Comparison of the Activities of Platelets with Different Cryopreservation Methods / 대한혈액학회지

ABSTRACT

BACKGROUND: The limit and the optimal method of the cryopreservation of platelets have not been determined. Moreover, the functional changes platelets after cryopreservation were not clearly defined. This study was conducted to determine the limit and optimal method for cryopreservation of platelet concentrates. METHODS: We compared the recovery, expression of membrane GpIb, GpIIb/IIIa, and aggregatory function of the platelets preserved in three different conditions. Platelet samples were collected from four healthy volunteer donors by apheresis, and placed in 22degrees C agitator for standard preservation. For cryopreservation, after treating 5% DMSO, platelets were either inserted directly in -80degrees C freezer or in liquid nitrogen after computer-controlled rate freezing. After storage for 5 days, 1 week, 2 weeks, 3 weeks, 4 weeks, and 12 weeks, platelets were thawed and analyzed for the evaluation of in vitro functions. RESULTS: Platelets preserved at 22degrees C or cryopreserved with each condition displayed equivalent recovery (90%). With each cryopreservation procedures, platelets showed moderate loss of GpIb and retained more than 90% of GpIIb/IIIa in comparison with fresh platelets. At the third week, loss of GpIb in the directly frozen platelets was augmented compared with those of controlled rate frozen group. The aggregatory response to ristocetin began to decrease drastically after storage for 5 days in platelets frozen by each procedures and to less than 5% at 12 weeks of storage. However, controlled rate frozen platelets retained more aggregatory response to ristocetin and surface GpIb expression than those of directly frozen platelets at 3, 4, 12 weeks of storage. CONCLUSION: This study showed the possibility of moderate preservation of in vitro functions of frozen-thawed platelets after 12 weeks of storage compared with those of the liquid stored 5-day old platelets.