Pre-activated lyophilized platelets show non-inferior hemostatic effect compared with fresh platelets in rabbits with traumatic bleeding and shock

A high activation level is a normal characteristic of lyophilized platelets (LPs); however, the effects of this activation level on the efficacy and safety of LPs after transfusion are debated. We aimed to test the efficacy and safety of pre-activated LPs (PLPs) in rabbits with traumatic bleeding and shock. In vitro characteristics of PLPs, including activation level, aggregation, migration, and thromboelastography parameters, were evaluated. Limb soft tissue injury accompanied by seawater immersion and controlled hemorrhagic shock was induced in 50 rabbits, which were then divided into five groups: A (no resuscitation), B (resuscitation with Lactated Ringer’s solution, LR), C (resuscitation with LR and fresh platelets), D (resuscitation with LR and LPs), and E (resuscitation with LR and PLPs pre-activated by thrombin). Blood loss, platelet count, blood urea nitrogen and lactic acid concentrations, and in vivo thromboelastography R value and maximum amplitude were recorded. Biotin-X-N-hydroxysuccinimide labeling and flow cytometry were used to measure the number of infused platelets left in circulation. Histology was used to assess whether aberrant thrombi were formed in the kidney, lung, or liver. PLPs exhibited an increased P-selectin level, enhanced aggregation, and shortened R values, with no obvious changes in migration ability or maximum amplitude. PLPs transfusion had a non-inferior effect on all in vivo parameters compared with fresh platelet transfusion, and the circulation time of PLPs was much shorter than that of fresh platelets. No obvious thrombi were found. PLPs transfusion demonstrated non-inferior efficacy and safety compared with fresh platelet transfusion. What is the context? Platelets are a key component in hemostasis. Fresh platelets are commonly used in hemostatic therapy; however, they have a short storage time—only five days at room temperature. Although platelet storage time can be extended by freezing, this makes transportation inconvenient. Lyophilized platelets are more convenient as they can be stored at room temperature; however, concerns exist regarding their efficacy and safety after activation. What is new? We compared pre-activated lyophilized platelets with fresh platelets in animal experiments simulating severe trauma and blood loss. Pre-activated lyophilized platelets demonstrated non-inferior efficacy to fresh platelets in reducing blood loss, improving hematological parameters, and enhancing coagulation function. No obvious thrombi were found in the kidneys, lungs, or livers of animals that received pre-activated lyophilized platelets, ordinary lyophilized platelets, or fresh platelets. The circulation time of pre-activated lyophilized platelets in vivo was significantly shorter. The pre-activation treatment enhanced the aggregation ability of lyophilized platelets, helping to initiate the coagulation process more quickly. What is the impact? The study demonstrates that pre-activated lyophilized platelets are not inferior to fresh platelets in terms of hemostatic efficacy. Furthermore, no significant thromboembolic risk was observed in this study. These findings provide compelling supporting evidence for the development of “standby” platelet products that are easier to store and transport, which may address some of the challenges associated with the clinical use of fresh platelets.