A major source of Von Willebrand factor (vWF) –
Circulating factor VIII has two components.

a)   Factor VIIIc (Procoagulant protein)

This is the smaller component
It is synthesized in the liver (main source) and kidney.
It is an intrinsic pathway component required for activation of factor X.

b)   Von Willebrand factor (vWF)

This is the larger component.
It is produced by endothelial cells (main source) and megakaryocytes.
It has two major functions -


Helps in platelets adhesion by interacting platelet membrane glycoprotein Ib-IX.
Stabilizes factor VIIIc.
Erythrocytes
Neutrophils
Endothelial cells
Monocytes