Q 1991 zyxw S. zyxw Karger AG. Basel Vox Sang 1991;60:1622 zyxwvutsrq 0042-9007/9Y0601-0016 $2.75/0 In vitro Evaluation of Bum-Coat-Derived Platelet Concentrates Stored in a Synthetic Medium' zyxw R. Fijnheer, H . A . Veldman, A . J. M. van den Eertwegh, C. W. N. Gouwerok, C. H. E. Homburg, M. N. Boomgaard, D. de Korte, D. Roos Central Laboratory of the Netherlands Red Cross Blood Transfusion Service and Laboratory for Experimental and Clinical Immunology of the University of Amsterdam, The Netherlands Abstract. Human blood platelets, prepared by the buffy-coat method, were prepared and stored in different synthetic media. In a synthetic medium based on gluconate, acetate and citrate (GAC), the pH was 6.8 on day 6. This medium was chosen for further evaluation. The total platelet count and the leukocyte contamination were significantly lower in the platelet concentrates (PCs) prepared in GAC compared to PCs prepared in plasma. Platelets stored in plasma or in GAC were equally functional when tested for aggregation and adenosine triphosphate (ATP) secretion. Only stimuli that act through the arachidonic-acid pathway induced a lower platelet response in GAC. Platelet morphology was quantified by measuring the difference in light transmission during stirring at different rates in an aggregometer; no significant differences for platelets stored in GAC as compared to plasma were observed. Activation of platelets was measured by binding of monoclonal antibodies (McAb) against the Gp IIbAIIa complex and against activation-dependent antigens (GMP 140 from the a-granules and a 53-kD glycoprotein from the lysosomal granules). There was no difference in binding of these McAb between platelets prepared and stored in plasma or GAC. We conclude that platelets prepared by the buffy-coat method and stored in GAC have the same in vitro qualitities as platelets stored in plasma, except for the lower aggregation response by the archidonic-acid pathway, This is probably due to an acetate-induced decrease in intracellular pH. Introduction Numerous reports [l-31 have demonstrated a progres- sive decline in platelet function during storage. We and others have shown the activation of platelets [4], change in platelet morphology zyxwvutsr [5], alteration in contractile proteins [6] and depletion of adenosine triphosphate (ATP) during storage [7]. Reports that platelet concentrates (PCs) can be stored in synthetic media [ a l l ] led us to compare the ef- fects of storage on platelets in several media with those in plasma. Platelets were prepared by the buffy-coat method [12, 131. This method of PC preparation has several advantages: leukocyte-poor platelets are obtained and early platelet ' Supported by the Netherlands Laboratory for the Production of Blood Transfusion Equipment and Infusion Fluids, Emmer-Compascu- um, The Netherlands, and the Ministry of Economic Affairs, The Netherlands. activation is prevented because the platelets concentrated in the buffy coat have been sedimented on a cushion of red cells [14]. The prevention of platelet activation is important for the function in vivo after transfusion. First, activation induces a change in morphology from disc to sphere, and platelet morphology is associated with the viability of plate- lets after transfusion [l]. Second, platelets lose their dense granules when activated, and their constituents are impor- tant for platelet function [15]. After centrifugation of the blood, not more than 10-15ml of plasma was left on the buffy-coat layer. Subsequently, the buffy coat was pressed in a satellite bag, and 60ml of the synthetic medium or plasma was added under sterile conditions. To obtain a medium that prevents or reduces a decrease in pH during PC storage, and thus prevents irreversible loss of platelet function, we first studied several media. A medi- um containing gluconate, acetate and citrate (GAC) showed a pH of 6.8 on day 6 of storage and was further evaluated.