Fig. 6. MSCs derived from FA-iPSCs demonstrate characteristics of premature senescence.

A, FACS analyses of common MSC surface markers on MSCs differentiated from control-iPSCs, FA-iPSCs, and FA-iPSCs corrected by HR (C-FA-iPSCs). B, Growth curve representing the accumulated population doubling of iPSC-derived MSCs. Data are shown as mean±s.d. n=3. C, Representative SA-β-galactosidase staining in passage 3 MSCs derived from control-, FA-, C-FA-iPSCs. Bar, 10 μm. Note that senescent FA-MSCs are larger in size. D, RT-qPCR analysis of the indicated gene transcripts in iPSCs and their MSC derivatives. Data are shown as mean±s.d. n=3. **p<0.01 (t-test). At mRNA levels, MSCs demonstrated significant upregulation of MSC-specific marker CD44 and downregulation of pluripotency marker NANOG. No significant difference was observed in NANOG and c-KIT expression between the isogenic pairs (FA-iPSCs and C-FA-iPSCs). When compared with control MSCs, FA-MSCs showed a robust upregulation of the cell proliferation suppressor p21, the cell senescence marker p16 and the stress sensor HO-1, at passage 1. E, Control- and C-FA-iPSC-derived MSCs were induced to undergo adipogenesis, chondrogenesis, and osteogenesis. Oil red, Alcian blue, and von Kossa were employed for staining of adipocyte, cartilage, and bone-specific markers, respectively. Scale bar, 25 μm.