In vitro coagulation dynamics of conformational changes in ADAMTS13

Severely injured trauma patients present in 40% of cases with a trauma-induced
coagulopathy (TIC), characterized by platelet dysfunction, coagulation factor
consumption and hyperfibrino(geno)lysis.1,2 Restoring or not worsening this
coagulopathy has been associated with improved outcomes.3,4 However,
mechanistically, primary hemostasis during TIC is still poorly understood.5,6
To produce a viable first clot, one needs activated platelets, von Willebrand
factor and fibrinogen. This clotting is kept in check (e.g. minimizing
hypercoagulability) by enzyms such as plasmin causing fibrino(geno)lysis.
ADAMTS13 (A disintegrin and metalloprotease with a thrombospondin like motif,
member 13) is a cleaving enzyme of von Willebrand factor and its level is
diminished after traumatic injury.7 However, although levels might be
decreased, in preliminary data we have shown that in trauma patients ADAMTS13
converts to an open allosteric conformation which is linearly correlated to
increased ADAMTS13 activity. These trauma patients were also
hyperfibrino(geno)lytic as determined by rotational thromboelastometry. Our
hypotheses are that ADAMTS13 changes its conformation when it is cleaved by
plasmin and amplifies hyperfibrino(geno)lysis. This study on coagulation
effects of conformation changes of ADAMTS13 will be performed in vitro using
anticoagulated whole blood from healthy volunteers. This study will add
mechanistic knowledge of the role of ADAMTS13 in hyperfibrino(geno)lysis which
can be used to treat dysfunctional fibrinolysis.

The main objectives of this study are:
1. To identify the role of conformational changes of ADAMTS13 on
hyperfibrino(geno)lysis in in vitro coagulation tests (primary)
2. To identify the role of plasmin on ADAMTS13 conformation on in vitro
coagulation tests (secondary)
3. To identify the effects of conformational changes in ADAMTS13 in in vitro
coagulation flow models either with or without endothelial cells (secondary)

Type of study: healthy volunteer observational study

We will draw whole blood from 24 male volunteers (age 18-35), in which every
volunteer will be asked to come in for 30 minutes on one day. Volunteers will
be screened beforehand whether they can participate in this study. Screening
will consist of a medical history and current medication use. A qualified and
certified person for performing vena puncture will draw blood . Blood will be
incubated under various conditions.

There is no benefit from participation. The risk is very low, as the amount of
blood taken (30 ml) is well tolerated. Vena puncture can have mild side effects
such as a bruise, but not severe side effects. Volunteers will be asked about
their medical history and medication use. Taken together, the burden can be
considered low. With the results, therapy of future trauma/bleeding patients
can be improved.