Expression of Bone Morphogenetic Protein-6 in Dental Follicle Stem Cells and Its Effect on Osteogenic Differentiation

Abstract

The dental follicle (DF) plays an essential role in tooth eruption via regulation of bone resorption and bone formation. Bone morphogenetic protein-6 (BMP6) expression in the DF is coincident with bone growth in the tooth crypt. DF stem cells (DFSCs) have been shown to possess strong osteogenic capability. This study aims to determine the expression of BMP6 in DFSCs and to elucidate the role of BMP6 in the osteogenesis of DFSCs. DFSCs and their non-stem cell counterpart, DF cells (DFCs), were obtained from the DFs of rat pups. We showed that expression of BMP6 was significantly higher in the DFSCs than in the DFCs. DFSCs lost osteogenic capability during in vitro expansion, and DFSCs in late passages had reduced BMP6 expression as compared to early passages of DFSCs when they were subjected to osteogenic induction. Addition of exogenous human recombinant BMP6 (hrBMP6) to the osteogenic medium dramatically enhanced the osteogenesis of the late-passage DFSCs. Knockdown of BMP6 by short interfering RNA in the DFSCs in early passages resulted in a decrease in osteogenesis, which could be restored by addition of hrBMP6. We concluded that DFSCs need to express high levels of BMP6 to maintain their osteogenesis capability. Increased BMP6 expression seen in vivo in the DF may reflect the activation of DFSCs for osteogenic differentiation for bone growth during tooth eruption.

Purmorphamine increased adhesion, proliferation and expression of osteoblast phenotype markers of human dental pulp stem cells cultured on beta-tricalcium phosphate

“…In all three studies, cell proliferation was evaluated in differentiation medium containing dexamethasone, ascorbic acid and b-glycerophosphate which are in favor of osteoblast phenotype differentiation [32,33]. In this study, we evaluated cell proliferation and attachment in the standard culture medium, while osteogenic differentiation was evaluated in osteogenic medium.…”

Evaluation of bone regeneration potential of dental follicle stem cells for treatment of craniofacial defects

“…In a human ASC transplantation study, significant improvement of bone regeneration could be achieved when recombinant BMP2 was injected to the defects after stem cell transplantation (5). Our laboratory has shown that bone morphogenetic protein 6 (BMP6) and dentin matrix protein 1(DMP1) can enhance the osteogenic differentiation of DFSCs in vitro (12, 24). It would be interesting to determine whether addition of these growth factors to scaffolds can accelerate the bone regeneration from DFSCs.…”

“…Adherent cells were passaged at 90% confluency until passage 3. To evaluate the osteogenic capability of the established cultures, 10 5 cells were seeded in each well of a 6-well plate and cultured in osteogenic induction medium consisting of DMEM, 10% FBS, 50μg/mL ascorbic acid, 100nM dexamethasone and 10mM β-glycerolphosphate for 2 weeks as previously described (9, 12). The osteogenic cultures were stained with 1% Alizarin Red solution to reveal osteogenic capability of the established cells (Figure 1A).…”

“…Thus, dental follicle stem cells (DFSCs) have been isolated and tested for stem cell properties (9-11). DFSCs possess strong osteogenic capability to differentiate toward the osteoblast lineage (12), which makes them suitable for repair of skeletal defects. In addition, since the DF is derived from the neural crest, the same origin of craniofacial tissues, it may be preferential to utilize DFSCs for treatment of defects in this region.…”

RANKL is associated with persistent primary teeth and delayed permanent tooth emergence

“…Tooth eruption is a localized process resulting in the movement and emergence of the tooth from the gingivae. This event requires the dental follicle that controls the formation and resorption of alveolar bone to form the eruption pathway . The normal eruption of primary and permanent teeth into the oral cavity occurs over a broad chronologic age range…”