Human Amniotic Mesenchymal Stem Cells Effects On The Lymphocyte Proliferation And Its’ Tumorigenicity

This experiment studied the influence between human amniotic mesenchymal stem cells (hAMSCs) and lymphocyte proliferation in vivo and in vitro condition. To observe the tumorigenicity of hAMSCs, Cells were inoculated in immunodeficiency mice. These observations could let us understand the potential mechanism about the low immunogenicity of hAMSCs. Study on tumorigenicity of hAMSCs could provide safety evidence for clinical stem cell therapy.hAMSCs were isolated and cultured by enzyme digestion method. Using flow cytometry and immunofluorescence method, cells were identified. Immunogenicity study could be observed the influence of hAMSCs in allogeneic lymphocytes proliferation induced by Concanavalin protein (ConA) and the IFN-y secrection of allogeneic lymphocyte in vitro. Using the method of cck-8 determined the number of living cells of lymphocytes, and determined the expressing IFN-γ in cells’supernatant by ELISA. The cells were injected into the mice with liver injury through the tail vein in vitro. By observing the lymphocytes and plasma interferon-γ (IFN-γ) changes in mice could explore the immunogenicity of hAMSCs.5×106 hAMSCs and 5×106, 1×107 liver cancer cells(HepG2)cells were injected subcutaneously in the back of the immunodeficiency mice, and then to observe the tumor formation. HE staining for pathological observation was used in tumor after 50 days.Results show that high purity hAMSCs were obtained using the method of enzyme digestion.5μg/ml ConA could induce lymphocyte proliferation. In culture condition, hAMSCs could inhibit lymphocyte proliferation induced by conA, and with the increasing number of hAMSCs, the inhibitory effect was more obvious. The number of living cells of ConA group was significantly higher than the co-culture group (P<0.01). Chose the best inhibitory effect groups, and ELISA measurement was used to evaluate the IFN-y secretion of lymphocyte supernatant with 1Τ105 hAMSCs after 72h. Co-culture group was significantly lower than the lymphoproliferative group caused by ConA (P <0.01). Compared to the control group of liver damage mice, the number of lymphocytes in the injected mice of liver damage decreased. The IFN-γ content in peripheral blood of injected liver damage mice with extension of the injected time was also reduced gradually. hAMSCs group has no tumor formation, and the positive control of HepG2 group all grew with tumors. hAMSCs group tumor counts were normal.