Quotes of the Day

The crash-course in cellular biology that is the stem cell debate continued Friday when the Washington Post revealed that most if not all of the 60 lines of stem cells currently approved for federally-funded research have been mixed with, or developed in, a medium of mouse cells.

The reaction, on radio talk shows and online, was swift and incredulous — how can rodent cells possibly help scientists find cures for human diseases? — except among scientists, who calmly accepted the news for what it is: A reiteration of well-known research protocol.

"In terms of research, this does not create any kind of impediment," says Terry Devitt, director of research communications for the University of Wisconsin at Madison, where much of the pioneering work on stem cells has been conducted. "No one in the scientific community is surprised by this — it's not exactly a revelation."

Human embryonic stem cells, says Devitt, need a medium in which to grow. So researchers use a culture of embryonic cells from mice — which we know a lot more about than we do about human cells — to create a universally understood base for growing the human cells.

"The science is intact," says Devitt, "and the research integrity of these cells lines is not affected. It's just a part of the science that's going on in a petri dish. These stem cell lines are experimental. The hope is they will advance knowledge to a point that in the long term, say, ten years, we might be able to start looking at treatments or cures."

Granted, says Devitt, there could be controversy when it comes time to actually implement any experimental treatments derived from the mouse-human mixture. "Separating the human cells from the mouse cells can be tricky," he explains. "But we have seen human cell lines successfully developed while in extensive contact with mouse cells."

And what about the political questions? Did the President know all this when he made his decision on stem cell research? Friday morning, midway through a Crawford press conference, Bush was given the chance to answer that very question.

"Here's what I knew. I knew that I sat down with the NIH experts, people charged to follow the developments in this field. And their opinion, upon which I based my judgment, was that there are ample stem cell lines to determine whether future research is merited."

So the mouse-human connection comes, apparently, as no surprise to the President. Now, if the rest of us can just catch up on our college-level biology...

• Jessica Reaves
• It looks like the President's 60 precious stem cell lines may be mixed with rodent cells. But don't worry, researchers say. This is standard procedure