PEGylation preserves FVIII activity in treating acute bleeding by tail clip in HemA mice. (A) Blood loss in HemA mice after tail clip at 5 minutes after treatment with 12, 40, 100, or 200 IU/kg full-length rFVIII, 60-kDa PEG-K1804C, or 60-kDa PEG-F129C (20 mice/dose/treatment). Bar represents the median blood loss. Dotted line represents the normal level of blood loss (155 μL; mean + 3 SDs) found in C57Bl/6 mice. (B) Plots of dose response in percentage of protection for data shown in panel A. Mice with blood loss of 155 μL or less are considered protected. The ED₅₀ for rFVIII (●), 60-kDa PEG-K1804C (▴), and 60-kDa PEG-F129C (■) is calculated from the respective dose response curve and labeled on the graph.