] The study reports that the cell lines currently approved
] for study under federal funding contain a sialic acid
] called N-glycolylneuraminic acid, or Neu5Gc.
]
]
] Human embryonic stem cells are contaminated by this acid
] "even when grown in special culture conditions with
] commercially available serum replacements, apparently
] because these are also derived from animal products,"
] said the lead researcher, Dr. Ajit Varki. Human cells are
] unable to make the acid, Varki said. In earlier research
] he had found that humans have antibodies directed against
] Neu5Gc.