Clonogenicity and colony pattern of CB-MSC in response to HF. Clonal capacity was determined by CFU-F assay. A: Clonal efficiency in percent (number of colonies comprising more than 50 cells per number of plated cells) for each experimental group. CB-MSC clonal efficiency was significantly reduced in the HF group. The boxplot indicates interquartile range (box), median (line), range (whiskers) and outliers (+/−). B-D: Relative frequencies of cell cluster size categories in percent for single samples of all groups (D). In the HF group there was an increase in the number of small (<50 cells) and a decrease in the number of large (>200, >500 cells) clusters. Bar = 50%. Representative bright field images of a typical large and a small cluster (B, C). Scale bars = 1 mm.