Megakaryocytic YAP1 facilitates thrombopoiesis during ITP development. (A) Sketch map of BMT mouse model. (B) Changes in peripheral platelet levels in mice with anti-CD41 antibody administration after BMT recovery (n ≥ 5). (C) Confocal images of BM sections from transplanted WT and YAP1^+/− mice after immunostaining for YAP1 (green, YAP1), vascular sinusoids (yellow, laminin A), and MKs (red, CD41). Scale bar, 100 μm (n ≥ 10). Analysis of the number of MKs in the field (top) and the number of MKs located around the sinusoids (bottom; n ≥ 10). (D) Confocal images of BM MKs from WT and YAP1^+/− mice after immunostaining for YAP1 (green, YAP1), F-actin (yellow, phalloidin), and MKs (red, CD41) and proplatelet formation were observed. Scale bar, 20 μm. (E) Sketch map of optimized BMT model. (F) Changes in the peripheral platelet levels in mice after optimized BMT. (G) Confocal images of BM sections from different groups of mice after immunostaining for YAP1 (green, YAP1) and MKs (red, CD41). Scale bar, 100 μm. Analysis of MK numbers (top) and number of MKs located around the sinusoids (bottom; n ≥ 10). ∗P < .05; ∗∗P < .01; ∗∗∗P < .001; ∗∗∗∗P < .0001. D, donor; MNC, mononuclear cell; R, recipient; W3, WT D3-MK; W8, WT D8-MK; W H, WT HSC; Y 3, YAP1^+/− D3-MK; Y 8, YAP1^+/− D3-MK; Y H, YAP1^+/− HSC.