An in vitro method for screening anti-platelet agents using a microchannel array flow analyzer.

New in vitro methods are desirable for the analysis of platelet aggregation and screening novel anti-platelet agents using whole blood. To this end, we examined platelet aggregation and thrombus formation in whole human blood from healthy volunteers using a microchannel array flow analyzer (MC-FAN). Platelet aggregation in whole blood, treated with the activating agents ADP, collagen or ristocetin was detected in the MC-FAN by measuring the decrease in flow rate as a function of agent concentration. The results were compared with aggregation in platelet rich plasma (PRP) in a conventional aggregometer, as measured by the increase in optical density. The MC-FAN detected platelet aggregation in whole blood at two- to four-fold lower concentrations of agonist compared to those in PRP in the aggregometer. Anti-platelet agents attenuated the decrease in blood flow rate in the MC-FAN by inhibiting fibrin formation and platelet aggregation, but anticoagulants only inhibited fibrin formation and did not affect blood flow rates. These findings suggest that the MC-FAN system may be a useful method for the evaluation of platelet activation and facilitate the development of novel anti-platelet agents.