In vitro spontaneous thrombin generation in human factor-IX concentrates

Area of Science:

• Biochemistry
• Hematology
• Thrombosis Research

Background:

• Factor IX concentrates are crucial for treating hemophilia B.
• Assessing the in vivo thrombogenicity of these concentrates in vitro is essential for patient safety.
• Previous quality control methods may not fully capture the prothrombotic potential of these products.

Purpose of the Study:

• To investigate the in vitro thrombogenicity of human factor IX-containing concentrates.
• To identify reliable in vitro assays for predicting the in vivo thrombotic risk of factor IX concentrates.
• To characterize the thrombin generation properties of different factor IX concentrate preparations.

Main Methods:

• In vitro studies using various factor IX concentrates from different sources.
• Measurement of fibrinogen clotting time and plasma recalcification time.
• Development and application of a thrombin generation test (TGt50) to assess the rate of thrombin generation.
• Correlation analysis between TGt50, plasma recalcification time, and levels of antithrombin III and factor VIII antigen.

Main Results:

• Some factor IX concentrates exhibited shortened fibrinogen clotting times or plasma recalcification times.
• All diluted factor IX concentrates generated thrombin upon recalcification, with varying rates.
• The TGt50 assay demonstrated a strong correlation with the recalcification time of celite exhausted plasma (P < 0.001).
• No correlation was found between TGt50 and antithrombin III or factor VIII antigen levels.

Conclusions:

• The thrombin generation test (TGt50) appears to be a characteristic property of individual factor IX concentrate preparations.
• TGt50 and recalcification time of celite exhausted plasma show promise as in vitro quality control assays.
• These assays may help ensure the safety and efficacy of factor IX concentrates by assessing their thrombotic potential.