In baby teeth, hope for healing

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In baby teeth, hope for healing
April 21, 2003
By SUSANNE QUICK
JS Online
In the future, a quarter may not be the tooth fairy's preferred under-the-pillow payment.
Instead, if initial findings by a group of cell biologists at the National Institutes of Health and the Institute of Medical and Veterinary Science in Australia pan out, young children will be finding small, airtight vials filled with preserving fluid nestled under their pillows.
That's because researchers have discovered that baby teeth are fruitful providers of stem cells.
And if preserved correctly, baby teeth have the potential to provide a child with a lifetime's worth of future treatment and therapy.
"This is very exciting," said Songtao Shi, a scientist at the National Institute of Dental and Craniofacial Research, and a senior author of the paper, which appeared online Monday in the Proceedings of the National Academy of Sciences.
"It provides a means to get easy access to durable stem cells," Shi said.
Indeed, he said, if placed in a glass of milk and stored in the refrigerator, the cells will remain alive for about 24 hours - providing ample time to get the sample to an appropriate storage facility.
Stem cells taken from adults and developed children have received a great deal of interest for their potential to provide easily accessible - and uncontroversial - sources of regenerative cells.
However, unlike embryonic stem cells - which can be coaxed to develop into all sorts of tissue cell types, such as brain, bone, liver, heart and skin cells - adult versions tend to show limited growth potential. They appear to be restricted in the types of tissues they can generate.
For instance, stem cells harvested from wisdom teeth can generate dentin and bone, but they don't show the ability to form heart or pancreatic cells.
"That's not really surprising," said Ronald Kalil, a professor of neuroscience at the University of Wisconsin-Madison Medical School who studies embryonic stem cells.
If a stem cell is found in a tooth, it's presumably there for the purpose of repairing damaged or diseased teeth, said Kalil, not to create new liver cells.
But initial research conducted by Shi and his co-authors shows that stem cells from baby teeth may be a bit more plastic - and definitely more prolific - than their grown-up counterparts.
"This suggests that these teeth may be in a more immature state than adult stem cells," Shi said.
Indeed, they showed higher rates of growth and duplication than stem cells derived from bone marrow and adult teeth.
And experiments in which the baby teeth were coaxed into developing into tissue types other than bone and dentin, there were indication of success. Under certain conditions, the cells showed signs of transforming into both nerve and fat cells.
But Kalil expressed concern with these findings.
"They don't show what percent was coaxed into nerve cell generation," he said. "It could have been 1 percent, a half-percent, 5 percent or 20 percent. But I suspect that because they didn't include the number, it was probably insignificant."
"And the number of cells that turned into adipose (fat) tissue was less than 5 percent," he said. "I think these cells, like other adult stem cells, show only limited potential to differentiate."
But Shi said his research has only just begun. And the results published were only preliminary.
"We have a lot still to look into and test," he said. "But this is my dream. I'm a pediatric dentist and researcher. And if we could harvest stem cells from such an easily accessible source, it would be wonderful."
Cesar Gonzalez, director of pediatric dentistry and associate professor of dentistry at Marquette University's School of Dentistry, agreed.
"I think what they have shown is potential," Gonzalez said. "They demonstrated that with the right stimulation, these cells could form fat, nerve, bone and tooth tissue."
"I see possibilities for future work and use in this area," he said. "You don't have to cut someone or go in for a biopsy to extract cells with this technique."
In fact, all the teeth examined by Shi and his colleagues were donated by friends of Shi's 6-year-old daughter.
"It was totally voluntary," he said, "I didn't yank a tooth out of any child that wasn't about to fall out on its own."