Measurement of FVIII activity levels of the three ratios of the HC and LC combination in transfected 293 T cells. The expression plasmids driven by the CB promoter were co-transfected into 293 T cells with combinations of hHC + hLC and rHC + rLC by dual-chain strategy. The ratios of HC:LC were 1:1, 2:1, and 4:1. Then, FVIII activity was detected 48 h post-transfection by the aPTT assay. NHP was used as the standard (n = 3, *p < 0.05, **p < 0.01, ***p < 0.001).