Bioengineered 3D tooth germs for tooth regeneration in vitro and in vivo

Project Summary Dental decay and tooth loss are common problems. Bridges and implants are the primary treatment options but cannot completely restore the tooth biology and function. Although using cells from embryo to rebuild a functional bioengineered tooth has been demonstrated in animals, little is known in how to use a cell source to

regenerate teeth in humans. Human induced pluripotent stem cells (hiPSCs) hold tremendous promise to regenerate teeth because of their near-unlimited regenerative capacity that can produce almost any tissues in the body. However, stem cell-based therapy has been hindered by our limited ability to provide an adequate

microenvironment for stem cell renewal and differentiation and lack of understanding on the key signals required to regulate cell fate and cell-cell interaction during tooth development. The proposed research aims to develop a well-defined, feeder-free 3D material microenvironment for regulating self-renewal and

differentiation of hiPSCs into odontogenic epithelial stem cells (OESCs) and neural crest cells (NCCs), and to co-culture OESCs with NCCs for tooth regeneration. The proposed 3D construct is made of a hybrid scaffold of chitosan and alginate (CA), two natural polymers that have a proxy structure of glycosaminoglycans, a

major component of the native extracellular matrix (ECM). Natural polymer-based materials are clinically preferable over synthetic polymers or protein-based materials due to their excellent biocompatibility, biodegradability, and minimal immunogenicity. In addition, unlike synthetic polymers, The CA scaffold can be

readily decomposed in cell-compatible solutions thus posing no harm to grown stem cells facilitating subsequent use and analysis. The specific aims of the proposed research are to (1) investigate how material composition and mechanical properties regulate stem cell renewal and if CA scaffolds optimized for stem cell

renewal can support long-term growth of OESCs and NCCs in vitro; (2) differentiate hiPSCs into OESCs and NCCs, and identify proper reciprocal interactions of epithelial-mesenchymal stem cells for odontogenesis by co-culturing OESCs with NCCs in CA scaffolds; (3) enable odontogenic differentiation of hiPSCs and tooth

tissue formation in an orthotopic mouse model. Successful completion of the proposed research would make a profound impact on stem-cell biology and technology and on human tooth tissue regeneration. Studies of tooth formation from human pluripotent stem cells will enhance the research community’s understanding on the fate

decisions of tooth-specific lineages in odontogenesis and the epithelial-mesenchymal interactions required during tooth development.