Alteration in production of vasomediators associated with in vitro aging in cultured human umbilical vein endothelial cells

Abstract

Differences in the secretion of some vascular regulators, endothelin-1 (ET-1), prostacylin (PGI2), thromboxane A2 (TXA2) and nitric oxide (NO) associated with in vitro aging, were investigated in cultured endothelial cells isolated from normal human umbilical veins (HUVECs). HUVECs from different population doubling levels (PDLs) were cultured in a medium MCDB-104 supplemented with FBS and ECGF. Cell saturation density of HUVECs decreased by 5-fold between PDL 7 and 67. PGI2 secretion per cell increased by 6-fold, and TXA2 secretion per cell increased by 18-fold between PDL 7 and 67. The ratio of PGI2 to TXA2 secretion decreased 3-fold between PDL 7 and 40 and remained at the lower level between PDL 40 and 67. The secretion of ET-1 by HUVECs at a young stage of growth (PDL 7) increased linearly with time between 0 and 36 hours of incubation. ET-1 secretion per cell increased between PDL 7 and 67 by 5-fold after 4-hr incubation and by 3-fold after 9-hr incubation. The release of NO was assayed by a newly established, highly sensitive assay system monitoring guanosine 3':5'-cyclic monophosphate (cGMP) formation in a pig kidney epithelial cell line cocultured with HUVECs. The cGMP formation by NO released from HUVECs decreased 3.3-fold between PDL 8 and 50. These results suggest that the vaso-constrictive activity of endothelial cells increases during in vitro aging which may reflect the increased vascular disorders in the aged people.