Biospecific Extraction and Neutralization of Anticoagulant Heparin with Fibroblast Growth Factors (FGF)

Abstract

The polyanionic sulfated carbohydrate heparin is a mixture of anticoagulant and nonanticoagulant activity that is best known for its pharmacological benefit as an anticoagulant. The objective of this study was to design and evaluate a simple purification method for an anticoagulant fraction of heparin from a crude heparin mixture as an alternative to antithrombin. Similar to blood clotting, the fibroblast growth factor signaling system is heparan sulfate‐regulated and comprised of components with structurally distinct heparin‐binding domains. A rare and highly specific motif within a single heparan sulfate chain has been proposed to tether both FGF and the FGFR ectodomain together. The diversity of heparin‐binding motifs within the large FGF family of polypeptides and receptors provides a repertoire of diverse templates for capture of diverse heparin/heparan sulfate motifs in biology. We show here that, similar to antithrombin, a member of the FGF family, FGF7, selectively captures anti‐Factor Xa and anti‐Factor IIa activity from commercially and clinically applied heparin mixtures. In the presence of purified anticoagulant heparin and derivative, FGF7 has the similar activity as protamine sulfate for reversal of anticoagulant effect, while FGF1 is much less potent than FGF7. This may provide a novel cost‐effective, bioaffinity‐based alternative to antithrombin for concurrent enrichment and recovery of anticoagulant and nonanticoagulant heparin from the same heparin mixture. In addition, FGF7 and homologues may be useful in pharmaceutical neutralization of anticoagulant heparin and heparan sulfate. © 2003 Wiley‐Liss, Inc. and the American Pharmacists Association J Pharm Sci 92:2117–2127, 2003