Summary
We studied the role of fibrinogen in platelet thrombus formation under flow on adhesive
proteins using afibrinogenemic blood (LMWH anticoagulated) in a perfusion system.
Perfusions with afibrinogenemic blood showed strong increased surface coverage and
thrombus volume that normalized upon addition of fibrinogen. Similar studies using
citrate anticoagulated blood showed that this was due to fibrinogen and not fibrin.
Morphological analysis showed that afibrinogenemic thrombi were loosely packed and
consisted mainly of dendritic platelets that contacted one another through filopodia.
However, in the presence of fibrinogen, platelets formed lamellipodia and spread out
on top of one another. Studies with radiolabeled platelets showed similar numbers
of platelets in both conditions demonstrating that the difference is one of packing
and the larger size is due to absence of lamellipodia formation and spreading. The
found increased thrombus size and loosely packed platelets might help to understand
thrombotic complications sometimes seen in afibrinogenemia patients.
Keywords
Afibrinogenemia - thrombus - flow - fibrinogen - platelet