Currently, several platelet additive solutions for long-term platelet storage have been introduced. The aim of this study was to compare the deterioration of functional status of platelets stored for up to 5 days in autologous plasma (AP) only, with platelet stored in PAS-2, a salt solution containing acetate, citrate and sodium chloride. Change in platelet adhesion, aggregation and activation was measured by flow cytometric technique. In addition, beta-Thromboglobulin (beta-TG), lactate and glucose were determined. After 5 days of storage, the expression of P-Selectin was significantly higher, the production of lactate and the consumption of glucose were significantly lower, in platelets stored in PAS-2 than in autologous plasma. No significant differences were detected on day 5 between the two groups with regard to fibrinogen, von Willebrand factor binding capacity, or to beta-TG release. It can be concluded that neither storage medium was consistently better for the parameters tested. However, it must be emphasized that platelets stored in autologous plasma exhibited less lesion, in terms of P-Selectin expression compared with platelets stored in PAS-2.

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Platelets and leucocytes are important effector cells of the haemostatic and inflammatory responses to tissue injury. To investigate the effects of surgical trauma on platelet activation (assessed by measuring levels of P-selectin and beta-thromboglobulin), leucocyte activation (CD11b expression) and leucocyte-platelet interactions (leucocyte-platelet complexes), 30 patients undergoing primary hip arthroplasty were studied before and at the end of surgery, and on days 1 and 10 post-operatively, using a whole-blood flow cytometry assay. The inflammatory response was followed by measurement of the levels of C-reactive protein and interleukin-6 in plasma, and the activation of coagulation was monitored by determination of prothrombin fragment 1+2 levels. On day 1 post-operatively a significantly increased expression of CD11b on monocytes was noted, but no direct correlation was found between monocyte activation and interleukin-6 production or C-reactive protein at this time point. The percentage of monocyte-platelet and neutrophil-platelet complexes was markedly increased on day 10 post-operatively compared with pre-operative levels, and levels of these complexes were significantly positively correlated with beta-thromboglobulin levels. Activation of coagulation (prothrombin fragment 1+2) on day 10 post-operatively was positively correlated with the extent of surgical trauma (duration of surgery, amount of blood loss) and with the increase in platelet activation (beta-thromboglobulin). In conclusion, hip arthroplasty induces platelet and coagulation activation, and also an inflammatory response that is maintained for more than 10 days post-operatively. This indicates an interaction between the immune and the haemostatic systems in the post-operative phase after hip arthroplasty.

Rapid and relevant evaluation of platelet function is often clinically important. By means of fluorescent labelled chicken antibodies (which do not bind to Fc-receptors) against fibrinogen and von Willebrand factor and flow cytometry, we have determined the time course of ligand association to platelets after stimulation with adenosine 5'-diphosphate and ristocetin respectively. The expression of guanosine 5'-phosphate (GMP)-140 was also measured. We have applied this technique to evaluate platelet function during platelet storage and cardiopulmonary bypass. There was a significant reduction of the binding of fibrinogen and von Willebrand factor and significantly increased expression of GMP-140 after 9 days of storage. Changes in metabolic variables such as lactate accumulation, glucose consumption and decrease in pH confirm that the functional impairment is due to a large extent to a deteriorated platelet metabolism. No significant differences were found between samples taken before and during cardiopulmonary bypass, but there was a tendency towards increased ligand binding as well as increased expression of GMP-140 at the end of cardiopulmonary bypass. The flow cytometric technique that is described may be useful for evaluation of platelet function and platelet activation in vivo.

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