Inductive Ability of Human Developing and Differentiated Dental Mesenchyme

Abstract

The development of cell-based therapeutic strategies to bioengineer tooth tissue is a promising approach for the treatment of lost or damaged tooth tissue. The lack of a readily available cell source for human dental epithelial cells (ECs) severely constrains the progress of tooth bioengineering. Previous studies in model organisms have demonstrated that developing dental mesenchyme can instruct nondental epithelium to differentiate into enamel-forming epithelium. In this study, we characterized the ability of fetal and adult human dental mesenchyme to promote differentiation of human embryonic stem cell (hESC)-derived ECs (ES-ECs) into ameloblast-lineage cells. ES-ECs were co-cultured either with human fetal dental mesenchymal cells (FDMCs) or with adult dental mesenchymal cells (ADMCs) in either a three-dimensional culture system, or in the renal capsules of SCID mice. When co-cultured with FDMCs in vitro, ES-ECs polarized and expressed amelogenin. Tooth organ-like structures assembled with epithelium and encased mesenchyme and developing enamel-like structures could be detected in the complexes resulting from in vitro and ex vivo co-culture of ES-ECs and FDMCs. In contrast, co-cultured ES-ECs and ADMCs formed amorphous spherical structures and occasionally formed hair. Transcription factors were significantly upregulated in FDMCs compared to ADMCs including MSX1, GLI1, LHX6, LHX8,LEF1 and TBX1. In summary, FDMCs but not ADMCs had the capacity to induce differentiation of ES-ECs into ameloblast lineage cells. Further characterization of the functional differences between these two types of dental mesenchyme could enable reprogramming of ADMCs to enhance their odontogenic inductive competence.

BMP7 and EREG Contribute to the Inductive Potential of Dental Mesenchyme

“…We have previously shown that hESCs can be chemically induced to differentiate into ES-ECs that share similarities with dental epithelial cells 15 . Moreover, by co-culture with dental papilla cells in vitro and in vivo , ES-ECs can be further induced into ameloblast-lineage cells that express amelogenin 16 . In the future, adult dental pulp cells may be used in enamel regeneration following modification of their growth factor expression profiles ( Fig.…”

“…Our previous study showed that human embryonic stem cell-derived epithelial cells (ES-ECs) are similar to ameloblast-lineage cells 15 and that the developing human dental mesenchyme from the bell stage possesses the required signal to induce these ES-ECs to differentiate into dental epithelial cells 16 . This and other previous investigations have broadened the possibilities of cell-based enamel regeneration.…”

Meeting report: a hard look at the state of enamel research

“…Co-culture of human epithelial cells with mature dental pulp from erupted human teeth formed acinar type epithelial structures, similar to those found when ameloblast lineage cells were cultured alone. 57 - 58 These studies show the promise of human embryonic epithelial cells as a source for ameloblasts, and they raise the possibility that if adult dental pulp cells could be reprogramed to an earlier stage of differentiation, co-culture of these cells could regenerate teeth.…”

Engineering epithelial-stromal interactions in vitro for toxicology assessment

“…Tooth organ germs with a 1:1 ratio of rat apical bud cells and dental pulp stromal cells exhibited the highest alkaline phosphatase activity and elicited tooth-like structures containing dentin, differentiated ameloblasts and odontoblasts, and enamel, whereas germs with a higher proportion of bud cells or pulp cells lacked odontoblasts or ameloblasts, respectively (Yu et al, 2008). Finally, hESC-derived ECs (CK14+) expressed amelogenin and formed primordial tooth-like structures when co-encapsulated with fetal dental pulp stromal cells in culture and after implantation to sub-renal capsules (Zheng et al, 2013).…”