  We propose a combination of microrheological and structural characterizations
of fibrin networks to study blood hypercoagulability. Fibrin is the central
element of coagulation as its polymerization creates the network of fibers in
which platelets and red blood cells are included. This is a controlled process
via cascades between various coagulation factors. An alteration in the
concentrations of coagulation factors and inhibitors will lead to
hypocoagulation or hypercoagulation. These changes in the conditions of
polymerization of fibrin lead to the formation of networks with different
architectures and thus modify its mechanical behavior. We have performed
microrheology by recording Brownian motion of microbeads caught in the network
of clots. The structure was quantified under the same polymerization conditions
with confocal microscopy images. We have tested our approach by adding
fibrinogen to the plasma, which leads to a stiffer, denser network with shorter
fibers. The addition of coagulation Factor VIII at 400% induces the same
correlated trend between a denser network and a higher modulus. This
comparative approach is promising for the study of other conditions altering
clot formation and may lead to a new diagnosis approach for hypercoagulability.
