A recent study published in Nature Communications has created an atlas for the various differentiated and stem cell populations found in our teeth.
Growing new teeth is not just for kids
Because of the many ways in which dental pathologies can come back to bite us and the many limitations of artificial implants and dentures, there is a significant interest in tooth regeneration. There are quite a few obstacles in the way of tooth regeneration, which combine the major difficulties of several other tissues. Similar to the gut and the skin, teeth are subjected to the unique stressors of the harsh external environment. Like bone and cartilage, their mechanical properties are critical to their success and must be recapitulated fully. Finally, their structure and the different regions of teeth are key components to their function. Directing regeneration in such an organized fashion is challenging in a number of other tissues, such as the kidneys.
Furthermore, we know only a small fraction of the biology of teeth and of their natural growth and regeneration. A recent publication resulting from a large collaboration of researchers led by the Medical University of Vienna has shed quite a bit of light in this arena . Using the most advanced transcriptomics techniques (RNAseq, also known as Next-Generation Sequencing), this study examined cell populations in depth. The researchers focused on comparisons between the different regions within teeth, the differences between human and mouse teeth, and the differences between teeth that are actively growing/regenerating and teeth that are not.
Understanding our teeth through the power of RNA sequencing
RNA sequencing is a powerful tool. It can tell us a lot about a cell’s behavior at a given point in time based on the proteins which are being actively synthesized. Among many other findings, the researchers showed mouse incisors to be much more heterogeneous whereas human teeth tended to have a lot more variations within their cell populations. The results identify several cell types and cell populations previously uncharacterized in dental tissue as well as novel and more specific markers for dental mesenchymal stem cells (MSCs). Additionally, the differentiation of stem cells towards odontoblasts is characterized throughout the entire process, providing insights to the mechanisms underlying this cellular behavior. Finally, the studies identify several previously unidentified factors that are involved in natural tooth growth and regeneration in both human and mouse teeth.
Combined, these results have immediate impacts on our understanding of tooth biology and for the isolation and culture of dental cell populations. They also identify several novel points of intervention in the differentiation of dental stem cells and the natural generation of dental tissues. Additionally, they highlight some key differences between mouse and human teeth – knowledge that is notably important because mice are frequently used to test tooth regeneration strategies. However, it remains to be seen if these findings can be applied directly to improve approaches in dental tissue engineering and tooth regeneration.
Overall, we hope that the presented detailed and validated map of dental cell types, supplemented by human comparison, will serve as a key resource stimulating further studies of cell dynamics in tooth morphogenesis, also including reparative and regenerative therapies.
 Krivanek, J., Soldatov, R. A., Kastriti, M. E., Chontorotzea, T., Herdina, A. N., …, Adameyko, I. (2020). Dental cell type atlas reveals stem and differentiated cell types in mouse and human teeth. Nature Communications, 11(4816). DOI: 10.1038/s41467-020-18512-7