Fig. 2
Cell culture characteristics. A Colony-forming unit (CFU) potential. The optimal seeding cell density was determined for normal (circle) and osteoarthritic (OA, square) donors by testing three densities. For OA donors, a cell density of 1.0*103 was chosen, and for the normal donors a cell density of 0.25*103. The amount of CFUs was displayed as the percentage of CFU of the total seeded cells. B Population doublings are displayed as the cumulative population doublings per passage for normal (black dots) and OA (clear dots). # p < 0.15 with a large effect size and *p < 0.05 in the normal compared to the OA cSM-MSCs C Senescence of the normal and OA cSM-MSCs was investigated using a β-galactosidase assay in passage (P) 2, 5, and 10. The number of senescent cells (stained blue in the microscopic images (black arrows)) was depicted as the percentage of senescent cells of the total cells. Each dot represents an individual donor. *p < 0.05; **p < 0.01 compared to the percentage of senescent cells at P2