Fig. 2

Preconditioned MSCs impair polarization toward the M1 phenotype. Unstimulated or preconditioned MSCs were co-cultured with macrophages (ratio 1:2) in the presence of M1-polarizing cytokines (20 ng/ml IFN-ɣ + 100 ng/ml LPS) for 24 h. Then, cells were separated using autoMACS. In parallel experiments, MSCs were cultured in transwells (TW) to avoid direct contact to co-cultured macrophages. a The expression of the surface receptors CD86 and CD206 as well as intracellular iNOS expression in macrophages was quantified by flow cytometry. Percentage of positive cells is depicted. For iNOS expression, the mean fluorescence units (MFU) are additionally displayed. n = 7, *p < 0.05, **p < 0.01 vs. macrophages cultured alone (M1); #p < 0.05. b TNF-α levels in culture supernatants were quantified by ELISA and NO₂ levels were quantified by Griess assay. Results are representative for seven independent experiments. *p < 0.05, **p < 0.01 vs. macrophages cultured alone (M1); #p < 0.05. M macrophage, MSCs mesenchymal stem cells, iNOS inducible nitric oxide synthase, NO₂ nitrite, TNF-α tumor necrosis factor alpha