Researchers at the Karolinska Institutet in Sweden have discovered that stem cells inside the soft tissues of the tooth come from an unexpected source, namely nerves. Part-funded by the European Research Council, the investigation contributes to brand new knowledge of how teeth are formed, how they grow and how they are able to self-repair.
The research found that with age, teeth become more susceptible to infection, wear and damage. It was previously known that the living, soft part of the tooth, or the pulp, in addition to connective tissues, blood vessels and nerves, also contains a small reserve of stem cells. These stem cells are capable of repairing a damaged tooth by assisting the reformation of both hard and soft tooth tissue. Researchers have long been discussing the origin of these stem cells. By studying the teeth of mice, the researchers behind this new study have been able to map the fate of individual cells.
Speaking about the investigation, Kaj Fried, joint head researcher of the study, said: “We have identified a previously unknown type of stem cell that surprisingly enough belongs to the nerves of the tooth; these are nerves that would normally be associated with the tooth’s extreme sensitivity to pain.”
The researchers discovered that young cells, which at first are part of the neural support cells, or the glial cells, leave the nerves at an early stage of the foetal development. The cells change their identity and become both connective tissues in the tooth pulp and odontoblasts, i.e. the cells that produce the hard dentin underneath the enamel. Currently, this does not make possible the growing of new teeth in adults, but the discovery of the new type of stem cell is an important step towards the knowledge and technology that is required to make it a future possibility.
Adding his thoughts, Igor Adameyko, who also headed the study, said: “The fact that stem cells are available inside the nerves is highly significant, and this is in no way unique for the tooth. Our results indicate that peripheral nerves, which are found basically everywhere, may function as important stem cell reserves. From such reserves, multipotent stem cells can depart from the nerves and contribute to the healing and reformation of tissues in different parts of the body.”
The findings are being published in the journal Nature.