The effects of cementum protein 1 and periostin on the osteoblastic differentiation of human periodontal ligament cells

Human periodontal ligament (PDL) cells are able to undergo differentiation into an osteogenic phenotype. PDL cells lines from a 46-year-old female and a 59- and 68-year-old male were grown on a collagen scaffold for 7- or 21-days. Growth was carried out in a control media and one of three treatment conditions of osteogenic media by itself, with periostin, or with cementum protein 1. Alizarin red staining (ARS) and absorbance assays were used to quantify the amount of mineralization. Relative changes in expression of alkaline phosphatase (ALP), bone sialoprotein, periostin and osteocalcin (OCN) were determined using real-time quantitative PCR. All three treatment conditions had visible mineralization present at 21-days, while the 21-day controls and all 7-day samples did not. ARS concentrations were also much higher for these samples. All treatment conditions showed OCN and ALP levels to decrease from 7- to 21-days. Relative to controls, all treatment conditions showed higher OCN levels at 7-days and lower ALP levels at 21-days.