Detailed insight into the teeth: For the first time, researchers have created a complete atlas of all human tooth cells. Among other things, he reveals that the cells of the internal tooth pulp and the tooth-holding apparatus differ greatly in terms of cell type, but that their stem cells are surprisingly similar. In the future, the single-cell atlas could provide new ways for cell-based dental therapy approaches.
Teeth – we need them to chew, they help us to speak and shiny white teeth are considered aesthetic. Researchers have also found out a lot about our chewing tools. For example, how the cold pain comes about or what food and toothbrushes are good for our teeth. And in initial laboratory tests, it has even been possible to grow small tooth germs that can grow into a new tooth in the jaw.
How are our teeth composed?
But so far there has been no overall picture of the cellular and molecular composition of human teeth. A research team led by Pierfrancesco Pagella from the University of Zurich has now changed that. The scientists created the first single-cell atlas of human teeth, which examined the development and behavior of tooth cells in detail.
The researchers used modern dentistry and DNA sequencing techniques to genetically and molecularly analyze their cell samples. These came from the tooth pulp and the tooth holding apparatus. The pulp is the soft pulp beneath the hard mineral layer of tooth enamel and dentin. The tooth holding apparatus, the periodontium, consists of the tooth neck and the tooth root with the periodontal membrane and cementum.
From the examination of a total of more than 300 pulp and 2,000 periodontal cells, the researchers created a first atlas of the tooth cells. “Our study shows the exact composition of these two tissues,” says Pagella. “Both are prone to tooth decay and periodontitis and at the same time contain stem cells that have great regenerative potential.”
The analyzes also revealed something surprising: “Unexpectedly, the stem cell populations of the pulp and the periodontium showed very similar molecular signatures,” explains the research team. This is astonishing because both tissues otherwise consist of very different cell types: The pulp mainly contains fibroblasts, a cell type that is also found in connective tissue. The tooth-supporting apparatus, on the other hand, consists mainly of epithelial cells.
Shaped by cellular signals
Because stem cells are the precursors of these different cell types, it would be expected that they too differ in their molecular composition and gene activity. But that is not the case: “In contrast to current ideas, the mesenchymal stem cells of the tooth show an astonishing homogeneity”, report Pagella and his team. But what then determines whether they develop into dentin or periodontal cells?
The detailed analyzes of the tooth cells also provided a possible explanation for this: “We suspect that the different behavior of individual cell types is caused by their respective environment,” says Pagella. As he and his colleagues discovered, the already differentiated fibroblasts and epithelial cells produce very different mixtures of messenger substances. “These cells release signals that could influence the behavior of the stem cells,” the scientists report.
The specific composition of the cellular microenvironment seems to be responsible for the large functional differences of the stem cells in the various tooth compartments.
Useful for dentistry
According to Pagella and his colleagues, the new findings that are now described in the dental atlas represent an important contribution to a better understanding of the complex cellular and molecular composition of human tooth tissue. and to better understand periodontal cells involved in the immune response to bacterial attacks.
And healing methods for damaged cells could also advance the new findings: “The single cell analysis could not only be useful for diagnostic purposes and support the early detection of dental diseases, but also contribute to the cell-based regeneration of damaged parts of the teeth,” explains Pagella’s colleague Thimios Mitsiadis finally. (IScience, 2021, doi: 10.1016 / j.isci.2021.102405)