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Sensitized recipients are at a high risk of graft rejection in hematopoietic stem cell transplantation. To explore the trace of donor cells, we tried to explore homing and engraftment of bone marrow cells (BMCs) derived from different donors in a murine model of sensitization. Sensitized BALB/c mice were used as transplanted recipients, which received BMCs derived from C57BL/6 or BALB/c donors after lethal irradiation. The homing study showed that the donor cells decreased along with time in recipients of the C57BL/6 donor group, but the donor cells increased along with time in recipients of the BALB/c donor group. For the engraftment assay, all the sensitized recipients transplanted with BMCs derived from C57BL/6 donors died after lethal irradiation. In contrast, all the recipients transplanted with BMCs derived from BALB/c donors got long-term survival. Our results suggest that it is crucial to have human leukocyte antigen identical donors for sensitized recipients during hematopoietic stem cell transplantation.

Sensitized patients are at high risk for graft rejection during transplantation. It is of interest to investigate the effect of mesenchymal stromal cells (MSCs) in sensitized hematopoietic stem cell transplantation. MSCs were generated from bone marrow cells of BALB/c mice. The molecular markers of MSCs were detected by flow cytometry. MSCs labeled with green fluorescent dye were transplanted into nonsensitized and sensitized recipients, respectively. Homing of MSCs in vivo was monitored at different time points post-transplantation. Additionally, sensitized BALB/c mice under irradiation were transplanted with syngeneic MSCs and allogeneic bone marrow cells, and the rate of survival was monitored daily. The fourth passage of MSCs presented a typical spindle-shaped morphology and met the identification criteria of MSCs. Forty-eight hours post-transplantation, the homing of MSCs was found mainly in the bone morrow of nonsensitized recipients and the spleen of sensitized recipients, respectively. Moreover, all of the sensitized recipients died 12-16 days after receiving syngeneic MSCs and allogeneic bone marrow cells, with a median of 14 days. Our results suggest that the MSCs mainly homed to the spleen of sensitized recipients post-transplantation. MSCs could not enhance the engraftment of allogeneic bone marrow cells in sensitized recipients., (Copyright © 2011 S. Karger AG, Basel.)

Objective: To establish a murine model of sensitization, and investigate the effect and mechanism of sensitization on allogeneic donor bone marrow cells (BMCs)., Methods: Sensitized BALB/c mice were established by transfusions of allogeneic splenocytes. The donor reactive antibodies were detected by binding and complement-dependent cytotoxicity assays. After irradiation, 1 × 10(7) BMCs of C57BL/6 donor mice were injected into non-sensitized or sensitized BALB/c recipient mice. The distribution pattern of donor BMCs in peripheral blood, spleen and bone marrow of recipient mice were analyzed at different time points (2 h, 12 h and 48 h) post transplantation. Hematopoietic recovery post transplantation was assessed, and survival was monitored. Moreover, sera and splenocytes derived from non-sensitized or sensitized recipients were incubated with allogeneic BMCs in vitro, and the cytotoxic indexes were calculated in the immune experiments., Results: The binding and complement-dependent cytotoxicity assays showed that a high level of donor reactive antibodies was presented in sensitized sera. Compared with the non-sensitized recipients, the homing assay showed significantly decreased distributions of allogeneic donor BMCs in peripheral blood, spleen and femur of sensitized recipients. Non-sensitized recipients survived long term after irradiation, while all the sensitized recipients died within 12-15 days. Fourteen days post transplantation, the white blood cells and BMCs of non-sensitized recipients were (3240 ± 300) × 10(6)/L and (396 ± 27) × 10(6)/femur, respectively; while the white blood cells and BMCs of sensitized recipients were (320 ± 80) × 10(6)/L and (6 ± 2) × 10(6)/femur, respectively; the differences were statistically significant between this two groups (P < 0.05). Seven days post transplantation, the percentage of donor cells in bone marrow of non-sensitized and sensitized recipients was (48.07 ± 4.70)% and (0.77 ± 0.11)%, respectively, and the differences were statistically significant (P < 0.05). Furthermore, the white blood cells and BMCs following transplantation decreased along with time in sensitized recipients. The immune experiments of complement-dependent cytotoxicity reaction, cytotoxic T lymphocytes reaction and antibody-dependent cellular cytotoxicity showed the cytotoxic indexes were higher in sensitized group than the non-sensitized group., Conclusion: A sensitized model was established by transfusions of allogeneic spleen cells. Allogeneic donor BMCs were rejected in sensitized recipients, and its mechanism might be through immune impairment pathways.

We aim to investigate the efficacy and safety of the treatment with fully matched allogeneic hematopoietic stem cell transplants for children with severe aplastic anemia (SAA) in the first prospective trial in China. Six SAA children received allogeneic hematopoietic stem cell transplantation combined with chemotherapy. Five patients had successful engraftment while the sixth child regained normal peripheral blood counts consistent with spontaneous autologous hematopoiesis. Mean duration of follow-up was 2.75 years, and survival was 83%(5/6). The results indicated that allogeneic hematopoietic stem cell transplantation is a good option for the treatment of children with severe aplastic anemia., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

This study was aimed to establish sensitized animal models, explore the changes of immune function in these sensitized recipients, and investigate effects of sensitization on the engraftment of hematopoietic stem cells (HSCs). Different doses of spleen cells (1x10(5), 1x10(6) and 1x10(6)x2 at intervals of 7 days) from C57BL/6 were infused into BALB/c, the immunity function of sensitized models was tested by complement-dependent cytotoxicity method, mixed lymphocyte reaction and ELISA. After irradiation with gamma-ray of 60Co in dose 8 Gy, sensitized mice were transplanted 1x10(7) C57BL/6 bone marrow cells via tail vein or intra-bone marrow, and survival rate was detected daily. The results showed that different levels of donor reactive antibody were induced in all sensitized models. Comparing with normal mice, profound proliferation of spleen cells were found in groups of injected 1x10(6) and 1x10(6), continuous injections at intervals of 7 days. Sensitized model received bone marrow cells of C57BL/6 via tail vein died on day 10 to 14 after transplantation, and sensitized model mice received bone marrow cells of 1x10(6)x2 at intervals of 7 days via intra-bone marrow also died within two weeks after transplantation. It is concluded that different sensitized mouse models are established by different doses of allogeneic spleen cells infusion, the changes of immune function in sensitized mice are correlative with sensitization. Donor HSCs are rejected in sensitized models, and the engraftment can not be improved by intra-bone marrow injection.