Multilineage differentiation of dental follicle cells and the roles of Runx2 over-expression in enhancing osteoblast/cementoblast-related gene expression in dental follicle cells.
OBJECTIVE
Dental follicle cells (DFCs) provide the origin of periodontal tissues, and Runx2 is essential for bone formation and tooth development. In this study, pluripotency of DFCs was evaluated and effects of Runx2 on them were investigated.


METHODS
The DFCs were induced to differentiate towards osteoblasts, adipocytes or chondrocytes, and alizarin red staining, oil red O staining or alcian blue staining was performed to reveal the differentiated states. Bone marrow stromal cells (BMSCs) and primary mouse fibroblasts served as controls. DFCs were also infected with recombinant retroviruses encoding either full-length Runx2 or mutant Runx2 without the VWRPY motif. Western blot analysis, real-time real time RT-PCR and in vitro mineralization assay were performed to evaluate the effects of full-length Runx2 or mutant Runx2 on osteogenic/cementogenic differentiation of the cells.


RESULTS
The above-mentioned staining methods demonstrated that DFCs were successfully induced to differentiate towards osteoblasts, adipocytes or chondrocytes respectively, confirming the existence of pluripotent mesenchymal stem cells in dental follicle tissues. However, staining intensity in DFC cultures was weaker than in BMSC cultures. Real-time PCR analysis indicated that mutant Runx2 induced a more pronounced increase in expression levels of OC, OPN, Col I and CP23 than full-length Runx2. Mineralization assay also showed that mutant Runx2 increased mineralization nodule formation more prominently than full-length Runx2.


CONCLUSIONS
Multipotent DFCs can be induced to differentiate towards osteoblasts, adipocytes or chondrocytes in vitro. Runx2 over-expression up-regulated expression levels of osteoblast/cementoblast-related genes and in vitro enhanced osteogenic differentiation of DFCs. In addition, mutant Runx2-induced changes in DFCs were more prominent than those induced by full-length Runx2.
Pan
K
K
Department of Periodontology and Institute of Oral Biomedicine, School of Dentistry, Shandong University, Jinan, China.
Sun
Q
Q
Zhang
J
J
Ge
S
S
Li
S
S
Zhao
Y
Y
Yang
P
P
D017667:Adipocytes / Q000166:cytology / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D002454:Cell Differentiation / Q000235:genetics; D019070:Cell Lineage / Q000235:genetics; D019902:Chondrocytes / Q000166:cytology / Q000378:metabolism; D050659:Core Binding Factor Alpha 1 Subunit / Q000235:genetics*; D003739:Dental Cementum / Q000166:cytology / Q000378:metabolism; D003795:Dental Sac / Q000166:cytology / Q000254:growth & development*; D018507:Gene Expression Regulation, Developmental / Q000235:genetics*; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D009154:Mutation / Q000235:genetics; D041681:NIH 3T3 Cells; D010006:Osteoblasts / Q000166:cytology / Q000378:metabolism; D039904:Pluripotent Stem Cells / Q000166:cytology / Q000378:metabolism*; D014070:Tooth / Q000166:cytology / Q000254:growth & development*; D014162:Transfection
D050659:Core Binding Factor Alpha 1 Subunit; C493716:Runx2 protein, mouse