Basic MSC properties in response to HF serum treatment. A, E, I: Phase contrast imaging of CB-MSC morphology did not reveal obvious differences between FCS, the human control and the HF serum group. Scale bar = 100 μm. B-D, F-H, J-L: Tripotential mesodermal differentiation capacity: Osteogenesis (calcium deposits) was visualized by Alizarin Red S (B, F, J) (bar = 250 μm), adipogenesis (lipid vesicles) by Oil Red O (C, G, K) (bar = 50 μm) and chondrogenesis (proteoglycans) by Alcian Blue staining (D, H, L) (bar = 125 μm). M-O: Relative gene expression of lineage-specific markers in undifferentiated and differentiated cells: osteogenesis, ALP (M), adipogenesis, PPARγ (N), chondrogenesis, SOX9 (O). The boxplots indicate interquartile range (box), median (line), range (whiskers) and outliers (+/−). * p < 0.05 vs. undifferentiated cells. GOI: gene of interest. P-V: Surface marker expression pattern of CB-MSC, as examined by flow cytometry, was not affected by HF serum treatment. Shown are histograms for CD73 (P), CD90 (Q), CD105 (R), CD14 (S), CD34 (T), CD45 (U) and HLA-DR (V), in which cell counts are plotted against fluorescence intensity. All histograms are representative for both human serum groups and the FCS control.