Umbilical Cord Mesenchymal Stem Cells Regulate Secretion Of Antiplatelet Antibody In Vitro

Object To investigate the potential immunotherapeutical effects of umbilical cord-derived mesenchymal stem cells(UC-MSC) on patients with idiopathic thrombocytopenic purpura(ITP),an autoimmune disease characterized by autoantibody-mediated destruction of the platelets by macrophages in the reticuloendothelial system.Methods Different doses of UC-MSC were cocultured in vitro with splenocytes isolated from eight cases of ITP patients and three cases of hereditary spherocytosis(HS) patients who experienced splenectomy. After a short term culture,the level of IgG antiplatelet antibody(PAIgG) in supernatants was determined by a competitive micro-enzyme-linked immunosorbent assay(ELISA) method.The proliferation of platelet-reactive CD4~+ T lymphocytes was also measured with Brdu incorporation ELISA method after coculture with UC-MSCs for 7 days. In the T subsets experiment,peripheral blood mononuclear cells(PBMCs) were isolated from another 12 chronic ITP patients and 8 healthy donors. After cocultured with UC-MSCs(at the ratio of 1UC-MSC:10 PBMCs) for 3-4 days in vitro,PBMCs were harvested and activated by the combination of PMA,ionomycin and BFA.The ratio of Th1/Th2 was studied by analysis of intracellular cytokines with flow cytometry. Results UC-MSC could significantly promote the spontaneous secretion of PAIgG by splenocytes from all ITP patients.In the platelet-inducing condition,UC-MSC inhibited the production of PAIgG in splenocytes of ITP patients at a low ratio of 1 UC-MSC to 100 splenocytes,while promoted at 1:10.In contrast,UC-MSC slightly stimulated spontaneous secretion of PAIgG from splenocytes of HS patients.Platelet-induced PAIgG production was enhanced in only one HS sample.In addition,UC-MSC exerted a definitely suppressive effect on the proliferation of platelet-reactive T helper cells in a dose-dependent manner.However,UC-MSCs failed to obviously change the polarization of T cell subsets isolated from PBMCs of ITP patients and healthy donors.Conclusion UC-MSC can regulate IgG antiplatelet antibodies secretion by splenocytes of ITP patients in vitro,and further study about exact modulation mechanism and prospect for clinical application is expected.