MODIFIED TECHNIQUE FOR MEASURING PLATELET-AGGREGATION

The turbidimetric method of Born is the current approach for assessing the aggregation behavior of platelets. It has been of modest practica l value, due to difficulty in standardizing laboratory techniques for plasma preparation and inadequate quantification of the aggregation pr ocess. We report a new technique of sedimented platelet rich plasma (S PRP) preparation that reduces the irregularities caused by factors ass ociated with procuring and preparing blood samples and permits a more flexible protocol for laboratory practice. We quantified results with a platelet aggregation score, which is calculated by multiplying the r atio of the height of the initial wave of aggregation to the maximum h eight of the aggregation pattern by the total area under the aggregati on curve and by the ratio of the whole blood platelet count and the nu mber of platelets in the sample. Comparative analysis of platelet aggr egation scores (n = 95) obtained with both plasma preparation techniqu es using a paired t test demonstrated no statistical differences (t = 1.368, p = 0.174). To demonstrate the application of this modified met hod to evaluation of antiplatelet agents, the effects of aspirin and a spirin combined with citric acid on platelet aggregation were studied in vitro. The antiaggregatory effect of aspirin combined with citric a cid was dependent on the pH and on their molar ratio, and was greater than the effect of aspirin alone. The SPRP protocol with platelet aggr egation scoring methodology could be a valid alternative for measureme nt of the platelets' propensity to aggregate and the effect of antithr ombotic treatments.