Fillings with protein additives
British scientists have figured out how to make teeth grow again
Molecular biologists from the UK have tracked how the incisors of mice grow and discovered a set of genes and signaling molecules that control this process. Their study will help to create techniques that allow teeth to be restored in a "natural" way, according to an article published in the journal Nature Communications (Walker et al., Transit amplifying cells coordinate mouse incisor mesenchymal stem cell activation).
"So far, all these are laboratory experiments, and we will have to do a lot of work before we can apply such techniques to human treatment. On the other hand, we can already say that this is a big breakthrough in regenerative medicine, which will radically change the lives of patients in the near future," said Bing Hu from the University of Plymouth (in a press release A new method of tooth repair? Scientists discover mechanisms that could help future dental treatment – VM).
The teeth of humans and other mammals consist of "dead" enamel and several "living" parts: dentin, pulp and nervous tissue. Enamel, in turn, consists of two main elements – strong and extremely resistant to the action of various irritants of hydroxyapatite threads, as well as the "glue" that binds them in the form of a mixture of various amorphous minerals.
This "cement" gradually corrodes if carious microbes that secrete acids appear on the surface of the teeth, or if the enamel is mechanically damaged. In the resulting microcracks, new colonies of bacteria settle, whose appearance accelerates the process of tooth destruction and leads to the formation of a carious cavity.
Human teeth stop growing in childhood, whereas in many animals, such as camels, llamas, rats, mice and other rodents, some of them continue to grow throughout life. This is possible due to the fact that at the base of each tooth there are several colonies of "adult" stem cells capable of producing all types of its tissues.
These cells, as scientists have known for a long time, are also present in human teeth, but for unknown reasons they are not involved in repairing or replacing fallen or removed incisors, canines or molars. Four years ago, biologists from Harvard discovered that they could be made to do this by treating stem cells with laser pulses.
Hu and his colleagues discovered the signaling molecule Dlk1, which controls how much dentin is produced by stem cells living at the base of the incisors of rats and mice. It helps these animals maintain their teeth in optimal shape throughout their lives, keeping their length approximately at the same mark.
Initially, as biologists note, they were not looking for similar proteins, but for new types of stem cells, since already known ones are found in gums and jaws, but they can regenerate far from all tooth tissues. In addition, they were unable to initiate the formation of new incisors, canines or molars.
To search for them, scientists analyzed which genes are involved in the formation of the "embryo" of the tooth, and identified the set of DNA sections that should have been found in such stem cells. This allowed them to find cells that play the role of a kind of "conductors" of the growth of dental tissues, and produce molecules that control this process.
The appearance of Dlk1 protein in the nutrient medium causes stem cells to actively divide and form dentin and other types of tissues, which, as biologists have suggested, can be used to regenerate damaged teeth.
Guided by this idea, the scientists drilled holes in the molars of several rats and filled them with two formulations – a drug that is usually used to fill the cleaned channels during nerve removal, and its mixture with Dlk1. In the second case, this procedure led to pulp healing and dentin restoration, which confirmed that this protein can be used to restore teeth.
In the near future, Hu and his colleagues plan to find out exactly how Dlk1 awakens stem cells and whether there are any dangerous side effects of their activation. Scientists hope that these experiments will pave the way for the creation of technologies for full-fledged restoration of teeth.
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