I’ll leave it to Chris Mooney to sort out the political implications of this, but there’s an interesting paper in Friday’s Science (sub. req.) by Fraidenraich et al. on the use of embryonic stem cells to treat cardiac defects.

A review also in Science (more $ req.) by Kenneth R. Chien of UC San Diego, calls it “an exciting new study … (that) expands the potential therapeutic repertoire of ES cells.”:

These investigators provide direct evidence that ES cells can rescue otherwise lethal cardiac defects in mouse embryos.

I’ve not followed the embryonic stem cell debates closely (am I the only one who’s uncomfortable with the way this issue has been transformed from science into tribal politics?), so I may be munging the science here. But as I understand from reading Chien’s review, the importance here is not that the transplanted embryonic stem cells differentiate into cardiac cells. Instead, the embryonic stem cells secrete stuff that gets the regular cells to do what they’re supposed to.

Here’s how Rick Weiss explained it in yesterday’s Washington Post:

The new work offers the most definitive evidence yet that the versatile cells, derived from embryos, can help repair organs two ways: by filling in damaged areas — the primary focus of stem cell research to date — and also by secreting potent chemicals that can make tissues rejuvenate themselves.