stem_blood_cells.jpg People usually require blood transfusions that match their own blood type: A mismatch can be fatal. Yet type O-negative can be safely transferred into anyone — but it is only possessed by 7 percent of the population, leaving supplies perpetually short. Now, scientists have used stem cells to generate blood — a feat that could eventually lead to endless supplies of type O-negative blood. (The UK Sun has full report)

Stem Blood Cells image on WikiMedia Commons