Microarray Analysis of Human Dental Follicle Cells in Osteogenic Differentiation

The dental follicle is an ectomesenchymal tissue surrounding the developing tooth germ, lineage committed progenitor cells, or precursor cells for osteoblasts. In this study, we investigated gene expression in human dental follicle cells (hDFC) during osteogenic differentiation in vitro. hDFC were cultured with mesenchymal stem cell osteogenic induction medium (MSCOIM) or growth medium (MSCGM). The ability of hDFC to differentiate into osteoblasts was examined using the alizarin red S and von Kossa stains, and alkaline phosphatase (ALP) activity. Gene expression profiling was performed with oligonucleotide microarray. Then, mRNA levels were confirmed using real time-PCR. The morphology of hDFC cultured with MSCGM exhibited fibroblast-like spindle shapes and became cuboidal shaped in MSCOIM for 3 days. Calcium deposition was observed in hDFC cultured with MSCOIM by staining with alizarin red S and von Kossa. ALP activities increased in hDFC during osteogenic differentiation. Expression monitoring of 54,675 genes in hDFC cultured for 3 days identified 951 genes with a greater than twofold difference in intensity between hDFC cultured with MSCOIM and MSCGM; 522 genes were up-regulated and 429 genes were down-regulated. Gene expression of IGF-II and IGFBP-2 increased during the hDFC differentiation into osteoblasts. Gene expression profile analysis revealed an interesting feature of hDFC in the initiation phase of osteogenic differentiation. IGF-II and IGFBP-2 also have important roles in hDFC during differentiation. Here we suggest that the dental follicle may serve as a therapeutic cell reservoir for bone regeneration.