyclin-Cdk complexes. Although plasma does not significantly increase the proportion of Kip1 bound to cyclin D-Cdk4, stimulation of PDGF-treated cells with plasma does overcome the threshold inhibition of p27 by further increasing the expression of cyclins E and A and decreasing the amount of Kip1 over a prolonged time period. Our results indicate that the distinct mitogenic activities of PDGF and PPP differentially influence the activation of cyclin E- and cyclin A-associated kinases that ultimately regulate entry into S phase.
Infusion of either embryonic or mesenchymal stem cells prolongs the survival of organ transplants derived from stem cell donors and prevents graft-versus-host-disease (GVHD). An in-depth mechanistic understanding of this tolerization phenomenon could lead to novel cell-based therapies for transplantation. Here we demonstrate that while human mesenchymal stem cells (hMSCs) can promote superantigen-induced activation of purified T cells, addition of antigen-presenting cells (APCs; either monocytes or dendritic cells) to the cultures inhibits the T-cell responses. This contact- and dose-dependent inhibition is accompanied by secretion of large quantities of interleukin (IL)-10 and aberrant APC maturation, which can be partially overridden by the addition of factors that promote APC maturation (ie, lipopolysaccharide [LPS] or anti-CD40 monoclonal antibody [mAb]). Thus, our data support an immunoregulatory mechanism wherein hMSCs inhibit T cells indirectly by contact-dependent induction of regulatory APCs with T-cell-suppressive properties. Our data may reveal a physiologic phenomenon whereby the development of a distinct APC population is regulated by the tissue's cellular microenvironment.
A constitutively active form of mitogen-activated protein kinase kinase (MEK1) was synthesized under control of a zinc-inducible promoter in NIH 3T3 fibroblasts. Zinc treatment of serum-starved cells activated extracellular signal-regulated protein kinases (ERKs) and induced expression of cyclin D1. Newly synthesized cyclin D1 assembled with cyclin-dependent kinase-4 (CDK4) to form holoenzyme complexes that phosphorylated the retinoblastoma protein inefficiently. Activation of the MEK1/ERK pathway neither triggered degradation of the CDK inhibitor kinase inhibitory protein-1 (p27(Kip1)) nor led to activation of cyclin E- and A-dependent CDK2, and such cells did not enter the DNA synthetic (S) phase of the cell division cycle. In contrast, zinc induction of active MEK1 in cells also engineered to ectopically overexpress cyclin D1 and CDK4 subunits generated levels of cyclin D-dependent retinoblastoma protein kinase activity approximating those achieved in cells stimulated by serum. In this setting, p27(Kip1) was mobilized into complexes containing cyclin D1; cyclin E- and A-dependent CDK2 complexes were activated; and serum-starved cells entered S phase. Thus, although the activity of p27(Kip1) normally is canceled through a serum-dependent degradative process, overexpressed cyclin D1-CDK complexes sequestered p27(Kip1) and reduced the effective inhibitory threshold through a stoichiometric mechanism. A fraction of these cells completed S phase and divided, but they were unable to continuously proliferate, indicating that other serum-responsive factors ultimately became rate limiting for cell cycle progression. Therefore, the MEK/ERK pathway not only acts transcriptionally to induce the cyclin D1 gene but functions posttranslationally to regulate cyclin D1 assembly with CDK4 and to thereby help cancel p27(Kip1)-mediated inhibition.
We have recently shown that expression of the enzyme indoleamine 2, 3-dioxygenase (IDO) during murine pregnancy is required to prevent rejection of the allogeneic fetus by maternal T cells. In addition to their role in pregnancy, IDO-expressing cells are widely distributed in primary and secondary lymphoid organs. Here we show that monocytes that have differentiated under the influence of macrophage colony-stimulating factor acquire the ability to suppress T cell proliferation in vitro via rapid and selective degradation of tryptophan by IDO. IDO was induced in macrophages by a synergistic combination of the T cell-derived signals IFN-gamma and CD40-ligand. Inhibition of IDO with the 1-methyl analogue of tryptophan prevented macrophage-mediated suppression. Purified T cells activated under tryptophan-deficient conditions were able to synthesize protein, enter the cell cycle, and progress normally through the initial stages of G1, including upregulation of IL-2 receptor and synthesis of IL-2. However, in the absence of tryptophan, cell cycle progression halted at a mid-G1 arrest point. Restoration of tryptophan to arrested cells was not sufficient to allow further cell cycle progression nor was costimulation via CD28. T cells could exit the arrested state only if a second round of T cell receptor signaling was provided in the presence of tryptophan. These data reveal a novel mechanism by which antigen-presenting cells can regulate T cell activation via tryptophan catabolism. We speculate that expression of IDO by certain antigen presenting cells in vivo allows them to suppress unwanted T cell responses.
Dendritic cells (DCs) are antigen-presenting cells that play a major role in initiating primary immune responses. We have utilized two independent approaches, DNA microarrays and proteomics, to analyze the expression profile of human CD14(+) blood monocytes and their derived DCs. Analysis of gene expression changes at the RNA level using oligonucleotide microarrays complementary to 6300 human genes showed that approximately 40% of the genes were expressed in DCs. A total of 255 genes (4%) were found to be regulated during DC differentiation or maturation. Most of these genes were not previously associated with DCs and included genes encoding secreted proteins as well as genes involved in cell adhesion, signaling, and lipid metabolism. Protein analysis of the same cell populations was done using two-dimensional gel electrophoresis. A total of 900 distinct protein spots were included, and 4% of them exhibited quantitative changes during DC differentiation and maturation. Differentially expressed proteins were identified by mass spectrometry and found to represent proteins with Ca(2+) binding, fatty acid binding, or chaperone activities as well as proteins involved in cell motility. In addition, proteomic analysis provided an assessment of post-translational modifications. The chaperone protein, calreticulin, was found to undergo cleavage, yielding a novel form. The combined oligonucleotide microarray and proteomic approaches have uncovered novel genes associated with DC differentiation and maturation and has allowed analysis of post-translational modifications of specific proteins as part of these processes.
Cross-tolerization of T lymphocytes after apoptotic cell uptake by dendritic cells may be involved in self-tolerance maintenance. Furthermore, immunosuppressive properties are attributed to apoptotic cells. This study evaluated the consequences of apoptotic leukocyte administration in a restrictive engraftment model of murine bone marrow (BM) transplantation. Sublethally irradiated recipients received a limited number of allogeneic BM, with or without irradiated apoptotic leukocytes of different origins. No graft-versus-host disease was observed. Whereas only a low proportion of mice receiving BM cells alone engrafted, addition of apoptotic irradiated leukocytes, independently of the origin (donor, recipient, third-party mice, as well as xenogeneic peripheral blood mononuclear cells), significantly enhanced engraftment. Similar results were obtained after infusion of leukocytes rendered apoptotic by UVB irradiation or by anti-Fas monoclonal antibody stimulation, thus confirming the role of apoptotic cells in engraftment facilitation. Overall, these results suggest that apoptotic leukocytes can nonspecifically facilitate allogeneic BM engraftment. Such a simple approach could be of interest in BM transplantation settings involving an important HLA donor/recipient disparity, a T-cell-depleted graft, or reduced conditioning regimen intensity.
The regulation of stem cell proliferation is a poorly understood process balancing rapid, massive blood cell production in times of stress with maintenance of a multipotent stem cell pool over decades of life. Transforming growth factor beta 1 (TGF-beta 1) has pleiotropic effects on hematopoietic cells, including the inhibition of primitive cell proliferation. It was recently demonstrated that the cyclin-dependent kinase inhibitors, p21(Cip1/Waf1) (p21) and p27(Kip1) (p27), can inhibit the proliferation of hematopoietic stem cells and progenitor cells, respectively. The relation of TGF-beta 1 stimulation to p21 and p27 was examined using a fine-mapping approach to gene expression in individual cells. Abundant TGF-beta 1 expression and p21 expression were documented in quiescent, cytokine-resistant hematopoietic stem cells and in terminally differentiated mature blood cells, but not in proliferating progenitor cell populations. TGF-beta 1 receptor (T beta R II) was expressed ubiquitously without apparent modulation. Cell- cycle-synchronized 32D cells exposed to TGF-beta 1 demonstrated a marked antiproliferative effect of TGF-beta 1, yet neither the level of p21 mRNA nor the protein level of either p21 or p27 was altered. To corroborate these observations in primary cells, bone marrow mononuclear cells derived from mice engineered to be deficient in p21 or p27 were assessed. Progenitor and primitive cell function was inhibited by TGF-beta 1 equivalently in -/- and +/+ littermate controls. These data indicate that TGF-beta 1 exerts its inhibition on cell cycling independent of p21 and p27 in hematopoietic cells. TGF-beta 1 and p21 or p27 participate in independent pathways of stem cell regulation, suggesting that targeting each may provide complementary strategies for enhancing stem or progenitor cell expansion and gene transduction.
CD2(+) T lymphocytes obtained from either the donor of bone marrow stromal cells (BMSCs) or a third party were cultured in mixed lymphocyte reactions (MLRs) with either allogeneic dendritic cells (DCs) or peripheral blood lymphocytes (PBLs). When autologous or allogeneic BMSCs were added back to T cells stimulated by DCs or PBLs, a significant and dose-dependent reduction of T-cell proliferation, ranging from 60% +/- 5% to 98% +/- 1%, was evident. Similarly, addition of BMSCs to T cells stimulated by polyclonal activators resulted in a 65% +/- 5% (P =.0001) suppression of proliferation. BMSC- induced T-cell suppression was still evident when BMSCs were added in culture as late as 5 days after starting of MLRs. BMSC-inhibited T lymphocytes were not apoptotic and efficiently proliferated on restimulation. BMSCs significantly suppressed both CD4(+) and CD8(+) T cells (65% +/- 5%, [P =.0005] and 75% +/- 15% [P =.0005], respectively). Transwell experiments, in which cell-cell contact between BMSCs and effector cells was prevented, resulted in a significant inhibition of T-lymphocyte proliferation, suggesting that soluble factors were involved in this phenomenon. By using neutralizing monoclonal antibodies, transforming growth factor beta1 and hepatocyte growth factor were identified as the mediators of BMSC effects. In conclusion, our data demonstrate that (1) autologous or allogeneic BMSCs strongly suppress T-lymphocyte proliferation, (2) this phenomenon that is triggered by both cellular as well as nonspecific mitogenic stimuli has no immunologic restriction, and (3) T-cell inhibition is not due to induction of apoptosis and is likely due to the production of soluble factors.
Antigen-presenting cells (APCs) can induce tolerance or immunity. We describe a subset of human APCs that express indoleamine
2,3-dioxygenase (IDO) and inhibit T cell proliferation in vitro. IDO-positive APCs constituted a discrete subset identified
by coexpression of the cell-surface markers CD123 and CCR6. In the dendritic cell (DC) lineage, IDO-mediated suppressor activity
was present in fully mature as well as immature CD123+ DCs. IDO+ DCs could also be readily detected in vivo, which suggests that these cells may represent a regulatory subset of APCs in
humans.
Trans-differentiation of stem cells shows promise for use in tissue repair medicine. Although poorly defined, mesenchymal stem cells (MSC) appear useful for applications in repair medicine. Despite the low frequency of MSC, they are relatively easy to expand. The expression of MHC class II on MSC, however, could deter their use in repair medicine, since these molecules could stimulate an allogeneic host response. This study sought to compare the immune stimulatory and suppressive effects of MSC. Primary human MSC were cultured from bone marrow aspirates and then passaged at least three times before use in assays. Morphologically, MSC were symmetrical; were SH2(+), MHC class II(+), CD45(-), CD44(+), CD31(-), CD14(-), proly-4-hydroxylase(-); and showed normal karyotype patterns and elevated telomerase activities. MSC elicited significant stimulatory responses when cocultured with allogeneic PBMC. Despite the production of different types of growth factors, allogeneic effects of MSC could not be explained by the production of these growth factors. One-way MLR reactions were significantly blunted by third-party MSC. Similar suppression was not observed for responses to three different recall Ags. Based on these functional differences by MSC in responses to allo- and recall Ags, we examined whether MSC could exert veto-like functions. We showed that MSC could blunt the cytotoxic effects of allogeneic-induced effectors to mitogen-activated targets. The results showed that although MSC elicited allogeneic responses in a model that mimics a graft-vs-host reaction, they also exerted veto-like activity, but caused no effect on responses to recall Ags.
Marrow stromal cells (MSCs) inhibit allogeneic T-cell responses, yet the molecular mechanism mediating this immunosuppressive effect of MSCs remains controversial. Recently, expression of indoleamine 2,3-dioxygenase (IDO), which is induced by interferon-gamma (IFN-gamma) and catalyzes the conversion from tryptophan to kynurenine, has been identified as a T-cell inhibitory effector pathway in professional antigen-presenting cells. Here we show that human MSCs express IDO protein and exhibit functional IDO activity upon stimulation with IFN-gamma. MSCs inhibit allogeneic T-cell responses in mixed lymphocyte reactions (MLRs). Concomitantly, IDO activity resulting in tryptophan depletion and kynurenine production is detected in MSC/MLR coculture supernatants. Addition of tryptophan significantly restores allogeneic T-cell proliferation, thus identifying IDO-mediated tryptophan catabolism as a novel T-cell inhibitory effector mechanism in human MSCs. As IDO-mediated T-cell inhibition depends on MSC activation, modulation of IDO activity might alter the immunosuppressive properties of MSCs in different therapeutic applications.
The fates of dendritic cells (DCs) after antigen presentation have been studied extensively, but the influence of lymphoid microenvironments on DCs is mostly unknown. Here, using splenic stromal cells to mimic the immune microenvironment, we show that contact with stromal cells promoted mature DCs to proliferate in a fibronectin-dependent way and that both stromal cell contact and stromal cell-derived transforming growth factor-beta induced their differentiation into a new regulatory DC subset. We have identified an in vivo counterpart in the spleen with similar phenotype and functions. These differentiated DCs secreted nitric oxide, which mediated the suppression of T cell proliferation in response to antigen presentation by mature DCs. Thus, our findings identify an important mechanism by which the microenvironment regulates immune responses.
Mesenchymal stem cells (MSCs) are multipotent cells found in several adult tissues. Transplanted allogeneic MSCs can be detected in recipients at extended time points, indicating a lack of immune recognition and clearance. As well, a role for bone marrow-derived MSCs in reducing the incidence and severity of graft-versus-host disease (GVHD) during allogeneic transplantation has recently been reported; however, the mechanisms remain to be investigated. We examined the immunomodulatory functions of human MSCs (hMSCs) by coculturing them with purified subpopulations of immune cells and report here that hMSCs altered the cytokine secretion profile of dendritic cells (DCs), naive and effector T cells (T helper 1 [T(H)1] and T(H)2), and natural killer (NK) cells to induce a more anti-inflammatory or tolerant phenotype. Specifically, the hMSCs caused mature DCs type 1 (DC1) to decrease tumor necrosis factor alpha (TNF-alpha) secretion and mature DC2 to increase interleukin-10 (IL-10) secretion; hMSCs caused T(H)1 cells to decrease interferon gamma (IFN-gamma) and caused the T(H)2 cells to increase secretion of IL-4; hMSCs caused an increase in the proportion of regulatory T cells (T(Regs)) present; and hMSCs decreased secretion of IFN-gamma from the NK cells. Mechanistically, the hMSCs produced elevated prostaglandin E2 (PGE(2)) in co-cultures, and inhibitors of PGE(2) production mitigated hMSC-mediated immune modulation. These data offer insight into the interactions between allogeneic MSCs and immune cells and provide mechanisms likely involved with the in vivo MSC-mediated induction of tolerance that could be therapeutic for reduction of GVHD, rejection, and modulation of inflammation.
Although dendritic cell (DC) precursors have been isolated from many lymphoid sites, the regulation and location of early DC development is still poorly understood. Here we describe a splenic microenvironment that supports DC hematopoiesis in vitro and identify gene expression specific for that niche.
The DC supportive function of the STX3 splenic stroma and the lymph node-derived 2RL22 stroma for overlaid bone marrow cells was assessed by coculture over 2 weeks. The DC supportive function of SXT3 was identified in terms of specific gene expression in STX3 and not 2RL22 using Affymetrix microchips.
STX3 supports DC differentiation from overlaid bone marrow precursors while 2RL22 does not. A dataset of 154 genes specifically expressed in STX3 and not 2RL22 was retrieved from Affymetrix results. Functional annotation has led to selection of 26 genes as candidate regulators of the microenvironment supporting DC hematopoiesis. Specific expression of 14 of these genes in STX3 and not 2RL22 was confirmed by reverse transcription-polymerase chain reaction.
Some genes specifically expressed in STX3 have been previously associated with hematopoietic stem cell niches. A high proportion of genes encode growth factors distinct from those commonly used for in vitro development of DC from precursors. Potential regulators of a DC microenvironment include genes involved in angiogenesis, hematopoiesis, and development, not previously linked to DC hematopoiesis.
It has been shown that mesenchymal stem cells (MSCs) induce T cells to become unresponsive. We characterized the phenotype of these T cells by dissecting the effect of MSCs on T-cell activation, proliferation, and effector function. For this purpose, an in vitro murine model was used in which T-cell responses were generated against the male HY minor histocompatibility antigen. In the presence of MSCs, the expression of early activation markers CD25 and CD69 was unaffected but interferon-gamma (IFN-gamma) production was reduced. The inhibitory effect of MSCs was directed mainly at the level of cell proliferation. Analysis of the cell cycle showed that T cells, stimulated in the presence of MSCs, were arrested at the G1 phase. At the molecular level, cyclin D2 expression was profoundly inhibited, whereas p27(kip1) was up-regulated. When MSCs were removed from the cultures and restimulated with the cognate peptide, T cells produced IFN-gamma but failed to proliferate. The addition of exogenous interleukin-2 (IL-2) did not restore proliferation. MSCs did not preferentially target any T-cell subset, and the inhibition was also extended to B cells. MSC-mediated inhibition induces an unresponsive T-cell profile that is fully consistent with that observed in division arrest anergy.
Cyclooxygenase-2 (COX-2)-mediated prostaglandin synthesis has recently been implicated in human cholangiocarcinogenesis. This
study was designed to examine the mechanisms by which COX-2-derived prostaglandin E2 (PGE2) regulates cholangiocarcinoma cell growth and invasion. Immunohistochemical analysis revealed elevated expression of COX-2
and the epidermal growth factor (EGF) receptor (EGFR) in human cholangiocarcinoma tissues. Overexpression of COX-2 in a human
cholangiocarcinoma cell line (CCLP1) increased tumor cell growth and invasion in vitro and in severe combined immunodeficient mice. Overexpression of COX-2 or treatment with PGE2 or the EP1 receptor agonist ONO-DI-004 induced phosphorylation of EGFR and enhanced tumor cell proliferation and invasion, which were
inhibited by the EP1 receptor small interfering RNA or antagonist ONO-8711. Treatment of CCLP1 cells with PGE2 or ONO-DI-004 enhanced binding of EGFR to the EP1 receptor and c-Src. Furthermore, PGE2 or ONO-DI-004 treatment also increased Akt phosphorylation, which was blocked by the EGFR tyrosine kinase inhibitors AG 1478
and PD 153035. These findings reveal that the EP1 receptor transactivated EGFR, thus activating Akt. On the other hand, activation of EGFR by its cognate ligand (EGF) increased
COX-2 expression and PGE2 production, whereas blocking PGE2 synthesis or the EP1 receptor inhibited EGF-induced EGFR phosphorylation. This study reveals a novel cross-talk between the EP1 receptor and EGFR signaling that synergistically promotes cancer cell growth and invasion.
Hepatocyte growth factor (HGF) has an anti-proliferative effect on many types of tumor cell lines and tumors in vivo. We found previously that inhibition of HGF-induced proliferation in HepG2 hepatoma cells is caused by cell cycle arrest
at G1 through a high intensity ERK signal, which represses Cdk2 activity. To examine further the mechanisms of G1 arrest by HGF, we analyzed the Cdk inhibitor p16INK4a, which has an anti-proliferative function through cell cycle arrest at G1. We found that HGF treatment drastically increased endogenous p16 levels. Knockdown of p16 with small interfering RNA reversed
the arrest, indicating that the induction of p16 is required for G1 arrest by HGF. Analysis of the promoter of the human p16 gene identified the proximal Ets-binding site as a responsive element
for HGF, and this responded to the high intensity ERK signal. HGF treatment of the cells led to a redistribution of p21CIP1 and p27KIP1 from Cdk4 to Cdk2. The redistribution was blocked by the knockdown of p16 with small interfering RNA, which restored the
Cdk2 activity repressed by HGF, demonstrating the requirement of p16 induction for the redistribution and eventual repression
of Cdk2 activity. Our results reveal a signaling pathway for G1 arrest induced by HGF.
Human mesenchymal stem cells (hMSCs) suppress T-cell and dendritic-cell function and represent a promising strategy for cell therapy of autoimmune diseases. Nevertheless, no information is currently available on the effects of hMSCs on B cells, which may have a large impact on the clinical use of these cells. hMSCs isolated from the bone marrow and B cells purified from the peripheral blood of healthy donors were cocultured with different B-cell tropic stimuli. B-cell proliferation was inhibited by hMSCs through an arrest in the G0/G1 phase of the cell cycle and not through the induction of apoptosis. A major mechanism of B-cell suppression was hMSC production of soluble factors, as indicated by transwell experiments. hMSCs inhibited B-cell differentiation because IgM, IgG, and IgA production was significantly impaired. CXCR4, CXCR5, and CCR7 B-cell expression, as well as chemotaxis to CXCL12, the CXCR4 ligand, and CXCL13, the CXCR5 ligand, were significantly down-regulated by hMSCs, suggesting that these cells affect chemotactic properties of B cells. B-cell costimulatory molecule expression and cytokine production were unaffected by hMSCs. These results further support the potential therapeutic use of hMSCs in immune-mediated disorders, including those in which B cells play a major role.
Mesenchymal stem cells (MSCs) have been recently shown to inhibit T-cell proliferation to polyclonal stimuli. We characterized the effect of MSCs of bone marrow origin on the T-cell response of naive and memory T cells to their cognate antigenic epitopes. The immune response to murine male transplantation antigens, HY, was selected because the peptide identity and major histocompatibility complex (MHC) restriction of the immunodominant epitopes are known. C57BL/6 female mice immunized with male cells were the source of memory T cells, whereas C6 mice transgenic for HY-specific T-cell receptor provided naive T cells. Responder cells were stimulated in vitro with male spleen cells or HY peptides in the presence or absence of MSCs. MSCs inhibited HY-specific naive and memory T cells in a dose-dependent fashion and affected cell proliferation, cytotoxicity, and the number of interferon gamma (IFN-gamma)-producing HY peptide-specific T cells. However, the MSC inhibitory effect did not selectively target antigen-reactive T cells. When MSCs were added to the T-cell cultures in a Transwell system or MSCs were replaced by MSC culture supernatant, the inhibitory activity was abrogated. T-cell reactivity was also restored if MSCs were removed from the cultures. The expression of MHC molecules and the presence in culture of antigen-presenting cells (APCs) or of CD4(+)/CD25(+) regulatory T cells were not required for MSCs to inhibit. We conclude that MSCs inhibit naive and memory T-cell responses to their cognate antigens. Overall our data suggest that MSCs physically hinder T cells from the contact with APCs in a noncognate fashion.
Stimulation of quiescent Balb/c 3T3 fibroblasts into S phase requires the synergistic action of platelet-derived growth factor (PDGF) and progression factors found in platelet-poor plasma (PPP). Traverse of the G1/S phase boundary and the initiation of DNA replication require functional cyclin E-cyclin-dependent kinase (Cdk) 2 and cyclin A-Cdk2 complexes; however, the mechanisms by which PDGF and PPP regulate Cdk2 activation are not known. Density-arrested fibroblasts contain low levels of cyclins E and A, and high levels of the Cdk inhibitor p27kip1. Exposure of PDGF, which stimulates cell cycle entry but not progression through G1, induces the formation of cyclin D1-Cdk4 complexes that bind p27kip1 and titrate the pool of Kip1 available to inhibit Cdk2. In addition, PDGF stimulates a moderate transient reduction in the abundance of p27kip1 protein. However, limited expression of cyclin E and cyclin A is observed after PDGF treatment, and in the absence of PPP, p27 levels are sufficient to bind and inactivate existing cyclin-Cdk complexes. Although plasma does not significantly increase the proportion of Kip1 bound to cyclin D1-Cdk4, stimulation of PDGF-treated cells with plasma does overcome the threshold inhibition of p27kip1 by further increasing the expression of cyclins E and A and decreasing the amount of Kip1 over a prolonged time period. Our results indicate that the distinct mitogenic activities of PDGF and PPP differentially influence the activation of cyclin E- and cyclin A-associated kinases that ultimately regulate entry into S phase.
Dendritic cells (DC) are a distinct population of leukocytes and specialized antigen-presenting cells for T cell responses. Prior work has shown that GM-CSF can induce the development of large numbers of DC from proliferating progenitors in mouse bone marrow. We have monitored the effects of potentially enhancing and suppressive cytokines in these cultures. In this system, many immature DC develop from proliferating precursors during the first six days of culture, and between days 6-8 maturation of typical nonadherent and nonreplicating DC takes place. The maturation is accompanied by a large increase in the expression of major histocompatibilities complex class II (MHC II) and B7-2/CD86, and in mixed leukocyte reaction stimulating activity. Tumor necrosis factor-alpha (TNF-alpha), previously shown to be required for development of human DC, was found to enhance the maturation of mouse DC in the last two days of culture. Transforming growth factor-beta 1 (TGF-beta 1), on the other hand, almost totally blocked DC maturation, but it had to be given in the first six days of culture when the DC were actively proliferating. TGF-beta 1 did not block the production of immature, MHC II-positive but B7-2/CD86-negative DC. Maturation would take place between days 6-8 as long as the cultures were depleted of Fc-receptor-bearing cells, or if TNF-alpha were added. In both instances, maturation was not blocked even when TGF-beta 1 remained in the culture. We conclude that the development of DC, in response to GM-CSF, can be modified by other cytokines. TGF-beta 1 is suppressive but only indirectly via Fc-receptor-bearing suppressive cells, presumably suppressive macrophages, while TNF-alpha enhances the final maturation of DC.
Mesenchymal stem cells (MSCs), multipotential cells that reside within the bone marrow, can be induced to differentiate into various components of the marrow microenvironment, such as bone, adipose, and stromal tissues. The bone marrow microenvironment is vital to the development, differentiation, and regulation of the lymphohematopoietic system. We hypothesized that the activities of MSCs in the bone marrow microenvironment might also include immunomodulatory effects on lymphocytes.
Baboon MSCs were tested in vitro for their ability to elicit a proliferative response from allogeneic lymphocytes, to inhibit an ongoing allogeneic response, and to inhibit a proliferative response to potent T-cell mitogens. In vivo effects were tested by intravenous administration of donor MSCs to MHC-mismatched recipient baboons prior to placement of autologous, donor, and third-party skin grafts.
MSCs failed to elicit a proliferative response from allogeneic lymphocytes. MSCs added into a mixed lymphocyte reaction, either on day 0 or on day 3, or to mitogen-stimulated lymphocytes, led to a greater than 50% reduction in proliferative activity. This effect could be maximized by escalating the dose of MSCs and could be reduced with the addition of exogenous IL-2. In vivo administration of MSCs led to prolonged skin graft survival when compared to control animals: 11.3 +/- 0.3 vs 7 +/- 0.
Baboon MSCs have been observed to alter lymphocyte reactivity to allogeneic target cells and tissues. These immunoregulatory features may prove useful in future applications of tissue regeneration and stem cell engineering.
Little is known about the homeostatic mechanisms by which the levels of peripheral lymphocytes are maintained. The survival of naïve T cells in vivo must be maintained by some factors that have not been characterized in an in vitro culture system. In this study, we established a culture system of stromal cells derived from murine lymph nodes and investigated the action of the stromal cells in supporting the survival of resting T cells in vitro. Most of the T cells cocultured with the stromal cells did not die, and the supernatant of cultured stromal cells increase the viability of T cells. This T-cell survival-supporting activity was maintained for more than 7 days. Although interleukin (IL)-4, IL-6, IL-7, and interferon-beta also rescued peripheral T cells from spontaneous cell death, medium-soluble and heat-sensitive factor(s) derived from the stromal cells supported the survival of T cells more effectively and for a longer time than did these cytokines. T cells maintained in the culture system with the stromal cells appeared to remain in a resting G0/G1 state and did not show remarkable DNA synthesis. From these results, it is presumed that some soluble factor(s) other than the tested cytokines that have been identified as supporting T-cell survival are produced from lymph node stromal cells. These factor(s) play an important role in maintenance of resting T cells.
Mesenchymal stem cells (MSCs) can reduce the incidence of graft-versus-host disease because of their ability to inhibit T-lymphocyte proliferation. There are no publications on the effect that MSCs have on cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells, effector cells vital for the graft-versus-leukemia effect.
Cytotoxic T cells were primed in mixed lymphocyte culture (MLC) against irradiated stimulator lymphocytes, and irradiated third-party MSCs were added at different time points. The CTLs were collected, and their cytotoxic potential was analyzed in a chromium-release assay against the same stimulator cells as in the MLC. Purified NK cells were mixed with irradiated MSCs, and the lysis was measured in chromium-release assay against K562 target cells.
We found that MSCs inhibited CTL-mediated lysis by 70% if added at the beginning of the 6-day MLC. The lysis was not affected on day 3 or in the cytotoxic phase. Furthermore, MSCs inhibited the formation of cytotoxic lymphocytes when the cells were separated in a transwell system, which indicates that the effect is mediated by a soluble factor. NK cell-mediated lysis of K562 cells was not inhibited by MSCs. MSCs did not induce proliferation of allogeneic lymphocytes, and they were not lysed by allogeneic CTLs or NK cells.
Our findings indicate that MSCs escape recognition by CTLs and alloreactive NK cells, and inhibit the formation of cytotoxic T cells by secreting a soluble factor, but that they do not interfere with CTLs and NK cell lysis.
Mesenchymal stem cells (MSCs) reportedly inhibit the mixed lymphocyte reaction. Whether this effect is mediated by dendritic cells (DCs) is still unknown. In this study, we used an in vitro model to observe the effects of MSCs and their supernatants on the development of monocyte-derived DCs. Phenotypes and the endocytosic ability of harvested DCs were determined by flow cytometry; interleukin 12 (IL-12) secreted by DCs was evaluated by enzyme-linked immunosorbent assay (ELISA); and the antigen-presenting function of DCs was evaluated by MLR. Our results show that MSCs inhibit the up-regulation of CD1a, CD40, CD80, CD86, and HLA-DR during DC differentiation and prevent an increase of CD40, CD86, and CD83 expression during DC maturation. MSCs supernatants had no effect on DCs differentiation, but they inhibited the up-regulation of CD83 during maturation. Both MSCs and their supernatants interfered with endocytosis of DCs, decreased their capacity to secret IL-12 and activate alloreactive T cells. Thus, effects of MSCs on DCs contribute to immunoregulation and development.
CD11c(hi) dendritic cells (DC) play an essential role during the initiation of cell-mediated immunity. Recently, CD11c(lo)CD45RB(hi) DC with regulatory properties have been described. However, the origins of regulatory DC are poorly understood. Here, we show that spleen-derived stromal cells promote selective development of CD11c(lo)CD45RB(+) IL-10-producing regulatory DC from lineage-negative c-kit(+) progenitor cells. These DC have the capacity to suppress T cell responses and induce IL-10-producing regulatory T cells in vitro and to induce antigen-specific tolerance in vivo. Furthermore, stromal cells from mice infected with Leishmania donovani more effectively supported differentiation of these highly potent regulatory DC. The ability of tissue stromal cells to direct the development of DC with a regulatory phenotype thus provides a new mechanism for local immune regulation.
Mesenchymal stem cells (MSCs), in addition to their multilineage differentiation, have a direct immunosuppressive effect on T-cell proliferation in vitro. However, it is unclear whether they also modulate the immune system by acting on the very first step. In this investigation, we addressed the effects of human MSCs on the differentiation, maturation, and function of dendritic cells (DCs) derived from CD14+ monocytes in vitro. Upon induction with granulocyte-macrophage colony-stimulating factor (GM-CSF) plus interleukin-4 (IL-4), MSC coculture could strongly inhibit the initial differentiation of monocytes to DCs, but this effect is reversible. In particular, such suppression could be recapitulated with no intercellular contact at a higher MSC/monocyte ratio (1:10). Furthermore, mature DCs treated with MSCs were significantly reduced in the expression of CD83, suggesting their skew to immature status. Meanwhile, decreased expression of presentation molecules (HLA-DR and CD1a) and costimulatory molecules (CD80 and CD86) and down-regulated IL-12 secretion were also observed. In consistence, the allostimulatory ability of MSC-treated mature DCs on allogeneic T cells was impaired. In conclusion, our data suggested for the first time that human MSCs could suppress monocyte differentiation into DCs, the most potent antigen-presenting cells (APCs), thus indicating the versatile regulation of MSCs on the ultimate specific immune response.
Dendritic cell (DC) maturation and function are influenced by the surrounding cytokine milieu. We demonstrate tumor-associated suppression of DCs in stimulating allogeneic and tumor-specific CTL and type 1 (IFN-gamma-producing) responses in both CD4- and CD8-positive T cells. DCs from MB49-bearing female mice fail to stimulate proliferative and IFN-gamma-producing responses in allogeneic mixed lymphocyte cultures. MB49 also inhibited DC function in stimulating type 1 responses against our tumor-specific antigen, the male antigen, HY. DCs from MB49-bearing male mice were unable to restimulate effective HY-specific CTLs or IFN-gamma. Tumor-induced interleukin (IL) 10 was found to be specifically responsible for DC dysfunction in response to antigenic driven maturation. This was demonstrated by restoration of DC function in splenic DCs from MB49-bearing female IL-10 knockout mice (HY disparity), whereas not in MB49-bearing male IL-10 knockout mice (no HY disparity). Finally, any tumor-induced systemic inhibitory effect on bone marrow precursors could be overcome by generation of bone marrow-derived DCs ex vivo. These bone marrow-derived DCs derived from MB49-bearing B6 mice were capable of inducing control levels of proliferation in allogeneic mixed lymphocyte reactions and a type 1 (IFN-gamma) cytokine profile. The BM-DCs were also capable of restimulating HY-specific CTL and IFN-gamma production. These studies reveal the tumor-associated in vivo effects of IL-10 inhibition on DC function in eliciting a type 1 immune response in both allogeneic and tumor-specific responses.