Platelet Function Assay

Blood samples were collected in 5-mL tubes containing 0.5 mL 3.2% buffered sodium citrate (0.105M mol/L) (Becton, Dickinson). Assessment of platelet function was performed by Light transmission aggregometry (LTA). The sample tubes were mixed by gentle inversion before analysis. At first, samples were analyzed for platelet count. Then, PRP was obtained by the centrifugation for 10 minutes. Speed of centrifugation was determined according to the baseline platelet count for PRP containing 200- 400 x 10 ⁹/L. Resultant PRP was separated and transferred into polypropylene tubes. Platelet-poor plasma was obtained by the centrifugation of the remaining plasma for 10 minutes at 2499 RCF. Aggregation was measured with a ChronoLog Aggregometer (ChronoLog 700 model, USA) after stimulation with 5 µM of adenosine diphosphate (ADP), 5 µM arachidonic acid (AA), and 0.5 µg/mL collagen (COL). All agonists were provided from Hyphen-biomed (Neuville sur Oise, France). Aggregation curves were recorded after 10 minutes and the percentage (%) of maximal aggregation was reported. According to the recommendation of Hyphen biomed company, we calculated and established the reference value with normal samples for our laboratory. The reference values for healthy adults were 64-96 % for ADP- induced aggregation, 73-100% for AA-induced aggregation, and 78-100% for COL-induced aggregation.