Objectives: The first aim was the development of a human blood miniature mock-loop system consisting of 2 identical extracorporeal circuits, which enable systematic head-to-head comparisons of test substances. In a second step, we evaluated the suitability of the mock-loop system, by comparing 2 different brands of heparin (ROTEXMEDICA vs B.BRAUN), which have showed different anticoagulation capacities in the clinic.
Methods: For 1 experiment (18 in total), blood of the same healthy human donor was divided into 2 portions (2 × 50 ml), heparinized with 37.5 IU⋅ml-1 of the competing test substances and diluted to a haematocrit value of 20-25%. Each mock loop was filled with 70 ml, and in vivo heparin degradation was simulated in 3 different groups by protamine application, representing 0%, 50% and 100% heparin antagonization. At baseline, 5, 60, 120, 240 and 360 min, blood samples were taken to perform thromboelastometry, flow cytometry, haemolysis and general haemostasis analysis.
Results: Blood pressure, blood flow and blood temperature within the loops remained stable for 6 h in all groups. After 6 h, in the 100% antagonized ROTEXMEDICA heparin group, significantly increased haemolysis (148.7 ± 80 mg⋅dl-1 vs 57.5 ± 15.8 mg⋅dl-1), activated platelets (8 ± 3.8% vs 3.3 ± 0.7%), D-dimers (7376 ± 7144 ng ml-1 vs 576.2 ± 190 ng ml-1) and fulminant blood clots were detected.
Conclusions: Our in vitro system is suitable for the detection of reduced anticoagulation capacity of a test drug, which was reported in vivo previously.