CB-MSC proliferation in response to HF serum. To assess CB-MSC kinetics of proliferation and activity in response to individual sera, three independent assays were performed with P4 cells after 1, 3 and 5 days of treatment. A: DNA synthesis levels were obtained from BrdU assay. Graphs show optical densities recorded at 450 nm (OD 450 nm) for all treatment groups. B: DAPI-based cell counting approach for direct quantification of CB-MSC number. C: Metabolic activity determined by MTS assay, given as optical density at 490 nm. In all assays, CB-MSC proliferation was impaired after 1 and 3 days, but not after 5 days of treatment with HF serum as compared with human control serum treatment. The effect of time and group and their interaction were determined by ANOVA for repeated measurements. The boxplots indicate interquartile range (box), median (line), range (whiskers) and outliers (+/−).