Electrokinetic properties of human cryopreserved platelets

A method for the cryopreservation of human platelets with glycerol/glucose is described which was a simplified modification of the method of Dayian and Pert (1979). The effect of cryoinjury of the platelet surface membrane was investigated by studying the surface electrokinetic properties of the platelet. A significant increase in platelet electrophoretic mobility was found after cryopreservation. The fresh platelets had a mean electrophoretic mobility of 1.04 +/- 0.05 microns s-1 V-1 cm-1 and cryopreserved platelets 1.18 +/- 0.05 microns s-1 V-1 cm-1, P < 0.05. However, the total platelet sialic acid of fresh platelets was 62.5 +/- 5.6 nmol 10(-9) platelets compared to 47.2 +/- 4.6 nmol 10(-9) platelets after cryopreservation, P < 0.001. Similarly, the neuraminidase-labile sialic acid was 26.4 +/- 4.3 nmol 10(-9) platelets for fresh platelets and 17.6 +/- 4.0 nmol 10(-9) platelets after cryopreservation, P < 0.001. Using polyacrylamide gel electrophoresis with Western blotting, we showed a reduction in the platelet glycoprotein Gp Ib after cryopreservation, this was confirmed by using crossed immunoelectrophoresis. Electron microscopy revealed a significant change in platelet morphology after the cryopreservation procedure with disruption of the platelet membrane and also platelet shape change. These features may explain the changes in platelet electrokinetic properties.