Recently, multipotent stem cells have been studied as a material for regeneration of missing craniofacial bone. Research using stem cells, embryonic stem cells and induced pluripotent stem cells is being carried out in the field of dentistry. We investigated cranial facial bone differentiation from mouse embryonic stem cells. Mouse ES cells were cultured in a serum-free neuroinduction medium for sphere formation. The size of sphere formation and the influence of BMP4 was then immunohistochemicaly examined. We found that the frequency of appearance of AP 2α-positive neural crest cells was influenced by both the addition of BMP4 and the number of cells exhibiting sphere formation.

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Recently, multipotent stem cells have been studied as material for regeneration of missing craniofacial bone. Almost all craniofacial structures are derived from cranial neural crest cells. We investigated the possibility of craniofacial bone induction from mouse embryonic stem (ES) cells differentiated into neural crest via neuroectoderm.
    First, we cultured mouse ES cells in serum-free neuroinduction medium for sphere formation and confirmed the existence of precursors of neuronal and neural crest cells by immunostaining using specific antibodies for Nestin and AP2α, respectively. The sphere contained Nestin and AP2α positive cells, indicating that a portion of the ES cells differentiated into neural crest cells through neural precursor cells during sphere formation. Subsequently, these spheres were transferred to an alternative plate and grown for 18 days in osteogenic medium containing dexamethasone. Alizarin red S staining revealed mineral deposition, suggesting that the cells within the spheres were induced to osteogenesis. These findings indicated the possibility that craniofacial bone can be generated from mouse ES cells through spheres cultured in serum-free medium.

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Cyclin D1 governs phosphorylation of the retinoblastoma protein (RB) and controls the G1 phase of cell cycles. This gene may well be necessary for cancer development. We investigated the expression and localization of cyclin D1 protein in HSC 4, an oral squamous cell carcinoma cell line. The results showed that cyclin D1 protein is located in the nuclei of proliferating cells in HSC 4. Furthermore, cyclin D1 protein is decreased and translocated from the nucleium to the cytoplasm under dense culture conditions. In anchorage-independent growth, HSC 4 stopped proliferation and cyclin D1 protein was localized in the cytoplasm. These findings suggest that cyclin D1 protein is related to the proliferation of cells and regulation of the cell cycle in oral squamous cell carcinoma.

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Cancer stem cells of oral squamous cell carcinoma (OSCC) are reported to have relevance to growth, differentiation and proliferation of the tumor. OSCC, like many solid tumors, contains a heterogeneous population of cancer cells. Recent data suggest that a rare subpopulation of cancer cells, termed cancer stem cells (CSC), is capable of initiating, maintaining, and expanding the growth of tumors. Identification and characterization of CSC from OSCC facilitates the monitoring, therapy, and prevention of OSCC. We investigated oral cancer stem-like cells (OC-SLC) through sphere formation by cultivating OSCC cells from established OSCC cell lines within a defined serum-free medium and under anchorage independent conditions. Although HSC3 and HSC4 cells did not promote growth, SAS cells did. Sphere formation was also noted. These findings suggest that SAS possesses the characteristic of CSC.

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