Characterisation and reproducibility of a human ex vivo model of thrombosis

BackgroundThe Badimon chamber is a clinical ex vivo model of thrombosis that mimics flow conditions within the coronary circulation of man. The aims of this study were to characterise thrombus formation in the chamber and evaluate its reproducibility.MethodsUsing blood from 24 healthy human volunteers, thrombus formation was assessed at low and high shear rates with porcine aortic tunica media as the thrombogenic substrate. Thrombus area was measured histomorphometrically. Reproducibility was assessed by paired measurements made both within and between days. Platelet activation was assessed before and at selected points within the extracorporeal circuit using flow cytometry, and fibrin content and distribution within the thrombus were assessed by immunohistochemistry.ResultsTotal thrombus area was highly reproducible within and between days in the low shear ([mean thrombus area, mean difference ± SEM] 8,018 μm2, 58 ± 204 μm2 and 8,177 μm2, -154 ± 168 μm2 respectively) and high shear chambers (11,802 μm2, -52 ± 175 μm2 and 11,877 μm2, 220 ± 181 μm2 respectively). Total thrombus area was greater in the high compared to the low shear chamber (11,970 ± 285 μm2versus 7,892 ± 298 μm2; P < 0.0001). Transit through the extracorporeal circuit did not result in platelet activation which was only detected after blood passed across the perfusion chambers (P = 0.02 for platelet-monocyte aggregate formation and P = 0.05 for P-selectin expression). Thrombus in the low shear chamber contained a greater proportion of fibrin (25.0 ± 6.0% versus 8.3 ± 1.6%, P < 0.001).ConclusionsThe Badimon chamber provides a highly reproducible technique for the assessment of ex vivo platelet-rich thrombus formation in man.