Culturing of human vascular endothelial cells strongly affects their endothelin-1 and prostacyclin production

Cultured human umbilical vein endothelial cells (HUVECs) are a widely used model to study the regulation of endothelial production of vasoactive substances such as endothelin-1 (ET-1) and prostacyclin (PGI2) in human. As even short term culturing is known to affect the function of many cell types, we studied whether there are differences in the production of ET-1 and PGI2 between freshly isolated HUVECs and HUVECs cultured for two passages, and whether variation in cell density affects the production of ET-1 and PGI2 by these cells. At confluency, freshly isolated HUVECs produced only from one-tenth to one-fifth of ET-1, but 46-86 times more PGI2 (p < 0.001), when compared to respective productions by similar amounts of cultured HUVECs. When the cell density of freshly isolated HUVECs was lowered either by diluting the cell suspension or by plating the same amount of cells on different size wells, the production of ET-1 increased: lowering cell density to one-tenth led to 18 fold increase in ET-1 production (p < 0.001). PGI2 production was not affected by cell density. Thus our data imply that the production of both ET-1 and PGI2 are differently regulated in freshly isolated and cultured HUVECs, and that cell density is an important determinant in the regulation of ET-1 production.