sels is a complex process including

sels is a complex process including endothelial cell activation,controlled proteolytic degradation of the extracellular matrix,proliferation and migration of endothelial cells, and formation ofcapillary vessel lumina. It has been postulated that angiogenic growthfactors such as vascular endothelial growth factor (VEGF) and basicfibroblast growth factor (bFGF) can bind to and be stored in heparansulfate proteoglycans present on the surface of endothelial cells and inthe extracellular matrix. Soluble heparins compete with heparansulfate to reverse this effect. Heparins induce increased levels of tissuefactor (TF) pathway inhibitor in plasma and have been demonstratedto hinder TF production in stimulated human monocytes. In vitroexperiments showed that heparins can influence angiogenesis bychanging the structure of fibrin matrices [3]. The formation ofcapillary-like tubulary structures after activation of microvascularendothelial cells is enhanced by UHF forming a more porous fibrinmatrix and hindered by LMWHs forming a more rigid fibrin matrix [5].