Cardiomyocytes damaged by a heart attack.
As it turns out, nature has its own method for transplanting stem cells. When a pregnant mouse has a heart attack, her fetus goes to work to help repair the damage! The experiment mated female lab mice with males who had the genes to produce green fluorescent protein (GFP). Around half the embryos produced also had the ability to produce the protein. This way, scientists could track fetal cells separately from maternal cells. Then heart attacks were induced in the pregnant mice…
When the scientists examined the female mice’s heart tissue two weeks after the heart attacks, they found lots of glowing green tissue—cells that came from the fetus—in the mom’s heart. Mice who had heart attacks had eight times as many cells from the fetus in their hearts as mice who hadn’t had a heart attack did, meaning the high volume of fetal cells was a response to the heart attack.
What’s more, the embryo’s stem cells had differentiated into various types of heart tissue, including cardiomyocytes, the rhythmically contracting muscle cells that produce a heartbeat.
Doctors have observed that women who experience weakness of the heart during pregnancy or shortly after giving birth have better recovery rates than any other group of heart failure patients. This study suggests that fetal stem cells may help human mothers, as well as mice, recover from heart damage. It may also explain another curious clinical observation: The hearts of two women who suffered from severe heart weakness were later found to contain cells derived from the cells of a male fetus years after they gave birth to their sons.