Japanese scientists have found that menstrual blood can be used to repair heart damage.

Scientists gathered cells called mesenchymal cells (MMCs) from menstrual blood donated by nine women and cultivated it for about a month. After the cells were put together in a culture with cells from the hearts of rats, about 20 percent of the cells began beating spontaneously and eventually formed sheets of heart muscle tissue.

The success rate was 100 times higher than the 0.2 percent rate for stem cells taken from human bone marrow.

Another set of experiments showed that live rats that had suffered heart attacks improved after being implanted with the MMCs.