Dulbecco s modified eagle s medium dmem

The DP cells were freshly derived from caries-free, intact premolars extracted for orthodontic treatment, as previously described.^{19 (link)} The patients provided informed consent, and approval from the Ethics Committee of the Chung Shan Medicine University Hospital was obtained (CSMUH No. CS11187). The tooth was split sagittally with a chisel. The pulp tissue was then immersed in a phosphate-buffered saline (PBS; Caisson, North Logan, UT, USA) solution and digested in 0.1% collagenase type I (Sigma-Aldrich, St Louis, MO, USA) for 30 min. After being transferred to a new plate, the cell suspension was cultured in Dulbecco's modified Eagle's medium (DMEM; Caisson, North Logan, UT, USA), supplemented with 20% foetal bovine serum (FBS; Caisson, North Logan, UT, USA), 10 U⋅mL⁻¹ penicillin G solution and 10 g⋅L⁻¹ streptomycin (Caisson, North Logan, UT, USA) in a humidified atmosphere with 5% CO₂ at 37 °C; the medium was changed every 3 days. The cells were subcultured via successive passaging at a 1∶3 ratio until they were used for the experiment (passages 3–8). Then, the DP cells were cultured on tissue culture plates and pre-treated with 200 μg⋅L⁻¹ LPS (Sigma-Aldrich, St Louis, MO, USA) in DMEM for 12 and 24 h.