Summary
The interaction between von Willebrand factor (VWF) and platelet glycoprotein Ibα
(GPIbα) is a critical step that allows platelet adhesion, activation and subsequent
thrombus formation to the injured vessel wall under high-shear conditions. In this
study, we sought to investigate 1) whether GPG-290, a recombinant human GPIbα chimeric
protein, would prevent thrombosis in a canine model of coronary thrombosis by blocking
VWFGPIbα interaction; and 2) whether desmopressin (DDAVP), a VWF release stimulant,
could reduce the prolonged bleeding time caused by a 10x efficacious dose of GPG-290.
The antithrombotic efficacy of GPG-290 was evaluated by the in-vivo ability to prevent
cyclic flow reductions (CFRs) and ex-vivo inhibition of platelet adhesion/aggregation
reflected by prolongation of Platelet Function Analyzer (PFA-100®) collagen /ADP closure time. The anti-hemostatic effect was assessed by template
bleeding time. GPG-290 at doses of 25, 50 and 100 μg/kg abolished CFRs in 67%,100%
and 100% of the treated dogs without bleeding time prolongation, respectively; GPG-290
dose-dependently prolonged the ex-vivo collagen/ADP-closure time, while it had no
effects on plasma VWF antigen level (VWF:Ag) and VWF-collagen binding activity (VWF:CB);
the prolonged template bleeding time caused by 500 μg/kg of GPG-290 was prevented
by intravenous infusion of DDAVP (0.3 μg/kg). In conclusion, GPG-290 appears to be
an effective agent for treating arterial thrombosis without bleeding time prolongation.
Keywords
Glycoprotein (GP) Ibα - DDAVP - vonWillebrand factor - thrombosis - platelet adhesion/activation