PB0154 - Lyophilized human platelets are superior to apheresis or fresh-drawn platelets in their ability to accelerate thrombin production

Background: Platelet transfusions are used to treat bleeding or prophylactically increase platelet counts in thrombocytopenic patients. Unfortunately, the platelet supply is limited by many logistical challenges and presents a need for additional treatment options. One strategy to combat the danger of platelet shortages are Thrombosomes®, a shelf-stable human platelet derived lyophilized hemostatic (LHP), currently in clinical trials for the treatment of thrombocytopenic bleeding. Direct comparisons of LHP’s hemostatic capabilities compared to apheresis platelet concentrates or fresh platelets needs additional investigation.

Aims: Compare the thrombin generation capacity of LHP to apheresis or fresh-drawn platelets

Methods: Apheresis platelets units (APU) were sourced from a blood center and collected per AABB guidelines. Fresh-drawn platelets were prepared from whole blood and used within four hours. Thrombin generation assay (TGA) using the calibrated automated thrombogram (CAT) or the Thrombodynamics analyzer, were used to determine thrombin generation in the presence of 2,000 LHP/µL or 20,000 LHP/µL versus 20,000/µL apheresis or fresh-drawn platelets initiated by tissue factor in the absence of additional phospholipids.

Results: LHP (2,000/µl) decreased the lag time (0.1 min vs. 0.6 min) and increased the maximum thrombin concentration (176 Units/L vs. 118 Units/L) compared to fresh platelets at 20,000/µl using the Thrombodynamics assay. Likewise, LHP decreased lag time to 6.5 min compared to 10-fold amounts of fresh (9.1 min) or APU (24.7 min) using the TGA method. At equal concentrations, LHP increased the maximum thrombin peak height to 169 nM compared to fresh (80 nM) or apheresis (63 nM).

Conclusion(s): These in vitro results demonstrate that LHP produce a quicker thrombin burst and are more potent at thrombin generation compared to apheresis or fresh platelets. The data suggests that LHP are likely to have equal or better hemostatic benefits relative to APU. Additional in vivo confirmatory experiments are planned.