A Study On Immunocompetence Of Mononuclear Cell Of Placenta

Objective Hematopoietic stem cell(HSC) transplantation has not only been increasing used for correction of abnormal hematopoiesis in patients with malignant and nonmalignant many solid maglignancies. It has been reported that there are more than 4 million patients with kinds of dieases waiting for hematopoietic stem cell transplantation, however, the sources of hematopoietic stem cell are so limited. At present, HSC transplantation of peripheral blood and bone marrow demand the HLA completely matched. And the rate of completely matched-HLA is 25% between compatriots. What's more, the rate is only 1/400—1/10000 among non-consanguineous people. Clinical transplantation evidence has indicated that cord blood is useful in the hematopoietic reconsititution in the children, but not well in the adult. Because of the low cell count, cord blood has to be expanded. Now all the sources of the hematopoitic stem cell can't satisfy the clinic requirement. Thus, the search for possible alternative hematopoietic stem cell sources remains to be validated. Recent years, it has been reported that placenta contains hematopoitic stem cell. This means the placenta what is always discarded is possible to be one of the sources of the hematopoitic stem cells. Like cord blood, because of the limited hematopoitic stem cell, the HSC of placenta demands to be expanded before transplantation which has been reported aboard. And graft-versus-host-disease(GVHD) is the dominate placenta hasn't been reported. So this study compare the immunocompetence of mobilized peripheral blood and the expanded HSC from placenta and cord blood. And provide theory prove for the HSC of placenta to be used for transplantation.Subjects and Methods1. Collecting 8 healthy adults' mobilized peripheral blood, 8 healthy pregnant women mature placenta tissue and responding cord blood under sterile condition.2. Preparation of mononuclear cell(MNC):Cut the placenta tissue into 1 -2mm³ pieces, MNC in human mature placenta tissue were isolated by enzyme-digesting method and 320 eye cell screen and separated by Ficoll-Hypague fluid.3. Culture of MNC in vivo: MNC of placenta and cord blood is cultured in DMEM with some cytokine,37℃,5%CO₂,saturated moisture for 7 days.4. Measuring the proliferation of peripheral blood, cord blood, placenta in one-way mixed lymphocyte culture by CCK-8; Measuring surface markers including CD₃,CD₁₉,CD₁₆,CD₅₆,HLA-DR of mononuclear cell from placenta, cord blood, and mobilized peripheral blood by Flow Cytometric Sortring(FCS).Result1. One-way mixed-lymphocyte reactions (MLR): There was a significant decrease in proliferative responsiveness in MLR assay of placenta compared with cord blood and mobilized peripheral blood. Proliferative responsiveness of cord blood was higher than placenta, but was much lower than mobilized peripheral blood.2. Phenotypic analysis: T lymphocyte (CD₃⁺) and B lymphocyte(CD₁₉⁺) of placenta was less than that of cord blood and peripheral blood, and there was significant difference among them. The count of NK cell(CD₁₆⁺CD₅₆⁺) and HLA-DR⁺ cell of placenta was significant more than that of cord blood and peripheral blood.Conclusion1. In one-way MLR, the proliferative responsiveness of expanded MNC of placenta is lower than that of expanded MNC of cord blood and that of mobilized peripheral blood. It suggests that the immunocompetence of expanded MNC of placenta is lower than that of expanded MNC of cord blood and that of mobilized peripheral blood. 2. The percent of CD₃⁺ and the percent of CD₁₉⁺ of expanded MNC of placenta is lower than that of expanded MNC of cord blood and that of mobilized peripheral blood. It suggests that the immunocompetence of expanded MNC of placenta is lower than that of expanded MNC of cord blood and that of mobilized peripheral blood.3. The percent of CD₁₆⁺CD₅₆⁺ of expanded MNC of placenta is higher than that of expanded MNC of cord blood and that of mobilized peripheral blood, which perhaps helps for graft-versus-leukemia while doesn't increase the incidence and severity of GVHD.4. It is possible for placenta to be used as a source of hematopoitic stem cell transplantation. If we use expanded MNC of placenta and cord blood and mobilized peripheral blood for transplantation, the incidence and severity of GVHD of placenta is lowest.