Regenerative medicine researchers are fairly close to reprograming ordinary skin cells back to the embryonic state, reports Nicholas Wade in the New York Times. Embryonic cells can be developed into virtually any other kind of the body’s cells. If the current research, which uses mice as test subjects, can be adapted to human cells—no small feat in itself—a patient’s own skin cells could be used to generate new organs that would not be rejected by the source patient’s immune system.
The new technique, developed by Shinya Yamanaka of Kyoto University, is markedly different than therapeutic cloning, where an adult cell’s nucleus is inserted into an egg whose nucleus has been removed. The new, much simpler, technique calls for inserting four genes into a skin cell. Additionally, the ethical controversy of using human eggs is avoided.
“Recent studies have shown that the chromatin, the complex protein material that clads the DNA in chromosomes, is not passive packaging material but highly dynamic. It contains systems of switches that close down large suites of genes but allow others to be active, depending on the role each cell is assigned to perform. Dr. Yamanaka’s four genes evidently reset the switch settings appropriate for a skin cell to ones that specify an embryonic stem cell.”
The new technique is not without problems. The mice used in Yamanaka’s research have been interbred and the cells must be infected with the gene-carrying virus. Perhaps of most concern is that two of the four genes in Yamanaka’s recipe can cause cancer. In Yamanaka’s research, fully 20% of the subject mice developed terminal cancer.
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