VWF activity assays and multimer analysis
Binding of the recombinant VWF (rWF) to platelet GPIb (VWF:GPIb) was
assessed using a particle enhanced assay (Siemens Healthcare, Marburg,
Germany) on a BCS XP coagulation analyzer. Furthermore, binding of the
rVWF to collagen type I (VWF:CB) was determined by the ELISA method
(Technoclone, Vienna, Austria) according to the manufacturer’s
instructions. The VWF activities were expressed as ratios to secreted
VWF. rVWF multimers of concentrated secreted rVWF were analyzed by 1.6%
SDS-agarose gel electrophoresis as described before .