Analysis of ex vivo platelet release by Mks differentiated from adult human peripheral blood hematopoietic progenitors. (A) Confocal microscopy imaging of Mks from 1 healthy control and 2 patients within the silk-based bone marrow system. (Ai-Aiii) Imaging of mature Mks immediately after seeding into the silk sponge (green = CD61; blue = nuclei; scale bar = 50 μm). (Aiv-Avi) Mks forming proplatelet through the silk microtube wall (green = CD61; blue = nuclei; scale bar = 50 μm). Arrows indicate proplatelet branching and elongation. Silk fibroin 3D scaffolds were stained with Hoechst 33258 and visualized in blue. (B) Flow cytometry analysis of ex vivo-produced platelets. Samples were mixed with counting beads to quantify the number of CD61⁺CD42b⁺ platelets. (C) Comparison of platelet count between in vivo and ex vivo quantified numbers.