sciencecenter:

Helpful fetuses donate stem cells to their mother 

This is a pretty astounding finding. Researchers have long discussed the potential for stem cells to be used to replace dead or damaged tissue, but, once again it appears that nature has beaten us to the punch. A team from the Mt Sinai School of Medicine bred male mice whose cells expressed GFP (a fluorescent protein, allowing for the cells to be tracked) and mated them with normal female mice. This meant that the fetus cells, with half of the male’s genetic material, would also be tagged fluorescently. Then the researchers induced a heart attack in half of the female mice. When they checked the heart afterwards, they found lots of glowing green stem cells which had to have been donated by the fetus. Incredibly, some of the cells had even differentiated into, for example, smooth muscle cells responsible for beating. 

Fetal stem cells have already been implicated in helping human mothers heal from heart disease. Hopefully more research along these lines can finally deliver on the promise of stem cells.