Monday, February 2, 2009

A new study says efforts to produce stem cells by putting human DNA into animal eggs may be futile.

The idea drew harsh criticism in Britain last year, as authorities debated whether to let scientists try it. Animal eggs are considered attractive options because human ones are hard to get for research.

Embryonic stems cells can develop into virtually any cell of the body. By inserting a person's DNA into an egg and growing an embryo, scientists hope to be able to extract stem cells that are a genetic match for that person. Those cells could help disease research and also help develop transplant tissues that avoid rejection.

But the study published today by the journal Cloning and Stem Cells says animal eggs aren't a substitute for human eggs because they don't reprogram human DNA in the right way to generate stem cells. Some scientists dispute the findings, but the study's senior author says instead of turning on the right genes, animal eggs turn them off.