Interferon-gamma combined with lipopolysaccharide polarizes human umbilical cord-derived mesenchymal stem cells to a MSC2 phenotype / 中国组织工程研究

ABSTRACT

BACKGROUND: Mesenchymal stem cells have been widely applied in autoimmune diseases and graft-versus-host diseases because of their immunomodulatory capabilities. However, mesenchymal stem cells have plasticity in immunomodulation, which leads to heterogeneity and instability when used in vivo. OBJECTIVE: To investigate the polarization of human umbilical cord derived mesenchymal stem cells to an immunosuppressive phenotype (MSC2) in the inflammatory microenvironment induced by interferon-γ and lipopolysaccharide. METHODS: Human umbilical cord-derived mesenchymal stem cells were isolated and cultured in vitro, and then were identified by morphological characteristics, surface markers, adipogenesis and osteoinduction activity. Human umbilical cord-derived mesenchymal stem cells were treated with interferon-γ (10 μg/L), lipopolysaccharide (100 μg/L), or their combination for 24 hours, respectively, and were then co-cultured with phytohemagglutinin pre-treated peripheral blood mononuclear cells for 5 days under direct or Transwell indirect contact. The percentages of regulatory T cells and T helper 1 cells were analyzed by flow cytometry at different times. The mRNA expression levels of Toll-like receptors 2, 3 and 4 were detected by real-time fluorescence quantitative PCR. RESULTS AND CONCLUSION: (1) Human umbilical cord derived mesenchymal stem cells exhibited spindle-shaped or fibroblast-like morphology, highly expressed CD73, CD90 and CD105, and lacked expression of CD34, CD45 and HLA-DR. (2) Under direct or indirect co-culture, human umbilical cord-derived mesenchymal stem cells pre-treated with interferon-γ and lipopolysaccharide could promote the generation of regulatory T cells, which was superior to the interferon-γ, lipopolysaccharid, un-treated and control groups (P < 0.05). (3) The percentage of T helper 1 cells gradually decreased over time. (4) Under indirect co-culture, human umbilical cord derived mesenchymal stem cells pre-treated with interferon-γ and lipopolysaccharide were polarized into immunosuppressive MSC2 phenotype at an earlier period and highly expressed Toll-like receptor 3 (P < 0.05). (5) In conclusion, the combination of interferon-γ (10 μg/L) and lipopolysaccharide (100 μg/L) results in the high-efficient polarization of mesenchymal stem cells toward the MSC2 phenotype under indirect co-culture, and the immunosuppressive capability of MSC2 is independent of intercellular contact, which provides clinical evidence for the MSC2-derived exosome therapy in the future.