ADAMTS13 and endothelial dysfunction: VWF levels are thought to be a vital indicator for endothelial dysfunction, after release of VWF from storage, some endothelial derived VWF multimers remain anchored to the surface of endothelial cells, forming string-like structures, which, under normal flow, elongate the VWF multimers from a globular to a string-like form, thereby exposing the cleavage site in the A2 domain to the metalloproteinase ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13).