Treatment, proliferation, and viability of cultured cord blood-derived megakaryocytes. (A) Treatment plan for CD34⁺-derived human megakaryocytes. The different interventions at different days are indicated by arrows. At days 15 and 16, cells were counted and trypan blue staining was performed to assess viability of the differentiated cells. ICC indicates immunocytochemistry; MoAb IV.3, FcRIIa-blocking monoclonal antibody. (B) The percentage of dead cells on day 16 in the different treatment groups (mean ± SEM; n = 4). Megakaryocytes treated with eptifibatide and patient IgG showed a significantly increased rate of cell death compared with the control experiments (P = .01). This effect was not inhibited by preincubation with the Fc-RIIa-blocking MoAb IV.3 (P = .458). * P < .05. (C) ICC images of cultured megakaryocytes that were stained for GPIIbIIIa (indicated in red) as described in “Immunocytochemistry of cultured cord blood stem cells.” The buffer-treated cells (Ci), the eptifibatide-treated cells (Cii), as well as the cells treated with patient IgG only (Ciii) show intense staining for GPIIbIIIa, whereas eptifibatide + patient IgG (Civ) treated cells show minimal GPIIbIIIa expression. Scale bars represent 10 μm. This figure is representative of 4 independent experiments.