Showing papers by "Yanding Zhang published in 2018"

Efficient induction of functional ameloblasts from human keratinocyte stem cells.

Abstract: Although adult human tissue-derived epidermal stem cells are capable of differentiating into enamel-secreting ameloblasts and forming teeth with regenerated enamel when recombined with mouse dental mesenchyme that possesses odontogenic potential, the induction rate is relatively low. In addition, whether the regenerated enamel retains a running pattern of prism identical to and acquires mechanical properties comparable with human enamel indeed warrants further study. Cultured human keratinocyte stem cells (hKSCs) were treated with fibroblast growth factor 8 (FGF8) and Sonic hedgehog (SHH) for 18 h or 36 h prior to being recombined with E13.5 mouse dental mesenchyme with implantation of FGF8 and SHH-soaked agarose beads into reconstructed chimeric tooth germs. Recombinant tooth germs were subjected to kidney capsule culture in nude mice. Harvested samples at various time points were processed for histological, immunohistochemical, TUNEL, and western blot analysis. Scanning electronic microscopy and a nanoindentation test were further employed to analyze the prism running pattern and mechanical properties of the regenerated enamel. Treatment of hKSCs with both FGF8 and SHH prior to tissue recombination greatly enhanced the rate of tooth-like structure formation to about 70%. FGF8 and SHH dramatically enhanced stemness of cultured hKSCs. Scanning electron microscopic analysis revealed the running pattern of intact prisms of regenerated enamel is similar to that of human enamel. The nanoindentation test indicated that, although much softer than human child and adult mouse enamel, mechanical properties of the regenerated enamel improved as the culture time was extended. Application of FGF8 and SHH proteins in cultured hKSCs improves stemness but does not facilitate odontogenic fate of hKSCs, resulting in an enhanced efficiency of ameloblastic differentiation of hKSCs and tooth formation in human–mouse chimeric tooth germs.

Induction of Rhesus Keratinocytes into Functional Ameloblasts by Mouse Embryonic Dental Mesenchyme.

Abstract: Fast progresses in stem cell-based tooth tissue engineering have been achieved in recent years in several animal models including the mouse, rat, dog, and pig. Moreover, various postnatal mesenchymal stem cells of dental origin have been isolated and shown capable of differentiating into odontoblasts and generating dentin. Meanwhile, human keratinocyte stem/progenitor cells, gingival epithelial cells, and even iPSC-derived epithelium have been demonstrated to be able to differentiate into functional ameloblasts. Translational medicine studies in the nonhuman primate are irreplaceable steps towards clinical application of stem cell-based tissue engineering therapy. In the present study, we first examined the epithelial stem cell markers in the rhesus skin using immunostaining. Keratinocyte stem cells were then isolated from rhesus epidermis, cultured in vitro, and characterized by epithelial stem cell markers. Epithelial sheets of these cultured keratinocytes, which were recombined with E13.5 mouse dental mesenchyme that possesses odontogenic potential in the presence of exogenous FGF8, were induced to differentiate into enamel-secreting ameloblasts. Our results demonstrate that in the presence of appropriate odontogenic signals, rhesus keratinocytes can be induced to gain odontogenic competence and are capable of participating in odontogenesis, indicating that rhesus keratinocytes are an ideal epithelial cell source for further translational medicine study of tooth tissue engineering in nonhuman primates.