Blocking the initiation of coagulation by RNA aptamers to factor VIIa

Area of Science:

• Biochemistry
• Molecular Biology
• Hematology

Background:

• The tissue factor/factor VIIa complex initiates most physiological blood coagulation.
• Targeting factor VIIa offers a strategy for developing new anticoagulants.

Purpose of the Study:

• To generate novel inhibitors of tissue factor/factor VIIa activity by targeting factor VIIa.
• To isolate a high-affinity, nuclease-resistant RNA ligand that specifically binds to coagulation factor VII/VIIa.

Main Methods:

• Utilized a combinatorial RNA library and in vitro selection methods.
• Investigated the mechanism of action through kinetic analyses.
• Assessed the RNA's effect on prothrombin time and in vitro half-life in human plasma.

Main Results:

• Isolated a specific RNA ligand that binds to coagulation factor VII/VIIa.
• Demonstrated that the RNA inhibits tissue factor-dependent activation of factor X by factor VIIa.
• Observed significant, dose-dependent prolongation of prothrombin time in human plasma with an in vitro half-life of approximately 15 hours.

Conclusions:

• The identified RNA ligand antagonizes factor VIIa activity by preventing the formation of a functional factor VII/tissue factor complex.
• This RNA ligand represents a novel class of anticoagulant agents targeting factor VIIa.
• The findings suggest potential therapeutic applications for this RNA in managing coagulation disorders.