Isolation and Culture of SCAPs

For the harvesting of SCAPs, healthy immature human third molars were collected from patients aged 16–20 years (n = 5) according to the previous studies [6 (link)]. All protocols in the present work were approved by the Ethics Committee of the School of Stomatology, Wuhan University, China. In brief, apical papilla tissues were gently separated from teeth, thoroughly rinsed with phosphate buffered saline (PBS, Hyclone, Logan, UT), minced, and digested with 3 mg/mL type I collagenase (Biosharp, Hefei, China) and 4 mg/mL dispase (Roche, Mannheim, Germany) at 37 °C for 40 min. The digested mixtures were passed through a 70 μm cell strainer to get single-cell suspensions. SCAPs were cultured in the α-MEM (Hyclone) containing 10% fetal bovine serum (FBS, Gibco, Thornton, NSW, Australia) and 100 U/mL penicillin–streptomycin (Hyclone). Cells were incubated at 37 °C in an atmosphere with 5% CO₂. SCAPs at passages 2 to 5 were used in this study.