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Wisdom Teeth: Not So Useless After All
Researchers have found a new source of stem cells in an unusual place — wisdom teeth. This discovery should help scientists by increasing the number of stem cells available for research. It could also mean that everyone is carrying around an easily accessible supply of stem cells for use on a rainy day.
Until a few years ago, two types of stem cells were known: adult and embryonic. Unlike other adult cells, adult stem cells are capable of changing into a few different types of cells. The best known adult stem cells are found in bone marrow. These are somewhat plastic cells that are capable of turning into different types of blood cells. Blood cells are constantly being worn out and need to be replenished. It is these stem cells that replenish them. Other adult stem cells have been found in many types of tissue, including skin and muscle.
Embryonic stem cells are present only during the first few days of life. They are capable of turning into every type of cell present in the adult body. Stem cells that can give rise to all types of cells found in the body are called pluripotent.
In 2006, scientists found a way to reprogram adult stem cells. By turning on four specific genes, they were able to change some adult stem cells into cells that resembled embryonic stem cells. These cells are called induced pluripotent stem cells (IPS) because they are able to produce all the body's cell types. This discovery looked like the breakthrough needed to turn some of the promise of stem cells into actuality.
Of course, there have been a few problems.
Only a small number of adult stem cells end up being successfully reprogrammed. It was hoped that stem cells found in adult skin would be a prime source of IPS, but they turned out to have one of the lowest reprogramming rates of all adult stem cell types. Stem cells from bone marrow are exceedingly difficult to obtain. So there have been very few IPS cells available for researchers to study. In fact, there haven't been enough available to thoroughly investigate just how closely IPS cells resemble embryonic stem cells.
The pulp inside of teeth contains a type of adult stem cell called mesenchymal stem cells. Japanese researchers doing preliminary research with wisdom teeth recently found that these cells could be reprogrammed into IPS cells up to 100 times more efficiently than the stem cells from adult skin. And they say that the IPS cells they derived appear very similar to embryonic stem cells.
Lots of wisdom teeth are extracted every year under sterile conditions. Currently, they're thrown out as medical waste. Saving them should provide a lot more stem cells for researchers to use. Wisdom teeth can survive freezing and be stored for many years. And the stem cells from tooth pulp are present in all teeth, not just wisdom teeth. If the promise of stem cells ever becomes a reality, who wouldn't sacrifice a tooth to repair a damaged heart or spine?
An article detailing the study was published in the September 17, 2010 issue of the Journal of Biological Chemistry.
September 26, 2010
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