Characterization of canine coagulation factor VII and its complex formation with tissue factor: canine-human cross-species compatibility.
BACKGROUND
Canine models have been good predictors of efficacy of hemophilia treatments, including recombinant human coagulation factor (F)VIIa (hFVIIa). However, canine FVIIa and tissue factor (TF) have remained incompletely characterized.


OBJECTIVE
To explore canine-human cross-species FVIIa-TF compatibility in order to strengthen the predictive value of canine models in research on FVIIa and TF.


METHODS
Canine FVIIa (cFVIIa) and canine TF((1-217)) [cTF((1-217))] were produced by recombinant techniques, and canine-human cross-species FVIIa-TF interactions were characterized in vitro.


RESULTS
Recombinant cFVIIa and soluble cTF((1-217)) were produced and purified to homogeneity. hFVIIa and cFVIIa bound with comparably high affinities to cTF((1-217)) (K(D)=6.0±0.7 nm and K(D)=6.0±0.3 nm, respectively) and to cell surface-expressed cTF (K(D)=8.4±0.4 nm and K(D)=7.2±1.2 nm, for (125) I-labeled hFVIIa and cFVII, respectively). In contrast, cFVIIa bound to human TF (hTF) with decreased affinity, both in solution and on cell surfaces. The decreased binding resulted in reduced activity of cFVIIa in functional assays with hTF((1-209)) . In direct comparison, cFVIIa was more active than hFVIIa, both in the absence and the presence of cognate TF.


CONCLUSIONS
The present finding that hFVIIa binds to cTF essentially as it does to hTF substantiates the hypothesis that human FVIIa-TF biology can be reliably recapitulated in canine models on administration of hFVIIa to dogs.
Knudsen
T
T
Department of Small Animal Clinical Sciences, University of Copenhagen, Copenhagen, Denmark. tmkn@novonordisk.com
Kristensen
A T
AT
Sørensen
B B
BB
Olsen
O H
OH
Stennicke
H R
HR
Petersen
L C
LC
D000818:Animals; D001777:Blood Coagulation; D002462:Cell Membrane / Q000378:metabolism; D003001:Cloning, Molecular; D004195:Disease Models, Animal; D004285:Dogs; D005167:Factor VII / Q000378:metabolism*; D015942:Factor VIIa / Q000737:chemistry; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D011485:Protein Binding; D011994:Recombinant Proteins / Q000737:chemistry; D013045:Species Specificity; D013925:Thromboplastin / Q000378:metabolism*
D011994:Recombinant Proteins; D005167:Factor VII; D013925:Thromboplastin; D015942:Factor VIIa