Studies of released human platelets, agonist responsiveness, and hemostatic efficacy. (A) Flow cytometric studies of removed murine blood at 2 hours after infusion of donor-derived platelets or uninfected, shNT-, or shRX-megakaryocytes into NSG mice for P-selectin level analysis after activation with various concentrations of TRAP. Mean ± 1 SD is shown. N = 3 per arm. ∗P ≤ .05 by 1-way ANOVA comparing shNT-platelets released vs shRX-platelets. (B) Schematic of the Rose Bengal photochemical carotid artery thrombotic challenge with NSG/VWF^R1326H mice and infused human megakaryocytes or platelets. (C) Same as in panel A except that NSG mice were studied as a hemostatic control because the untreated NSG/VWF^R1326H mice had a hemostatic defect. Studies were done 4 hours after infusion of human platelets or megakaryocytes. Mean ± 1 is shown for residual blood flow after carotid artery injury. N = 4 to 6 animals per arm. ∗∗P ≤ .01, ∗∗∗P ≤ .001, and not significant (ns) by 1-way ANOVA. AUC, area under the curve.