High cell count prevents presence of zymogen inhibition in a TF-bearing cell model. Experiments were carried out in 96-well cell culture-treated plates in the presence of rFVIIa (6nM) with (100nM) or without FVII, and clotting was activated by fibroblast cells grown on the bottom of each well. Means and SD are shown for n = 5 experiments. Data from individual experiments are presented in supplemental Figure 7. (A) Dependence of thrombin peak height on the presence of FVII activated at different cell numbers. Individual cell counts per well ranged from minimal (approximately 1-5 cells/well), low (approximately 100-500 cells/well), medium (approximately 1000-5000 cells/well), to high (approximately 10 000-50 000 cells/well). *Statistically significant difference between presence of FVII (0 or 100nM; P < .05 by paired t test). (B) Dependence of clot time on the presence of FVII in the same experiments shown in panel A.