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Activation of blood coagulation at heparin-coated surfaces

Activation of blood coagulation at heparin-coated surfaces

Authors :
Benedicte Fouache
George M. Willems
Theo Lindhout
Ron Blezer
Source :
Journal of Biomedical Materials Research. 37:108-113
Publication Year :
1997
Publisher :
Wiley, 1997.

Abstract

It is hypothesized that immobilized heparin exerts a dual role in blood coagulation. On the one hand, the heparinized surface is because of its dense negative charge, thought to initiate the intrinsic pathway of blood coagulation. On the other hand, heparin is known as a potent anticoagulant drug. However, it remains to be seen how much contact-phase activation of factor XI contributes to thrombin formation and how this process is counterbalanced by which of the anti-protease activities of immobilized heparin. In the present study we examined the generation of factors XIa, IXa, and Xa, and thrombin in recalcified normal and antithrombin-depleted plasma exposed to polyacrylamide-graft polyurethane (PU) sheets modified by multipoint attachment of two different heparin species. One of them, HAH, contained the specific antithrombin binding sequence and the other one, NAH, had a low affinity for antithrombin and had no anticoagulant activity. Our data demonstrate that in contrast to PU, PU-NAH and PU-HAH are strong mediators of factor XIa and factor IXa formation in normal and antithrombin-deficient plasma. Interestingly, compared to PU-HAH and PU-NAH, thrombin formation was only slightly diminished in antithrombin-deficient plasma exposed to PU. In contrast, thrombin formation was dramatically delayed and diminished in normal plasma exposed to PU-HAH. These findings indicate that very low amounts of factor XIa apparently suffice to induce significant amounts of thrombin. In this sense, heparinized surfaces are highly thrombogenic, but our data also indicate that this activity is effectively counterbalanced by the anti-thrombin activity of the immobilized anti-coagulant species of heparin.

Details

ISSN :
10974636 and 00219304
Volume :
37
Database :
OpenAIRE
Journal :
Journal of Biomedical Materials Research
Accession number :
edsair.doi.dedup.....f3f0d65a22d8118a943e59f114ca6ca6
Full Text :
https://doi.org/10.1002/(sici)1097-4636(199710)37:1<108::aid-jbm13>3.0.co;2-c