Fig. 1
Scheme for the colony formation and chondrogenesis assays. a Colony formation assay. Synovial mesenchymal stem cells (MSCs; 8 × 105 cells) were suspended in 400 μL medium containing 10% fetal bovine serum (FBS) as a time 0 control. Synovial MSCs (8 × 105 cells) suspended in 400 μL medium containing 10% FBS, 95% FBS, or 100% FBS were cryopreserved at − 80 °C for 7 days and thawed. A 1.5 μL volume of cell suspension (containing 3 × 103 cells, including living and dead cells) was added to 60 cm2 dishes for colony formation and cell proliferation assays. b Chondrogenesis assay. A 62.5 μL volume of cell suspension (containing 1.25 × 105 cells, including living cells and dead cells) was added to 15 mm tubes for chondrogenesis assays