Researchers from King’s College London have successful grown rudimentary teeth from a combination of human epithelial cells taken from adult gums, and mesenchymal cells borrowed from mouse embryos. After the cell mixture was incubated in culture, it was transplanted to the kidney of a mouse where it developed into recognizable, but small, teeth complete with dentin, enamel, and rests of Malassez.
In case you need to brush up on your dentistry, the rests of Malassez are epithelial cells that are part of the periodontal ligament that connects teeth to bone — an important component to have if you are trying to grow teeth from scratch. Stem cells that can be extracted from the pulp of human wisdom teeth are a good starting point, but they need the right environment to be coaxed into forming a whole tooth. At the moment, the researchers don’t know how to make adult mesenchymal cells produce all the necessary tooth-inducing factors that the embryonic version does. Their immediate goal is to develop protocols to transform the adult cells, and hopefully eliminate the middle-mouse.
Mesenchymal-epithelial interactions have been the go to tool that evolution has co-opted time and time again for making all sorts of complex tissues. Not just teeth, but for making eyes, ears, and even hair follicles. Better understanding of each of these systems individually will yield broad interpretive power for making replacement tissues and organs for many parts of the body.
It is not entirely clear whether the kidney connective tissue is unique in any way as the growth site for teeth once they were moved from the culture environment. Other tissues and perhaps human tissue environments can be used once human mesencynmal cells are up to the transformation task.
The tiny teeth produced in this fashion are not quite ready for human use, but encouragingly, they did posses the critical root structure. There are several issues to be addressed before attempting to transplant these structures directly into a human mouth, but the latest findings are important for the future of dentistry and the greater medical community as well.
Study in Journal of Dental Research: Adult Human Gingival Epithelial Cells as a Source for Whole-tooth Bioengineering