Summary
Additional therapeutic options are needed for patients with bleeding disorders such
as hemophilia A, hemophilia B, severe von Willebrand disease, and other rare factor
deficiencies. A novel approach to improve coagulation in such clotting disorders has
been identified that, parodoxically, involves heparinlike sulfated polysaccharides.Select
molecules of this broad class are largely devoid of anticoagulant activity and are
here denoted Non-Anticoagulant Sulfated Polysaccharides (NASPs).A mechanism involving
blockade of the extrinsic pathway downregulator,Tissue Factor Pathway Inhibitor (TFPI)
by NASPs, was conceived as an approach for improving procoagulant behavior in hemophilic
settings.A subset of NASPs, including pentosan polysulfate (PPS) and fucoidan inhibited
both full-length and Kunitz 1 and 2 (K1K2) TFPI and, at concentrations from 4-500
nM, improved (i.e. accelerated) the clotting time of human hemophilia A and hemophilia
B plasmas or plasma with reduced factor VII levels when tested in dilute prothrombin
time (dPT) assays. Fucoidan did not reduce normal plasma APTT times implying specificity
for extrinsic pathway control. Improved hemostasis in vivo was observed in mice with hemophilias A orB following low dose subcutaneous administration
of PPS or fucoidan, or a combination of NASP plus factor supplement. Increased survival
of factor deficient mice following a bleeding challenge was observed. Accordingly,
administration of select NASP(s), via mechanism(s) not fully understood, represents
a unique means of improving coagulation in bleeding disorders.
Keywords
Hemophilia - sulfated polysaccharides - fucoidan - TFPI - coagulation