Irving Weissman directs Stanford University's Stem Cell Biology and Regenerative Medicine Institute in California. His laboratory was the first to identify and isolate blood-forming stem cells from mice. He has developed techniques to track haematopoietic stem cells and their progeny and used both to study the development of healthy blood and immune systems as well as the progression of malignancies like leukaemia. This summer, he became the seventh president of the International Society for Stem Cell Research (ISSCR).