The race to create induced pluripotent cells—cells capable of developing into most types of cells in the body—in humans began in 2006, when scientists at Kyoto University in Japan announced they had inserted genes into cells from the tails of mice and reprogrammed them into cells with properties of embryonic stem cells.
(Related: "Mouse Testicles Yield Promising Stem Cells" [March 24, 2006].)
In 2007 researchers from Kyoto University and the University of Wisconsin, Madison, separately announced that they had successfully applied the technique to human cells by using viruses to ferry four genes—OCT4, SOX2, NANOG, and LIN28—into skin cells.
Researchers from the two teams said they had given properties of stem cells to human cells taken from skin and connective tissues.
Now Ohgushi and his colleagues claim they used just three sets of genes—OCT4, SOX2, and KLF4—to program cells cultured from the center of a wisdom tooth into adult stem cells.
The researchers add that their success rate, about 10 stem cells for every 50,000 cells, matches that of the Kyoto researchers.
Ohgushi said stem cells derived from wisdom teeth are not only easier to store—the tooth they used had been sitting in a freezer for three years—but also better than those extracted from bone marrow.
Stem cells found in bone marrow cannot express telomerase reverse transcriptase (TERT), a type of protein crucial to cell division and growth, Ohgushi explained.
"Our cells clearly express TERT and showed [more] extensive activity than stem cells from bone marrow."
Though clinical trials are still years away, the researcher envisions banks where donors could store their wisdom teeth and access their own stem cells to treat potential diseases later in their lives.
Shinya Yamanaka, a researcher from Kyoto University who was not involved in the teeth research, agreed that the discovery could provide an alternative source of stem cells for use in regenerative medicine.
But he said it was odd that the discovery was apparently announced directly to the press and that the results did not seem to be backed by a peer-reviewed publication.
"I know venture companies do this to keep investors' interest," Yamanaka said. "It was surprising to me that government-backed scientists did this."
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