In vivo expression of VWF fragments elevates basal FVIII levels in Vwf−/− mice. Circulating VWF levels (A) and FVIII levels (B) were measured from 6 to 8 hydrodynamically injected Vwf−/− mice at the indicated time points (mean ± standard deviation [SD]). (A) VWF concentrations measured in the PPP were converted to molarity of subunits based on the molecular mass of each VWF fragment calculated from the amino acid sequence (wtVWF = 228 kDa, ∆Pro = 228 kDa, D1D3-GS-CK = 71 kDa, D1-D3 = 56 kDa, D′D3 = 56 kDa, truncD′D3 = 33 kDa). The black line corresponds to the VWF level in pooled PPP from 10 C57BL/6J mice (3.4 μg/mL). Preinjection VWF levels were undetectable by ELISA. Plasma levels were not measured for SS. The width of the error bars likely stemmed from the highly variable response to the hydrodynamic injection and subsequent recovery from this injury. (B) FVIII levels are expressed as %C57BL/6J, where 100% is defined as the amount of FVIII in PPP pooled from 10 C57BL/6J mice. d, day; wk, week.