The stem cells in teeth can contribute to the regeneration of non-dental organs, particularly mammary glands, according to researchers at the University of Zurich. Dental epithelial stem cells from mice can generate mammary ducts and even milk-producing cells when transplanted into mammary glands, the researchers reported, noting that these findings could have potential for post-surgery tissue regeneration in breast cancer patients.
The ability of adult stem cells to generate various tissue-specific cell populations is of great interest in the medical and dental research fields, the researchers said. These cells can replace damaged cells and therefore represent a good alternative to classical medical treatments for tissue regeneration, the researchers added, perhaps even allowing the de novo formation of entire tissues and organs in the future.
Dental epithelial cells can generate all epithelial cell types in the teeth, but it was not clear if these cells also could produce non-dental cell populations. The researchers at the Institute of Oral Biology of the University of Zurich, however, have shown for the first time that epithelial stem cells isolated from the continuously growing incisors of young mice can form mammary glands in female mice.
After removing all cells of mammary origin, the researchers directly injected dental epithelial stem cells and mammary epithelial cells into the areas where the mammary glands normally develop. The researchers used advanced genetic, molecular, and imaging tools that allow for the precise follow-up of the transplanted dental stem cells in the mammary gland fat pad of the animals.
“The results show that the dental stem cells contribute to mammary gland regeneration and are able to generate all mammary cell populations and, even more strikingly, milk-producing cells,” said Thimios Mitsiadis, a professor with the Institute of Oral Biology.
This work demonstrates the exceptional plasticity of dental epithelial stem cells to generate not only dental tissues but also other tissues of the body, the researchers said.
“These findings represent a major contribution to the understanding of the cellular and molecular mechanisms involved in the regenerative capacity of dental stem cells and, furthermore, indicate the clinical potential of these specific stem cell populations,” Mitsiadis said.
In a second set of experiments, dental epithelial stem cells were injected alone, without mammary epithelial cells. In this case, the dental stem cells also were able to form small ductal systems consisting of branching rudiments. But in some cases, this resulted in the formation of cysts.
“This plasticity might be unique for dental epithelial stem cells, since all other non-mammary epithelial cells examined so far have never shown the ability to generate mammary ducts without the support of mammary epithelial cells,” said study coauthor Pierfrancesco Pagella of the Institute of Oral Biology.
One of the most severe pathological conditions is breast cancer, the researchers said, which is often treated with surgery.
“Our discovery that dental epithelial stem cells are able to replace cells from the mammary gland opens up new paths for developing stem cell-based therapies that could be used for breast regeneration in the future,” said Mitsiadis.
The study, “Dental Epithelial Stem Cells As a Source for Mammary Gland Regeneration and Milk Producing Cells in Vivo,” was published by Cells.