Objective To investigate the possibility of immune tole rance induced by bone marrow-derived mesenchymal stem cells in allogeneic organ transplantation. Methods Allogeneic bone marrow-derived mesenchymal stem cells and syngeneic bone marrow cells were cotransplanted to lethally irradiated female C57BL/6 recipient mice. FACS was used to analyze the chimerism 150 days later. Mixed lymphocyte reaction and ConA induced proliferation test were performed to evaluate proliferative activity of mice spleen cells in cell-transplanted group. Skin transplantation test was done to observe immune response of cell-transplanted group mice against organ graft from donor mice. Results About 5 97% donor T cells were detected in splenocytes of cell-transplanted group mice. MLR showed that mean SI of cell-transplanted group mice was 1.79, and that of untreated group mice was 7 28. ConA induced proliferation test showed that mean SI of cell-transplanted group mice was 31 92; and that of untreated group mice was 34 99. Mean survival time of donor-derived skin graft in cell-transplanted group mice was more than 90 days; and that in untreated group mice was 8 days. Conclusion Our results showed for the first time that induction of stable mixed hematopoietic chimerism after allogeneic bone marrow derived mesenchymal stem cells transplantation lead to stable donor-specific tolerance in allogeneic host and skin graft survival from donor mice.

OBJECTIVESTo assess the feasibility and efficacy of eliciting leukemia-specific T-cell responses in syngeneic mice in vitro and in vivo using dendritic cells (DCs) pulsed with total RNA from leukemia cells.

METHODSDCs generated from bone marrow culture in vitro in the presence of combined cytokines were pulsed with cellular total RNA isolated from cultured L615 cells by cationic lipid 1,2-dioleoyloxy-3-(trimethylammonium) propane (DOTAP). T-cell responses were evaluated by in vitro proliferation, and cytotoxicity assay. And in vivo immune protection and prognosis of mice with leukemia were studied.

RESULTSDCs pulsed with total RNA isolated from cultured L615 cells (DCs/RNA) were remarkably effective in stimulating L615-specific T-cell response in vitro, but did not cross-react with other leukemia cells from syngeneic mice. Vaccination of naive mice with viable DCs/RNA vaccine was able to partly protect from challenge with a lethal dose of live L615 cells, leading to low leukemia incidence and overall survival prolongation. Statistically significant survival was also observed in a low lethal dose of L615-bearing mice that received treatment using viable DCs/RNA vaccine alone, suggesting that systemic administration of IL-2 could enhance the anti-tumor efficacy of leukemia RNA/DCs vaccine.

CONCLUSIONSThese data support the use of DCs/RNA vaccine as a feasible and effective route to elicit leukemia immunity against unidentified leukemia-associated antigens for treatment of leukemia-bearing animals.

Animals ; Cancer Vaccines ; Dendritic Cells ; immunology ; Leukemia, Experimental ; immunology ; Mice ; RNA, Neoplasm ; immunology ; isolation & purification ; T-Lymphocytes ; immunology ; Tumor Cells, Cultured