Currently it is a pig's teeth in a rat's intestine
By: Yanai Ofran
In sterile rooms, behind heavy metal doors at the Forsyth Institute in Boston, rats have been living for the past few months, carrying in their bellies a great promise for the future of dentistry.
Every few days the researchers brought X-ray equipment into the rooms and excitedly followed the developments. At the end of long weeks of anticipation, white cubes began to appear on the x-rays. Pig's teeth grew in the rats' intestines.
In recent years there has been a debate in scientific circles about the dominant paradigm in modern dentistry. Critics say that the approach accepted by dentists today is outdated. Most of the dental treatments are mechanical - with the help of drills and drills and other aids they create and glue bridges and crowns. Biological problems, the critics claim, should be solved with biological tools. The great promises of modern medical research are based on finding biological solutions to medical problems - starting with types of antibiotics and vaccines, ending with genetic engineering and the use of stem cells. So, for example, one of the hottest fields in medical research today is tissue engineering - the attempt to grow organs for transplantation in the laboratory. The question is whether these developments are also relevant to dentistry.
In 1999, Pamela Yelik from the Forsyth Dental Research Institute was sitting on the entrance steps to the institute. By chance he was replaced by Joseph Vacanti, a well-known expert in tissue engineering. And Canty previously did studies in rats and showed that in the right environment cells are able to organize into complex structures. This chance meeting, Yelik said this week, made her think about Vacanti's findings and their relevance to dentistry. Is it possible to grow replacement teeth? To answer this question, Yelik needed not only tissue engineering, but also another field, one of the hottest in medical research - the field of stem cells.
Stem cells are divided into two types: embryonic cells and adult cells. Embryonic stem cells are able to develop into all types of tissues, while adult stem cells are cells that belong to a certain tissue, but are able to develop into different components of the tissue. Yilik and her team collected the jaws of pigs from a meat factory near the institute and applied a tissue engineering technique to them, in an attempt to extract from them mature dental stem cells, which could develop into teeth. They removed from one of the jaws a molar tooth that had not yet grown from the palate. The tooth was shredded into small pieces, and the researchers treated these pieces with enzymes to break them down into small segments of cells. The cells were then placed inside permeable molds, which were used as scaffolds for the teeth to grow. These molds were implanted inside the intestines of rats so that they would receive a regular supply of oxygen and food, and allow the dental stem cells to develop. The researchers used rats whose immune systems were weakened, so that they would not reject the foreign implant.
In the article, which will be published next month in the "Research" Journal of Dental, Yalik and her team will report on the teeth that grew in the intestines of the rats. Externally these teeth were large, strong and healthy. But they still cannot be used for transplantation, not even in the jaws of pigs. The inner parts of these teeth, and especially the root, are still missing; Furthermore, it is not yet clear how to transfer the technology from pigs to humans. One of the possibilities is to apply the method, using the patient's own cells to grow the teeth; Another possibility is to use pigs that have undergone genetic engineering, so that they will match the human immune system.
Yelik believes that within a decade it will be possible to use her discoveries to grow teeth for those who have lost a tooth due to an accident, caries, or gum problems. A biological tooth, especially one produced from the patient's own cells, is superior to any mechanical solution. The tooth and the gums maintain a complex biochemical relationship between them that a mechanical implant or crown cannot imitate. Biological teeth can, for example, gradually move inside the mouth when too much pressure accumulates in one place; Researchers also estimate that they secrete proteins that maintain the health of the surrounding tissue.
The question is whether Yelik's discovery could indeed one day lead to the creation of a complete and functioning tooth from autologous stem cells. Researchers and dentists this week were quick to question this. Among them were also those who expressed opposition to Yelik's initiative, even if it would ultimately lead to achievements. The British Dental Association even saw the whole thing as a cultural problem. "It is very appropriate for a company that loves disposable products to think that when your teeth rot you just go buy a new set," said a reprimanding message issued by a spokesperson for the association. "But you'll still need someone to take care of those teeth."
