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Scientists Turn Human Skin Cells Into Stem Cells
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Page: << Prev | 1 | 2 | 3 | 4 | Next >> This year, the researchers tried the same method in humans: using a retrovirus to activate specific transcription genes in the skin cells. Transcription genes regulate gene expression, explained Yamanaka.
Using this method, his group generated about 10 cell clones from 50,000 human facial skin cells.
The new "induced pluripotent stem" (iPS) cells were identical to embryonic stem cells in terms of appearance and behavior in cell culture. They also expressed genetic markers that were the same as those observed in embryonic stem cells.
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The iPS cells could also differentiate into other tissue types, the team found.
However, a screen of more than 30,000 genes showed that the iPS cells were not actually indistinguishable from embryonic stem cells. In fact, roughly 1,000 genes were expressed differently.
"Human iPS cells are similar, but not identical, to human embryonic stem cells, Yamanaka said. "DNA microarray analyses identified differentially expressed genes between the two stem cell lines. Further studies are required to determine whether human iPS cells can replace human ES cells."
The team at the University of Wisconsin-Madison also used human skin cells, then added two of the same genes as Yamanaka's team and two different genes in their approach. The outcome was essentially the same.
"The actual combination of the factors they put in are different, the rationale is the same," Tsai explained. "There are some tiny differences between the two different combinations."
The advent of the new cells does not render embryonic stem cells unnecessary, however.
"This does not mean that it is the end of embryonic stem cell research, if only that we need a gold standard to compare to," the University of Wisconsin's Thomson told reporters. "Over time, I believe embryonic stem cells will be used by fewer and fewer labs. These new stem cells would not have been derived if it had not been for the last 10 years of research on embryonic stem cell lines. I do, nonetheless, think that the world has changed."
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Copyright © 2007 ScoutNews, LLC. All rights reserved.
Last updated 11/20/2007
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SOURCES: Shinya Yamanaka, M.D., Ph.D., Kyoto University, Japan, and Gladstone Institute of Cardiovascular Disease, San Francisco; Robert Tsai, M.D., Ph.D., assistant professor, Center for Cancer and Stem Cell Biology, Texas A&M Health Science Center Institute of Biosciences and Technology, Houston; Paul Sanberg, Ph.D., D.Sc., distinguished professor of neurosurgery, and director, University of South Florida Center for Aging and Brain Repair, Tampa; Nov. 20, 2007, news teleconference with James Thomson, Ph.D., professor, departments of medicine and public health, University of Wisconsin-Madison; Nov. 30, 2007, Cell, Nov. 20, 2007, Science
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