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Updated: Jan 19, 2026
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Measurement of Factor V Activity in Human Plasma Using a Microplate Coagulation Assay
Published on: September 9, 2012
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Enhanced potency of recombinant factor VIIa with increased affinity to activated platelets
Mari Enoksson1, Erika J Martin2, Heidi Holmberg1
1Novo Nordisk A/S, Måløv, Denmark.
Journal of Thrombosis and Haemostasis : JTH
|September 25, 2019
Summary
This study developed platelet-targeted recombinant factor VIIa (PT-rFVIIa) by linking it to a TLT-1 binding Fab. PT-rFVIIa demonstrated a 50-fold increase in potency for enhancing thrombin generation in vitro and in vivo, offering a promising hemostatic agent.
Area of Science:
- Hemostasis and Thrombosis
- Biotechnology
- Pharmacology
Background:
- Recombinant factor VIIa (rFVIIa) enhances thrombin generation but has low affinity for activated platelets.
- Triggering receptor expressed on myeloid cells (TREM)-like transcript (TLT)-1 is found exclusively on activated platelets.
Purpose of the Study:
- To enhance rFVIIa potency by conjugating it to a TLT-1 binding Fab, creating platelet-targeted rFVIIa (PT-rFVIIa).
Main Methods:
- Conjugated rFVIIa to a TLT-1 binding Fab.
- Assessed in vitro potency using factor X activation and whole blood viscoelastic changes.
- Evaluated in vivo potency in a murine bleeding model (F8-/- mice expressing human TLT-1).
Main Results:
- PT-rFVIIa showed similar tissue factor binding affinity but increased catalytic efficiency on TLT-1-loaded vesicles and activated platelets.
- In vitro, PT-rFVIIa was 49-fold more potent in clot time in hemophilia A blood with maximally activated platelets.
- In vivo, PT-rFVIIa exhibited a 53-fold lower effective concentration for blood loss in mice.
Conclusions:
- Increasing rFVIIa affinity to activated platelets via TLT-1 binding resulted in approximately 50-fold increased potency.
- The correlation between in vivo and in vitro data using maximally activated platelets validates these conditions for evaluating platelet-targeted hemostatic agents.
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