BETHESDA, Md., April 21 (UPI) -- Instead of leaving baby teeth out for the tooth fairy, parents might do better to send them to doctors, who someday could harvest their hidden stem cells to help combat diseases, researchers reported Monday.
Just like the primordial tissue from which all organs arise, the stem cells in baby teeth can transform themselves into nerve and fat cells in laboratory dishes, investigators said. In the future, stem cells plucked from a child's discarded molar could be frozen in cell banks to benefit its donor for decades.
"These cells are a very surprising resource that is exciting, and (also important), they are very capable of providing huge numbers of cells," stem cell researcher Songtao Shi, a pediatric dentist at the National Institutes of Health, told United Press International.
All stem cells begin as "blanks" without a dedicated task, unlike nerve, blood, fat and other cells. They have the potential to become specialized, a power scientists have been attempting to harness in order to replace damaged cells in diseases such as Parkinson's and diabetes.
Stem cells from embryos can transform into virtually any of the more than 200 types of cells found in the human body. "Of course, they pose a major controversy. It's ethically very tough to deal with embryonic stem cells," Shi acknowledged.
Instead, Shi and his team investigated stem cells from adults, which remain versatile, though apparently not as flexible in terms of the variety of cells they can become. Shi and colleagues found stem cells in the pulp of adult teeth, while other teams have isolated stem cells from bone marrow, skin, brains and hair.
Two years ago, Shi's then 6-year-old daughter lost her first baby teeth. "I'm a pediatric dentist, so naturally I was the first person to take care of it," Shi said.
"Then I thought about the pulp tissue left inside. I was a dentist for years, but I never even thought about baby teeth until I looked at my daughter's carefully," he recalled. Because children are physically immature, stem cells from baby teeth could differ importantly from those from adults studied so far.
Shi and his team experimented with baby teeth from seven children. In findings made public Monday and appearing online this week in the Proceedings of the National Academy of Sciences, Shi revealed stem cells from the pulp of baby teeth not only became a range of cells, but also could trigger bone formation in mice. They also found the cells multiply two to three times faster than stem cells from adult bone marrow and adult teeth.
"We were very surprised that they were that highly proliferative," Shi said.
Incisors and canines only yield roughly 20 stem cells each, with molars yielding even less. Nevertheless, each stem cell from a baby tooth can reproduce itself many times, yielding trillions upon trillions of cells.
"We haven't had a problem with having enough cells to work with," Shi said.
Someday, he added, "we can ask parents to put (baby) teeth that comes out in milk, put it in the refrigerator and give a call the next day, and we can get stem cells out. You can freeze them in liquid nitrogen and save them for years and years."
If the cells are grown into tissues and implanted back into a person's body, they should avoid the immune rejection often seen in organ transplants. "But more studies definitely need to be done before we can use them to treat disease," Shi said.
Developmental biologist Anthony Mahowald of the University of Chicago said one focus of further research should be what types of cells the baby teeth stem cells can become. One possibility: beta cells of the pancreas, "the source of insulin, or dopamine-producing cells, relevant to Parkinson's disease," he said.
When employing stem cells from patients with genetic diseases, Mahowald added, "it will be important to demonstrate that gene replacement -- that is, correction of genetic defects -- can be accomplished in these cells."
(Reported by Charles Choi, UPI Science News, in New York)