Fig. 2
Morphology and growth characteristics of CB-MSC. a Colony of CB-MSC 10 days after initial seeding (passage 0). b Non-proliferative fibroblast-like cells and osteoclast-like cells, the latter with very large cytoplasm and occasional multiple nuclei (passage 0). c Morphology of CB-MSC at passage P1. Scale bars: 100 μM. d Growth patterns of CB-MSC grouped by similar cPD (cPD cutoff = 20 at P9). Black circles: LL-CBMSC; white circles: SL-CBMSC. e Comparison of cPD between LL- (black bars) and SL- (white bars) CBMSC at each passage; the differences were computed by Mann-Whitney U test, * p < 0.05, ** p < 0.01, *** p < 0.001; data are presented as mean with SEM. f Secondary colony formation of LL-CBMSC (black circles) and SL-CBMSC (white circles) at defined passages. g Colonies formed after plating 200 MSC in 100-mm culture dishes are shown from one representative LL- and one SL-CBSMC (CB010 and CB019, respectively). h Secondary colony formation of LL-CBMSC (black boxes) and SL-CBMSC (white boxes) at P4. The differences were computed by Mann-Whitney U test, p < 0.05. Boxes extend from 25th percentile to the 75th percentile, the middle line represents median value and the whiskers extend from minimum to maximum values. i Comparison between CB volumes between LL-CBMSC and SL-CBMSC (n = 5 and n = 16, respectively); the differences were computed by Mann-Whitney U test, p < 0.05. Abbreviations: LL-CBMSC long-living CBMSC, SL-CBMSC short-living CBMSC, NS not significant