Abstract
In vitro differentiation induction of normal human periodontal ligament fibroblasts, HpdLF, into an osteoblast lineage was attempted and the changes in gene expression were examined. The cells changed to an osteoblast-like cuboid morphology at 3 weeks after induction. Moreover, calcified nodules were detected and osteocalcin expression was confirmed at 3 weeks after induction, suggesting that the differentiation was progressing toward an osteoblast lineage. The expression of bone differentiation markers such as alkaline phosphatase, type 1 collagen, insulin-like growth factor (IGF) 1, IGF2, bone morphogenic protein 2 (BMP2) and osteocalcin at 3 weeks after induction were increased compared with pre-induction. The up-regulation of IGF1 or IGF2 may be due to activation of pathways for the induction of alkaline phosphatase and type 1 collagen, and the differentiation of HpdLF into an osteoblast lineage. The increased expression of BMP2 may be due to the production of osteocalcin and maturation of osteoblasts.
