Background information: Although the mechanism of cementogenesis is an area full of debate, the DFCs (dental follicle cells) are thought to be the precursors of cementoblasts. At the onset of cementogenesis, DFCs come into contact with the root dentin surface and undergo subsequent differentiation. But the exact effects of dentin or dentin matrix on DFCs remain an open question. In the present study, we hypothesized that dNCPs (dentin non-collagenous proteins) extracted from dentin could stimulate DFCs to differentiate into cementoblast lineages.
Results: DFCs were isolated from tooth germs of SD (Sprague-Dawley) rats and then co-cultured with dNCPs. Treated DFCs presented several features of cementoblast lineages in vitro, as indicated by morphological changes, decreased proliferation, enhanced ALP (alkaline phosphatase) activity and increased matrix mineralization. The expression of mineralization-associated proteins and genes were up-regulated after induction, whereas the expression of specific markers of odontoblast were not detected. Incubation of treated DFC pellets in vivo revealed that a large amount of cementum-like tissues was formed within the novel dentin carriers, which were quite distinct from the newly formed osteodentin secreted by DPSCs (dental pulp stem cells). The negative expression of DSP (dentin sialoprotein) also excluded the possibility of producing dentin matrix by treated DFCs.
Conclusions: dNCPs can stimulate DFCs to differentiate into cementoblast lineages. The present study provides new insights into the mechanism of cementogenesis.