Human activated protein C variants in a rat model of arterial thrombosis

Karl Malm¹ , Björn Arnljots¹ and Björn Dahlbäck²

¹Department of Clinical Sciences, Division of Reconstructive Surgery, Lund University, University Hospital, SE-20502 Malmö, Sweden

²Department of Laboratory Medicine, Division of Clinical Chemistry, Lund University, University Hospital, SE-20502 Malmö, Sweden

author email corresponding author email

Thrombosis Journal 2008, 6:16doi:10.1186/1477-9560-6-16


Published:	29 October 2008

Abstract

Background

Activated protein C (APC) inhibits coagulation by degrading activated factor V (FVa) and factor VIII (FVIIIa), protein S (PS) functioning as a cofactor to APC.

Methods

By mutagenesis of the vitamin K-dependent Gla domain of APC, we have recently created an APC variant having enhanced anticoagulant activity due to increased affinity for negatively charged phospholipid membranes. In the present study, the potential antithrombotic effects of this APC variant, and of a variant APC that is additionally mutated in the serine protease domain, have been evaluated in a blind randomized study in a rat model of arterial thrombosis. In this model, we have previously found the combination of bovine APC and PS to be highly antithrombotic. Four treatment groups each containing 10 rats were, in a blind random fashion, given intravenous bolus injections of wild-type or mutant variants of APC (0.8 mg/kg) together with human PS (0.6 mg/kg) or human PS (0.6 mg/kg) alone. A control group with 20 animals where given vehicle only.

Results

A trend to increased patency rates was noted in a group receiving one of the APC variants, but it did not reach statistical significance.

Conclusion

In conclusion, administration of human APC variants having enhanced anticoagulant efficacy together with human PS in a rat model of arterial thrombosis did not give an efficient antithrombotic effect. The lack of effect may be due to species-specific differences between the human protein C system and the rat hemostatic system.