Figure 7. Summary of changes in pulp cultures grown in presence and absence of FGF2.

During the proliferative phase of in vitro growth (first 7 days), pulp cultures undergo proliferation and contain early progenitors. Following addition of the mineralization-inducing medium at day 7, these cells undergo differentiation and give rise to an extensive amount of mineralized matrix (differentiation/mineralization phase of in vitro growth). The first sign of mineralization is around day 10 with significant increases in the extent of mineralization thereafter. In these cultures Dmp1 and Dspp are expressed at low levels at day 7 and 10 respectively. DMP1-GFP+ and DSPP-Cerulean+ cells are detected at day 7 and 10 respectively, with increases thereafter.

Continuous exposure of pulp cultures to FGF2 resulted in decreases in the extent of mineralization. FGF2-treated cultures displayed increases in the levels of Dmp1, and percentage of DMP1-GFP+ cells at day 7 followed by decreases between days 10–21 as compared to control. However, despite decreases, the intensity of DMP1-GFP transgene and expression of Dmp1 in FGF2-treated cultures between days 7–21 remained relatively unchanged. FGF2-treated cultures also displayed increases in the levels of Dspp at day 7, followed by decreases in the levels of Dspp and percentage of DSPP-Cerulean+ cells between days 10–21 as compared to control.