Fig. 1

Senescent markers and stemness properties of iMSCs changed with serial culture. A Representative morphology of long-term iMSCs from passages 6, 9, 11, and 13 imaged. Scale bar: 500 μm. B Mean cell area and length increased with extended in vitro cell culture. C Mean cell areas, corresponding cell length, and fold-changes in comparison to P6. D Proliferation of iMSCs at P6 and P13. The mRNA levels of cell cycle genes (E), stemness genes (F), and inflammatory cytokines (G) of iMSCs at P6 and P13. H Osteogenic and chondrogenic differentiation of iMSCs at P6 and P13. Scale bar: 1000 μm. I The lysosomal density of iMSCs at P6 and P13. Scale bar: 200 μm. J The mitochondrial density of iMSCs at P6 and P13. Scale bar: 200 μm. K The MMP of iMSC at P6 and P13. Scale bar: 200 μm. Data were representative of over three independent experiments. n = 3, * p < 0.05; ** p < 0.01; *** p < 0.001; **** p < 0.0001 by Student’s t test