Human iPSC platelets circulate in NOG mice and adhere to vessel during thrombus formation in vivo. (A) NOG (nod-scid/IL-2 γc-null) mice were irradiated (2.0 Gy) to induce thrombocytopenia. 9 d later, human iPSC platelets, human PB-derived platelets (107), or PBS alone was injected via the tail vein. Platelet chimerism was quantified by flow cytometry. Representative dot plots for the same experiment are shown. Circulation of injected platelets was evaluated after 2 and 24 h (orange squares). Experiments were independently performed three times. (B) Sequential images of circulating iPSC platelets. A combination of FITC-dextran (green) and 107 TMRE-stained iPSC platelets (red) in PBS was injected via the tail vein into NOG mice. Mesenteric capillaries were visualized using a confocal laser-scanning microscope. Red arrows indicate circulating iPSC platelets in vivo. Original videos are available as Video 2. (C) Representative sequential images of thrombus formation by iPSC platelets in a blood vessel. Hematoporphyrin was administrated to induce thrombus formation after laser-induced injury, as described previously (Nishimura et al., 2008; Takizawa et al., 2010). Red arrows indicate iPSC platelets in a developing thrombus. White arrows indicate host (mouse) platelets. Original videos are available as Videos 3–5. Experiments were independently performed three times. Bars, 10 µm.
