We constructed a first-generation adenovirus vector (AVC3FIX5) that we used to assess the rhesus macaque as a nonhuman primate model for preclinical testing of hemophilia B gene therapy vectors. Although we succeeded in our primary objective of demonstrating expression of human factor IX we encountered numerous toxic side effects that proved to be dose limiting. Following intravenous administration of AVC3FIX5 at doses of 3.4 x 10(11) vector particles/kg to 3.8 x 10(12) vector particles/kg, the animals in our study developed antibodies against human factor IX, and dose-dependent elevations of enzymes specific for liver, muscle, and lung injury. In addition, these animals showed dose-dependent prolongation of clotting times as well as acute, dose-dependent decreases in platelet counts and concomitant elevation of fibrinogen and von Willebrand factor. These abnormalities may be caused by the direct toxic effects of the adenovirus vector itself, or may result indirectly from the accompanying acute inflammatory response marked by elevations in IL-6, a key regulator of the acute inflammatory response. The rhesus macaque may be a useful animal model in which to evaluate mechanisms of adenovirus toxicities that have been encountered during clinical gene therapy trials.

On March 25-26, 2015, the National Heart, Lung, and Blood Institute sponsored a meeting on the State of the Science in Transfusion Medicine on the NIH campus in Bethesda, MD, which was attended by a diverse group of 330 registrants. The meeting's goal was to identify important research questions that could be answered in the next 5-10 years, and which would have the potential to transform the clinical practice of transfusion medicine. These questions could be addressed by basic, translational, and/or clinical research studies and were focused on four areas: the three “classical” transfusion products (i.e., red blood cells, platelets, and plasma) and blood donor issues. Prior to the meeting, four Working Groups, one for each area, prepared five major questions for discussion along with a list of 5-10 additional questions for consideration. At the meeting itself, all of these questions, and others, were discussed in Keynote lectures, small group breakout sessions, and large group sessions with open discourse involving all meeting attendees. In addition to the final lists of questions, provided herein, the meeting attendees identified multiple overarching, cross-cutting themes that addressed issues common to all four areas; the latter are also provided. It is anticipated that addressing these scientific priorities, with careful attention to the overarching themes, will inform funding priorities developed by the NIH and provide a solid research platform for transforming the future practice of transfusion medicine.

The surface expression of prion protein (PrPC) on human platelets, as detected by flow cytometry with the monoclonal antibody 3F4, increased more than two‐fold (4300 v 1800 molecules/platelet) after full activation. Maximal surface expression of PrPC occurred within 3 min of platelet activation and declined to approximately half of maximal levels by 2 h at 37°C. In comparison, PrPC on the surface of platelets, activated at 22°C took 10 min to reach maximum but then remained constant for 2 h. In sonicated resting platelets, PrPC and P‐selectin remained in intact granules after subcellular fractionation. Both glycoproteins were found in the ruptured membranes of activated platelets, suggesting that the PrPC was translocated from internal granules to the plasma membrane during activation, as is P‐selectin. Platelet PrPC was not removed from the surface of platelets by phosphatidylinositol‐specific phospholipase C (PIPLC) treatment but was degraded by proteinase K. Platelets may serve as a useful model for following the cellular processing of PrPC.

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