Fig. 3

Effect of different preconditioning strategies on ALP expression and calcium nodules formation of PDLSCs. PDLSCs were treated in a culture medium with or without stimulations for 48 h and then cultured in an osteogenic inductive medium without stimulations for 7 and 21 days. A 7 day later, cells were collected for the ALP activity assay. B 21 day later, Alizarin Red staining was performed to detect the formation of mineralized nodules