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Updated: Jun 23, 2026
Investigating von Willebrand Factor Pathophysiology Using a Flow Chamber Model of von Willebrand Factor-platelet String Formation
Published on: August 14, 2017
Species-dependent variability of ADAMTS13-mediated proteolysis of human recombinant von Willebrand factor
K Varadi1, H Rottensteiner, S Vejda
1Baxter Innovations GmbH, Industriestrasse 67, Vienna, Austria.
Background:
von Willebrand factor (VWF) is composed of a series of multimers, the sizes of which are regulated by the plasma metalloprotease ADAMTS13.
Objective:
Proteolysis of human recombinant VWF (rVWF) by ADAMTS13 present in the plasma of different species typically used as preclinical animal models was investigated to evaluate the efficacy and safety of rVWF.
Methods:
Degradation of rVWF was studied in vitro under moderate denaturing conditions and was monitored by multimer analysis, residual collagen binding, and immunoblot analysis. In vivo cleavage was determined by administration of rVWF to cynomolgus monkeys, rabbits and VWF-deficient mice and subsequent analysis of plasma samples by immunoblot. Plasma ADAMTS13 levels were determined with a synthetic human VWF peptide (FRETS-VWF73).
Results:
From the animals tested, only rabbit plasma was as efficient as human plasma in proteolysing rVWF in vitro. Mouse plasma virtually failed to cleave rVWF. Administration of human rVWF resulted in ADAMTS13-specific cleavage products in rabbits and, to a lesser extent, in cynomolgus monkeys at various doses of rVWF. Virtually no cleavage occurred in mice. ADAMTS13 activity levels in rabbit and monkey plasma were similar to those in human plasma and were not significantly altered upon infusion of rVWF up to very high doses, indicating that rVWF did not lead to an exhaustion of endogenous ADAMTS13 in both species.
Conclusions:
The differences in susceptibility to cleavage of rVWF by different species need to be considered when interpreting the physiology of human rVWF from results of tests in animal models.
Insights
Rabbit plasma effectively cleaves recombinant von Willebrand factor (rVWF), unlike mouse plasma. These species-specific differences in ADAMTS13 activity are crucial for interpreting preclinical rVWF efficacy and safety studies.
Area of Science:
- Biochemistry
- Hematology
- Pharmacology
Background:
- von Willebrand factor (VWF) exists as multimers regulated by ADAMTS13.
- Understanding VWF multimer regulation is key in hemostasis and thrombosis research.
Purpose of the Study:
- To investigate the proteolysis of human recombinant VWF (rVWF) by ADAMTS13 in preclinical animal models.
- To evaluate the efficacy and safety of rVWF based on species-specific ADAMTS13 activity.
Main Methods:
- In vitro degradation studies of rVWF under denaturing conditions using multimer analysis, collagen binding, and immunoblotting.
- In vivo cleavage assessment by administering rVWF to cynomolgus monkeys, rabbits, and VWF-deficient mice.
- Quantification of plasma ADAMTS13 levels using a synthetic VWF peptide (FRETS-VWF73).
Main Results:
- Rabbit plasma demonstrated efficient in vitro proteolysis of rVWF, comparable to human plasma.
- In vivo administration of rVWF led to ADAMTS13-specific cleavage products in rabbits and cynomolgus monkeys, but not in mice.
- Plasma ADAMTS13 levels remained stable in rabbits and monkeys after rVWF infusion, indicating no exhaustion of endogenous enzyme.
Conclusions:
- Significant species-dependent differences exist in the susceptibility of rVWF to ADAMTS13-mediated cleavage.
- These variations must be considered when extrapolating preclinical findings of rVWF efficacy and safety to human physiology.
