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Background aims. Mesenchymal stromal cells (MSC) from several tissues have immunomodulatory properties that involve various immunosuppressive molecules. An example is human leukocyte antigen (HLA)-G, a non-classical major histocompatibility complex (MHC) class I molecule that induces tolerance via interactions with inhibitory receptors present on major immune effector cells. Recently, the molecular mechanisms that regulate MSC-mediated immunosuppression have come under investigation. Our goal was to determine whether HLA-G plays a crucial role in immunosuppression and whether human adipose tissure (hAT) MSC can be used as a tool for biologic immunosuppression with HLA-G in transplantation. Methods. MSC were characterized by fluorescence-activated cell sorting (FACS) analysis, reverse transcriptase (RT)-polymerase chain reaction (PCR) and staining for differentiation. The immunogenicity and immunomodulatory effects of MSC were monitored by peripheral blood mononuclear cell (PBMC) proliferation assay with or without phytohemagglutinin (PHA) stimulation. Stable expression of HLA-G1 in MSC was done using a lentiviral system. Results. MSC from different tissues had similar morphology, immunophenotypic characters and differentiation potential. We also found that the immunosuppressive effect of MSC was monitored along with their endogenous HLA-G mRNA and protein levels. Stable expression of HLA-G1 appeared to enhance the immunosuppressive effect of hAT MSC, and the function of HLA-G1 was significantly decreased by HLA-G antagonistic antibody in PBMC proliferation assays. Conclusions. Although the HLA-G molecule is not the sole factor for MSC-mediated immunosuppression, our data provide evidence that HLA-G plays an important role in immunosuppression and that hAT MSC can be used as a tool for biologic immunosuppression during transplantation procedures. [ABSTRACT FROM AUTHOR]

Purposes: To probe into immunosuppressive effect and cell cycle arrest effect of different dose of FTY720. Method: we study immunosuppressive effect and cell cycle arrest effect of different dose of FTY720 and time and dose dependence of FTY720 with control and random method in vivo, respectively. Results: (i) survival time of graft in rat cardiac transplantation model is prolonged in group treated with FTY720. It is longer in group treated with FTY720 10 mg/kg than that in group treated with FTY720 2 mg/kg. (ii) The mean sum of lymphocyte in periphery blood decrease obviously 2 h after administration, reaches its peak 4 h after administration, and then maintain at low level stably. The mean sum of lymphocyte shows a linear relationship with dose of FTY720 and decrease with increasing of dose of FTY720. (iii) The percent of cell in G1-G0 increased in group treated with FTY720, not only in thymus but also in lymph node; this is more prevalent in the group treated with FTY720 10 mg/kg than that in group treated with FTY720 2 mg/kg. Similarly, the percent of cell in S and G2-M decreased in group treated with FTY720, not only in thymus but also in lymph node, and this decrease is more associated with group treated with FTY720 10 mg/kg than the one treated with FTY720 2 mg/kg. Conclusion: FTY720 is an effective immunosuppressant and immunosuppressive effect of FTY720 show a tendency of time and dose dependent. Effect of cell cycle arrest of FTY720 is related to dose of this new immunosuppressant. [ABSTRACT FROM AUTHOR]

Mesenchymal stem cells (MSCs) have received much attention because of their capabilities of differentiating into multiple mesenchymal lineages and supporting hematopoiesis. Recently, MSCs have gained further interests after the demonstration of an immunosuppressive role. However, it's still unclear whether the immunosuppressive capability of MSCs will be altered with disease state. In this study, our results showed that MSCs derived from patients with lymphoblastic leukemia (ALL), Hodgkin disease (HD), and non-Hodgkin lymphoma (NHL) capable of suppressing the proliferation of T-lymphocyte stimulated in a mixed-lymphocyte reaction (MLR). The immunosuppressive effect of MSCs derived from ALL, HD and NHL on T-cell proliferation was dose-dependent. The supernatants of MSCs derived from ALL, HD and NHL had effect on T-cell proliferation. By using neutralising monoclonal antibodies, we found that transforming growth factor β1 (TGFβ1) and hepatocyte growth factor were major mediators of T-cell suppression by MSCs derived from ALL, HD and NHL. Although MSCs derived from patients with myelodysplastics syndromes (MDS) could inhibit T-cell proliferation stimulated with mitogen or in MLR, the inhibitory effect of MDS-MSCs was impaired. However, adherent cells derived from patients with acute myeloid leukemia (AML) showed abnormal immunomodulatory functions. Adherent cells derived from AML failed to suppress the proliferation of T-cell stimulated in MLR. [ABSTRACT FROM AUTHOR]

Mesenchymal stem cells (MSCs) have emerged as excellent candidates for clinical application because of their capabilities of differentiating into multiple mesenchymal lineages and supporting hematopoiesis. Recently, MSCs have gained further interests after the demonstration of an immunosuppressive role. However, it is still unclear whether the immunosuppressive capability of MSCs will be altered with disease state. In this study, we obtained and expanded MSCs from bone marrow of patients with chronic myeloid leukemia (CML). Our results showed that MSCs derived from CML do not express costimulatory molecules CD40, CD80, and CD86. When MSCs derived from CML were added back to T cells stimulated by mitogens, a significant inhibition of T-cell proliferation was evident. MSCs differentiated into various mesenchymal lineages did not alter their immunosuppressive effect on T-cell proliferation. A significant T-cell inhibition was found in a transwell system, in which cell-cell contact between MSCs and effector cells was prevented. Furthermore, we found that transforming growth factor β1 (TGF β1) and hepatocyte growth factor (HGF) were major mediators of T-cell suppression by MSCs derived from CML. These results demonstrated that autologous MSCs derived from CML could effectively suppress T-cell proliferation. [ABSTRACT FROM AUTHOR]