March 1, 2012 at 10:00 AM ET
By Andrew Winner
There are those who say there’s a use for every little thing in this world, no matter how vile or off-putting. An enterprising dentist is doing his part to prove that's true. Japanese dental researchers have found that halitosis -- that is, bad breath -- is an ideal incubator for cultivating hepatic (liver) cells.
In a finding that could have far-reaching impacts on diseases such as Alzheimer’s and Parkinson’s, stem cells harvested from human dental pulp became liver cells at an astonishing rate when incubated with hydrogen sulphide, the chemical compound responsible for bad breath.
Talk about the ultimate silver lining. The study was published Monday in IOP Publishing's Journal of Breath Research.
Stem cell therapy treats damaged tissue by introducing new cells, but it can sometimes be difficult to safely and effectively produce these new cells. Study author Dr. Ken Yagaeki and his team at Nippon Dental University believe the use of stem cells from dental pulp could eventually replace existing methods of stem cell production, two of which use human bone marrow and fetal bovine serum as source material. In fact, Yagaeki went out on a limb to show that dental pulp is a viable source of stem cells.
For Yagaeki, observing the resilience of teeth plagued by cavities made him wonder if there weren’t more stem cells in dental pulp than previously thought. Despite some skepticism from colleagues, he reports that 60-80 percent of human dental pulp cells are stem cells, up markedly from the previous estimate of 1 percent.
“Although nobody reported regeneration of those tissues from dental pulp, I had a hypothesis that dental pulp would be a good source of somatic stem cells,” Dr. Yagaeki wrote in an e-mail. “Of course all people denied my hypothesis. In the meeting of International Association for Dental Research, a chairman of my session called us as stupid.”
After this vindicating discovery, Yagaeki looked to test the impact of halitosis on the development of stem cells into hepatic cells.
After stem cells were harvested from the center of human teeth (don’t worry – the teeth extractions were part of normal dental treatments), the samples were then split into test and control groups. Using a battery of tests, researchers were able to show that a very high percentage of the stem cells incubated in an environment with hydrogen sulphide successfully became hepatic cells.
It was a lucky discovery. Initially, Yagaeki had attempted to learn about negative effects of hydrogen sulphide on the samples before noticing that in small concentrations, the compound had the opposite effect.
Finally, the testing showed high purity in the end result -- fewer cells differentiated into different kinds of cells or remained as stem cells. Pure stem cells greatly reduce the chance of teratomas or cancers in the patient as compared to stem cells originating from bone marrow, making this a promising area for further research.
“After transplantation into animals or human, those contaminated stem cells or cells differentiating to other tissues may produce teratoma or cancer,” Yagaeki said. “Bone marrow stem cell transplantation is frequently carried out, but the incidence of cancer increases dramatically.”
As it happens, even bad breath might have a therapeutic use. Easy on the Listerine next time.
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