Alternative Anticoagulant Strategy to Improve the Test Sensitivity of ASTM F2888-19 Standard for Platelet and Leukocyte Count Assay

The ASTM F2888-19 standard for platelet and leukocyte count assay is the only standardized test method for assessing platelet and leukocyte interactions with blood-contacting device materials. This study aimed to address two limitations of the ASTM F2888-19 standard: low test sensitivity for leukocyte count and high test sample surface area to blood ratio (12 cm²/mL). Human blood from healthy adult donors was drawn into polypropylene tubes with either 3.2% sodium (Na) citrate or anticoagulant citrate dextrose solution A (ACDA). Immediately before starting the test, the blood was recalcified and heparinized to a concentration of 1, 1.5, or 2 U/mL and incubated with the test materials of varying thrombogenic potential at an exposure ratio of 6 or 12 cm²/mL for 1 h at 37°C ± 2°C in a shaking water bath. Complete blood count was measured using a hematology analyzer. The results show that both, Na-citrated blood (6 or 12 cm²/mL exposure ratio) and ACDA blood (6 cm²/mL ratio), were able to differentiate thrombogenic materials from commonly used biomaterials based on platelet count changes. The magnitudes of difference between the thrombogenic materials and biomaterials depends on heparin concentration. The test sensitivity was highest when ACDA blood, heparinized to 1 U/mL heparin, was used. Moreover, the use of ACDA blood, unlike Na-citrated blood, also allowed the assay to distinguish between the thrombogenic materials from commonly used biomaterials based on leukocyte count changes. In conclusion, the use of ACDA blood significantly increased test sensitivity of the ASTM F2888-19 test method in differentiating materials with varying thrombogenicity based on both platelet and leukocyte counts, while reducing blood exposure ratio to 6 cm²/mL. These findings will be used to revise the ASTM F2888 standard in the future.