Inhibition of RHOA activity preserves the survival and hemostasis function of long-term cold stored platelets.

Thrombocytopenic patients require platelet transfusion to prevent and stop hemorrhage. Cold storage of platelets results in complex molecular lesions including changes in membrane microdomains that are recognized by host macrophages and hepatocyte counter-receptors, resulting in phagocytosis and clearance upon transfusion. For this reason, platelets are stored at room temperature, a method that confers increased risk of bacterial contamination. By applying signaling analysis as well as genetic and pharmacological approaches, we identified that the cold induced activation of RHOA GTPase is causal for the major hallmarks of platelet cold storage lesions. RHOA deficiency renders murine platelets insensitive to cold storage induced damage, and pharmacological inhibition by a RHOA activation inhibitor, R-G04, can prevent the cold storage induced lesions. RHOA inhibition prevents myosin activation and clathrin-independent formation and internalization of lipid rafts enriched in active glycosyltransferases as well as abnormal distribution of GpIb. RHOA inhibition further prevents the metabolic reprogramming of cold induced storage lesions and allows the maintenance of glycolytic flux and mitochondrial dependent respiration. Importantly, human platelets transfused in mice after cold storage, in the presence of R-G04 or its more potent enantiomer S-G04, can circulate in vivo at similar levels as room-temperature stored platelets while retaining their hemostatic activity in vivo as assessed by bleeding time correction of aspirin-treated mice. Our studies provide a new mechanism based translational venue to prevent cold storage induced damage useful for human platelet transfusion in thrombocytopenic patients.