Exploration On The Regulation Of Graft-versus-host-disease Derived From HLA-haploidentical Peripheral Blood Hematopoietic Stem Cell Transplantation By Human Umbilical Cord Blood Stromal Cells

Background：Allo-HSCT is the most effective therapy for various kinds of diseases,such asmalignant or non-malignant hematopoietic disorders, some immunodeficiencysyndrome,autoimmune diseases, congenital metabolic disorders and so on.During the lasttwo decades, the application of Allo-HSCT changed into a more complicated field fromsingle HLA-identical BMSCT under myeloablative conditioning,especially muchprogresses have been made in HLA-haploidentical transplantation.HLA-haploidenticaltransplantation solve the problem of shortage of donor source,which existed since theappearance of HSCT. It is reported that more than90%patients can get suitable donorsfrom parents, children, brothers, and sisters.Recently, lots of new methods have been developed about HLA-haploidentical stem celltransplantation. Bone marrow (BM), associated or not with PBSCs and primed or unprimed,has been used as the stem cell source in most of these methods. However,BM contains highamount of red blood cells (RBC)and plasma,when there is mismatch in blood group betweenthe donor and the recipient, as harvested donor BM must be processed to deplete RBC orplasma or bothbefore infusion to recipient.Besides，bone marrow extraction is an invasiveprocedure which may bring some risks to the donors. PBSCs is easy to get,they can avoid theproblems in BM transplantation effectively. Graft from PB contains lots of CD34+cellswhich can promote implantation, more over, PBSCs are pure and affected by RBCslightly.However, PBSCproducts contain approximately5-10times higher numbers ofCD3-positive T-cells than BM harvests,which correlate with higher rates of GHVD comparedto BM. Our previous study demonstrated CB contains hematopoietic stromal precursorcells, named human umbilical cord blood derived stromal cells. hUCBDSCs can be culturedand amplificated in vitro.It is demonstrated that hUCBDSCs has low immunogenicity and itcan constitutively express HLA-I but little HLA-II or other costimulators,exertimmunosuppressive effects on xenogenic T cells in vitro and suppress GVHDin mousehaploidentical stem cell transplantation. This experiment is aim to observe whetherhUCBDSCs can regulate GVHD after PBSCT as well as the possible mechanisms.Method：1.6%gelatin together with1.077g/LPercoll separates mononuclear cells from humanumbilical cord blood, just as previous report.2. Female C57BL/6×BALB/c F1receives male C57BL/6peripheralbloodmononuclear cells (1×106/per),spleen lymphocytes ((1×107/per) through tailintravenous injection after total body irradiation(7.0Gy) to make GVHD model.3. hUCBDSCs were infused into GVHD model, the GVHD manifestation will beobserved,include survival time, clinical manifestation,and pathological change of GVHD.4. The expression of NK cells on different time(first week, second week, third weekand fourth week) and the expression of Th1,Th2on third week in spleen of recipients micewas examined by FCM after transplantation.Results：1.The hUCBDSCs was cultured and proliferated successfully.2.The MHC-haploidentical peripleral blood hematopoietic stem cell transplantationGVHD model was contructed sucessfully,which is confirmed by typical GVHDmanifestation,include clinical and pathological changes.3. hUCBDSCs can prolong recipients suvival time,reduce motality (P<0.05),decreaseclinical and pathological GVHD scores(P<0.05).4. hUCBDSCs can increase NK cell、Th2expression and decrease Th1cell expressionin spleen of recipients （P<0.05.Conclusion：hUCBDSCs can alleviate GVHD derived from MHC-haploidentical PBSCT, this maydue to they can increase the NK cell、Th2cell expression and decrease the expression ofTh1cells.