Ex vivo coagulation test on tissue factor-expressing cells with a calibrated automated thrombogram

A calibrated automated thrombogram is not affected by the turbidity of platelet and cell preparations because the measurement is based on fluorescence. To examine conditions that mimic the physiological state, we investigated thrombograms that show thrombin generation on tissue factor (TF)-bearing cells. An increase in the number of J82 cells did not affect the endogenous thrombin potential (ETP) of normal plasma, although the lag time (LT), the peak height, and the time to peak (ttPeak) did depend on cell concentration. When 5 parameters of coagulation factor-deficient plasmas were plotted on a radar graph, the thrombogram pattern of factor XI (FXI)-deficient plasma became slightly reduced. The thrombogram did not improve when washed normal platelets or washed normal platelets with adenosine diphosphate (ADP) were added. FVII-depleted plasma, FVIII-deficient plasma, and FIX-deficient plasma showed remarkably reduced peak heights, ttPeaks, and times to the end of thrombin generation (start tails). The thrombogram of FVII-depleted plasma was characterized by a remarkably prolonged LT, unlike the patterns of FVIII- or FIX-deficient plasma and FXI-depleted plasma. The ETP of FVIII- and FIX-deficient plasma, but not FVII-depleted plasma, improved significantly upon addition of washed normal platelets or washed normal platelets with ADP. The thrombograms of coagulation factor-deficient plasma containing TF-bearing cells differed from those for recombinant TF and phospholipid in the liquid phase. We suggest that thrombograms using TF-bearing cells can be a useful ex vivo test, because this experimental model may be analogous to most coagulation processes in vivo.