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Mixed hemopoietic chimerism is capable of inducing donor specific tolerance, thus eliminating the chronic immunosuppressive therapy following organ transplantation. As yet no safe and effective tolerance protocol is available for clinical implementation. Here we describe an alternative nonmyeloablative based strategy of using a single injection of recombination adenovirus vector encoding CTLA4.FasL fusing gene and donor bone marrow cells to promote durable mixed macrochimerism (>20% on 140 d). Chimeras exhibited robust donor-specific tolerance, as evidenced by acceptance of fully allogeneic skin grafts (the mean survival time (MST)>200 d) and rejection of third-party skin grafts in a normal manner (MST<10 d). In this model, the frequencies of helper T lymphocyte precursor (HTLp) and cytotoxic T lymphocyte precursor (CTLp) were greatly reduced on day 14 after transplantation, suggesting that CTLA4-FasL led to rapid systemic peripheral tolerance to facilitate the bone marrow engraftment, while both HTLp and CTLp remained at low level only in recipient mice with mixed chimerism on day 140 after transplantation, demonstrating that long-term skin grafts tolerance was associated with stable mixed chimerism, and central deletion of donor specific T cell may be the main mechanism for tolerance maintenance. [ABSTRACT FROM AUTHOR]

Type 1 diabetes is the result of a selective destruction of insulin-producing β cells in pancreatic islets by autoreactive T cells. Depletion of autoreactive T cell through apoptosis may be a potential strategy for the prevention of autoimmune diabetes. Simultaneous stimulation of Fas-mediated pathway and blockade of costimulation by a CTLA4-FasL fusion protein has been reported to lead to substantial inhibition of mixed lymphocyte reaction and enhanced in vitro apoptosis of peripheral lymphocytes. To test the feasibility of CTLA4-FasL-based gene therapy to prevent autoimmune diabetes, we developed recombinant adenovirus containing human CTLA4-FasL gene (AdCTLA4-FasL). A single injection of 2 × 108 plaque forming units (PFU) of AdCTLA4-FasL via tail vein dramatically reduced the incidence of autoimmune diabetes in mice induced by multiple low doses of streptozotocin. AdCTLA4-FasL administration maintained islet insulin content, significantly increased apoptosis of pancreatic lymphocytes, quantitatively reduced IFN-γ and Vβ8.2 TCR chain mRNA expression in pancreatic lymphocytes. These results indicate the therapeutic potential of simultaneous stimulation of Fas-mediated pathway and blockade of costimulation by adenovirus-mediated CTLA4-FasL gene transfer in the prevention of autoimmune diabetes. [ABSTRACT FROM AUTHOR]

The induction of transplantation tolerance and the improvement of immune reconstitution after allogeneic bone marrow transplantation are the main research fields in the clinic organ transplantation and transplantation immunology. Over the past 5 years serial studies have been performed in our lab to induce robust transplantation tolerance by using combined strategies and improve the immune reconstitution of mice following allogeneic bone marrow transplantation by using gene-engineered bone marrow stromal cells. The results are encouraging. (1) The long-term survival of allografts was received by blockade of both CD28/B7 and CD40/CD40L or CD28/B7 and OX40/OX40L costimulation signals. In the case of blockade of both CD28/B7 and OX40/OX40L, the islet allograft survival was over 150 days compared to the control 14 days. (2) The CTLA4Ig-FasL fusion molecule expressed by adenoviral vector containing CTLA4Ig-FasL gene can prevent the autoimmune diabetes of mice and significantly prolong the survival time of cardiac allografts in rats, indicating that Fas-FasL-mediated apoptosis is able to enhance CTLA4Ig-induced transplantation tolerance. (3) In the time-window of peripheral tolerance induced by various methods, the systemic infusion of donor bone marrow cells and spleen cells obtained stable allogeneic mixed chimerism and robust transplantation tolerance. In the case of CTLA4Ig-FasL treatment combined with donor bone marrow cells more than 20% donor-origin blood cells chimerism, and more than 200 days prolonged skin allograft survival were obtained or received. (4) The murine bone marrow stromal cell line QXMSC1 transfected with IL-6 gene or IL-2+IL-3 genes significantly improved the immune reconstitution of mice following allogeneic bone marrow transplantation. Furthermore, It was observed that the mesenchymal stem cells transfected with IL-7 gene suppressed 90% of GVHD and expressed antileukemic effect, while accelerating immune reconstitution in mice following allogeneic bone marrow transplantation, which might be valuable in the clinic setting.

Arsenic trioxide albumin microspheres (As2O3-BSA-NS) were prepared by using methods of chemical cross-linking. The desirability function (DF), calculated according to the size (<1 microm) distribution, drug loading and drug trapping efficiency, was introduced as a total index for the microspheres formulation. Four factors, inculding W/O ratio, decentralization speed, BSA concentration and stirring stabilization time, were selected and arranged in an orthogonal experimental table. The release characteristic was studied by the drug release experiment in vitro. The four factors affected DF differently. Decentralization speed behaved as the maximum (P<0.01), followed by BSA concentration (P<0.05) and the W/O ratio dose (P<0.05). Stirring stabilization time did not influence DF (P>0.05). The release experiment in vitro showed that As2O3 in As2O3-BSA-NS was released more slower than pure As2O3. It was concluded that regular As2O3-BSA-NS may be prepared by the methods of chemical cross-linking, which was optimized by orthogonal experimental analysis of different factors, and the microspheres can release As2O3 slowly.

Objective: To explore whether bone marrow stromal cell line QXMSC1 (H-2(d)) engineered to secrete IL-3 (QXMSC1 IL-3) can improve the hematopoiesis post-allogeneic bone marrow transplantation (BMT) in mice., Methods: The stromal cell line QXMSC1 IL-3 was established by transfecting QXMSC1 (H-2(d)) cell with a recombined retrovirus vector PL3SN containing mice IL-3 gene cDNA. Lethally irradiated mice C57BL/6 (H-2(b)) were transplanted with T cell depleted allogeneic bone marrow (BALB/c, H-2(d), 1 x 10(7)/mice) and QXMSC1 IL-3 cells (5 x 10(5)/mice). The numbers of RBC and WBC in peripheral blood were counted 20 and 40 days after bone marrow transplantation. The marrow nucleated cells, CFU-S, CFU-GM, CFU-E and CFU-GEMM yields were measured in recipient mice., Result: QXMSC1 IL-3 cells could stably secrete IL-3 and increase the peripheral RBC and WBC counts as well as the number of marrow nucleated cells and CFU-GM, CFU-E, CFU-GEMM yields., Conclusion: Cotransplantation of QXMSC1 IL-3 cells with T cell depleted marrow grafts improve hematopoiesis post allogeneic BMT in mice.