If you're not already awed by stem cell biology...

... take a look at this report in Circulation Research from researchers at Mount Sinai Medical Center which demonstrates that in a pregnant female experiencing myocardial (heart) injury, stem cells from her fetus can navigate to the mother's heart to assist in the repair process.

We report that fetal cells selectively home to injured maternal hearts and undergo differentiation into diverse cardiac lineages. Using enhanced green fluorescent protein (eGFP)-tagged fetuses, we demonstrate engraftment of multipotent fetal cells in injury zones of maternal hearts. In vivo, eGFP+ fetal cells form endothelial cells, smooth muscle cells, and cardiomyocytes.

This study was conducted in mice, but there is no reason to expect that it would not apply to humans, and it may in fact help explain earlier observations that pregnant women experience better recovery from heart injuries than persons in other demographic groups. Also of note:

Previous research has identified fetal stem cells in other damaged organs of pregnant women, including the brain, liver, kidney and lung. Fetuses also produce cells that are known to protect the mother against breast cancer.

Finally, note that fetal stem cells can be harvested from placentas; their use doesn't imply the need for abortions.
 
Via Neatorama.