2.9. Proliferation Assay

The proliferation of BMSCs was detected by cell counting kit-8 (CCK-8; Epizyme, China). Briefly, 2 × 10³ cells/well (three replicates per group) were seeded into 96-well plates and cultured at 37°C with 5% CO₂ for 1, 3, 5, 7, and 9 days. CCK-8 solution (10 μl) was added to each well and incubated at 37°C for 2 hr. The absorbance was observed at 450 nm by using a microplate reader (Molecular Devices, USA).