Proliferation and osteo/odontoblastic differentiation of stem cells from dental apical papilla in mineralization-inducing medium containing additional KH2PO4

Objectives Stem cells from the dental apical papilla (SCAPs) can be induced to differentiate along both osteoblast and odontoblast lineages. However, little knowledge is available concerning their differentiation efficiency in osteogenic media containing additional KH2PO4. Materials and methods Stem cells from the dental apical papilla were isolated from apical papillae of immature third molars and treated with two kinds of mineralization-inducing media, MM1 and MM2, differing in KH2PO4 concentration. Proliferation and osteo/odontogenic differentiation capacity of MM1/MM2-treated SCAPs were investigated and compared both in vitro and in vivo. Results Cell counting and flow cytometry demonstrated that MM2 containing 1.8mm additional KH2PO4 significantly enhanced proliferative potential of SCAPs, compared to MM1. Osteo/odontogenic capacity of SCAPs was much better in MM2 medium than in MM1, as indicated by elevated alkaline phosphatase activity, increased calcium deposition and upregulated expression of osteo/odontoblast-specific genes/proteins (for example, runt-related transcription factor 2, osterix, osteocalcin, dentin sialoprotein, and dentin sialophosphoprotein). In vivo transplantation findings proved that SCAPs in MM2 group generated more mineralized tissues, and presented higher expression of osteo/odontoblast-specific proteins (osteocalcin and dentin sialoprotein) than those in the MM1 group. Conclusion Mineralization-inducing media supplemented with 1.8mm additional KH2PO4 significantly enhanced cell proliferation and improved differentiation capacity of SCAPs along osteo/odontogenic cell lineages, compared to counterparts lacking additional KH2PO4.