Fig. 5

a Telomere length in ADMSCs gradually shortened during cell expansion in both 2D and 3D cultures. But telomere length shortened significantly in 2D cultures when compared to 3D, especially at 14 days and 21 days. Moreover, the shortening tendency in telomere length of ADMSCs in 3D cultures was steadier. b TERT expression revealed that changes in telomerase activity agreed with relative telomere length in ADMSCs for both cultures. c Relative mtDNA copy numbers in ADMSCs were gradually decreased, while mtDNA copy numbers in 3D cultures were significantly higher when compared with 2D cultures at 14 days and 21 days. Data represented as average ± SD from n = 3 experiments, *p < 0.05, **p < 0.01, ***p < 0.001