Turbulence is a critical physical factor that promotes the large-scale production of functional platelets from human induced pluripotent stem cells (hiPSCs), researchers in Japan report July 12 in the journal Cell. Exposure to turbulent energy in a bioreactor stimulated hiPSC-derived bone marrow cells called megakaryocytes to produce 100 billion platelets—blood cell fragments that help wounds heal and prevent bleeding by forming blood clots. Moreover, transfusion of these platelets in two animal models promoted blood clotting and prevented bleeding just as well as human donor platelets.