Researchers find stem cells contaminated

Researchers published in Nature Medicine that currently available lines of human embryonic stem cells, including those approved under federal funding in the U.S., have been contaminated by a non-human, cell-surface sialic acid called N-glycolylneuraminic acid (Neu5Gc). Neu5Gc was incorporated into the stem cells from laboratory cultures that contained animal sources of Neu5Gc. The contamination of the stem cells renders them useless as therapeutics, because contaminated cells are attacked by human antibodies. More research has been done to eliminate contamination of the stem cells. However, many of the specialized media used for growth and differentiation contain materials from contaminated animal sources, and completely starting over "could not be pursued under existing rules for the use of federal grant dollars," said Ajit Varki, a professor of medicine and cellular & molecular medicine at the University of California at San Diego. ...