Fibrinogen γ-chain peptide-coated, adenosine 5′-diphosphate (ADP)-encapsulated liposomes (H12-ADP-liposomes) are potent hemostatic adjuvants that promote platelet thrombi formation at bleeding sites. Although we have reported the efficacy of these liposomes in a rabbit model of cardiopulmonary bypass coagulopathy, we are yet to address the possibility of their hypercoagulative potential, especially in human beings.

Considering its future clinical applications, we herein investigated the safety of using H12-ADP-liposomes in vitro using blood samples from patients who had received platelet transfusion after cardiopulmonary bypass surgeries.

Ten patients receiving platelet transfusions after cardiopulmonary bypass surgery were enrolled. Blood samples were collected at the following 3 points: at the time of incision, at the end of the cardiopulmonary bypass, and immediately after platelet transfusion. After incubating the samples with H12-ADP-liposomes or phosphate-buffered saline (PBS, as a control), blood coagulation, platelet activation, and platelet-leukocyte aggregate formation were evaluated.

Patients’ blood incubated with H12-ADP-liposomes did not differ from that incubated with PBS in coagulation ability, degree of platelet activation, and platelet-leukocyte aggregation at any of the time points.

H12-ADP-liposomes did not cause abnormal coagulation, platelet activation, or platelet-leukocyte aggregation in the blood of patients who received platelet transfusion after a cardiopulmonary bypass. These results suggest that H12-ADP-liposomes could likely be safely used in these patients, providing hemostasis at the bleeding sites without causing considerable adverse reactions. Future studies are needed to ensure robust safety in human beings.