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- Malm, Karl, et al.
(författare)
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Antithrombotic and anticoagulant effects of wild type and Gla-domain mutated human activated protein C in rats.
- 2007
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Ingår i: Thrombosis Research. - : Elsevier BV. - 1879-2472 .- 0049-3848. ; 120:4, s. 531-539
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Tidskriftsartikel (refereegranskat)abstract
- The antithrombotic and anticoagulant effects of recombinant wild type (WT) and mutated human activated protein C (hAPC) were investigated using a rat model of arterial thrombosis. Recent in vitro studies using human plasma have shown enhanced anticoagulant effects of hAPC by mutagenesis of either loop 148 in the serine protease domain or of the Gla domain. The Gla-domain mutant QGNSEDY-hAPC (=H10Q/S11G/S12N/D23S/Q32E/N33D/H44Y) was found to be particularly active as an anticoagulant. We now combined the two mutations to create the variant QGNSEDY-hAPC:B148 and investigated the in vivo effects of this variant as well as of QGNSEDY-hAPC and WT hAPC using a rat model of arterial thrombosis. In vitro clotting experiments using rat plasma demonstrated WT hAPC to be inefficient, whereas both mutant hAPC variants yielded distinct dose dependent anticoagulant effects. In the arterial injury model, a segment of the left common carotid artery was opened longitudinally. An endarterectomy was performed and the arteriotomy was closed, whereafter the vessel was reperfused and the patency rate determined after 31 min. Three treatment groups each containing 10 rats and a control group of 20 animals were in a blind random fashion given intravenous bolus injections of 0.8 mg/kg WTor mutant hAPC or vehicle only. The ex vivo clotting times of plasma drawn 3 min after the injections, as compared to baseline clotting times, were approximately doubled by QGNSEDY-hAPC and tripled by QGNSEDY-hAPC:B148 infusions, while WT APC had little effect. Compared to the control group, none of the hAPC preparations had significant antithrombotic effect or increased arteriotomy bleeding.
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| 2. |
- Malm, Karl, et al.
(författare)
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Human activated protein C variants in a rat model of arterial thrombosis
- 2008
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Ingår i: Thrombosis Journal. - : Springer Science and Business Media LLC. - 1477-9560. ; 6
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Tidskriftsartikel (refereegranskat)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.
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