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To develop standardized in vitro thrombogenicity test methods for evaluating medical device materials, three platelet activation biomarkers, beta‐thromboglobulin (β‐TG), platelet factor 4 (PF4), soluble p‐selectin (CD62P), and a plasma coagulation marker, thrombin–antithrombin complex (TAT), were investigated. Whole blood, drawn from six healthy human volunteers into Anticoagulant Citrate Dextrose Solution A was recalcified and heparinized over a concentration range of 0.5–1.5 U/mL. The blood was incubated with test materials with different thrombogenic potentials for 60 min at 37°C, using a 6 cm2/mL material surface area to blood volume ratio. After incubation, the blood platelet count was measured before centrifuging the blood to prepare platelet‐poor plasma (PPP) and platelet‐free plasma (PFP) for enzyme‐linked immunosorbent assay analysis of the biomarkers. The results show that all four markers effectively differentiated the materials with different thrombogenic potentials at heparin concentrations from 1.0 to 1.5 U/mL. When a donor‐specific heparin concentration (determined by activated clotting time) was used, the markers were able to differentiate materials consistently for blood from all the donors. Additionally, using PFP instead of PPP further improved the test method's ability to differentiate the thrombogenic materials from the negative control for β‐TG and TAT. Moreover, the platelet activation markers were able to detect reversible platelet activation induced by adenosine diphosphate (ADP). In summary, all three platelet activation markers (β‐TG, PF4, and CD62P) can distinguish thrombogenic potentials of different materials and detect ADP‐induced reversible platelet activation. Test consistency and sensitivity can be enhanced by using a donor‐specific heparin concentration and PFP. The same test conditions are applicable to the measurement of coagulation marker TAT. [ABSTRACT FROM AUTHOR]

Background Methods Results Conclusion To accommodate a wider range of medical device sizes, a larger in vitro flow loop thrombogenicity test system using 9.5 ‐mm inner diameter (ID) tubing was developed and evaluated based on our previously established 6.4 ‐mm ID tubing system.Four cardiopulmonary bypass roller pumps were used concurrently to drive four flow loops during testing. To ensure that each pump produced a consistent thrombogenic response for the same material under the same test conditions, a novel dynamic roller occlusion setting method was applied. Five materials with varying thrombogenic potentials were tested: polytetrafluoroethylene (PTFE), silicone, 3D‐printed nylon, latex, and nitrile rubber (BUNA). Day‐old bovine blood was heparinized to a donor‐specific concentration and recirculated through the flow loops containing test materials at 20 rpm for 1 h at room temperature. Material thrombogenicity was characterized by measuring the thrombus surface coverage, thrombus weight, and platelet (PLT) count reduction.The larger tubing system can differentiate thrombogenic materials (latex, BUNA) from the thromboresistant PTFE material. Additionally, silicone and the 3D‐printed nylon exhibited an intermediate thrombogenic response with significantly less thrombus surface coverage and PLT count reduction than latex and BUNA but more thrombus surface coverage than PTFE (p < 0.05).The 9.5 ‐mm ID test system can effectively differentiate materials of varying thrombogenic potentials when appropriate pump occlusion settings and donor‐specific anticoagulation are used. This system is being assessed in an interlaboratory study to develop standardized best practices for performing in vitro dynamic thrombogenicity testing of medical devices and materials. [ABSTRACT FROM AUTHOR]

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 cm 2 /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 cm 2 /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 cm 2 /mL exposure ratio) and ACDA blood (6 cm 2 /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 cm 2 /mL. These findings will be used to revise the ASTM F2888 standard in the future., (Published 2024. This article is a U.S. Government work and is in the public domain in the USA.)