1992 Volume 38 Pages 42-47
Although cryopreservation of platelets has been attempted for two decades, the recovery, survival in vitro function and clinical efficiency is still not satisfactory. To investigate the difficulty of cryopreserving platelets while retaining full function, we analyzed glycoproteins (GP), such as GP Ib, GP Ilb/IIIa and GP IV on frozen-thawed or osmotically stressed platelet membranes by monoclonal antibodies and flow cytometry. Cellular functions such as platelet aggregation induced by ADP, collagen and ristocetin and %HSR, etc., were also analyzed. Platelets loaded with 5% Me_2SO were frozen extracellularly to -80℃ at 2℃/min and thawed rapidly in a 37℃ water bath. The Me_2SO was removed and the expression of GP was analyzed. There was no change of expression of GP IIb/IIIa or GP IV but GP Ib was lost from about half of the population. Frozen platelets also showed about a 50% loss of ristocetin-induced platelet aggregation. Platelets frozen without Me_2SO lost GP Ib completely. Platelets osmotically stressed with plasma made hyperosmotic by addition of NaCl and resuspended in plasma were also anylyzed for GP. Again, only GP Ib was lost at osmotic stress greater than 1000mOsm/kg. Thus, GP I b is easily shed from stressed platelet membranes and may be an important reason for the difficulty in cryopreservation.
