EVALUATION OF PLATELET SHAPE BY A STOP AND FLOW METHOD USING AGGREGOMETER : Application to Quality Control of Stored Platelet Concentrates

Abstract

EVALUATION OF PLATELET SHAPE BY A STOP AND FLOW METHOD USING AGGREGOMETER: Application to Quality Control of Stored Platelet Concentrates Shiro Ohnoki and Hirotoshi Shibata Department of Research, Osaka Red Cross Blood Center Platelets change from a discoid to a spherical shape during storage or on activation. Discoid platelets show higher transmittance in the flow state than at rest, but spherical platelets do not. We developed a method for evaluation of platelet shape from the transmittance of PRP using this property. A switch for disconnecting the electrical signal to the recorder and speed controller was attached to the platelet aggregometer, such that it was able to determine the transmittance of PRP at desired stirring rates. Transmittance showed maximum increase at the speed of 800 rpm. The content of spherical platelets was expressed by the extinction ratio (E8/E0) of PRP based on light-scattering theory. Extinction was linearly proportional to the concentration of platelets below 3 X 108, /ml. E8/E0 values correlated with the percentage of spherical platelets but were independent of platelet count and extinction of PRP. Fresh PC had an E8/E0 value of 0. 81 ± 0. 02, with this value of increasing gradually with storage time at 22°C with agitation. These findings demonstrated that it is possible to estimate the shape of platelets with a standard aggregometer by determining the transmittance of PRP at rest and flow.