[Human Umbilical Cord-Derived Mesenchymal Stem Cells Prevent Acute Graft-Versus-Host Disease after Hematopoietic Stem Cell Transplantation Via Exosome-Mediated MicroRNA and Its Mechanism].

OBJECTIVE: To explore molecular mechanisms by which umbilical cord-derived mesenchymal stem cells suppress the development of GVHD after bone marrow hematopoietic stem cell transplantation. METHODS: A mouse model of aGVHD was constructed after bone marrow hematopoietic stem cell transplantation, and the umbilical cord-derived mesenchymal stem cells were cultured, and then injected into the aGVHD mouse model, so as to investigate its prophylactic efficacy. Prophylactic effect of the exosomes isolated from umbilical cord-derived mesenchymal stem cells on aGVHD mice was assessed. Sequencing analysis of miRNA from exosomes was performed. RESULTS: aGVHD model was successfully constructed after hematopoietic stem cell transplantation. By injecting umbilical cord-derived mesenchymal stem cells into the GVHD mouse model, it was found that the treatment significantly prolonged survival time of mice compared to the untreated group. Injection exosomes derived from umbilical cord-derived mesenchymal stem cells into the GVHD mouse model significantly prolonged the survival time of mice compared to the untreated group. High-throughput sequencing data showed that microRNA such as miR-21 in exosomes isolated from umbilical cord-derived mesenchymal stem cells, which mainly affected the signaling pathways such as cell adhesion, RNA degradation. CONCLUSION: The umbilical cord-derived mesenchymal stem cells can prevent the occurrence of aGVHD after HSCT, which is mediate by MicroRNA in the exosomes derived from umbilical cord-derived mesenchymal stem cells.

Leflunomide Inhibits rat-to-Mouse Cardiac Xenograft Rejection by Suppressing Adaptive Immune Cell Response and NF-κB Signaling Activation.

Xenotransplantation is a potential solution for the severe shortage of human donor organs and tissues. The generation of humanized animal models attenuates strong innate immune responses, such as complement-mediated hyperacute rejection. However, acute vascular rejection and cell mediated rejection remain primary barriers to xenotransplantation, which limits its clinical application. In this study, we systematically investigated the immunosuppressive effect of LEF using a rat-to-mouse heart xenotransplantation model. SD rat xenogeneic hearts were transplanted into C57BL/6 mice, and survived 34.5 days after LEF treatment. In contrast, BALB/c allogeneic hearts were transplanted into C57BL/6 mice, and survived 31 days after LEF treatment. Compared to normal saline treatment, LEF treatment decreased xenoreactive T cells and CD19+ B cells in recipient splenocytes. Most importantly, LEF treatment protected myocardial cells by decreasing xenoreactive T and B cell infiltration, inflammatory gene expression, and IgM deposition in grafts. In vivo assays revealed that LEF treatment eliminated xenoreactive and alloreactive T and B lymphocytes by suppressing the activation of the NF-κB signaling pathway. Taken together, these observations complement the evidence supporting the potential use of LEF in xenotransplantation.

Combination of N, N'-dicyclohexyl-N-arachidonic acylurea and tacrolimus prolongs cardiac allograft survival in mice.

Current immunosuppressive agents for organ transplantation are not ideal because of their strong toxicity and adverse effects. Hence, there is an urgent need to develop novel immunosuppressive agents. The compound N, N'-dicyclohexyl-N-arachidonic acylurea (DCAAA) is a novel highly unsaturated fatty acid from the traditional Chinese medicinal plant Radix Isatidis. In this study, we systematically investigated the toxicity, immunosuppressive effect and mechanisms underlying the activity of DCAAA. The toxicity tests showed that DCAAA treatment did not lead to red blood cell hemolysis and did not affect the liver and kidney functions in mice. The lymphocyte transformation test showed that DCAAA treatment inhibited lymphocyte proliferation in a dose-dependent manner. An in vivo cardiac allotransplantation experiment showed that DCAAA treatment could suppress the immune rejection and significantly prolong the survival of cardiac allografts in recipient mice by reducing the proportion of CD4+ T cells in the spleen and grafts, concentration of interferon-γ in the supernatant and serum and infiltration of inflammatory cells into the grafts. Moreover, a combination treatment with DCAAA and tacrolimus had a synergistic effect in preventing acute rejection of heart transplants. In vitro molecular biology experiments showed that DCAAA treatment inhibited activation of the T-cell receptor-mediated phosphoinostide 3-kinase-protein kinase B pathway, thereby arresting cell cycle transition from the G1 to the S phase, and inhibiting lymphocyte proliferation. Overall, our study reveals a novel, low-toxicity immunosuppressive agent that has the potential to reduce the toxic side effects of existing immunosuppressive agents when used in combination with them.