It was found that EMT is induced during repair of the lacrimal gland to generate MSCs to initiate repair, and that mesenchymal-epithelial transition is then activated to form acinar and ductal epithelial cells.

While it is known that precise dental epithelial-mesenchymal (DE-DM) cell interactions provide critical functions in tooth development, reliable methods to establish proper DE-DM cell interactions for tooth regeneration have yet to be established. To address this challenge, and to generate bioengineered teeth of predetermined size and shape, in this study, we characterize three-dimensional (3D) pre-fabricated DE-DM cell constructs. Human dental pulp cell seeded Collagen gel layers were co-cultured with porcine DE cells suspended in Growth Factor Reduced (GFR) Matrigel. The resulting 3D DE-DM cell layers were cultured in vitro, or implanted and grown subcutaneously in vivo in nude rats. Molecular, histological and immunohistochemical (IHC) analyses of harvested implants revealed organized DE-DM cell interactions, the induced expression of dental tissue-specific markers Amelogenin (AM) and Dentin Sialophosphoprotein (DSPP), and basement membrane markers Laminin 5 and collagen IV, and irregular mineralized tissue formation after 4 weeks. We anticipate that these studies will facilitate the eventual establishment of reliable methods to elaborate dental tissues, and full sized teeth of specified sized and shape.

Silk scaffolds have been successfully used for a variety of tissue engineering applications due to their biocompatibility, diverse physical characteristics, and ability to support cell attachment and proliferation. Our prior characterization of 4-day postnatal rat tooth bud cells grown on hexafluoro-2-propanol (HFIP) silk scaffolds showed that the silk scaffolds not only supported osteodentin formation, but also guided the size and shape of the formed osteodentin. In this study, interactions between human dental pulp cells and HFIP and aqueous based silk scaffolds were studied under both in vitro and in vivo conditions. Silk scaffold porosity and incorporation of RGD and DMP peptides were examined. We found that the degradation of aqueous based silk is much faster than HFIP based silk scaffolds. Also, HFIP based silk scaffolds supported the soft dental pulp formation better than the aqueous based silk scaffolds. No distinct hard tissue regeneration was found in any of the implants, with or without additional cells. We conclude that alternative silk scaffold materials, and hDSC pre-seeding cell treatments or sorting and enrichment methods, need to be considered for successful dental hard tissue regeneration.