Porcine tooth germ cell conditioned medium can induce odontogenic differentiation of human dental pulp stem cells.

It is suggested that the differentiation of tooth-derived stem cells is modulated by the local microenvironment in which they reside. Previous studies have indicated that tooth germ cell-conditioned medium (TGC-CM) holds the potential to induce dental pulp stem cells (DPSCs) to differentiate into the odontogenic lineage. Nevertheless, human TGC-CM (hTGC-CM) is not feasible in practical application, so we conjectured that xenogenic TGC-CM might exert a similar influence on human dental stem cells. In this study, we chose swine as the xenogenic origin and compared the effect of porcine tooth germ cell-conditioned medium (pTGC-CM) with its human counterpart on human DPSCs. Morphological appearance, colony-forming assay, in vitro multipotential ability, protein and gene expression of the odontogenic phenotype and the in vivo differentiation capacity of DPSCs were evaluated. The results showed that pTGC-CM exerted a similar effect to hTGC-CM in inducing human DPSCs to present odontogenic changes, which were indicated by remarkable morphological changes, higher multipotential capability and the expression of some odontogenic markers in gene and protein levels. Besides, the in vivo results showed that pTGC-CM-treated DPSCs, similar to hTGC-CM-treated DPSCs, could form a more regular dentine-pulp complex. Our data provided the first evidence that pTGC-CM is able to exert almost the same effect on DPSCs with hTGC-CM. The observations suggest that the application of xenogenic TGC-CM may facilitate generating bioengineered teeth from tooth-derived stem cells in future.

The effects of age and sex on the expression of oestrogen and its receptors in rat mandibular condylar cartilages.

OBJECTIVE: Oestrogen expression may indicate a difference in resistance potential to mechanical strain. The purpose of this study was to investigate the expression of oestrogen and oestrogen receptors in mandibular condylar cartilages in male and female Sprague-Dawley rats at different ages. MATERIALS AND METHODS: One-hundred SD rats at the age of 2, 4, 8 weeks and 4, 12 months in both sexes, 10 in each age-sex group, were enrolled in this study. The expression of oestradiol, ERalpha and ERbeta was detected in mandibular condylar cartilages by the method of immunohistochemistry, and enzyme-linked immunosorbent assay or western blot. RESULTS: Oestradiol and ERs immunoreactivity were obvious in mandibular condylar cartilages of SD rats. Oestradiol and ERalpha were observed in hypertrophic and mature layers, while ERbeta only in hypertrophic layer. There was no sex difference of same age (except 8-week age group) in the expression of oestradiol. The expression of both ERs, however, was usually higher in male than in age-matched female rats (P<0.05), except that the 8-week-old female rats showed a higher ERalpha expression and the 4- and 8-week-old female rats showed a higher ERbeta expression than the age-matched male ones in western blot results (P<0.05). CONCLUSIONS: The results that oestradiol, ERalpha and ERbeta are co-expressed in rat mandibular condylar cartilage, indicate that mandibular condylar cartilage is a target for oestrogen. The age and sex related differences in ERs expression may indicate a difference in potential to resist mechanical loading between genders at different ages.

Odontogenic potential of mesenchymal cells from hair follicle dermal papilla.

Dental pulp stem cells from teeth can be used for tooth regeneration. Although nondental stem cells derived from bone marrow can differentiate into odontoblast-like cells when recombined with embryonic oral epithelium, these cells can lose their ability to differentiate after an extended number of cell culture passages. There has been limited research to identify stem cells from other tissue sources to regenerate teeth. As another candidate source for mesenchymal stem cells, hair follicle has obtained much more attention recently because of its easy accessibility. In this study, cultured vibrissae follicle dermal papilla mesenchymal cells (FDPMCs) from adult C57BL/6 GFP mice can differentiate into adipocytes and osteoblasts in vitro. Moreover, in the inductive microenvironment generated by apical bud and dental mesenchyme from 7-day-old C57 mice, FDPMCs in vitro demonstrated odontogenic potential, as indicated by the morphological transformation, cell-cycle change and expression of tooth-specific markers. Under the same microenvironment, FDPMCs were incubated in vivo for 3 weeks. Coexpression of GFP and DSP proteins in the odontoblast layer was detected in the recovered implants, suggesting that GFP(+) FDPMCs can function as odontoblasts in vivo. Together, our data indicate for the first time that whisker FDPMCs from adult mice can differentiate to odontoblast-like cells.

[Clinical research of rehabilitating bilateral total maxillary defects with a new improved implants and magnetic attachments bar frameworks: report of 9 cases].

PURPOSE: The purpose of this study was to research the clinical effects of a new improved implant-magnetic attachment bar framework supported the total maxillary prosthesis. METHODS: Nine patients underwent tumor resection with defect of bilateral maxilla, and after at least 1 year,4 implants was inserted into their bilateral zygomatics in every patient. A kind of new improved bar framework were fabricated with implants tightly. Based on these bar framework ,total maxillary prostheses were completed finally. RESULTS: The new improved bar framework was utilized to support the prosthesis, it was observed that the prosthesis was more stable. All patients were satisfied with mastication, speech and appearance after wearing the prosthesis. The prosthesis demonstrated a significant improvement in function and esthetics. CONCLUSIONS: It is concluded that from the practical point of view,the prosthesis with new bar framework is superior to the previous one, and its clinical prosperity is wide. But further studies are necessary to evaluate its long term effects.