Human stem cells trigger immune attack

From http://www.nature.com/news/channels/medicalresearch.html

Most human embryonic stem-cell lines, including those available to federally funded researchers in the United States, may be useless for therapeutic applications. The body's immune defences would probably attack the cells, say US researchers. When embryonic stem cells are added to serum from human blood, antibodies stick to the cells. This suggests the cells are seen as foreign, and that transplanting them into the body would trigger the immune system to reject them. "We've found a serious problem," says Ajit Varki, a cell biologist at the University of California, San Diego. The difficulty arises from the way human embryonic stem cells are grown and maintained in the lab. Scientists grow stem cells in petri dishes containing nutrient broth and other cells. These feed the stem cells, and give them a place to attach themselves. Feeder cells are typically embryonic cells from mice and nutrient broth usually contains animal serum. These mouse cells have a molecule on their surface called N-glycolylneuraminic acid or Neu5Gc. Varki's team had already found that human embryonic stem cells take up Neu5Gc; they now show that humans react against it. Eating red meat and dairy products has sensitized people to the molecule, Varki says. The team reports its latest finding in the February issue of Nature Medicine1.

The current stem-cell lines have little clinical value, but that is "not an issue for pursuing basic research", says James Battey, chairman of the National Institutes of Health's stem-cell task force.