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Easier Way To Create Stem Cells Discovered

Posted on: Monday, 13 October 2008, 13:15 CDT

Researchers said on Sunday they found a shortcut to transforming ordinary skin cells into powerful stem cells by "sprinkling" a chemical onto the cells.

The team at the Harvard Stem Cell Institute in Massachusetts added the chemical to use just two genes to transform ordinary human skin cells into more powerful induced pluripotent stem cells or iPS cells.

"This study demonstrates there's a possibility that instead of using genes and viruses to reprogram cells, one can use chemicals," said Dr. Doug Melton, who directed the study published in the journal Nature Biotechnology.

Danwei Huangfu, a postdoctoral researcher in his lab, developed the new method, Melton said.

Melton, a Howard Hughes Medical Institute Investigator, said in a statement: "The exciting thing about Danwei's work is you can see for the first time that you could sprinkle chemicals on cells and make stem cells."

Stem cells are the body's master cells, giving rise to all the tissues, organs and blood. Embryonic stem cells are considered the most powerful kinds of stem cells, as they have the potential to give rise to any type of tissue.

Someday doctors hope to use them to transform medicine. For instance, Melton wants to find a way to regenerate the pancreatic cells destroyed in type 1 diabetes and perhaps cure that disease.

However, pluripotent stem cells such as the embryonic cells are difficult to make, requiring the use of an embryo or cloning technology. Many people also object to their use, and several countries, including the United States, limit funding for such experiments.

Several teams of scientists in the past year have reported finding a handful of genes that can transform ordinary skin cells into iPS cells, which look and act like embryonic stem cells.

They have had to use retroviruses to get these genes into the cells, which integrate their own genetic material into the cells they infect. This can be dangerous and can cause tumors and perhaps other effects.

U.S. researchers did the same thing last month using a harmless virus called an adenovirus, but the method was not efficient. And last week, Shinya Yamanaka of Kyoto University in Japan, who discovered iPS cells in mice, used a loop of genetic material called a plasmid to reformat the cells.

Huangfu tried treating the cells first with valproic acid. She reported that after she did this, it only took two of the four usual genes to reprogram the cells into iPS cells.

She said this was good because the other two genes usually needed can promote cancer.

Retroviruses were used to carry the two genes in but the Melton team suggests they might not be necessary.

"These results support the possibility of reprogramming through purely chemical means, which would make therapeutic use of reprogrammed cells safer and more practical," they wrote in their report.

The valproic acid unraveled the chromatin -- the physical structure of the chromosomes -- making it possible to get in and alter the DNA more easily, Huangfu said.

She said they might need two types of chemicals, one to loosen the chromatin structure, and one to reprogram. “We are looking for that reprogramming chemical, and it should be possible to find it eventually.”

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Image Caption: A colony of embryonic stem cells, from the H9 cell line (NIH code: WA09). Viewed at 10X with Carl Zeiss Axiovert scope.

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On the Net:

• Harvard Stem Cell Institute
• Nature Biotechnology

Source: redOrbit Staff & Wire Reports

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