Expression of P-selectin on routinely stored or cryopreserved platelets obtained by single donator apheresis

Objective To explore the influence of routine storage or cryopreservation on platelet function. Methods Ten units of platelets were collected by single donator apheresis. Each one was divided into 2 equal parts which were preserved with routine storage and cryopreservation respectively. The samples of platelet were respectively collected on each day during the 5 days' routine storage and before and after 5 days of cryopreservation. The platelet aggregative rate, platelet count and pH value were detected with routine methods. The expression of P selectin on the platelet samples was measured by flow cytometry. Results In routine storage group, the platelet aggregative rate, platelet count and pH value had no change in the 5 days, and the expression of P selectin increased significantly from 3.77±1.86 to 10.87±4.75 ( P 0.01) on the first day of storage and remained higher levels thereafter. In the cryopreservation group, no change was found in the parameters mentioned above, and the expression of P selectin was found to increase significantly from 4.37±1.82 to 16.88±7.23 ( P 0.01) after cryopreservation. Conclusion The expression of P selectin on platelets is found to increase after collection under either the routine storage or cryopreservation, and thus it can be regarded as a sensitive marker for platelet activation.