Heparin modulates function of vascular endothelium. We studied the effects of unfractionated heparin (UFH) vs. enoxaparin vs. sulodexide on the levels and gene expression of osteoprotegerin (OPG), Receptor Activator of Nuclear Factor kB Ligand (RANKL) and von Willebrand factor (vWF) in Human Umbilical Vein Endothelial Cells (HUVEC) culture. HUVEC were isolated from human umbilical vein by a standard method. The supernatant concentrations (ELISA) and gene expression (Real Time-PCR) of OPG, RANKL and vWF in HUVEC were determined after incubation with various concentrations of UFH, enoxaparin and sulodexide for up to 16 hours. In control HUVEC strong positive correlation between OPG and vWF levels was observed, whereas sRANKL negatively correlated with OPG and vWF levels. Only in control HUVEC a negative correlation between the supernatant level of vWF and its gene expression was found. Already the lowest concentration of UFH caused 2.5-fold increase in OPG gene expression while higher UFH concentrations substantially increased RANKL mRNA level. A negative correlation between the OPG and sRANKL concentration was noticed in supernatant HUVEC which were incubated with enoxaparine. In conclusion, the observed interrelationships between OPG, RANKL and vWF levels in unstimulated HUVEC support the presumption of the pathophysiological links between these proteins. Of the tested heparin formulas UFH seems to be the most potent in altering the OPG, RANKL and vWF axis.

Objectives: This study aims to asses the effects of estradiol vs. raloxifene on the levels of osteoprotegerin and soluble Receptor Activator of Nuclear Factor kB Ligand (sRANKL) in Human Umbilical Vein Endothelial Cells (HUVEC) culture in standard and calcifying medium. Material and methods:Human Umbilical Vein Endothelial Cells were isolated from human umbilical vein by standard method. The supernatant concentrations of osteoprotegerin (OPG) and sRANKL (ELISA) were determined after incubation with glicerophosphate, estradiol , raloxifene, glicerophoshate and estradiol, glicerophosphate and raloxifene in comparison with control group at four designated time points (0, 1, 2 and 4 days of incubation).Results: Incubation of estradiol with HUVEC colony lowered the OPG level significantly after day 2 and 4. Meantime, the level of sRANKL was stable. Raloxifene added to standard growth medium also significantly lowered OPG concentration after day 4 only, with no impact on sRANKL concentration. When added to calcifying medium, both estradiol and raloxifene significantly changed OPG level during the experiment. In all treated groups OPG levels were lower than in groups exposed to calcifying medium only. Neither estradiol, nor raloxifene changed sRANKL levels during the experiment. Conclusions:Estradiol and raloxifene affect OPG secretion from endothelial cells in vitro which may suggest their modifying role in pathogenesis of vascular calcification in postmenopausal women.