An elegant system to derive blood cell precursors from human pluripotent stem cells (hPSC) has now been developed by researchers. This type of stem cell has the potential to develop into many different kinds of cells in the body, and is capable of participating in organ repair and function. These qualities have prompted scientists to test the use of hPSC to treat some diseases. However, the development of a fully defined system to generate functional blood cell precursors has proven to be a significant challenge.