Quality of harvested autologous platelets compared with stored donor platelets for use after cardiopulmonary bypass procedures

Platelet dysfunction has a major contribution in bleeding after cardiopulmo nary bypass (CPB) and transfusion of platelets is frequently used to secure haemostasis. Allogeneic platelets prepared for transfusion are functionall y impaired. Autologous platelets harvested preoperatively require a shorter storage time before transfusion and their use also avoids the risks associ ated with transfusion of allogeneic blood products. For the first time, we have compared the functional quality of autologous platelets with allogenei c platelets prepared by two methods, immediately before infusion. Platelet activation was assessed by P-selectin expression and fibrinogen binding usi ng flow cytometry. We also monitored the effects of CPB surgery and re-infu sion of autologous platelets on platelet function. Autologous platelet-rich plasma (PRP) contained a significantly lower (P < 0.05) percentage of P-se lectin-positive and fibrinogen-positive platelets compared with allogeneic platelet preparations, and also contained a significantly higher (P < 0.05) percentage of responsive platelets. Allogeneic platelets prepared by donor apheresis were more activated and less responsive than those produced by c entrifugation of whole blood. In patients' blood, the percentage of platele ts expressing P-selectin or binding fibrinogen increased significantly afte r CPB (P < 0.05), while the percentage of platelets responsive to in vitro agonists was decreased (P < 0.05 in autologous transfusion patients), consi stent with platelet activation during the procedure. The percentage of acti vated platelets decreased (statistically not significant) after re-infusion of autologous PRP. P-selectin expression had returned to pre-CPB levels 24 h post-operatively. Autologous platelet preparations display minimal activ ation, but remain responsive. Conservation of platelet function may contrib ute to the potential clinical benefits of autologous transfusion in cardiop ulmonary bypass.