Clinical trial assured safety and circulation of autologous iPSC-PLTs. (A) Clinical course of the participant from the onset of aplastic anemia. Institutional review board (IRB) approval by Kyoto University was received to establish the imMKCLs and produce the iPSC-PLTs. Then, the clinical trial for administering the iPSC-PLTs was approved by Kyoto University and by the Ministry of Health, Labour and Welfare, Japan, based on the Act on Safety of Regenerative Medicine. (B) iPSC-PLTs were administered in a dose-escalating manner in 3 dose cohorts: 0.5, 1.5, and 5 Japanese units, which correspond to 0.1 × 10¹¹, 0.3 × 10¹¹, and 1.0 × 10¹¹ platelets, respectively. No significant adverse event was observed. (C) Peripheral blood platelet count and D-dimer of the patient collected preinfusion on days 1 (D1, 1 hour after transfusion), 2, 3, and 14 for the 3 dose cohorts are shown. (D) Flow cytometry analysis of the patient peripheral blood PLT fraction in cohort 3. (i) An overlaid histogram of the forward scatter (FSC-A) of iPSC-PLTs before infusion (iPSC-PLT) and peripheral blood platelets on days 1 and 14. (ii) Percentage of the gated large PLT fraction on days 1, 2, 3, and 14 of the iPSC-PLT transfusion. Average of triplicates with standard deviation are shown. (iii) Representative scatter plots of the FSC-A and side scatters (SSC-A) with gating of the large platelet fraction on days 1 and 14.