| In recent years, with the development of new immunosuppressive drugs and the technology of tissue matching, and the rapidly advancement of transplantation surgery, plastic surgeons take more efforts to explore in the era of composite tissue allotransplantation. However, because of the complexity and antigenic heterogeneity of composite tissue allografts, CTA lags far behind organ transplantation. Since Dubernard successfully completed hand allotransplantation for the first time in the year 1998, there are 20 cases of hand allotransplantation and 8 cases of face allotransplantation has been reported in the world till 2007. According to literatures, the first case of face allotransplantation operated by the French had suffered acute rejection twice postoperative. And the second one completed by our institute had also encountered one more time. When given higher dose of immunosuppressive agents, rejection had been controlled at the cost of various intractable complications, such as acute renal failure, hypertension, hyperglycemia, leukopenia and so on. Therefore, it is the most important thing for the researchers in the field of composite tissue allotransplantation to minimize the risks of immunosuppressants.Every Graft rejection follows the general rule of immune response. Once naive T cells from the host recognize alloantigens presented by antigen-presenting cells, immune responses will be initiated. These naive T cells enter the activation phase and proliferation phase in sequence and then become effective T cells. Finally, various responses mediated by effective T cells happen such as immune rejection. Thus, selective blocking of any part of the response process will probably induce immune tolerance after transplantation.Dendritic cells are the most important antigen presenting cells, with high expression of MHC-II and costimulatory molecules CD80, CD86. Their classic function was thought to be that of potent initiators of innate and adaptive immunity to infectious organisms and other Ags, including allografts.They are APCs uniquely specialized in inducing primary immune responses, supporting the survival and effector functions in previously primed T cells. But, in the normal steady state, DCs are present as'immature'antigen - presenting cells. They express few surface MHC and accessory (intercellular adhesion/costimulatory) molecules (CD80, CD86, et al) with mainly phagocytosis function other than antigen presentation. Immature DCs are at best, poor stimulators of naive T cells, and can even induce T cells apoptosis or promote T-cell unresponsiveness to silence immune reactivity.Objective: The composite tissue allografts locate at body surface and could resistant to ischemic for a longer time. With these advantages, our research propose to use local cellular therapy intraoperative and postoperative in order to induce immune tolerance.That may cut down the incidence of complications brought from life-long systemic immunosuppression. Method:1. Cytokines are used to induce immature dendritic cells from bone marrow progenitor cells in vitro. Morphological observation, activity test and analysis of surface marker and in vitro immunological function test are used to identify the cells.2. Superficial inferior epigastric artery flap from Brown-Norway (RT1n) was transplanted to Lewis (RT11) rats (day 0). ImDCs were propagated from the recipient (Lewis, RT11) or donor (Brown-Norway, RT1n) bone marrow, stained with CFSE and then topically transfused into allografts through femoral artery pedicle on day 0 comined with low dose of rapamycin or not. Then observe the survival time of allotransplants.Results:1. The cells grew in clusters like grape under light microscope. They possessed large cytoplasmic 'veils' rather than dendrites and were rich in intracellular organelles and engulfed bubbles under electron microscopy. The survival cell rate and the purity were (91.13±1.25) % and (61.10±1.47) % separately. OX62-positive cells showed low expression of CD80, 86, MHC II. Test of suppression function showed that imDC did not have the capacity activate T cell directly. Accordingly, imDCs were poor stimulators of naive T cells in One-way mixed lymphocyte reaction.2. All animals treated with transfusion of donor derived imDCs suffered acute rejection firstly. Histopathology analysis showed significant perivascular infiltration which was typical characteristic of acute rejection. Conversely, All animals received combined treatment with recipient imDCs and low dose of Rapa showed evidence of longer survival time up to more than 20d. Through pathological analysis, we observed dense inflammation with the involvement of epidermal, subcutaneous and perivascular.The former group showed lower Treg in their spleen and lymph nodes, and the latter showed higher. But they both lower than the normal group.Conclusion:1. Those immature dendritic cells induced by cytokines in vitro showed low immunogenicity, and could reduce T cell activation and proliferation.2. Receptor imDC drug rapamycin combined with low dose prolong the survival time of allogeneic skin, stimulate Treg expansion in vivo may be related to the future autologous transfusion imDC and Treg joint basis.Recipient imDCs transfusion combined with low dose rapamycin therapy prolongs allograft survival, and may be correlated with the proportion of Treg. It would be an evidence to support application of Treg adoptive transfusion therapy in future research. |
PDF Full Text Request