By isolating dental stem cell lines, researchers from Inserm and Paris Descartes University have been able to demonstrate the natural mechanisms by which these stem cells repair lesions in the teeth. Publishing in the journal Stem Cells, it is hoped that this breakthrough discovery will allow the initiation of unprecedented therapeutic strategies to mobilise the resident dental stem cells and magnify their natural capacity for repair.
When a dental lesion appears, dormant stem cells in the dental pulp, or “living” part of the tooth, springs into action and try to repair the tooth. Through successfully extracting and isolating tooth stem cells from rats, the researchers were able to analyse them in detail. They identified 5 specific receptors for dopamine and serotonin on their surface, two neurotransmitters that are essential to the body. They then observed that the blood platelets, activated by the dental lesion for releasing a large quantity of serotonin and dopamine. Once released, these neurotransmitters then recruit the stem cells to repair the tooth by binding to their receptors. Furthermore, in rats were dental repair was absent, it was found that these rats had modified platelets that did not produce serotonin or dopamine, i.e. a failure to signal to repair the lesion.
Lead author of the research, Odile Kellermann, commented: “In stem cell research, it is unusual to be simultaneously able to isolate cell lines, identify the markers that allow them to be recognised (here the 5 receptors), discover the signal that recruits them (serotonin and dopamine), and discover the source of that signal (blood platelets). In this work, we have been able, unexpectedly, to explore the entire mechanism.”
The researchers were also able to analyse the characteristics of the 5 receptors and found encouraging signs there also. Only one 1 of the 5 receptors was found not to affect the repair process. The other 4, meanwhile, all strongly participated. In vivo blocking of just one, then, would not prevent dental repair occurring.
Speaking of how this could influence current dental strategies for repairing teeth, Odile Kellermann concluded: “Currently, dentists use pulp capping materials (calcium hydroxide) and tricalcium phosphate-based biomaterials to repair the tooth and fill lesions. Our results lead us to imagine unprecedented therapeutic strategies aimed at mobilising the resident pulpal stem cells in order to magnify the natural reparative capacity of teeth without use of replacement materials.”