Abstract: Objective To compare the immunological characteristics of BMSCs cultured in ScienCell (SCI) stem cell growth medium and low glucose (LG) complete medium. Methods The expressions of cell surface markers on BMSC were characterized by flow cytometry analysis and the multipotency of BMSC was confirmed by functional osteogenic and adipogenic differentiation. The immunogenicity and immunomodulatory properties of BMSC in SCI and LG groups were assessed and compared by mix lymphocyte reaction (MLR). The expression profiles of immune molecules on BMSC with and without IFN-γ stimulation were characterized by flow cytometry analysis. Results The MLR results showed that BMSCs in both SCI group and LG group exhibited low immunogenicity and immunosuppressive abilities. One-way lymphocyte proliferation index was significantly higher in SCI group than in LG group while no significant difference was observed for the two-way mix lymphocyte proliferation index between SCI group and LG group. Compared with BMSC in LG group, BMSCs in SCI group exhibited significantly higher percentage of cells that positive for co-stimulatory molecule CD40 but lower percentage of cells expressing HLA-DR and co-inhibitory molecules B7-H1 and B7-DC. The percentages of HLA-DR+cells of BMSC in both SCI group and LG group were significantly increased to more than 90% in response to IFN-γ stimuli. Treatment with low concentration of IFN-γ (10 U/mL) only slightly increased the percentage of CD40+cells in BMSCs of LG group, while treatment with high concentration of IFN-γ (1 000 U/mL) significantly increased the expression of CD40 and B7-H1 of BMSCs in both groups, and B7-DC in BMSCs in LG group. Conclusion The expression of immune relevant molecules on BMSC cultured in SCI medium in vitro was changed. The immunogenicity of BMSC in SCI group was significantly higher than in LG group while no significant difference was observed for their immunosuppressive properties.

Key words: Bone marrow mesenchymal stem cells, Immunological characteristics, Growth factors, Interferon-γ