A Murine Model Of Hemorrhagic Shock/Resuscitation Demonstrates Transfusion Related Acute Lung Injury (TRALI) Induced By Stored Platelet Transfusions

Transfusion related acute lung injury (TRALI) is one of the leading causes of transfusion fatalities. There have been several animal models of TRALI developed including ex vivo lung models demonstrating the importance of human anti-neutrophil antibodies in TRALI and in vivo transfusion models showing how biological response modifiers can induce recipient lung damage. In addition, an in vivo antibody-mediated TRALI model has also been established and has shown close similarities with human TRALI. Most of the animal models have a two-hit paradigm where the first hit is delivered in the form of a noxious substance such as lipopolysaccharide and the second hit is a transfusion of either a blood product or an antibody. Here we describe a novel clinically relevant two-hit model where the first hit is hemorrhagic shock followed by a second hit in the form of a platelet transfusion. Severe combined immunodeficient (SCID) mice were anesthetized and had half of their total blood volume was removed via a carotid cannula to instigate hypovolemic shock. After one hour of shock, the mice were reperfused with either Ringer’s lactate solution or fresh or three day aged platelets. 34-1-2s, a monoclonal anti-mouse MHC class I antibody known to induce TRALI was used as a positive reperfusion control. Two hours following reperfusion, the mice were sacrificed and blood was obtained via cardiac puncture in order to measure serum levels of the neutrophil chemoattractant macrophage inflammatory protein-2 (MIP-2). Lungs were removed to determine the percentage of accumulated neutrophils and to measure edema. Compared with control mice reperfused with Ringer’s lactate solution or mice administered fresh platelets, serum MIP-2 levels in mice administered with three day aged platelets were significantly elevated and were comparable to those observed in mice infused with 34-1-2s. Pulmonary neutrophil accumulation in the mice transfused with 3 day stored platelets was also elevated to levels observed in 34-1-2s treated mice. Pulmonary edema as measured by lung Wet/Dry ratios was elevated in mice receiving the 3 day aged platelets. In vivo administration of a MIP-2 antagonist (SB225002, 4mg/kg) intraperitoneally immediately before reperfusion significantly reduced all TRALI symptoms. These results show that an animal model of hypovolemic shock exhibits TRALI upon reperfusion with stored platelets and is dependent on MIP-2 production. This clinically-relevant model will be valuable in studying potential therapeutic interventions to prevent TRALI following transfusions,