ASCL-PLT production from ASCL-MKs. (A) Number of platelets, as assessed by CD42b+/anucleate platelet-sized cells, produced from 1 × 108 ASCL cells on days 4, 12, and 20. (B) Expression of VWF, β-1 tubulin, PF4, and serotonin in ASCL-PLTs cultured in MKLI media for 12 days. Cells were stained with antibody for CD42b (red), for DAPI (blue), and for VWF, β-1 tubulin, PF4, or serotonin (green). DAPI-stained nuclei were not observed. Scale bars, 2 μm. (C) ASCL-PLTs spreading on fibrinogen-coated glass upon stimulation. Scale bars, 10 μm. (D) Electron microscopic images of produced platelets. Scale bar, 2 μm. (E) Surface marker expression for ASCL-PLTs on day 12 and peripheral platelets. (F) Surface expression of CD42b and CD90 on ASCL-PLTs on day 12. G, granule; M, mitochondrion; OCS, open canalicular system.