Lab May Have Answer to Stem Cell Contamination

Growing cells with human protein avoids threat of animal taint

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TUESDAY, March 29, 2005 (HealthDay News) -- A new laboratory technique allows human embryonic stem cells to be grown and maintained without contamination by animal cells or products.

The finding may help overcome a roadblock to safe stem cell research and treatment.

Researchers at the University of California, San Diego, created controversy in January by noting that the animal-sourced "feeding layers" used to culture and maintain human stem cells in the lab could introduce potentially dangerous non-human molecules into transplanted stem cells.

However, a new study -- also by UCSD researchers and published in the April issue of the journal Stem Cells -- demonstrates that laboratory culture media enriched by a human protein called activin A can maintain human embryonic stem cells in a continuous undifferentiated state, ready to be used for research. An "undifferentiated state" means stem cells have not yet started the process of development toward becoming specific human organs or tissue.

"Our findings provide a new way to generate human stem cell lines without contamination by animal cells or products," study senior author Dr. Alberto Hayek said in a prepared statement. Hayek is a pediatrics professor at UCSD and director of the Islet Research Laboratory at the Whittier Institute in La Jolla, Calif.

Currently, human embryonic stem cells are grown and nourished in a petri dish material called feeder layers. These feeder layers are made using connective tissue from animals, primarily calves and mice. Previous research at UCSD found that human embryonic stem cells grown in this animal-derived material become contaminated with a non-human molecule called Neu5Gc.

If contaminated stem cells were transplanted into humans, they could trigger an attack by the person's immune system that would destroy the therapeutic value of the stem cells and possibly spark a dangerous immune reaction as well.

However, the researchers concluded that use of activin A may enable labs to maintain human stem cells "without the use of animal or human feeder layers," getting around those problems.

More information

The U.S. National Institutes of Health has more about stem cells.

SOURCE: University of California, San Diego, news release, March 22, 2005

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